Transcriber Note: Text emphasis denoted as _Italics_.


[Illustration: Frontispiece]




                                   A
                               MONOGRAPH
                                OF THE
                     TRILOBITES OF NORTH AMERICA:
                                 WITH
                    Coloured Models of the Species.

           Multa renacentur quæ jam cecidere.--Hor.

                                  BY

                          JACOB GREEN, M. D.
         Professor of Chemistry in Jefferson Medical College.


                             ·—▸⏵►●◓●◄⏴◂—·


                             PHILADELPHIA:

           Published by Joseph Brano, No. 12, Castle Street.

                       Clark & Raser, Printers.

                                 1832.


Entered according to the Act of Congress, in the year 1832, by Joseph
Brano, in the Clerk's Office of the District Court of the Eastern
District of Pennsylvania.




To JOHN GEORGE CHILDREN, Esquire, F. R. S. L. & E.

The kindness which a traveller receives when in a distant land, must
ever be among his most pleasing recollections your attentions therefore
to me, during any short residence in London a few years since, cannot
easily be forgotten. Suffer me, then, to inscribe this little work to
you as a token of my gratitude.

Our pursuits in the Natural and Physical Sciences have been congenial.
Your interesting researches with your original and magnificent Galvanic
Battery, first drew my attention to the calorific effects of that
mysterious agent; and your works on Natural History have stimulated my
exertions in the same fascinating pursuit.

A large portion of your time and fortune have been devoted to the
patronage or the cultivation of Natural Science so that the dedication
of this work to you, if it were infinitely more worthy of your
acceptance, would be due from me, both as a tribute of high respect, as
well as of grateful acknowledgment.

_Philadelphia, October 1st, 1832._


EXPLANATION OF THE PLATE.


  Figure 1. Trimerus Delphinocephalus.
         2. Calymene Diops.
         3. Asaphus Micrurus.
         4. Cryptolithus Tessellatus.
         5. Paradoxides Boltoni.
         6. Triarthrus Beckii.
         7. Isotelus Cyclops.
         8. Dipleura Dekayi.
         9. Head of D. Dekayi.
        10. Ceraurus Pleurexanthemus.

The above figures represented on the Frontispiece to this volume, were
first published in the Monthly Journal of Geology, &c. for June, 1832,
and I am indebted to C. A. Poulson, Esq., for the use of them in this
Monograph.




                             INTRODUCTION.
                                 —————


Some geologists imagine that the order of creation is registered in
the rocks which compose the external crust of the earth, and that they
can there clearly read a progressive development of organic life; in
other words, that a succession of more perfect animals may be traced in
ascending from the lower strata to the upper or more recent formations;
that there is a gradual approach to the present system of things, and
a succession of destructions and creations; worlds of living beings
alternating with worlds of desolation and death, antecedent to the
existence of man.

Others, again, contend that there is often a wide and palpable
discrepancy between the nature of the rock, and the fossils which it
contains, and, therefore, that such inquiries afford no clue, whatever,
to the order of creation.[1] We propose not to enter the field of
controversy. Fossils are undoubtedly historic medallions of remote
periods in the natural history of our earth, and our design is, merely
to illustrate with them a neglected department of ancient zoology, by
describing a few which have recently fallen under our own observation.

[Footnote 1: Nothing can be more opposed to true science, than to
pronounce on the priority of formation, or the comparative age of
rocks, from either their structure, or the organic remains they
present. M. Alexandre Brongniart thus propounds his opinion: "In those
cases where characters derived from the nature of the rocks are opposed
to those which we derive from organic remains, I should give the
preponderance to the latter." This seems to us to imply an admission,
that nothing definite can be inferred from the _nature of the rocks_;
moreover, that between the nature of the rock, and the organic remains,
there may be a palpable discrepancy; and that these may be even at
complete antipodes with each other. The event has proved, from what we
have already mentioned, that no evidence as to priority can be obtained
from the nature of the fossil remains displayed in particular strata.
In addition to what has been said on this subject, we may further
state, that _encrinites_, _entrochites_, and _pentacrinites_ are found
in clay slate, grauwacke, transition limestone, alpine limestone,
lias, muschelkalk, and chalk. It may be reasonably asked how these
three species of fossils could indicate any particular formation, when
they are found in so many types and structures of rocks altogether
different? If they would go to prove any thing at all, it would be that
of a _contemporaneous_ formation; but certainly not distinct epochas.
_See Eclectic Review, July, 1832._]

In some varieties of rocks there is often found the fossil remains of
an animal which bears some resemblance to certain species of the crab.
The back of this organic relic is commonly divided by two deep grooves
or furrows, into three longitudinal lobes, and from this circumstance,
the term _Trilobite_ has been applied as a family name to distinguish
this whole race of beings. This general appellation, however, though in
most of the species, highly appropriate, is by no means applicable to
all.

The individuals which compose the family of the trilobites resemble
each other in many important particulars, and form together an
exceedingly natural group. The body, with but few exceptions, is
divided transversely into three parts. The anterior portion or head
often resembles the buckler of the _horse foot_ or _king crab_
(_limulus polyphemus_), so common on our sea coast. The middle portion
is the _abdomen_, and is always separated transversely into a number
of segments or articulations, generally diminishing in breadth as they
recede from the head. The posterior end is the _tail_, which, though
in some species, a mere prolongation of the abdomen, that can scarcely
be distinguished from it, yet in others it assumes a genuine caudal
appendage.

The head of the trilobite is also generally divided into three parts:
the middle is called the _front_, or forehead; and the lateral portions
the _cheeks_. In most cases, a projecting tubercle, or knob, is
observable on the anterior surface of each cheek, which has much the
appearance of an eye. Its reticulated structure is in many instances so
analogous to that of the eyes of some crustaceous animals, and also of
some species of insects, that there can be but little doubt that these
tubercular projections, were true organs of vision.

Some of the genera which belong to this remarkable race of fossil
animals, possessed the power of rolling or coiling themselves up into a
kind of ball, like certain species of insects, or like the armadillo;
and they are always found embedded in the rocks in this attitude.

Such are the general characters by which these petrifactions may be
known, and they will be found illustrated in a manner more or less
striking, in most of the species. The exceptions, which rarely occur,
will be distinctly marked, when the species are described.

The superior covering, or upper shell of the trilobite is the only part
of the animal, concerning which we have any satisfactory knowledge.
It is conjectured that it was furnished with articulated feet, but no
traces of any organs of progressive motion have hitherto been fairly
discovered.[2] Hence, it may be reasonably supposed, that the structure
of the lower portions of the animal were so soft and delicate, as to
render them incapable of sustaining the process of mineralization,
which the hard crustaceous covering of the back so successfully
undergoes.

[Footnote 2: Mr. Parkinson states, that in a trilobite which he
possessed he thought he perceived the _points_ of the feet; but on
endeavouring to detach the piece of rock in which it was embedded, the
specimen was entirely shivered, though he worked at it with the utmost
care. A portion of the underside of a trilobite (_Isotelus gigas_)
near the anterior edge of the head, was distinctly ascertained, by Dr.
Dekay, but only enough to convince him of its analogy in this part with
that of the limulus polyphemus no organs of locomotion could be seen.
Mr. Stokes, the distinguished fossilist of London, has confirmed the
observation of Dr. Dekay, by some dissections of his own.]

That these petrifactions were once marine animals there can be little
doubt, for they are always found associated in the same rocks with
shells, and other productions peculiar to the sea.

The Trilobite is supposed by many naturalists to be one of the first
animated beings of our earth called into existence by the great Author
of nature.[3] It was first noticed more than two centuries ago, among
the petrifactions which abound in a calcareous rock, at Dudley, in
England, and was from this circumstance, called for a long time, the
_Dudley fossil_. Linné gave it the name of the _Paradoxical insect_;
but whether an insect, a crustaceous animal, or a shell, is still
considered by many as problematical.

[Footnote 3: It is obvious, that if most of the gelatinous animals
which now inhabit our seas, were to become extinct, few or no traces
of them could be found in any succeeding depositions of earthy matter.
Whatever kind of animal life, therefore, may have been the first which
appeared in our planet, must be entirely hypothetical. All that we
can with certainty say of it, is, that it was best adapted to the
circumstances, in which it was to exist, and that it was consistent
with the wisdom and design which we see every where pervading the
universe.]

Notwithstanding the high antiquity of the family of the Trilobites,
and the remarkable characters the different individuals which compose
it, sustain in the animal kingdom; till within a very few years, the
whole race has been almost entirely neglected by naturalists. The
first attempt at any systematic arrangement of the genera and species,
was made in 1815, by Alexander Brongniart, Professor of Mineralogy,
&c. &c., in Paris.[4] Until that period, the term _Entomolithus
Paradoxus_, proposed by Linné, was applied to all the fossil remains,
which in their general appearance bore any resemblance to that found at
Dudley, and which he first described under that name. The confusion,
therefore, which existed in this department of natural science, may
readily be imagined; especially, as the species rapidly multiplied,
when they were supposed to throw some rays of light on certain
obscure geological phenomena. Soon after the appearance of Professor
Brongniart's excellent work, the attention of other naturalists was
directed to this neglected part of creation. The most important memoir,
on account of the number of species, well figured and described in
it, is one by Dr. E. W. Dalmann, published in the Transactions of the
Swedish Academy, for 1826. There is also in the Acts of the Royal
Society, at Upsal, an excellent paper on this subject by Professor
Wahlenberg. Our highly esteemed friend, Dr. James E. Dekay, has also
given in the first volume of the Annals of the Lyceum of Natural
History of New York, some very interesting and ingenious observations
on the nature and the structure of the Trilobites, with a description
of a new genus. These are the principal authorities which have been
consulted in arranging the present work.

[Footnote 4: I cannot let this opportunity pass, without acknowledging
my obligations to Professor Brongniart, for his civilities, when on a
late visit to Paris. Every one whose curiosity leads him to examine the
royal manufactory of porcelain, at Sevres, of which he is the director,
will no doubt acknowledge that his talents as a philosopher, are
rivalled by his accomplishments as a gentleman.]

Our object in the present undertaking being merely to give a monograph
of the species of Trilobites found in the rocks of North America; we
leave to other and abler hands the more difficult and interesting task
of determining with precision the connexion which may exist between
these organic reliques, and the relative ages of the strata in which
they are found.

It is supposed, indeed, that a sufficient number of well characterized
species have not yet been collected and accurately described, to throw
any certain and clear light on otherwise doubtful geological phenomena.
What has been remarked by De Candolle, with regard to botanical
geography, is perhaps true of these fossils as to solving the difficult
problems of geology--"Let us not forget," says he, "that this science
can only be commenced when the study of _species_ has been sufficiently
advanced to furnish us with numerous and well authenticated facts."

We are well aware of the difficulty of settling the line which ought
to divide species. Individuals perfectly identical in all their
parts, are rarely, if ever seen; though a general resemblance may be
easily traced. Among fossils, just discriminations of this kind are
more delicate, than in recent specimens. The hand of time, accidental
causes, and the influence of atmospheric changes often produce such
characters as to render the determination of fossil species an
exceedingly difficult task. We have no doubt, therefore, that a few of
our Trilobites, which are now considered as perfectly identical with
some found in Europe, will upon fuller examination, be discovered to be
dissimilar, and of course certain geological speculations grounded on
the first opinion, be ultimately abandoned.

The geographical distribution of organic remains, is an exceedingly
curious inquiry. If accurately pursued, without reference to any
preconceived theory, it will no doubt furnish much information as to
the comparative ages of the different strata which compose the external
crust of our planet--for that these strata were deposited or formed at
periods of time more or less remote from each other, every one knows,
to be a generally admitted _geological fact_. The occurrence of similar
fossils in districts of country remotely situated from each other,
certainly presents a phenomenon highly interesting to the speculative
naturalist, and apparently indicates that the same powerful and general
causes must have concurred to produce these isomorphous depositions. No
fossils have contributed more to this kind of information, than those
of shells, and as the mineralized species could not be satisfactorily
studied, except by accurately comparing them with those which now
inhabit our seas and continents; the search for shells, has become,
from a simple amusement, the study of scientific men--or, as a writer
remarks, "it was only after the period when it was perceived that
geology and ancient zoology were destined to be enlightened by their
fossil remains, that this research passed from the hands of amateurs
into those of naturalists."[5]

[Footnote 5: We have not unfrequently noticed, both in the writings
and conversation of some geologists, a disposition to sneer at the
subsidiary branches of natural history. Mineralogy and conchology, are
light and mean in their estimation, when compared with the study of
extensive strata and ponderous boulders. Like Irving's testy governor
of Manahatta, who settled the accounts of his clients by placing their
books in the opposite scales of a balance, they decide on the value
of a science, by the absolute weight of the objects embraced by it.
Geology, as well as any other branch of natural history, may degenerate
into a mere love for the curious, or have for its principal aim, the
perfection or improvement of some ideal system of classification,
without advancing a single step further.]

Another curious _geological fact_ appears to be established more
especially by fossil trilobites; it is that precisely the same species
of animal relic, is the most generally diffused over the globe, in
proportion to the antiquity of the rock which contains it. Thus the
transition limestone of England, France, Germany and Sweden, contains
the species called the Calymene of Blumenbach, in common with the same
formation which extends over so large a portion of the United States.

Different genera and species of the trilobite are now found in almost
every part of the globe, and are frequently exceedingly abundant in the
rocks which contain them. That they must have swarmed in particular
places, is abundantly evident from a number of localities in our own
country,--millions, for example, must have lived and died not far
from Trenton falls, in the State of New York. There are very few of
the numerous visiters to that romantic cascade, whose curiosity is
not awaked, by the multitude of these petrified beings, seemingly of
another world, which are there entombed.

Although many parts of the trilobite are now found distributed through
the rocks which contain them, in such a manner as to lead to the
conclusion, that they were separated by decomposition, after the death
of the animal; yet the perfect preservation of others, and the rolled
and disjointed attitudes which we should expect such creatures to
assume when disturbed, lead to the conjecture, that they have been
often suddenly destroyed, and as suddenly enveloped in that earthy
matter, which afterwards became an indurated rock; thus preventing the
separation of the harder parts, by the slow process of decomposition.[6]

[Footnote 6: Vide De la Beche's Geological Manual.]

