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             [Illustration: Slab with fossil impressions]




                               REMARKS
                               ON SOME
                           FOSSIL IMPRESSIONS
                                  IN
                 THE SANDSTONE ROCKS OF CONNECTICUT RIVER.

                                  BY
                         JOHN C. WARREN, M.D.
          PRESIDENT OF THE BOSTON SOCIETY OF NATURAL HISTORY.

                        [Illustration: Logo]

                                BOSTON:
                          TICKNOR AND FIELDS,
                        135, Washington Street.
                                 1854.



                                BOSTON:
                   PRINTED BY JOHN WILSON AND SON,
                          22, School Street.




The principal part of these remarks were made at the meetings of
the BOSTON SOCIETY OF NATURAL HISTORY. A portion of them also
have been printed in the Proceedings of the Society.

The object of this publication is to afford to those who are not
members of the Society an opportunity of obtaining some knowledge
of Fossil Impressions, which they might not be able to obtain
elsewhere so conveniently.

Some account of the Epyornis seems to be very properly connected
with Ornithichnites.

The first of these papers was written in October, 1853; the others
in the earlier part of the present year.




                      [Illustration: Epyornis]


                            THE EPYORNIS;

                                 OR,

                 GREAT BIRD OF MADAGASCAR, AND ITS EGGS.


In the course of the year 1851, an account was circulated of the
discovery of an immense egg, or eggs, in the Island of Madagascar. The
size of the eggs spoken of was so disproportionate to that of any
previously known, that most persons received the account with
incredulity; and, I must confess, I was one of this number. Being in
Paris soon after hearing of this report, I made inquiry on the
subject, and was surprised to learn, that the great egg was actually
existing in the Museum of Natural History in Paris. In a few days I
had an opportunity of seeing a cast of it in the hands of the artist,
M. Strahl, of whom I solicited one. He informed me that it could not
be obtained at that moment; but that, if my request were made known to
the Administration of the Museum, he had no doubt they would accede to
it. I accordingly did apply, and also presented them with the cast of
a perfect head of Mastodon Giganteus; and they very liberally granted
my request.

The distinguished naturalist, Professor Geoffroy St. Hilaire, the
second of that honorable name, has made a statement to the Academy of
Sciences, which, though only initiatory, contains many facts of a very
interesting nature, some of which I have had an opportunity of
verifying; and to him we are indebted for a greater part of the
others.

The eggs sent to me are, in number, two; one of which was purchased by
M. Abadie, captain of a French vessel, from the natives. Another was
soon afterwards found, equal in size. A third egg was discovered in an
alluvial stratum near a stream of water, together with other valuable
relics of the animal which had probably produced them; but,
unfortunately, it was broken during transportation. Of the two eggs,
one is of an ovoid form, having much the shape of a hen's egg; and the
other is an ellipsoid.

The ovoid egg is of enormous size, even when compared with the largest
egg we are acquainted with. Its long diameter exceeds thirteen inches
of our English measure, its short diameter eight, and its long
circumference thirty-three inches. Its capacity is thought to be equal
to eighteen liquid pints, or to be six times greater than that of the
largest egg known to us (the ostrich), although but twice its length.
It is said to be equal to a hundred and forty-eight hen eggs. The
ellipsoid egg has its longest diameter somewhat less than that of the
ovoid; its short diameter nearly equals that of the other egg, being
more than eight inches. The third egg, although broken, has been very
useful to science, by displaying the thickness of the shell, which is
about one-tenth of an inch.

The bones, of which I have received the casts, are three in number,
and of great interest. One of them is a characteristic fragment of the
upper part of a fibula; the other two, still more interesting, as
enabling us to determine the class and genus of the animal to which
they belong, exhibit the extremities of the right and left
tarso-metatarsal bones. The former is somewhat broken; the latter is
nearly perfect, and exhibits the triple division of the inferior
extremity of the bone into the three trochleæ or pulley-shaped
processes of the struthious birds. It might be mistaken for a bone of
the great Dinornis, but is distinguished from this by the flatness of
the portion above the trochleæ. Still less is it one of the bones of
the ostrich, its three pulleys being separated from each other by
distinct intervals; whereas the pulleys of the ostrich have only one
such separation, constituting two distinct eminences.