The fossil remains of the trilobite family, are supposed by most
naturalists to belong to a race of beings now extinct; but from the
strong analogy which exists between them and certain species of
crustaceous animals now living, it is highly probable that they will
yet be found alive. This opinion will not be regarded as visionary,
when it is recollected how large a portion of the surface of the earth
is still unexplored by its enlightened and civilized inhabitants--how
small the number of animated beings are yet known to the scientific
world--and above all the fact, that many animals as confidently
declared to be peculiar to a former world, are now found to be among
the creatures at present in existence. This opinion, we think, is
quite as plausible, and far more interesting, than the blank and
unsatisfactory hypothesis that all the trilobites are confined to an
order of things before the present glorious creation.[7]

[Footnote 7: The incorrectness of the inference that all the genera
and species of fossil animals found in the transition rocks must be
now extinct, will appear from the following extract from Bakewell's
Geology:--"The _Madrepora stylina_, so common in transition lime-stone
rock, is entirely wanting in the secondary and tertiary strata, but a
living animal of this species has been recently discovered in the South
Seas. The Pentacrinus makes its first distinct appearance in the lias;
but is not frequently met with in the upper strata, and disappears
entirely in the uppermost formations: hence it was long supposed
that the species was extinct. A living Pentacrinus has recently been
discovered in the West Indies, and its stem and branches in a perfect
state have been sent to this country." (England.) In the Museum at
Albany, N. Y., I have examined a recent Pentacrinus, which I conclude,
came from the West Indies, from the proprietor's account of the manner
in which he obtained it. It has been a very perfect specimen but the
branches are gradually dropping off.]

There appears to have been known to naturalists, when the improved
edition of Prof. Brongniart's work on the trilobites appeared in 1822,
but 17 well marked species, and out of which he constructed the five
following genera, which he thus characterizes.


_Genus First._ Calymene.

_Body_ capable of contraction into nearly a semicylindrical sphere.

_Buckler_ with many tubercles or folds. Two reticulated eye-shaped
tubercles.

_Abdomen and Post-abdomen_ with entire edges. Abdomen divided by 12 or
14 articulations.

No elongated tail.


_Genus Second._ Asaphus.

_Body_ broad and rather flat. Middle lobe prominent and very distinct.

_Flanks or lateral lobes_ each double the size of the middle lobe.

_Submembranaceous expansions_ extending beyond the lateral lobes.

_Buckler_ semicircular, with two reticulated eye-shaped tubercles.

_Abdomen_ divided into 8 or 12 articulations.


_Genus Third._ Ogygia.

_Body_ much depressed into an oblong ellipsis not contractile into a
sphere.

_Buckler_ edged, a slight longitudinal furrow arising from its anterior
extremity. Posterior angles elongated into points.

_Without any tubercles_ except the eyes, which are neither prominent
nor reticulated.

_Longitudinal lobes_ slightly prominent.

_Abdomen_ with 8 articulations.


_Genus Fourth._ Paradoxides.

_Body_ depressed not contractile.

_Flanks_ much broader than the middle lobe.

_Buckler_ nearly semicircular three transverse furrows on the middle
lobe.

_Eye-shaped tubercles_ none.

_Abdomen_ with 12 articulations.

_Arches_ of the lateral lobes, more or less prolonged beyond the
membrane which sustains them.


_Genus Fifth._ Agnostus.

_Body_ ellipsoidal--semicylindrical.

_Buckler and flanks_ edged--the edges being slightly elevated.

_Middle lobe_ with two transverse divisions, each composed of a single
piece.

_Two glandular_ tubercles on the anterior part of the body.

In 1824, Dr. J. E. Dekay added a sixth genus to the family of the
trilobites, which he describes in the following manner.


_Genus Sixth._ Isotelus.

_Body_ oval oblong, often contracted, not unfrequently extended.

_Head_ or _buckler_ large and rounded, equalling the tail in size, with
but two oculiform tubercles.

_Abdomen_ with 8 articulations.

Frontal process beneath, with two semilunar terminations.

_Post-abdomen_ or _tail_ broad, expanded with indistinct divisions, as
large as the buckler.

_Longitudinal_ lobes very distinct.

This genus, he remarks, will be sufficiently distinguished from the
five genera proposed by _M. Alexandre Brongniart_ in his valuable and
truly philosophical work on the trilobites by the following particulars.

From _Calymene_. By the presence of but two tubercles on the buckler
not reticulated; by the abdomen with but 8 articulations.

From _Asaphus_. By the middle lobe, which is double the size of the
lateral ones; by the absence of a membranaceous expansion on the sides;
by the non-reticulation of the eyes, &c.

From _Ogygia_. By the rolled form, the rounded posterior angles of the
buckler, and the distinct articulation of the longitudinal lobes.

From _Paradoxide_ and _Agnoste_ by characters too obvious to be
enumerated. (See Annals of N. York Lyceum, Sec. Vol. I. pp. 174-5.)

In 1826, J. W. Dalman published in the Transactions of the Swedish
Academy, and also in a separate work, an account of the trilobites
found in the North of Europe, in which he has enriched the family by
a number of fine species, and with the following genera, which he
modestly proposes merely as subdivisions.


_Genus Seventh._ Nileus.

_Body_ short, capable of contraction into a sphere, smooth, convex.

_Abdomen_ with about 8 articulations, without any dorsal longitudinal
furrows.

_Buckler_ sub-lunate, with large lateral eyes.

_Tail_ expanded, not so large as the buckler, without lobes.


_Genus Eighth._ Illænus.

_Body_ ovate oblong, contractile.

_Head_ rounded in front, eyes small, in the temples, very remote.

_Abdomen_ with from 9 to 10 articulations, trilobate.

_Tail_ expanded as large as the head.[8]

[Footnote 8: Some of the species described by Professor Dalman as
included in this genus, we think ought to be referred to that of the
Isotelus.]


_Genus Ninth._ Ampyx.

_Body_ very short, contractile.

_Buckler_ large, triangular, gibbous; eyes not remarkable.

_Abdomen_ short, articulations few (6?), trilobate.

_Tail_ expanded, not so large as the head.

Professor Dalman has two other genera, which he calls Olenus and
Battus, the first is the Paradoxides, and the second the Agnostus of
Brongniart.

In the 8th Volume of Annales des Sciences Naturelles there is a highly
valuable paper "Sur les Trilobites et leurs gisemens," by the Count
Rasoumowsky, in which he describes some new trilobites from Russia;
the one which he has figured and described as a Calymene[9] from
Tzarsko-Selo, undoubtedly belongs to a new genus, very near to the
Isotelus. The middle lobe is visible or naked through its whole extent,
and the lateral lobes near the tail are covered with a thick cuticular
membrane. This genus we propose to call Hemicrupturus, and may be thus
characterized.

[Footnote 9: The editors of the Annales remark that this is not a
Calymene, but that it appears to belong to the genus Asaphus.]


_Genus Tenth._ Hemicrupturus.[10]--_Green._

[Footnote 10: From three Greek words which signify _half-concealed
tail_.]

_Body_ contractile.

_Buckler_ oculiferous and not lobate.

_Abdomen_ trilobate, with 8 articulations.

_Tail_, costal arches covered, middle lobe naked.

The Asaphus expansus of Dalman, and several other known species may be
arranged under this genus.

As Count Rasoumowsky has given no specific appellation to the
fossil above alluded to, we propose to call it after his own name,
_Hemicrupturus Rasoumowskii_. We examined the fine specimen from which
our cast is taken in the cabinet of the Baltimore College, and for this
favour we are indebted to the kindness of Dr. J. J. Cohen, one of the
Professors in that rising institution.

The following list includes _all_ the genera and species of the
Trilobite Family, hitherto described as far as known to the author. It
is taken from De La Beche's Manual of Geology.

        NAMES.             AUTHORS.        LOCALITIES.

  Calymene Blumenbachii,   Al. Brong.     Europe--U. States.
           Macrophthalma,    do.          Europe--U. States.
           Variolaris,       do.          Europe.
           Tristani,         do.          Europe--U. States.
           Bellatula,      Dalman.        Europe.
           Ornata,           do.          Europe.
           Verrucosa,        do.          Europe.

  Calymene Polytoma,       Dalman.        Europe.
           Artinura,         do.          Europe.
           Sclerops,         do.          Europe.
           Schlotheimi,    Brown.         Europe.
           Latiferus,        do.          Europe.

  Asaphus Cornigerus,      Al. Brong.     Europe.
          Caudatus,          do.          Europe--U. States.
          Hausmanni,         do.          Europe--U. States.
          De Buchii,         do.          Europe.
          Brongniartii,    Deslongchamps. Europe.
          Extenuatus,      Wahlenberg.    Europe.
          Granulatus,        do.          Europe.
          Expansus,          do.          Europe.
          Crassicauda,       do.          Europe.
          Angustifrons,      do.          Europe.
          Heros,           Dalman,        Europe.
          Platynotus,        do.          Europe.
          Frontalis,         do.          Europe.
          Læviceps,          do.          Europe.
          Palpebrosus,       do.          Europe.
          Sluzeri,           do.          Europe.

  Ogygia  Guettardii,      Al. Brong.     Europe.
          Desmaresti,        do.          Europe.
          Wahlenbergii,      do.          Europe.
          Sillimani,         do.          Europe--U. States.

  Paradoxides Tessini,       do.          Europe.
          Spinulosus,        do.          Europe.
          Gibbosus,          do.          Europe.
          Scaraboides,       do.          Europe.
          Hoffii,          Goldfuss.      Europe.

  Nileus Armadillo,        Dalman.        Europe.
          Glornerinus,       do.          Europe.

  Illænus Centaurus,       Dalman.        Europe.
          Centrotus,         do.          Europe.
          Laticauda,       Wahlenberg.    Europe--U. States.

  Ampyx    Nasutus,        Dalman.        Europe.
  Olenus   Bucephalus,     Wahlenberg.    Europe.
  Agnostus Pisciformis,    Al. Brong.     Europe.
  Isotelus Gigas,          De Kay.        United States.
           Planus,           do.          United States.


Genera and Species not fully determined.

  Trilobites Cephaleurya,  Rafinesque,    United States.
            Simla,           do.          United States.
            Granulata,       do.          United States.
  Bilobites Lunulata,        do.          United States.
            Lobata,          do.          United States.

From the short descriptions given by Professor Rafinesque of the five
last mentioned fossils, I conclude that they belong to the genus
Calymene of Brongniart.

The study of the trilobites naturally leads to the consideration of
those beings which appear to have inhabited our earth previous to the
creation of man. Every one knows that the sceptical naturalist has
drawn from these vestiges of organic life, an argument contradictory
to the Mosaic account of the history of the world, and though every
cavil of the least importance, urged against the truth of the sacred
historian, has been triumphantly confuted, still, the geological
sciolist boldly impugns his veracity, whenever any new facts in his
science can be distorted to his purpose. Such being the case, we
cannot conclude this preface without briefly stating two or three
methods by which any seeming discrepancies may be explained. First,
those who imagine that the six periods of creation, mentioned in the
beginning of the pentateuch, mean literally days of 24 hours each,
believe that, as only a small part of the earth was at first required
for the abode of man and the higher animals, the present continents
might have remained as long beneath the waters, and have undergone
every change necessary to solve this geological puzzle.

Again, others have thought that Moses, after recording, in the first
sentence of Genesis, the great truth that all things were made by the
will of an intelligent Creator--passed silently over some intermediate
state of the earth, which had no direct relation to the history, or to
the duties of man--and proceeded to describe the successive appearance
of the present order of things. On this supposition, the fossil remains
and peculiarities in the structure of the earth may have belonged to
that intermediate state.

A third method of explaining the difficulty, and which we think highly
satisfactory, is, by understanding the days of creation to mean, not
ordinary days, but _periods of time_, in which the recorded events took
place in the order described so briefly by the sacred historian. It is
acknowledged by every one competent to judge, that among the Hebrews,
_days_ and _weeks_ were often used in this manner. The accordance
between the order in which, according to the account of Moses,
the work of creation was accomplished, and the order in which the
fossil remains of plants and animals are deposited in the earth, has
surprised, and has been acknowledged by learned sceptics themselves.[11]

[Footnote 11: The Baron Cuvier, on this subject, remarks, respecting
the Jewish legislator--"His books show us, that he had very perfect
ideas respecting several of the highest questions of natural
philosophy. His cosmogony, especially, considered purely in a
scientific point of view, is extremely remarkable, inasmuch as the
order which it assigns to the different epochs of creation, is
precisely the same as that which has been deduced from geological
considerations."]

It will be useless to push these arguments further. The catastrophes
which have produced the secondary strata, and the diluvian depositions,
could not have been local or partial phenomena; but rather than call
upon a comet, with the abstracted philosopher, to deluge the earth
for every new geological epoch--or to change the axis of motion of
our planet--or to resort to any of his wild, fanciful, and impious
theories, we should, with Sir Humphrey Davy, even prefer the dream that
all the secondary strata were _created_, filled with the remains, as it
were, of animal life, to confound the speculations of our geological
reasoners.




ACKNOWLEDGMENTS.


Every author who attempts a Monograph of any of the departments of
Natural History, must necessarily depend, in a greater or less degree,
upon the kindness and liberality of others. Rare and unique specimens,
particularly of fossil species, are often scattered through different
cabinets, and his work would be rendered very imperfect, if they were
not intrusted to his care. In preparing the following Monograph on the
plan of giving exact models of the species, instead of illustrating
them by engravings in the usual manner, the specimens when used by
the artist are perhaps more liable to accident, and it was at first
supposed that this circumstance might have prevented the original
design. But in no instance, where an application has been made, either
to a public institution or to a private cabinet, has the author met
with a refusal; indeed the courtesy, kindness, and liberality which
he has experienced from naturalists, who have every where aided him
in the prosecution of his work, form no inconsiderable portion of the
gratification which he has received. Besides the acknowledgments to
public museums, and to individuals, which are made in the body of the
work, the author is desirous of recording in this place, the following
cabinets from which he has derived much assistance.


                           IN PHILADELPHIA.

               The Cabinet of John P. Wetherill.
               The Cabinet of the Academy of Natural Sciences.
               The Philadelphia Museum. (Peale's.)
               The Cabinet of P. A. Browne, Esq.
               The Cabinet of Dr. R. Harlan.
               The Cabinet of William Hyde.
               The Cabinet of J. Pierce.
               The Cabinet of the Geological Society.
                                 ————
               Lambdin's Museum, Pittsburgh, Pa.
               The Cabinet of D. Keim, Reading, Pa.


                             IN NEW YORK.

               The Cabinet of the Lyceum of Natural History.
               The Cabinet of Dr. J. E. Dekay.
               The New York Museum. (Peale's.)


                              IN ALBANY.

               The Cabinet of the Albany Institute.
               The Cabinet of Professor T. R. Beck.
               Albany Museum.
               The Cabinet of Dr. James Eights.
                                 ————
               The Cabinet of the Rensselaer School.


                             IN BALTIMORE.

               The Cabinet of Dr. Joshua J. Cohen.
               The Cabinet of the Baltimore College.
               The Cabinet of the Atheneum.
               The Baltimore Museum.
                                 ————
               The Cabinet of Professor Hall, Mount Hope.




                            TRILOBITES, &c.

                             ·—▸⏵►●◓●◄⏴◂—·



Genus Calymene. _Brongniart_.

The name of this genus is derived from a Greek word which signifies
_obscure_ or _concealed_. The fossil animals included by it are
characterized as having contractile bodies; the buckler as bearing many
tubercles or folds--the cheeks as being oculiferous, and the abdomen
and tail as being composed of from twelve to fourteen articulations
or joints, without any membranaceous expansion. The Calymenes in
thickness are nearly semicylindrical, and the buckler in front presents
a _chaperon_ or upper lip more or Jess raised. In perfect specimens,
there is a small furrow which seems to indicate a separation between
the upper and under parts of this kind of lip. The eyes are always
raised, and frequently present the remarkable structure observable in
many of the _crustacea_; but as this part is generally very prominent,
the _reticulations_ of the eye are commonly worn off or injured.

Professor Brongniart places but little confidence in any of the generic
characters above enumerated, except the number of articulations of the
abdomen: these, however, in our opinion, are more vague and uncertain
than most of the others. The genus, however, we think may be readily
identified, after becoming familiar with one well characterized
species. The general aspect of the buckler is peculiar--the body is
not so depressed as in most other genera, and the lateral lobes are
destitute of all membranaceous expansion.

To the genus Calymene, belongs the celebrated Dudley fossil, called
_Entomolithus paradoxus_ by Blumenbach, but which is not the same
organic relic, to which Linné applied that name.

This genus includes a great number of species, and though some of them
are said to be found in different and distant parts of the globe, they
are according to our limited observation, for the most part confined,
like recent species of animals, to particular districts. The C.
polytoma, C. pulchella, C. bellatula, C. concinna, C. sclerops, and
the C. punctata, all finely figured by Professor Dalman, and which
are found in Sweden, have not yet been noticed in any part of North
America.[12]

[Footnote 12: See the valuable and extensive communication of J. W.
Dalman, M. D., on the Trilobites, in the Transactions of the Swedish
Academy for 1820, part 2d.]


Calymene Blumenbachii. _Brongniart._ Cast No. 1.

  Clypeo rotundato, tuberculis sex distinctis in fronte; oculis in
  genis emintissimis; corpore tuberculato.

In this species the upper lip presents a furrow parallel to its edges.
The lip is straight. The cheeks are a little projecting. There are
six rounded tubercles on the front, and fourteen articulations on the
back; the tail is small, and the shell is covered with small rounded
tubercles of unequal sizes.

The above is Professor Brongniart's description of this trilobite,
which is the famous Dudley fossil described and figured by Littleton,
in the Philosophical Transactions, (London) in 1750. According
to Dalman, several distinct European species have been published
under this name. The true C. Blumenbachii, he says, has thirteen
articulations to the abdomen, and about eight to the tail. In the
cabinet of G. W. Featherstonhaugh, Esq., we have examined a fine
perfect specimen from Dudley,[13] in which there is fourteen abdominal
joints. There can be no doubt, however, that several species have been
confounded under the name of C. Blumenbachii; Dalman's C. Tuberculata
and C. Pulchella are, we think, distinct from it, though he has marked
them only as varieties.

[Footnote 13: This famous trilobite, once formed a part of the cabinet
of Mr. Parkinson, the distinguished author of the "Organic Remains,"
and is accurately figured on one of the plates of that splendid work.
At the sale of the late Mr. Parkinson's fossils, it was purchased by
Mr. Featherstonhaugh,]

The true C. Blumenbachii, no doubt, abounds in North America, and is
one of the few examples of the occurrence of an identical species
on both continents. The late Abbe Correa sent a perfect specimen to
Brongniart, from the vicinity of Lebanon, in the state of Ohio. We
have also seen a number of specimens from that state, which could not
be distinguished from the Dudley trilobite. Our model was taken from a
specimen found at Trenton Falls, in the state of New York.

The three following species found in the United States, will no doubt
be considered by many as mere varieties of the C. Blumenbachii; we have
ventured, however, to call them by distinct names.


Calymene Callicephala.[14] _Green._ Cast No. 2.

[Footnote 14: From two Greek words, which signify "beautiful head."]

  Clypeo antice attenuato, figura liliiformi in fronte depicta;
  oculis minimis; abdomine quatuordecim articulis; corpore plano.

The buckler is subtriangular; on the front there is a figure in high
relief, somewhat resembling a _fleur de lis_; or perhaps more, the
capital of a Corinthian column. The oculiferous tubercles are rather
lower down on the cheeks than usual. The articulations of the abdomen
and the tail cannot well be distinguished from each, other; fourteen
in all may be easily counted. The middle lobe of the abdomen is nearly
equal in breadth throughout. The ribs, or costal arches, are not
grooved or bifurcated at their extremities. Length nearly two inches
and a half.

This beautiful species is in the Philadelphia Museum, where it is
labelled as being found in "Hampshire, Virginia." It is mineralized by
a dark yellowish limestone. It differs from the C. Blumenbachii, in
the form and number of its articulations; in the shape of the head; in
having only two flat tuberculous elevations on the front; and in other
particulars.

In the cabinet of the New York Lyceum, and in that of J. P. Wetherill,
Esq. there are some examples of this species from the Miami river, near
Cincinnati, Ohio. I have also seen it from Indiana, in a dark coloured
limestone, very much distorted. It has never been found at Trenton
falls, or at any other locality, as far as my knowledge extends, which
yields the true C. Blumenbachii.


Calymene Selenecephala.[15] _Green._ Cast No. 3.

[Footnote 15: From the Greek for "lunate head."]

  Clypeo antice rotundato, margine omni valde incrassato; prominentia
  frontali utrinque trituberosa; corpore tuberculato.

The buckler is regularly lunate; the margin is slightly reflected or
raised anteriorly, the posterior edge forms a continuous rim, running
nearly parallel with the articulations of the abdomen. The front on
each side has one large and two small tubercles, near its superior
edge. The oculiferous tubercles on the cheeks are on a line with the
lowest frontal tubercle. There are fourteen distinct articulations;
but as the tail is mutilated and distorted, the total number of
joints cannot, from this specimen, be ascertained. The body appears
to have been covered with small pustules. These are very evident on
the front. Costal arches simple, or not grooved. Length, one inch and
three-fourths, breadth of the buckler one inch and one-fourth.

This species resembles a little the C. Pulchella of Dalman. The
specimen from which the model was taken, is in the possession of Mr.
R. Peale, of New York, who willingly lent it for this monograph. He
informed me that it was found in the state of New York, but he was
unable to name its precise locality. It occurs in a soft ash coloured
limestone. No other petrifaction is observable in the fragment of rock
which contains it.


Calymene Platys.[16] _Green._ Casts No. 4 and 5.

[Footnote 16: From a Greek word which signifies Flat,]

  Clypeo antice rotundato; prominentia frontali utrinque quatuor
  tuberculis.

The buckler is probably semilunate; but as the anterior portion is
lost, this cannot be determined with precision. The posterior raised
rim is not continuous, as in the C. Selenecephala, but is separated by
the longitudinal dorsal furrows. The front is distinctly divided from
the cheeks, and has four tubercular prominences on each side. Three
of them are nearly on a line with the lateral edge of the cheeks, and
gradually diminish in size, as they descend to the anterior part of
the buckler. The other is smaller, and is between, and a little to
the side, of the upper two. The cheeks form spherical triangles. The
oculiferous prominences are close to the second large tubercle on the
front. The cheeks are, however, quite imperfect. The articulations
of the back cannot be distinguished from those of the tail. In our
specimen they are all beautifully distinct, and are twenty-two in
number. The posterior raised rim of the buckler seems to form an
articulation; its extremities on each side are a good deal thickened
and expanded. The costal arches suddenly curve downwards and backwards,
near their middle, so as to divide the abdomen and tail into five
unequal sections. The whole length is nearly three inches. The breadth
of the buckler nearly two inches.

This fine large Calymene was accidentally discovered on the Helderberg
mountain, by my friend, Professor T. R. Beck. One of the loose pieces
of sandstone rolling over, near his feet, presented him the fine
natural mould, from which he has kindly permitted our cast to be taken.
The animal relic once enclosed in this matrix, must still be near that
locality, and yet remains undiscovered, to reward the enterprise of
some more fortunate naturalist.

One of our models represents the natural mould found by Dr. Beck. The
other is a cast taken from it and exhibits, more satisfactorily, the
various parts of the animal.


Calymene Microps.[17] _Green._ Cast No. 6.

[Footnote 17: From the Greek for "small eyes."]

  Clypeo antice subattenuato; occulis minimis in lateribus capitis;
  abdominis articulis a 14 ad 18; corpore depresso.

The buckler is semi-elliptical, slightly punctate, and much depressed
anteriorly; the front and cheeks are not very distinctly marked. The
eyes are very remote from each other, being situated near the posterior
lateral angles of the head. They are not very prominent, and exhibit
no marks of being reticulated. Before the eye on each side, there is
a slight transverse indentation. It is difficult to distinguish the
articulations of the abdomen from those of the tail. They are from
fourteen to eighteen in number. Where the lateral lobes remain perfect,
two narrow raised lines appear between each of the ribs; these are
most evident on the caudal extremities of the animal. The middle lobe
is in the form of a long, slender, and acute cone. The whole animal is
an inch and a quarter long, and is much more depressed than any other
Calymene which we have seen.

I am indebted to Mr. Titian R. Peale for the use of the original from
which our model was taken, his liberality to those who cultivate
Natural History is proverbial, and needs no encomium from me. The C.
Microps is said to have been found near Ripley, Ohio. It occurs in
black limestone.

The eyes of this Calymene are small in comparison with those of some
other species--particularly the C. Bufo, C. Macrophthalma, and C.
Anchiops.


Calymene Anchiops.[18] _Green._ Cast No. 7.

[Footnote 18: From two Greek words which signify "eyes approximate."]

  Clypeo antice, caudaque postice rotundatis; oculis approximis,
  magnis, excertis; articulis vigenti; corpore plano.

The buckler of this species is irregularly hemispherical; the front
pyriform and without pustulations. The cheeks are almost entirely
occupied by the eyes, which are placed very near each other on the
upper part of the forehead; are very large and trilobate, the side
lobes being elongated and attenuated in front. The articulations
of the back are twenty in number, those of the abdomen not being
distinguishable from those of the tail. The costal arches of the side
lobes are round near their extremities, and are intersected with two or
three raised lines. Length nearly four inches. Breadth about two inches.

It gives me great satisfaction in being able to describe, and to
present to naturalists a good cast of this Calymene, which has
excited for a long time so much interest and perplexity. The original
fossil from which our plaster model was made is now deposited in
the cabinet of the Albany Institute, and is the identical specimen
from which a cast was long since made, by Dr. Hosack of New York, a
specimen of which he sent in July, 1819, to the Royal Academy of
Science, in France. Professor Brongniart referred the animal from
which this model was taken, though with much hesitation and doubt,
to the species, Calymene Macrophthalma. He remarks concerning it,
"Il est beaucoup plus gros que les autres individus, et a prés de
dneuf centimètres de longueur. C'est avec doute que je rapporté
cette empreinte tres-peu nette à l'espèce actuelle; mais malgré ses
formés obtuses, et l'absence de tout detail, elle est si remarquable
par la grosseur de ces yeux et par le prolongement de son bouclier
qu'on peut présumer qu'elle appartient an calyméne macrophthalme, et
avec d'autànt plus de probabilité qu'elle vient aussi des Etats Unis
d'Amérique. Elle a été trouvée, suivant M. Hosack, dans un schiste."
We have seen the cast alluded to in the above note, and are not at all
surprised at the uncertainty which it has occasioned. The apparent
prolongation of the buckler is entirely occasioned by the loss of a
small fragment from that portion of the head. The form and position of
the eyes, further distinguish it from any of the numerous specimens
of C. Macrophthalma, that we have examined. The raised lines which we
have noticed as intersecting the costal arches of the lateral lobes
are remarkable, though they may have been produced by accidental
fissures in the epidermal covering of the animal. The head of the C.
Macrophthalma is always marked by minute and prominent granulations,
like _shagreen_--nothing of this kind appears on the buckler of the C.
Anchiops.

I am informed by my friend, Dr. T. R. Beck, to whose liberality I owe
this interesting species, that it was found in Ulster county, New
York. It was supposed by Dr. Hosack, to have been discovered in the
vicinity of Albany. Respecting the locality and geological relations of
this trilobite, Professor Brongniart remarks, "un modéle en plâtre de
trilobite envoyé à l'Académie des Sciences, en Juillet, 1819, par M.
Hosack, et que j'ai rapporté, autant que la chose était possible, et
toujours avec doute, au calyméne macrophthalme, a été trouvé dans le
territoire d'Albany, êtat de New York. Or, les environs de cette ville
sont indiqués, sur la carte géologique de M. Maclure, comme formés de
terrains de transition. M. Hosack dit qu'il a été trouvé au milieu d'un
rocher ardoisé, c'est à dire, dans un schiste probablement analogue à
celui des environs d'Angers, qui renferme les Ogygies, et ce trilobite
ce rapproche un peu de ce genre par la grosseur des tubercules qui
recouvrent les yeux on en tiennent la place." The rock in which the
Calymene Anchiops is found, appears to be a clay slate.


Calymene Diops.[19] _Green._ Cast No. 8, and fig. 2.

[Footnote 19: From the Greek for "Double Eyes."]

  Clypeo lobato plano; rugis tribus in lateribus frontis; tuberculis
  oculiformibus, eminentissimis et duplicibus; articulis octodecim;
  cauda rotunda.

This species is very distinct from every other Calymene that we have
seen. The outline of the buckler is lobate lunate; the front is very
convex, and a good deal elevated above the cheeks or sides, from
which it is divided by a deep furrow; on the posterior margin of the
front on each side, close to the groove there is a prominent circular
tubercle, before which there are three small transverse wrinkles.
The cheeks are subtriangular; the oculiform tubercle is near the
posterior superior angle, and is only separated from the tubercle on
the front, by the furrow or groove, so that the animal seems to have
had double eyes on each side; there are two curved lines on each side
below the eyes, crossed near the front by a deep short canal. The
middle lobe of the abdomen and tail is rather longer than the lateral
lobes, and is rounded and very prominent throughout. It is composed
of 18 articulations, seven of which appear to belong to the tail; it
is, however, somewhat difficult to define the length of the tail with
precision. The costal arches of the lateral lobes, particularly those
near the tail, are bifurcate. Length almost three inches.

The original fossil, from which the cast was taken, is in the New York
Museum. I am indebted to Mr. Rubens Peale, the liberal proprietor of
that flourishing and important institution, not only for the use of
it in this Monograph, but also for some valuable information relating
to other species. The precise locality of Mr. Peale's specimen is
not known, but in the cabinet of J. P. Wetherill, Esq., there is a
fine head of the C. diops which was found in the State of Ohio. Both
specimens are mineralized by the same kind of soft grey coloured
limestone--and I have but little doubt that they were derived from the
same place.


Calymene Macrophthalma.[20] _Brongniart._ Cast No. 9.

[Footnote 20: From the Greek for "Great eyes."]

  Clypeo antice, caudaque postice attenuatis, oculis magnis exsertis.

This species, according to Al. Brongniart, who first described it,
is remarkable for the magnitude and protuberance of its eye-shaped
tubercles, and by the prolongation of the anterior portion of the
buckler, in the form of a snout.

The back is marked by 12 or 13 articulations, which are thicker than
those of the tail. The tail is short, pointed, and without expansion.

The middle lobe, or front of the _buckler_, in this calymene, is said
by Brongniart to be marked on its sides by three oblique plicæ or
wrinkles, but we have not been able to discover this character in any
of the specimens to which we have access; neither do they exhibit any
remarkable prolongation in the anterior portion of the _buckler_, as
stated in his specific character. The specimens which we have examined,
agree pretty well with the representation he has given of the C.
Macrophthalma, Plate I. fig. 5. A. B. & C. made from a drawing by Mr.
Stokes, from a fossil found in Coalbrookdale (Eng.).

This trilobite is common in several parts of the United States.
According to Dr. J. E. Dekay,[21] the C. Macrophthalma is found on
the Helderberg mountains, near Albany, and at Coshung creek, not
far from Seneca lake, in the State of New York. It occurs also at
Leheighton, in Pennsylvania--at the Falls of the Ohio, and at several
other localities. We have examined a number of specimens of the C.
Macrophthalma, contained in the rich cabinet of fossils, in the Academy
of Natural Sciences, and have never seen any individual which resembles
the fig. 4, Plate I. of Brongniart; and in no instance is the front
of the buckler marked by three oblique folds, a character stated as
peculiar to this species. The C. Macrophthalma, (variety) occurs in
large quantities in Leheighton in Pennsylvania, and we are indebted to
Mr. D. Keim, for some fine specimens from that locality.

[Footnote 21: See Annals of Lyceum, Vol. I. p. 188.]

The authority of Professor Brongniart is sufficient to place the C.
Macrophthalma among the species of the United States, though we have
been unable fully to identify it with his description.[22] He received
a specimen, transformed into red jasper, from Prof. Ducatel, said
to be found in the United States--no precise locality is given. Our
model represents the animal which is supposed to be the one intended
by Brongniart as the C. Macrophthalma of North America. It is, in our
opinion, a variety of the C. Bufo. There can be no doubt that several
species have been confounded under the name of C. Macrophthalma.

[Footnote 22: We have seen in the Cabinet of Mr. Featherstonhaugh, a
fine group of trilobites, in the transition limestone, from Dudley,
(Eng.) Among them there is a perfect head, which agrees exactly with
the description given by Mr. Brongniart of the head of his Calymene
Macrophthalma. If this belongs to the true macrophthalma, our species
under that name is entirely distinct. Since our work had been prepared
for the press, Dr. J. J. Cohen, of the Baltimore College, has shown
us the fragment of a calymene from Berkley, Virginia, which agrees
with Brongniart's description of the macrophthalma, and with the above
fossil from Dudley. We regret that the imperfection of the fossil
prevents our giving a satisfactory cast of it.]

The following extract of a letter from Professor Ducatel to the author,
referring to the locality of this species, will be read with interest.

"I cannot be positive as to my recollection of the locality of the
fossil referred to by Brongniart and yourself, but believe it is one
of several found by my friend Dr. M'Culloh, in the neighbourhood of
Berkley Springs, Virginia. I regret that I have not in my possession
another specimen to present to you."


Calymene Bufo. _Green._ Cast No. 10.

  Clypeo rotundato, convexo, punctato; abdominis articulis sexdecim;
  cauda attenuata; corpore plano.

Buckler semilunate, front very large, rounded before and arcuated at
the insertion of the middle lobe; surface convex, and marked with
numerous depressed pimples. Mouth large, lunate, resembling that of
a toad or frog, with a narrow raised rim on the upper and under lip.
Below the chin there are no pustulations. Cheeks small, triangular,
and separated from the front by a deep, rectilinear furrow; the eyes
in our specimen are much injured, but they are large, and near the
upper angle of the cheeks. Middle lobe with a series of distinct double
articulations. Lateral lobes wider than the middle lobe, ribs deeply
grooved near their insertion; articulations of the abdomen twelve; of
the tail ten. Length four inches and a half; breadth of the buckler
nearly two inches.

This fossil was presented to me some time since by Thomas P. Johnson,
Esq., who mentioned that it was found in New Jersey, but that he could
not learn its precise locality. Near Patterson, in that State, some
trilobites have been discovered--perhaps the C. Bufo may have been
derived from that locality. It is composed of a dark greyish limestone,
easily cut with a knife.


Calymene Bufo. Variety, Rana. Cast Nos. 11 & 12.

This fine specimen differs from the one above described, in having the
front of the buckler rather smaller, and of a different contour. The
whole of the shell is also covered with granulations, which only appear
on the head of the other; this, however, may be only an imperfection in
the specimens in our cabinet.

I am indebted to the Albany Institute for the originals of the models
Nos. 11 & 12. They were found at Seneca, Ontario County, New York, in
dark, slaty limestone, which also contains cubical crystals of iron
pyrites. A fortunate blow of the hammer has fractured the rock which
contains this trilobite, so neatly, as to present us at the same time
with the petrified animal in an almost perfect state, and also with
the mould or matrix in which it was imbedded. This arrangement is
beautifully illustrated by our models.


Genus Asaphus. _Brongniart._

This genus derives its name from the Greek word Ασαφης--obscure. It
embraces perhaps more species than any other genus of the family of
trilobites. About twenty have already been discovered. Most of them
are very characteristic and can easily be determined, but as the genus
Asaphus, is intermediate between Calymene and Ogygia, it is sometimes a
little difficult to decide the genus to which the inosculating species
on each side, belongs.

In general, the Asaphs may be known by the body being very much
depressed, and by the membranaceous development, which extends beyond
the lateral lobes. The middle lobe of the abdomen, is rarely more
than one-fifth the width of the body. As the abdomen and tail of the
Asaph are the only portions of the animal commonly found entire, the
distinctive characters of the genus above given, may generally be
ascertained.

Professor Brongniart remarks, that the ribs of the _Asaph_, which
correspond in number and position to the articulations of the middle
lobe, "are sometimes simple or undivided, at least in the post abdomen,
but that they are always bifurcated in the _Calymene_" As far as our
observations have extended, these remarks do not apply either in the
one case or the other.

The head or buckler of the _Asaph_, is not so deeply divided into
three lobes as the _Calymene_; they are, however, quite distinct. The
oculiferous tubercles are in some species exceedingly well marked by a
reticulated structure.

This genus often occurs at the same localities with the Calymene,
though in some instances it seems to occupy rocks peculiar to itself.
Dr. John Bigsby, in his list of organic remains occurring in the
Canadas, states, that he never found a single species of the genus
Calymene, on the north side of the River St. Lawrence, although
the Asaphs were very abundant.[23] In his Sketch of the Geology of
the Island of Montreal, he however observes: "Of Trilobites, the
Asaph genus is the most abundant, they approach nearest the species
_caudatus_, of Brongniart. I have found no entire Calymene, but many
bucklers or heads of the Blumenbach species, some of them an inch and a
half in diameter. They are found whole in considerable numbers in the
vicinity of Quebec."[24]

[Footnote 23: Silliman's Journal, vol. viii. p. 83.]

[Footnote 24: Annals New York Lyceum, vol. i. p. 214.]


Asaphus Laticostatus.[25] _Green._ Cast No. 13.

[Footnote 25: From the Latin for "broad ribbed."]

  Cauda prælonga, pars ad marginem vix membranacea; cute coriacea,
  tuberculis minimis; costis latis, convexis et valde distinctis.

The fragments of this species, which we have examined, comprise ten
articulations of the middle lobe, and the corresponding ribs of the
sides, all in a very good state of preservation; the extent to which
the membranaceous expansion reached beyond the tail and the lateral
lobes is very apparent, but it has been unfortunately broken off all
round. Our specimen appears to be a natural cast of the internal part
of the shell, or the coriaceous covering of the animal.

The portion of this specimen of trilobite which still remains perfect,
is two inches long, and three inches and a quarter broad. The middle
lobe exhibits the appearance of a very exact and gradually tapering
cone, its articulations being rounded and slightly flattened on the
top. The ribs of the lateral lobes are nearly straight, slightly
arched, broad, rounded, and gradually increase in width from the point
of their insertion; they are simple or not bifurcated throughout, and
are covered with very minute granulations, which are probably produced
by the sandstone in which the animal is mineralized. The membranaceous
expansion near the caudal termination, is a good deal prolonged.

The A. Laticostatus occurs in a light coloured ferruginous sandstone,
which contains a multitude of other fossil remains, particularly
a large species of Productus and of Terebratula. It is said to
have been found in Ulster county, in the State of New York, by the
late Charles Wilson Peale, Esq., the distinguished founder of the
Philadelphia Museum. During the memorable search after the bones
of the _Mastodon Giganteum_, in the marl pits of that county, this
enterprising naturalist procured our Asaph with many other remarkable
petrifactions. The rocks which contain them were probably found not
_in situ_, but were masses rolled from the neighbouring Shawangunk
mountains,[26] which by some geologists are supposed to be a link in
the grand chain of the Alleghanies. Mr. R. Peale, of New York, lately
visited the rich repository of fossils in Ulster County, and procured a
number of specimens of the A. Laticostatus, all of which he has kindly
permitted me to examine. These are much smaller than our cast, but in
many instances the caudal elongation is perfectly developed. The A.
Laticostatus also occurs in the Helderberg mountains, specimens of
which are in the Albany Institute.

[Footnote 26: The Lenape tribe of Indians, who formerly inhabited this
district of country, gave the name of Shawangunk to this stupendous
ridge of hills a name which has been very properly preserved.]


Asaphus Selenurus.[27] _Eaton._ Casts Nos. 14 & 15.

[Footnote 27: Derived from _Selene_, moon, and _ouros_, tail.]

  Cauda semilunari; costis angustis, valde distinctis; abdominis
  articulis duodecim; corpore convexo.

I am indebted to Professor Eaton, for two specimens of this very
interesting species. In his Geological Text Book, he thus describes
it: "Tail crescent-form, or concavo-convex, with the convex side
forward, upon which the post abdomen terminates: abdomen contains
about 12 articulations, with an abrupt termination equal in breadth
to one-fourth of the length of the transverse lunate tail; the
articulations of the side lobes gradually incline towards the axis
of the body, until the last pair terminate at the tail. Found in
transition limestone at Glenn's Falls, and Becroft's mountain, near
Hudson. I have a specimen from Becroft's mountain, with part of the
original covering of the animal remaining."

When we first noticed the remarkable lunate appearance of the tail
of this Asaph, we supposed that it was occasioned by some accident,
but there seems no doubt that this conformation is natural. In
our specimens of this species, which are not however perfect,
the articulations of the abdomen do not exceed 8 in number. The
representation of this animal remain given by Mr. Eaton, plate 1,
figure 1, is exceedingly inaccurate; it will confuse rather than
illustrate the subject. Our cast and the drawing, we believe, are taken
from the same specimen, which was kindly loaned by Mr. Eaton for this
work. It is but justice to the amiable, industrious, and indefatigable
author of the Geological Text Book to remark, that he regrets as much
as any one, the insufficiency of his figures of the trilobites, to give
any correct idea of the fossils they are intended to represent.

In the cabinet of the Albany Institute there are a number of specimens
of the A. Selenurus. One of our models represents the natural mould
made by the animal in the rock; the other is an impression taken from
it, in order to exhibit the animal in a more satisfactory manner.


Asaphus Limulurus.[28] _Green._ Cast No. 16.

[Footnote 28: From two Greek words, which signify "Limulus tailed."]

  Cauda longa, spina munita sicut in Limulo; costis abdominis in
  spinis retrorsum flexis, desinentibus.

It is very much to be regretted that the abdomen and caudal end only of
this remarkable Asaph have hitherto been discovered; it is, however,
exceedingly gratifying that the fragment still remains in so perfect a
state. It forms a part of the magnificent cabinet of organic remains
belonging to J. P. Wetherill, Esq., now deposited in the Academy of
Natural Sciences, of Philadelphia.

Dr. J. J. Cohen discovered a small specimen of this species at
Lockport, New York, which he has presented to the Athenæum, in
Baltimore.

Eight articulations of the abdomen, and ten of the tail, are all of
this fine species that we have seen. The ribs, or costal arches of
the abdomen have a deep furrow on their upper surface, commencing
at the middle lobe, and terminating near their free extremities;
these extremities appear all detached from each other, and end in
reflected points or spines, so as to give the side of the animal a
serrate appearance. The costal arches of the tail are grooved through
their whole extent, and present no spinous terminations. Beyond the
membranaceous expansion of the tail, which is somewhat similar to that
of the Asaphus Caudatus, there projects a single spine, like that from
the tail of the _Limulus polyphemus_; this spine may be traced under
the caudal membrane to its insertion into the middle lobe. A portion
of the crustaceous shell is still entire, and it seems to have been
covered with very minute granulations. A row of large granulations
may easily be traced on each side of the middle lobe. Length of the
fragment, one inch and a half. Breadth one inch and a fourth.

The A. Limulurus was found in the dark brown, shaly limestone, at
Lockport, in the State of New York; it is associated in the same rock
with the terebratula and several other fossils.

The singular spinous projection from the tail of this Asaph, furnishes
another analogy, between the trilobite and the limulus; an affinity
which was suggested by Dr. Dekay; and which has been argued with great
ingenuity both by himself and Professor Wahlenberg.[29]

[Footnote 29: See Nova Acta Regiæ Societatis Upsalensis: 1821. Also,
Annals of the Lyceum of Natural History. New York. Vol. i. pages
179-185.]


Asaphus Caudatus.[30] _Brünnich. Brongn._ Cast No, 17.

[Footnote 30: From the Latin word for "tailed,"]

  Clypeo antice subrotundato, postice valde emarginato, angulo
  externo in mucronem producto; oculis exsertis, conicis, truncatis,
  distincte reliculatis; post abdomine in caudam membranaceam, acutam
  extenso. (Vide Brongniart.)

The middle lobe of the buckler is marked by three transverse plicæ
or folds on its posterior part, and its cheeks or lateral portions
are triangular; the posterior exterior angles of which, are acute,
and considerably elongated. The cheeks are furnished with conical,
truncated, semilunar and externally convex tubercles, which were beyond
all doubt the eyes of the animal, being reticulated as in those of
the Limulus. The middle lobe of the back is narrow, and has twelve
articulations. The lateral lobes are composed of double ribbed costal
arches. Beyond the lateral lobes and the caudal termination, there is a
smooth, thick membranaceous expansion, which forms an acute projection
below the central portion of the tail.

The specimen in the Philadelphia Museum, by which I have identified
this species, is marked as coming from Ripley, Ohio. It reposes on a
fragment of ash coloured limestone--which contains also a mutilated
specimen of what seems to be a calymene, and a few small terebratulæ,
&c.

Dr. John Bigsby, in his "List of Organic Remains, occurring in the
Canadas," states that the A. caudatus is frequently met with, thrown
up by the water on the north shore of Lake Superior--on the bank of
Rainy river--at the Lake of the Woods, and at several other places. In
some localities they are astonishingly numerous, and so small as to be
almost microscopic. They occupy indiscriminately limestone of every
colour, but are most numerous in that which is brown or crystallized.
They are composed of the kind of limestone in which they happen to be
embedded.

We have seen a number of specimens of this species in the Albany
Institute, in Mr. Wetherill's cabinet, and in the Baltimore Athenæum;
but in all of them, the abdomen and caudal extremity only remain
perfect: from their exact resemblance, however, to the same parts of
the A. caudatus, figured by Brongniart, (plate 2, fig. 4, D.) we have
no hesitation with regard to their identity. The description which
we have given of the _buckler_, supposed to belong to our Asaph, is
therefore taken from Brongniart, whose specimens were found at Dudley,
the celebrated locality of the C. Blumenbachii.[31] The coriaceous
membrane, which extends beyond the lateral lobes and forms the caudal
termination of our species, is not covered with minute dots, as in
the European fossil; and if a new name is to be applied to it on that
account, it may be called _A. glabratus_.[32] M. Wahlenberg, has given
the figure of a trilobite which he calls _caudatus_, but ours cannot
be mistaken for that species, to which Brongniart has very judiciously
applied the name of _A. meucronatus_.

[Footnote 31: In the first volume, 2d series, of the Transactions of
the Geological Society of London, Mr. Weaver has published some highly
interesting observations on the fossils found in Gloucestershire,
England. The A. caudatus, he states, is there found in the transition
limestone, though very much mutilated. (Vide p. 326.)]

[Footnote 32: In the cabinet of G. W. Featherstonhaugh, Esq., I have
examined a fine specimen of the A. caudatus, from Dudley, England,
but could not perceive the minute dots on the tail, as mentioned by
Brongniart.]

The conical eye-like protuberances on the head of this species, are
very remarkable, and so much resemble the reticulated eyes of the
limulus, as to leave no doubt that they once contained the organs of
vision.


Asaphus Hausmanni. _Brongniart._

  Cauda rotundata; cute coriacea tuberculis minimis spinulosis tecta.

In De la Beche's Geological Manual, there is a list, of the trilobites
which have been discovered in the grauwacke group of rocks. This list
we have given in our introduction. Among the trilobites he states that
the Asaphus Hausmanni has been found in the United States; as we have
not seen the species, and presuming the author to be correct in his
locality, we give the following description from Professor Brongniart.

I know, he observes, only the tail of this Asaph, but it is so
different from that of other trilobites, that I do not hesitate to
establish a particular species, upon the consideration of this part
alone. Its general form is that of a semi-ellipsis; the middle lobe
represents a very slender cone. The arched ribs of the lateral lobes
are perfectly distinct and simple. I cannot perceive in them the
slightest appearance of bifurcation. This sufficiently characterizes
the species. But that which further distinguishes it from the others,
are the small, elevated points, scattered, and of course rough
(serrés), with which the skin or epidermis is covered, resembling, in
this respect, the tail of the _Apus canceriformis_.

This fragment of an Asaph is in a homogeneous, compact, blackish
limestone, which contains no other kind of petrifaction. I know not
where it was found. It is in the cabinet of M. de Drée.

On plate 2 of Professor Brongniart's work, he has given figures to
illustrate this species; fig. 3 A. represents the whole fragment,
and 3 B. two of the ribs of the lateral lobes, magnified to show the
arrangement of the tubercles, which are very peculiar.

From the above description it will be readily perceived, that the A.
Hausmanni comes very near to the A. Laticostatus. There are, however,
many striking differences, which will be obvious to those who compare
our cast with the figures of Brongniart. The shape of the ribs, and the
tubercles upon them; the form of the middle lobe and of the interstices
between the articulations, are all peculiar to each. The elongation of
the tail in our species is alone sufficient to distinguish it. We have
always been doubtful whether the minute granulations on our species
were not produced by the sandstone in which it is petrified.

Upon what authority the A. Hausmanni has been considered as a species
belonging to the United States we cannot determine. In the valuable
and extensive cabinet of trilobites belonging to the Albany Institute,
there are a number of specimens labelled with this name by Professor
A. Eaton. If we mistake not, he mentioned to us that similar fragments
of this fossil were sent by him to Brongniart, who, we understand,
is the author of the list of trilobites found in the manual of De la
Beche. The specimens which have been examined, both in the cabinet of
Professor Eaton, and in that of the Albany Institute, are certainly
not identical with the figures or descriptions published of the A.
Hausmanni. Professor Eaton, in his Geological Text Book, at page 31,
thus describes his A. Hausmanni:--"Tail rounded, and forming the middle
of a circular arc whose centre is in the fore abdomen, near the head;
covering tubercled or spined. Found in coral rag on the south shore of
Lake Erie. Also, in its underlaying grit slate on the Helderberg." Some
other trilobites mentioned in De la Beche's list as occurring in the
United States, we have not been so fortunate as to meet.


Asaphus Pleuroptyx.[33] Cast No. 18.

[Footnote 33: From the Greek word for "grooved ribs."]

  Corpore depresso; cute coriacea tuberculis minimis; costis
  striatis; cauda acuta, brevi.

This species like most other specimens of this genus, in our cabinets,
is decapitated--every other part, however, appears to be in a good
state of preservation.

The articulations of the abdomen and tail, which cannot readily be
distinguished from each other, are seventeen in number. The middle lobe
is flat, and regularly tapers to an obtuse lip; it is marked on each
side with longitudinal impressed lines or little grooves. The costal
arches on their upper side have a deep and narrow channel, running
through their whole course. The costal arches of the abdomen have no
membranaceous expansion beyond their terminations; this organization
is only visible immediately below the end of the middle lobe, where it
quickly finishes in an acute point. A large portion of the crustaceous
shell remains, and is covered with distinct granulations; those on the
tail are the least obvious.

This species approaches very near the A. caudatus, but the grooves on
the middle lobe, the smallness of the costal arches, and the limited
extent of the membranaceous expansion round the lower portions of the
shell, will sufficiently distinguish it.

Two specimens of this Asaph are in the cabinet of the Albany Institute.
The one from which our cast is taken, was found on the Helderberg
mountains; it is embedded in a light grey coloured limestone shale. The
other specimen, which is much smaller, was discovered near the Genessee
River, in the State of New York. The rock in which it occurs is
identical in its constitution with the other. It contains other species
of trilobites, and a number of shells.


Asaphus Micrurus.[34] Cast No. 19. Fig. 3.

[Footnote 34: From the Greek, for "minute tail."]

  Cauda attenuata, acuta; corpore valde convexo; costis striatis;
  parte marginali vix membranacea.

This fine, large caudal termination of an Asaph is in the cabinet
of the Albany Institute--and it is a subject of great regret, that
all that has yet been discovered relating to this highly interesting
trilobite, is to be seen in this fragment.

There are eighteen articulations of the tail and abdomen, which cannot
be distinguished from each other. The middle lobe is composed of a
series of straight, distinct, parallel articulations, very convex
about the middle, so as to form a kind of longitudinal ridge down
the back. The costal arches of the lateral lobes are very distinct,
and are longitudinally striated or grooved on their upper surface,
particularly those near the upper part of the animal. The membranaceous
expansion is very narrow along the sides of the body, and forms a sort
of hem; below the central portion of the tail it makes a short acute
projection, which seems to be supported by a short costal elongation of
the middle lobe. Length two inches and a half.

The A. Micrurus was found in the black fœtid limestone of Trenton
Falls, by M. H. Webster, Esq., and by him placed in the rich collection
of trilobites in the Albany Institute. The limestone in which this
Asaph is embedded, is almost one entire mass of petrifactions. The
general aspect of the A. Micrurus is very similar to that of a
calymene--but judging from its structure, it could never contract
its shell into a spherical figure. Its minute tail, and narrow
membranaceous expansion round the terminal edges of the lateral lobes
are quite peculiar, and determine it to be an Asaph.


Asaphus Wetherilli.[35] _Green._ Cast No. 20.

[Footnote 35: I have named this species in compliment to my friend,
John P. Wetherill, Esq., whose magnificent cabinet of fossils in the
Academy of Natural Sciences of Philadelphia, will ever remain as a
monument of his discrimination, enterprise, and liberality.]

  Clypeo postice arcuato, sulcato; abdominis articulis duodecim;
  cauda vix membranacea; cute coreacea vix punctata.

The contour of this beautiful Asaph is very regularly ovate; unlike
most of the remains of this genus, the buckler is still attached
to the abdomen, though one of the _cheeks_, and a portion of the
_front_ are obscured by the rock in which the animal is imbedded. The
cheeks form spherical triangles. The oculiferous tubercles, though a
good deal defaced, seem to have been circular and not lunate, as in
the A. Caudatus. A raised, curved line passes from and over the eye,
between it and the lateral lobe of the abdomen. The central lobe of
the back is composed of twelve double joints, and that of the tail of
six single articulations; where the epidermis or shell is perfect,
all the articulations appear single. The last joint of the tail is
longer than in any other of our species. The ribs of the abdomen are
rather broad, and have a deep furrow scooped out along their upper
surface; their extremities, where they can be discovered, are detached
from each other, and terminate in reflected points, like those of the
A. Limulurus. The costal arches of the tail are delicately grooved,
and terminate in the membrane. The membranaceous expansion round the
edge of the tail is very narrow, and appears to form no projection
beyond its central part. The whole epidermis is finely marked with
granulations. Length one inch and three-fourths--breadth one inch and
one-fourth.

This interesting species was found in limestone shale, near Rochester,
in Munroe County, N. Y.; and is now in the valuable cabinet of the
Albany Institute. An accidental fissure of the rock disclosed not only
a fine specimen of both the mould and the cast of this animal, but
also another individual of the same species in contact with it. From
the peculiar attitude which these fossilized animals maintain towards
each other, they appear to have been combatants at the very moment when
the catastrophe occurred which produced their mineralization. In the
Museum of the Garden of Plants at Paris, there is a large specimen of
two fossil fish, which are supposed by many to have been destroyed and
covered with mineral matter, when one of them was in the very act of
swallowing the other. Mr. Bake well, however, who accurately examined
this specimen, is of opinion, that the two heads of the fish had been
pressed together by the superincumbent weight.


Genus Paradoxides. _Brongniart._

The animals arranged under this generic name, include the organic
remains described by Linné as Entomolithus paradoxus, and Brongniart
has given the specific appellation which the great Swedish naturalist
applied to these singular animals, out of compliment to him, though he
considers it quite inappropriate. The late Professor Dalman calls this
genus Olenus, and quotes Paradoxides as a synonyme, but the term of
Brongniart seems to have the priority, and therefore must be preferred.

The animals belonging to the Paradoxides have the body very much
depressed, and the lateral much wider than the middle lobe.

The buckler is nearly semicircular, the cheeks are destitute of eyes,
and the front is marked with three transverse furrows. This last
character is probably not a permanent one.

But the most distinguishing character, is the prolongation of the
costal arches, particularly those of the tail, beyond the membrane
which they are supposed to support; the termination of these arches
is in teeth or spines. Some species of the Asaph have prolongated
extremities to the ribs of the abdomen, but we have never seen them on
the arches of the tail.

This genus is said to comprise a great number of species, but the only
one found in North America, as far as our knowledge extends, is that
described by J. J. Bigsby, in the fourth volume of the Journal of the
Academy of Natural Sciences of Philadelphia. As we have not seen the
specimen, we add the description of it in the author's own words.


Paradoxides Boltoni. _Bigsby._ Figure 5.

Oval, blind; surface with small tubercles and striæ; clypeus rounded
before; exterior angle extending in a broad spine; abdomen fourteen
jointed; segments recurved, falcate; tail membranaceous and serrate.

The shape of this individual is oval, approaching ovate; it is
moderately flat; the whole length is five inches and four-fifths; its
breadth across the middle is four inches and nine-tenths; wherever the
cutis is not removed, it is covered profusely and irregularly with
small tubercles. The denuded portions in this specimen, for the space
of three quarters of an inch from the external margin, is, in a very
small degree, depressed, and displays a number of broken and continuous
striæ, parallel to that margin. There are no traces of organs of
vision. The buckler is nearly the segment of a circle; anterior edge,
in the present case, imperfect; it is four inches and three-fifths
broad, and one inch and one-ninth long at the centre; it joins the
abdomen by a somewhat sinuous transverse line; cheeks and front of
equal breadth; the former are flat, but rise at the sharp ridge by
which they unite with the front; they are triangular in shape; their
outer angles terminating by an acute tip. The striæ mentioned above
are here not quite parallel to the external border; the front is a
shallow depression; rounded but tapering anteriorly; it is intersected
from above on each side obliquely towards the mesial line, by a ridge
bifurcating downwards; another smaller ridge nearly bisects the front
perpendicularly.

The abdomen and post abdomen are not distinct. The abdomen exclusive
of the cauda is three inches and a half long; it exhibits fourteen
costæ varying indiscriminately from one-fifth to one-fourth of an inch
in breadth, except the three inferior ones, which are rather broader;
they occupy the whole abdomen without membranous interspaces, and are
separated by a black sulcus, not always well defined, and sometimes a
line in diameter. Each costa is canaliculated from the upper and under
angle to the tip.

The middle lobe is separated from the lateral by a shallow, rude
sulcus, which however, does not always destroy the continuity of the
costæ, as they cross it; this lobe is slightly convex, one inch and
a half broad at the top, and so continues to the sixth costa, after
which it gradually contracts, until at the bottom it is one-fifth of
an inch broad, subsiding insensibly into a flat membrane-like surface;
its longitudinal sulci pass one inch farther downwards, and expanding
a little, unite with the costæ on each side the posterior edge of the
space included by them, being dentated.

The lateral lobes are quite flat, one inch and a half broad anteriorly,
and, by gradual prolongation, become at the fourth costa one inch and
four-fifths in breadth; this dimension is maintained to the ninth
articulation, when it slowly decreases to one inch at the bottom;
the recurvature of the costæ is gentle in the upper eight, but then
decreases rapidly. Their extremities, advancing two-fifths and
four-fifths of an inch into the embedding rock, are falcate with their
raised black edges, and clearly marked points.

This trilobite was found by Lieut. Bolton, at Lockport, in the state
of New York, in the black, shaly, horizontal limestone forming the
lower part of the ravine by which the Erie canal ascends the _parallel
ridge_ of Lake Ontario. Dr. Bigsby remarks on this locality, "I am not
prepared to assign to this limestone its exact place in the series
of geological formations; it is above the saliferous sandstone, and
therefore more recent than the rocks best known as abounding in
trilobites." We have, therefore, in this instance, another fact, which
demonstrates that blind trilobites are not confined to a geological
period more remote than That which has produced the animals with
oculiferous tubercles.


Genus Ogygia. _Brongniart._

In the vast quarries of slate at Angers, in France, there is frequently
noticed two very remarkable organic remains, which have for a long
time excited the attention of naturalists. To receive these curious
relics, Professor Brongniart established the genus, Ogygia, which he
thus characterizes. Body much depressed--elongated into an ellipse,
terminated in points--nearly equal at its extremities, and not capable
of contracting itself into a spherical form. The buckler is bordered by
a slight longitudinal furrow, rising from its anterior extremity, and
its posterior angles terminating in elongated points. The abdomen has
eight articulations, and its longitudinal lobes are not very prominent.
The eyes are neither prominent nor reticulated and there are no other
protuberances on the buckler.

In Professor Brongniart's original work on the Trilobites, he has
described the two specimens from Angers, under the specific names
of Guettardi, and Desmarestii, in compliment to M. M. Guettard and
Desmarest; and in De La Beche's Manual of Geology, we are informed that
he has since identified two other species; one of which is supposed to
be found in North America; this he calls _Ogygia Sillimani_; the banks
of the Mohawk River, near Schenectady, is the locality from which it
is said to have been derived.

As we have not been able to find any detailed account of this species,
we have admitted both it and the genus to which it is said to belong
into our Monograph exclusively on the high authority of Professor
Brongniart, as quoted in the Manual of Geology. We are not ignorant of
the species of Trilobites found near Schenectady, and if permitted to
offer a suggestion on this subject, it would be, that the description
of the American ogygia, was made out by its distinguished author from
the fragment of an Isotelus. The Isotelus is not uncommon in that
vicinity, and one of its extremities might, even by a very close
observer, be mistaken for that of an Ogygia--especially by those who
are not perfectly familiar with the Isotelus.


Genus Isotelus. _Dekay._

This fine genus of trilobites was established November, 1824, by my
friend James E. Dekay, M. D. It embraces a considerable number of
species so analogous to each other, that except in a very few cases,
it is exceedingly difficult to point out their distinctive characters.
Some of the species of Isotelus, appear to have reached a greater size
than any other trilobite. In the cabinet of P. A. Browne, Esq., there
is the fragment of one, which must have been fourteen or fifteen inches
long.

The Isotelus is found in several parts of North America, but most
abundantly in the black transition limestone, in the northern section
of the country. The richest locality, not only of this genus, but also
of the Calymene and the Asaph, is Trenton Falls, on West Canada Creek,
about 13 miles to the north of Utica, in the state of New York. The
following extracts from the notes of Professor Renwick, which accompany
Dr. Dekay's account of the Isotelus, will give some idea of this vast
depository of the medals of ancient zoology. West Canada Creek, is one
of the principal branches of the Mohawk River. At Trenton Falls it has
worn itself a passage through the rock for the distance of nearly two
miles, forming a series of water falls; and has thus laid open to view
the strata to the depth of probably 300 feet. The layers of the rock
thus disclosed are nearly horizontal, and of various thicknesses: they
are composed of limestone, with the exception of numerous thin veins
of argillaceous matter. The higher strata are composed of carbonate of
lime nearly pure, of a light grey colour and crystalline structure. At
greater depths it is more compact and darker in colour, and finally it
appears quite black and highly fœtid.[36]

[Footnote 36: See Annals of N. Y. Lyceum, vol. i. page 185.]

Animal remains are contained in every part of the rock; besides several
genera of trilobites, we have several species of orthocera. Encrinites
and Fungites--Nautili--Terebratulæ and Producti, are quite common.
The favosites here are sometimes six inches in diameter, and in such
numerous columns, as to have induced the late worthy proprietor of
this interesting spot, Mr. J. Sherman, to consider them as analogous
in structure to the basaltic columns of Staffa and the Giant's
Causeway; he therefore maintains the extravagant theory that these
columns are nothing more than gigantic favosites.[37] We visited this
famous locality of trilobites not long since, and were almost as much
delighted with the sublimity and grandeur of the cataract, and the
picturesque and romantic character of the glen, as with the reliques of
olden times, which are scattered here in such profusion.

[Footnote 37: See a Description of Trenton Falls, by John Sherman, p.
17.]

The genus Isotelus, derived from Ἱσος, equal, and τελος, extremity, is
thus characterized by Dr. Dekay.

_Body_ oval often contracted, not unfrequently extended.

_Head_ or buckler large and rounded, equalling the tail in size, but
with two oculiform tubercles.

_Abdomen_ with eight articulations.

Frontal process beneath, with two semilunar terminations.

_Post abdomen_ or tail, broad, expanded with indistinct divisions, as
large as the buckler.

Longitudinal lobes very distinct.

Other distinguishing marks by which this genus may be known, have been
given in our introduction.


Isotelus Gigas. _Dekay_. Casts Nos. 21 and 22.

_Head_ representing a spherical triangle, surface punctate, convex,
descending from between the eyes to the anterior border, which has
a narrow raised rim; posterior extremity concave and corresponding
to the articulation of the abdomen. Eyes elevated, prominent,
sub-pedunculated; cornea oblong, lunated, highly polished; _abdomen_
with eight distinct articulations, the middle lobe double the size
of the lateral one: these latter are continuous with the middle
lobe, have a deep furrow impressed on their upper surfaces, which
becomes gradually effaced towards their narrow free extremities.
These lateral lobes are rounded at their extremities, and flattened
in such a manner as to allow each lobe to slide easily under the lobe
immediately preceding. _Tail_ subtriangular, convex, equalling the
head in size, with the posterior termination rounded. On the centre of
its surface, when accidentally decorticated, a slight elevation may be
traced, if the specimen be held in a certain light, which appears to
be a continuation of the middle lobe; this extends to within a short
distance of the posterior angle of the tail, when it is either entirely
effaced or terminates in an abrupt truncation. Another elevation runs
parallel to and at a short distance from the edge of the tail. These
elevations are connected by obscure parallel lines, imitating the
spaces between the lateral lobes. When the tail is fractured on the
borders, a semilunar depression is visible, exhibiting concentric
striæ. The whole Surface of the animal has a jet black polish. Length
from 6 to 12 inches.

The original of our cast is in the cabinet of J. P. Wetherill, and was
found near Cincinnati, Ohio. It is of a yellowish colour, and occurs in
argillaceous slate. Specimens are common in most cabinets of American
fossils. The Lyceum in New York, possesses a fragment of an individual
of this species, which must have been at least 17 inches long. Our
cast, No. 22, is from the gigantic tail in the cabinet of P. A. Brown,
Esq. Mr. Stokes describes the I. gigas as a new species under the name
of Asaphus Platycephalus, in Geolog. Trans. vol. i. N. Series. His
specimen was found in the limestone of. St. Joseph's, Canada.


Isotelus Planus.[38] _Dekay._ Cast No. 23.

[Footnote 38: The general usage of naturalists is to prefix a short
Latin caption to the species which they discover--but as some
authors do not follow this fashion, we are satisfied to suffer their
descriptions to stand without it. We believe, indeed, that the time is
not very distant, when every author will be expected to publish his
discoveries in his vernacular tongue.]

_Head_ more rounded than the preceding, and less elevated. _Tail_
flat, rounded. Total length two inches and one-tenth. Breadth one
inch and one-tenth. Length of the head, six-tenths--of the abdomen,
eight-tenths, and of the tail seven-tenths.

Dr. Dekay is of opinion that this species may possibly prove to be the
young of the preceding. The relative proportions of its buckler and
tail vary considerably from those of the I. gigas; and the depth of
the lateral lobes, which exceeds three-tenths of an inch, would almost
of itself determine it to be a new species. The original, from which
our cast was taken, is in the cabinet of J. P. Wetherill. It was found
near Newport, Kentucky, and occurs in argillaceous slate. The fossil is
of a dirty yellow colour.


Isotelus Cyclops.[39] _Green._ Cast No. 24. Fig. 7.

[Footnote 39: From the Greek for "round eyes,"]

  Clypeo antice attenuato, plano; oculis rotundis, proximis; cauda
  ovata, acuminata.

The head of this species is much more elongated than it is in the
two preceding species. The anterior portion of the buckler is much
prolonged. The eyes are approximate, rounded, and near the posterior
edge of the head. The abdomen is furnished with eight distinct
articulations; the middle lobe is scarcely broader than the lateral
lobes; tail rather broader than the head, and ovate; posterior
termination more rounded than the buckler. Length nearly three inches.

The specimen from which our model was taken belongs to the Albany
Museum. No label is attached to it, but I was informed by Mr. Meach,
one of the proprietors, that it was found in the western part of the
State of New York. It is embedded in an ash-coloured limestone. The
specimen is a good deal worn--but the peculiar form of the eyes, and
the narrowness of the middle abdominal lobe, clearly distinguish it
from either of Dr. Dekay's species.


Isotelus Megalops.[40] _Green._ Cast No. 25.

[Footnote 40: From the Greek for "great eyes."]

  Clypeo antice subrotundato, postice arcuato; oculis magnis,
  rotundis, eminentissimis; cauda suborbiculari, limbo lato;
  articulis abdominis octo.

The buckler in its contour resembles very much the head of the I.
gigas; it is, however, rather more rounded before, and arcuated behind.
The oculiferous tubercles, are very peculiar, being very large, round,
and exceedingly prominent. They have a good deal the appearance of
solid hemispheres placed on the forehead of the animal. They are
exactly on a line with the two abdominal furrows. The abdomen is
composed of eight distinct articulations; the middle lobe is rather
larger than the lateral lobes. The tail is suborbicular, convex, and
rather less than the head. Length nearly five inches. Breadth almost
three inches.

This magnificent Isotelus was obtained near Trenton Falls, in New York,
by P. A. Browne, Esq., and now forms a part of his fine collection
of fossils, in this city. It occurs in black transition limestone.
It differs essentially from the I. gigas of Dekay, in the magnitude,
collocation, and contour of the eyes. Those of the I. gigas are oblong
and lunate, and nearly half the distance between the anterior and the
posterior edges of the buckler; those of the I. Megalops are not only
much larger, but they are round, and very near the posterior border of
the head.


Isotelus Stegops.[41] Green. Casts Nos. 26 and 27.

[Footnote 41: From two Greek words, which signify "covered eyes."]

  Clypeo antice, caudaque postice attenuatis; cute coreacea punctis
  minimis.

The head of this species is nearly in the form of a spherical triangle;
its anterior edge is vertically flattened all round, but does not
produce a narrow raised rim, such as is described by Dr. Dekay, to
belong to the I. gigas. The eyes are prominent, and rather nearer the
lateral edge of the buckler, than to its posterior border. The shell
of the buckler forms a remarkable projection over the top of each
oculiferous tubercle, something like an eye-lid. Continuous with the
edge of this cuticular projection, there is a curved linear depression,
which terminates on both sides, at the edge of the buckler. This
kind of suture, though remarkably developed in this species, is not
peculiar to it, being more or less distinct in most of the Isoteli.
The articulations of the abdomen are lost; there can be little doubt,
however, that they were eight in number. The tail is subtriangular, and
less in magnitude than the buckler.

This fossil is among the number of fine specimens in the cabinet of
J. P. Wetherill. It is in a rolled or contracted attitude, and is
somewhat distorted. We have given, however, models of the head and
the tail, in two distinct pieces. The external shell, or calcareous
covering, is more perfect in this specimen than in any other we have
ever seen. A considerable portion of the under side of the anterior
part of the buckler, is also well preserved, and perfectly coincides
with the figure and description given of it by Dr. Dekay and Mr.
Stokes. There is another fragment of an Isotelus in the cabinet of Mr.
Wetherill, showing eight articulations of the abdomen, which probably
belongs to another individual of this species. The dorsal shell is in a
high state of preservation. This species is embedded in clay slate, and
was found in Newport, Kentucky.


Genus Cryptolithus. _Green._

Among the numerous organic relics embedded in black limestone at
Trenton Falls, in the State of New York, there is often found the
fragment of a trilobite which cannot properly be referred to any of the
genera already mentioned. Dr. J. Bigsby, in his Sketch of the Geology
of the Island of Montreal, has figured and described a fossil which
occurs at that place, which approaches in its specific characters to
the fragments found at Trenton--but he does not suggest for his relic
any name. Professor Brongniart has also represented, plate 4, figs.
5 and 7 A. B. C., the fragments of trilobites from Russia and from
Llandillo, in Wales, which seem to differ but little from those above
noticed, these are also without names. Under such circumstances, we
have thought it expedient to group these relics under the generic term
of Cryptolithus, a name analogous to Calymene, Asaphus, Ogygia, and
Agnostus, and which may with propriety be applied to the animal, should
it ever be discovered entire.[42]

[Footnote 42: Since the above was written, and the C. Tessellatus
published, I have received a fine specimen of this trilobite from
Professor Eaton, in an almost perfect state, so that the entire animal
can now be described.]

_Body_, contractile.

_Buckler_, lunate, convex, outer edge surrounded by a semicircular,
reticulated, or tessellated border.

_Front_ or middle lobe of the buckler very protuberant.

_Oculiferous protuberances_, none.

_Abdomen_, much compressed, trilobate.


Cryptolithus Tessellatus. _Green._ Cast No. 28, and Fig. 4.

  Clypeo rotundato, fronte valde convexo, capite antice semicirculari
  margine tessellato ornato.

Outline of the buckler hemispherical, the edge surrounded by a
semicircular border of tessellated or rounded punctures, in three
concentric rows in front--on each side near the posterior angle of the
buckler, these rows of punctures are more numerous; the front is highly
convex; is rounded before, and gradually tapers towards the abdomen.
The cheeks form spherical triangles, and are entirely destitute of
oculiferous tubercles or any other markings; their posterior angles
project beyond the sides of the abdomen. Abdomen and tail very much
compressed, and composed of about ten articulations; costal arches of
the lateral lobes grooved; tail attenuated. Whole length half an inch.

The Cryptolithus Tessellatus, resembles a good deal the Entomostracites
Granulatus of Wahlenberg, and which Dr. D aim an calls Asaphus
Granulatus. The figure of this animal given by Brongniart, table 3,
fig. 7, appears to be quite imperfect, and is very unlike, except
in the buckler, the representation of Wahlenberg's fossil, given by
Dalman, table 2, fig. 6. Though the angles of the buckler in the
Asaphus Granulatus are much more elongated than those of the C.
Tessellatus, it may perhaps be another species of the same genus.[43]

[Footnote 43: The following, is Dr. Dalman's description of the Asaphus
Granulatus:--

  A. trunco sexarticulato pygidioque lævibus, capite antice
  semicirculari margine granuloso, angulis posticis extensis corpore
  longioribus.

  Animalculum singulare, inversum si inspicitur, lyram forma fere
  similans. Caput antice semicirculare, margine distincto, serie
  submoniliformi e granulis approximatis ornato, discus capitis
  lævis, sed ambitus intra marginem punctis elevatis obsitus. Hic
  ambitus, una cum margine, truncum quoque amplecti videtur, ad
  pygidii basin usque, ubi in cornua lævia, trunco multo longiora,
  abit. Glabella antice fere clavæformis, ad basin utrinque emittens
  lobi rudimentum. Truncus brevis lævis segmentis constans tantummodo
  sex, rhachide angusta. Pygidium breve, rotundatum, læve; adeo
  parvum ut ne quidem capitis disco respondeat.

  Obs.--Oculos atque suturam facialem ex autopsia describere licet.

Vide Om. Palæaderna eller de sa kallade Trilobiterna af. J. W. Dalman,
pages 50-4. ]

The animal described and figured by Dr. J. Bigsby, to which we have
already referred, seems rather different from our species. His
specimens were found at Montmorenci, near Quebec, (Canada) more than
an inch and a half in diameter. The following are his remarks on this
trilobite.[44] "The front of the buckler is remarkably convex, and has
on each side near the base, three very small transverse lines, scarcely
to be called depressions, corresponding to the sulci so strongly marked
in the genus Calymene. There is frequently, but not universally, a
very minute pisiform process on the centre of the front. The whole
upper edge of the buckler is always surrounded by a very ornamental
semicircular border, sometimes semi-elliptical, of punctures placed in
the meshes of a net-work in high relief and arranged close together,
in rays, passing perpendicularly from the buckler and forming at the
same time when observed transversely, curved lines parallel to its
upper rim or edge, excepting at the sides, where they diverge, leaving
a space occupied by other lines of dottings, parallel to the former,
but speedily terminating on the cheeks of the buckler. The lines which
are complete from side so side, are four in number. The imperfect
additional ones, vary from two to four; the smallest and inner,
consisting only of two or three punctures. A plain edging includes the
semicircle of punctures. In the beds of these casts, the places of
the punctures are shown by small conical elevations, and those of the
ridges of the net-work, by corresponding depressions."

[Footnote 44: See Geology of the Island of Montreal, in Lyceum of Nat.
History, N. Y. p. 214.]

Should this prove to be a distinct species, we propose to call it
_Cryptolithus Bigsbii_.

The _Nuttainia Concentrica_ of Professor Eaton seems also very nearly
allied to this species; he describes it as having "four or five
concentric arcs of punctures in front of the buckler, separated by
alternating arcs of fine elevated ridges." The genus Nuttainia, to
which he refers this species, cannot include it, and the N. Sparsa; for
these two relics have scarcely a single essential character in common;
we have, therefore, confined the genus Nuttainia, to the species which
he calls _Sparsa_.

The Cryptolithus Tessellatus is very common at Trenton falls. In the
transition limestone at Glenn's falls, in the state of New York, during
a very short visit to this place, Dr. R. Harlan procured a large number
of this fossil, but only the buckler, the projecting front of which
exhibited a pisiform protuberance above the level of the strata. Mr.
Eaton says that the N. Concentrica "occurs in the wacke variety of
transition of argillite, on the Champlain canal," between the town of
Waterford and the Mohawk river. The specimen in my cabinet, from which
our cast was made, is from that place.

The Cryptolithus Tessellatus occurs also in the limestone which,
according to Dr. Bigsby, overlays the sandstone in the island of
Montreal. At most of its localities, it is associated with the
Isotelus, the Calymene, and with several species of Asaphus. The
Cryptolithus, which is entirely destitute of eyes, being thus found
with the oculiferous species, is an interesting fact, and controverts
the opinion of Professor Wahlenberg, that the trilobites, which are
without eyes belong to a geological epoch more ancient than those which
are furnished with oculiform tubercles. That organic remains furnish us
with the most satisfactory evidence of the identity or dissimilarity
of certain formations, is a disputed point with some geologists[45] It
cannot reasonably be doubted, that new and isolated facts have been
made the basis of a too hasty generalization. On this subject Count
Rasoumowsky makes the following remarks:--"Les divers gisemens des
Trilobites ne me semblent pas non plus pouvoir être déterminés avec
quelque précision. M. Brongniart parait admettre que les trilobites
aveugles ne se trouvent que dans de tres anciennes formations dans
des schistes et des calcaires de transitions; mais nous avons donné
la description d'un trilobite [without eyes] des bords de la Yaousa
prés de Moscow, qui n'appartient certainement pas aux formations de
transition, ce qui me donné lieu de croire que de nouvelles recherches
et de nouvelles observations, prouveront qu'il n'est pas strictement
vrai qu'en France, en Angleterre, en Russie, _il n'existe point de
trilobites entiérement privés d'yeux_, comme le dit le savant auteur
que je viens de citer." See Annales des Sciences Naturelles, Vol. 8.
page 195.

[Footnote 45: See Eclectic Review, for July, 1832.]


Genus Dipleura. _Green._

_Body_, contractile, not much depressed, and slightly tapering.

_Buckler_, pustulous, trilobate, cheeks protuberant, with oblique,
annular, oculiferous tubercles.

_Abdomen_, with fourteen articulations, not lobate, the ribs double.

_Tail_, suborbicular, not so large as the buckler, covered with an
epidermis.

This genus derives its name from two Greek words, which signify
double ribs; many of the trilobites are thus characterized; but in no
species, is this organization so remarkable as in those which belong
to the Genus Dipleura. The expansion of the tail resembles, in some
degree, that of the Isotelus, but other obvious characters sufficiently
distinguish it from that interesting genus. The fossils arranged under
this section are larger than most other trilobites.


Dipleura Dekayi. _Green._ Casts No. 30, 31, and Figs. 8 & 9.

Clypeo lunato punctato; abdomine quatuordecim articulis duplicibus vix
lobatis; cauda suborbiculari; limbo lato convexo integerrimo; oculis
oblique deflexis.

The buckler is subtriangular, and covered with granulations; the
anterior portion of our specimen being mutilated, we cannot determine
its form exactly. The cheeks are very prominent, and swell up gradually
towards the oculiferous protuberances, which are oblique, and marked at
their apex with a depression, so as to give them an annular appearance.
The abdomen is crossed by fourteen double distinct articulations,
not interrupted in their course, by the two longitudinal furrows,
so common in most of the trilobites; but owing to certain curves or
irregularities in the ribs near their lateral termination, a trilobate
appearance may in some specimens be detected. Tail suborbicular,
convex, and covered with a thick epidermis.

The specific name of this species was given in compliment to Dr. James
E. Dekay, of New York, whose valuable paper on the genus Isotelus,
first directed my attention to the American trilobites.

The D. Dekayi has been found in several districts of the United States;
at Lockport in the State of New York, it is not uncommon. The small
specimen from which our cast of the abdomen and caudal end was taken,
is in the fine cabinet of Mr. William Hyde, who permitted me to use
it with his wonted liberality and kindness. It is said to have been
found in Northumberland, Pennsylvania, and occurs in grey carbonate
of lime. In the Philadelphia Museum, there is a fine fragment of this
species, in which there is embedded some crystals of iron pyrites; it
was obtained in Ulster County, New York. In the cabinet of the Academy
of Natural Sciences, there is a longitudinal and hollow fragment,
filled with ochre, and the oxide of iron; it is labelled from Lockport,
New York. At Mount Hope Institution, near Baltimore, there is also a
good specimen from the same locality. In the _Clinton collection_,
owned by the Albany Institute, there is a large extended fragment,
nearly five inches long. It is embedded in brown limestone, and was
found in Madison County, N. Y. There are twelve articulations of the
abdomen remaining, and the epidermal covering of the tail is distinctly
marked with numerous dots. In the same collection there is another
large fragment of this species, consisting of the tail and fourteen
articulations. It was found in Steuben County, New York; and occurs
in grey limestone. It is slightly contracted and very much depressed
laterally. There is also a head in the same kind of limestone, from
Cazenovia, Madison County, New York. In the cabinet of the Institute
there is another specimen of this species, about six inches in length,
and nearly perfect; it is also embedded in a similar rock, and was
brought from Rochester, Munroe County, New York.

The original of the head from which our cast was made, is in the
cabinet of P. A. Browne, Esq., and was found by that enterprising
geologist near Lehighton, Pa.


Genus Trimerus.[46] _Green._

[Footnote 46: From the Greek for "three divisions."]

_Body_, contractile, tapering, compressed.

_Buckler_, pustulous, indistinctly lobate, with only two small elevated
oculiferous tubercles.

_Abdomen_, with thirteen distinct, double articulations divided into
three lobes by a slight longitudinal furrow.

_Flanks_, or lateral lobes, not so broad as the middle lobe.

_Tail_, tapering to an obtuse point, pustulous, and marked with ten
articulations.

This genus resembles in some respects both the Calymene and Dipleura.
The form of the buckler, the position and structure of the oculiferous
tubercles, and the scarcely lobate divisions of the abdomen, will
readily distinguish it from the Calymenes. The articulations of the
tail, not being covered with a shelly crust, is a character too obvious
to confound it with the genus Dipleura. There is, we think, a beautiful
chain of gradations of resemblances, between the Isotelus, Dipleura,
Hemicrypturus and Trimerus. The lobes of the abdomen of the Isotelus
are very distinct, and the articulations of the tail are hid by a broad
thick shelly crust. The lobes in the Dipleura are scarcely apparent,
the ribs more numerous; and the covering of the tail much smaller. The
lobes of the Hemicrypturus are like those of the Isotelus; but the
lateral ones only of the tail are covered. In the genus Trimerus the
lobes are like those of Dipleura, but the articulations of the tail are
exposed.


Trimerus Delphinocephalus. _Green._ Cast No. 32, and Fig. 1.

Clypeo semilunari, antice compresso; oculis minimis, enimentissimis;
articulis duplicibus vix lobatis; cauda attenuata; corpore tuberculata.

In the rich cabinet of American fossils in the Albany Institute,
there are two fine specimens of this species, and I am indebted to
that rising and liberal institution, for the use of them in the
present work. Our cast is made from the smaller and more perfect
specimen of the two. The outline of the buckler forms an irregular
semi-ellipse. The front is convex between the eyes, and very much
depressed anteriorly, so as to form a sharp edge. The posterior part
of the buckler is marked with a transverse groove parallel with the
articulations of the back. The cheeks are small and triangular; the
small elevated eye-shaped tubercles being placed in the middle, nearly
equidistant from each of the angles. The eyes are not reticulated,
the summit of each tubercle only presenting a plain oval foramen. The
middle lobe of the abdomen is much broader than the lateral lobes, and
has 13 distinct, double articulations. The side lobes are curved, and
each costal arch is flattened anteriorly near their lower extremities,
no doubt for the purpose of enabling the animal to roll itself into a
ball. The tail is tapering, and is composed of ten articulations. The
crustaceous covering is here more thickly deposited than on any other
part. The entire shell seems to have been covered with minute elevated
dots; these are beautifully distinct on the buckler and on the tail.
Whole length of the specimen described, not quite two inches.

The other specimen of this species in the cabinet of the Albany
Institute, is a large caudal end, three inches and a half
long, entirely perfect. Both of these fossils were brought from
Williamsville, Niagara county, New York. They occur in a dark shelly
limestone, filled with other petrifactions. The calcareous matter which
has mineralized the trilobite, in this instance, as in most others, is
of a much darker hue than the surrounding rock.


Genus Ceraurus. _Green._

_Body_, very much depressed, and slightly tapering.

_Buckler_, scarcely trilobate; cheeks large, flat, with small remote
oculiform tubercles; posterior angle of the buckler spinous.

_Abdomen_, with twelve articulations.

_Tail_, rounded at the end, but terminating on each side with two
slightly curved spines.

The name of this genus is derived from the remarkable spinous
projections from the caudal end; this peculiar organization separates
it widely from the other genera. The _Paradoxides Spinulosus_ of
Wahlenberg, which is supposed to be the old _Entomolithus Paradoxus_
of Linné, the fossil, with which all the trilobites were for a long
time confounded, has not only projecting spines from the tail, but from
all the costal arches of the lateral lobes. The presence of eyes or of
oculiferous tubercles in the _Ceraurus_, would alone be sufficient to
separate it from the genus to which that interesting fossil belongs. In
the eighth volume of Annales des Sciences Naturelles, Count Rasoumowsky
has figured and described the fragment of a very curious relic, which
seems to be an intermediate link between our genus and paradoxides; in
addition to a number of filamentous elongations of the costal arches, a
curved spine seems to project from the end of the tail, as in the _A.
limulurus_. No name is given to this trilobite, which appears to have
been found on the banks of the Yaousa, near Moscow, where it occurs in
black, coarse, argillaceous schistus. The Ceraurus is probably a very
rare animal remain, as we have only met with it, in the unrivalled
cabinet of trilobites belonging to the Albany Institute.


Ceraurus Pleurexanthemus. _Green._ Cast No. 33. Fig. 10.

  Clypeo postice arcuato, angulo externo in mucronem valde producto;
  oculis minimis remotis, postabdomine in spinam arcuatam acutam
  utrinque extenso.

The exact contour of this species cannot be perfectly ascertained from
our specimen; it seems, however, to have been lunate. The horns of the
crescent which form the posterior angles, are very distinct, and they
project like curved spines, some distance on each side of the head.
The middle lobe or front is faintly scalloped on each side along the
cheeks. The cheeks are rather large, and are furnished with two small
oculiform tubercles, very remote from each other, and quite near to
the anterior portion of the buckler. The abdomen is composed of twelve
articulations. The lateral lobes of the abdomen are flat, and each of
the ribs, at about half their extent, is marked on the upper surface,
with an elevated pimple. These little pustules are nearly on a line
with the oculiferous tubercles of the buckler, and present two parallel
ranges down the body, one on each side of the middle lobe, and are
terminated by a curved spine, which projects to some distance beyond
the tail of the animal. Length one inch and a fourth.

This remarkable organic relic was found near Newport, in the State of
New York. It is embedded in black limestone shale, and so exceedingly
depressed is this animal, that a very thin lamen of the slate removed
from the surface would destroy every vestige of its appearance. I am
indebted to my early friend, Professor T. R. Beck, for the use of this
valuable petrifaction, which now belongs to the cabinet of the Albany
Institute.


Genus Triarthrus. _Green._

_Body_, slightly convex; contractile?

_Buckler?_

_Abdomen_, with three articulations, side lobes longitudinal, narrow,
and wedge-shaped.

_Tail_, broad, rounded, without any membranaceous expansion.

The name of this genus is derived from the circumstance, that the
abdomen has but _three_ articulations; an organization which is very
peculiar. These curious fossil animals are very abundant in the rocks
in which they are found; but though I have examined a multitude of
specimens from different localities, no vestige of the head or buckler
could, on the most minute examination, be discovered. Whether these
animals, during their petrifaction, were so contorted or rolled up,
as to bring the extremities of the body together, in such a manner as
to present the posterior folded part only to the view; or whether the
buckler has been destroyed by the process of mineralization, as appears
frequently to happen with the asaphs, we are at a loss to determine.

The animal remains which belong to the genus Triarthrus, differ so much
in their' form and general characters from all the other trilobites,
that we perhaps ought to regard them as forming another race of beings.
They are, however, more nearly allied to this family than the Agnosti
of Professor Brongniart.


Triarthrus Beckii. _Green._ Cast No. 34. Fig. 6.

  Cauda subrotunda, bipunctata; articulis abdominis tribus, absque
  lobis lateralibus consuetis, sed lobo arcuato utrinque apposito.

The only portions of this fossil which have yet been found, are the
abdomen and tail. The abdomen is composed of three joints; the first
passes from the side lobes completely over the body, and on its upper
surface, near the middle of the back, there is often a minute elevated
pimple. The other two, pass obliquely from the lateral lobes, and are
interrupted in their course over the body. The tail, or posterior
portion, is expanded, something like that of the Isotelus or Dipleura,
and has a deep puncture on each side, about half the distance between
its terminal border and the last articulation of the abdomen. The
lateral lobes are unlike those of any other genus. They form narrow
cuneiform appendages to the sides; near the first joint of the abdomen
they are crossed transversely by an elevated ridge, from which they
gradually taper along the sides of the body, and appear to inosculate
in a delicate point at the central border of the tail. The abdominal
articulations do not pass over these lobes, but just below the last
joint, a little transverse furrow, in perfect specimens, may be
noticed. The largest specimen of this fragment I have seen is exactly
half an inch in length.

This fossil occurs in black shaly limestone, on the canal near Cahooes
Falls, in the State of New York, and at a number of other places in
that State.

I have named this species in compliment to my early friend, Professor
Theodore Romeyn Beck, M. D., well known both at home and abroad, as
the learned author of the work on Medical Jurisprudence. Some time
after commencing this little Monograph, I communicated my plan to Dr.
Beck, and was surprised and gratified to find that he was also engaged
with the same inquiries, and that he was then busy in arranging and
examining the unique collection of trilobites belonging to the Albany
Institute. Without the smallest hesitation, he placed all his specimens
at my disposal, and has facilitated otherwise my undertaking, by every
means in his power.


Genus Nuttainia. _Eaton._

Professor A. Eaton, in his Geological Text Book, has proposed the
Genus Nuttainia, to include two remarkable trilobites which could not
properly be arranged in any of the previously established genera. The
two fossils here grouped together, bear no generic relation to each
other. The first species which he calls N. Concentrica, belongs to the
genus Cryptolythus, which was proposed before the appearance of his
work, and has therefore been noticed in another place.

The genus Nuttainia is thus characterized by its author: "Head in
three lobes, the middle one most prominent; the two lateral lobes
sub-hemispherical, or sub-quadrantal; the whole head bordered
anteriorly with a punctured fillet; body distinctly three lobed, middle
lobe sub-cylindric, and not so broad as the side lobes."


Nuttainia Sparsa. _Eaton._ Cast No. 35.

Fillet nearly straight in front of the middle lobe of the head,
punctures of the fillet scattered irregularly, without any alternating
ridges; head compressed, covered with scattered punctures, having its
side lobes much smaller than the middle one; middle lobe with straight
sides, giving it somewhat the form of a parallelogram.

Found in third grauwacke,[47] or grit slate in Coeymans, sixteen miles
south-west of Albany. I have the head of one before me two and a half
inches broad, and one and a half long. The whole of the animal must
have been six or seven inches in length.

[Footnote 47: In a manuscript note, Professor Eaton states that the
third grauwacke, or grit slate of Coeymans, "_alternates_ with the
underlaying cherty lime rock." This opinion some of our geological
friends, familiar with the formation at Coeymans, and with the
Professor's nomenclature of rocks, have called in question.]

The above account is copied from the "Text Book." Mr. Eaton was kind
enough to lend me the only specimen of this curious fossil remain,
which has yet been found; from which his description was taken, and of
which our cast is an exact copy. His generic characters do not in our
opinion at all apply to this fragment. Nothing but the head of this
singular trilobite remains, and it is doubtful whether what is said
to be the punctured fillet, "nearly straight in _front_ of the middle
lobe," be not the commencement of the articulations of the abdomen. The
whole fragment looks very much like the head of some large Asaph or
Ogygia.


Genus Brongniatia. _Eaton._

Professor Eaton has proposed the name Brongniatia (Brongniartia?) for a
genus of trilobites, which we think he has not defined with sufficient
accuracy to be of any practical use. The _Isotelus gigas_ of Dr. Dekay,
which has been for a long time so well established, is here ranked
merely as a species under the name of B. isotela. The relic which we
described before the Geological Text Book appeared as the _Triarthrus
Beckii_, forms the species B. carcinodea--and the trilobite which is
supposed to be the Asaphus platycephalus of Stokes, is the only other
species mentioned. The A. platycephalus,[48] we know to be identical
with the I. gigas, and as the animal remain described by Mr. Eaton
is entirely different from Dr. Dekay's fine species, we subjoin the
account given in the "Text Book."

[Footnote 48: For a figure and description of the Asaphus
Platycephalus, by Mr. Stokes, see Transactions of the Geological
Society. Second Series, vol. i.]

Genus Brongniatia--Fore abdomen always, and post abdomen in some
cases, longitudinally divided into three lobes, by regular series of
undulations traversing the joints, without grooves; articulations of
the side lobes being manifest continuations of those of the middle
lobe, and consequently, agreeing in number.


Brongniatia Platycephala. _Eaton._

Head and fore abdomen very broad and depressed, the abdomen with ten
joints curved forwards at the undulations; post abdomen and tail with
about fifteen joints curved backwards at the undulations; the three
lobes of the tail more distinctly separated; divisions between the
joints of the abdomen double.

The representation of B. platycephala, figure 20, plate 2, of the
Geological Text Book, if it be accurately drawn, is certainly of a
trilobite never before described. On the buckler, which is without
eyes, there is delineated a figure, not unlike some of the leaves of
the mulberry tree.

The tail is also very peculiar. In Silliman's Journal, Volume 21st,
page 136, Professor Eaton proposed for this curious fossil the
temporary name of Ogygies latissimus. It is found, he observes, "in the
upper soft slaty variety of the rock which has been so successfully
used for the lias cement at Chitteningo, &c. Dr Smith, of Lockport,
(N. Y.) sent me two specimens, taken from a continuation of the
Chitteningo lias rock, immediately beneath the geodiferous lime rock
on which the cherty (cornitiferous) reposes." The whole animal is six
inches long, and three broad.




Nature of the Trilobite.


Every one familiar with the history of the Trilobites, is aware that
a good deal of controversy has existed among naturalists, respecting
the precise link in the grand chain of organized beings, these
singular fossil animals, should occupy. Professor Brongniart, Dr.
Dekay, Audoúin, and several other acute observers, have placed them
in the vicinity of the Limuli, and other Entomostraca with numerous
feet; while P. A. Latreille and others, presuming that these animals
were destitute of locomotive organs, as no vestige of them has ever
been discovered, fix their natural position in the neighbourhood of
the Chitones; or rather that they constituted the original stock of
the Articulata, being connected on the one hand with these latter
Mollusca, and on the other with those first mentioned, and even
with the Glomeris.[49] It was our original intention to have closed
this Monograph with a short history of these theories--and of the
notion advanced by Latreille and others, that the Trilobites have
been annihilated by some ancient revolution of our planet. All these
matters, we think, are now put to rest by the late discovery of some
living Trilobites in the southern seas, near the Falkland Islands. In
the cabinet of the Albany Institute, we have examined some of these
recent animals, which have very nearly the size and general appearance
of the Paradoxides Boltoni, as represented on our frontispiece; the
species cannot, however, belong to that genus, as the buckler is
furnished with eyes very similar to those of the Calymene Bufo; its
organs of locomotion are short, numerous, and concealed under the
shell--but I do not feel at liberty to notice the interesting animal
more minutely. It will probably be described and figured shortly, in
a perfectly full and satisfactory manner, by Dr. James Eights, the
enterprising discoverer, together with several other new and remarkable
genera and species belonging to the Entomostraca.

[Footnote 49: See Cuvier's Animal Kingdom, vol. iii. pp. 135-6.]



FINIS.


                       Index to the Species.
                             ————

            CALYMENE Blumenbachii,           page 28
                     Callicephala,                30
                     Selenecephala,               31
                     Platys,                      32
                     Microps,                     34
                     Anchiops,                    35
                     Diops,                       37
                     Macrophthalma,               39
                     Bufo,                        41
                     Rana,                        42
            ASAPHUS  Laticostatus,                45
                     Selenurus,                   46
                     Limulurus,                   48
                     Caudatus,                    50
                     Hausmanni,                   52
                     Pleuroptyx,                  55
                     Micrurus,                    56
                     Wetherilli,                  57
            PARADOXIDES Boltoni,                  60
            OGYGIA   Sillimani,                   63
            ISOTELUS Gigas,                       67
                     Planus,                      68
                     Cyclops,                     69
                     Megalops,                    70
                     Stegops,                     71
            CRYPTOLITHUS Tessellatus,             73
                     Bigsbii,                     76
            DIPLEURA Dekayi,                      79
            TRIMERUS Delphinocephalus,            82
            CERAURUS Pleurexanthemus,             84
            TRIARTHRUS Beckii,                    87
            NUTTAINIA Sparsa,                     89
            BRONGNIATIA Platycephala,             91


                             JOSEPH BRANO,

                 No. 12, CASTLE STREET, PHILADELPHIA,

         _Teacher of the Art of Preparing Birds, Quadrupeds,
                         Reptiles, &c. &c._

                              AND OF THE

            Art of making Moulds and Casts in Wax, Plaster,
                           and Compositions.

In addition to the casts taken from the originals of the Trilobites,
he has also a few fine casts of the bones of the Megalonix Laqueatus,
_Harlan_.--Scaphites Cuvieri, _Morton_.--Mosasaurus tooth, and of
several rare fossil American Plants;--all taken from the original
fossils, in the Cabinet of the Academy of Natural Sciences, &c. &c.
These models are fac similes of the real objects, coloured according to
nature.

As the originals of the above are in the possession of different
public and private cabinets throughout the United States, I have at
great trouble and expense, taken from them exact patterns, so as
to accommodate museums and scientific gentlemen with them on very
reasonable terms. This practice is now used in several parts of Europe;
and thus the curious are able to supply their cabinets with rare
specimens, often superior to the originals.

                             ·—▸⏵►●◓●◄⏴◂—·


JOSEPH BRANO having finished for us a number of models of different
objects in Natural History, we have no hesitation in recommending him
as an exceedingly skilful artist.

                                          Jacob Green, M. D.
                                          Rich'd. Harlan, M. D.
                                          P. A. Browne, ESQ.
                                          Chas. A. Poulson.
                                          Isaac Parrish, M. D.
                                          S. G. Morton, M. D.

_Philadelphia, October 3d, 1832._

       *       *       *       *       *


Transcriber Note

Minor typos corrected. The quotation on page 91 has been corrected
based on the original article found at The Internet Archive.