M. Geoffroy St. Hilaire considered himself justified, from these and
other facts, in deciding this bone to belong to a bird of a new genus,
to which he gives the name of EPYORNIS, from _aipys_, _high_,
_tall_, and _ornis_, _bird_; and, as probably it is a specimen of the
largest animal of the family, he affixes the specific name of
_maximus_.

The size of this bird, inferred from that of its egg, would be vastly
superior to that of the ostrich. But if we notice the comparative size
of the trochleated extremity of the tarso-metatarsal bone, we shall
see that its height would be greatly exaggerated by adopting such a
basis for its establishment; in fact, it would not probably exceed a
height double that of the ostrich. And, though it must have been
superior to that of the Dinornis maximus of Prof. Owen, it might
perhaps excel it only by the difference of two or three feet. A bird
of twelve or thirteen feet in height would, however, if we stood in
its presence, appear enormous, and must have greatly astonished and
terrified the natives of Madagascar. Whether it now exists is
uncertain, as it may possibly have a habitation in the wild recesses
of the island, which have never yet been visited by any European
traveller.

The credit of most of the observations and discoveries relating to
this remarkable bird is attributable to French naturalists;[A] and it
seems to be a duty devolving on English and American navigators to
complete the history thus happily begun, and to tell us whether the
Epyornis still exists in the mountain-forests of Madagascar, or at
least present us with its extraordinary relics.

  [Footnote A: The following are the names of French travellers, who
  have been supposed to have seen the eggs of the Epyornis in the
  Island of Madagascar: M. Sganzin, in 1831; M. Goudot, in 1833; M.
  Dumarele, in 1848; and M. Abadie, in 1850.]




                      FOSSIL IMPRESSIONS.--I.


Ichnology, a newly created branch of science, takes its name from the
Greek word _ichnos_, a _track_ or _footstep_, and the tracks
themselves have been denominated Ichnites, or, when they refer to
birds only, Ornithichnites, from _ornis_, a _bird_. And this last term
has by custom been generally applied to ancient impressions, though
not correctly.

Geology has revealed to us not only the remains of animals and
vegetables, but the impressions made by them during their lives, and
even the impressions of unorganized bodies. The first notice of these
appearances was, as often happens, regarded with indifference or
scepticism; but their number and variety enlightened the public mind,
and opened a new source of information and improvement.

The first remarkable observation made on fossil footsteps was that of
the Rev. Dr. Duncan, of Scotland, in 1828. He noticed, in a _new red
sandstone_ quarry in Dumfriesshire, impressions of the feet of small
animals of the tortoise kind, having four feet, and five toes on each
foot. They were seen in various layers through a thickness of forty
feet or more.

Sandstone, in which these impressions are principally discovered, is a
rock composed chiefly of siliceous and micaceous particles cemented
together by calcareous or argillaceous paste, containing salt, and
colored with various shades of the oxide of iron, particularly the
red, gray, brown. It has been remarked by Prof. H. D. Rogers, that the
perfection of the surface containing fossil footmarks is often
attributable to a micaceous deposit. The layers of sandstone have been
formed by deposits from sea-water, dried in succession; such layers
are also seen in the roofing slate. These deposits on the shores of
the ocean, having in a soft condition received the impressions of the
feet of birds, other animals, vegetables, and also of rain-drops,
under favorable circumstances dried, hardened, and formed a rock of
greater or less solidity. Our colleague, Dr. Gould, has exhibited to
us a specimen of dried clay from the shores of the Bay of Fundy,
containing beautiful impressions, recently made, of the footsteps of
birds. The particles brought by the waves, and deposited in the manner
described, were derived from the destruction of other rocks previously
existing, particularly granite and flint, or silex, the shining atoms
of which compose no small part of the sandstone rock.

It is easy to conceive, that, while these deposits were taking place
in the soft condition, portions of vegetable matters might become
intermixed; and that these, with the impressions of the feet and other
parts of animals and unorganized substances, might be preserved by the
process of desiccation. The agency of internal heat may have also been
employed in some cases in baking and hardening these crusty layers.

The sandstone rock, though in some places actually in a state of
formation at the present time, lies in such a manner in the earth's
crust as to indicate an immense antiquity. The age of these beds
varies in different situations. The sandstone rocks which contain the
greater part of the impressions are called _new red sandstone_, to
distinguish them from the _old red_, which is of a greater age. The
deposits on Connecticut River may not be attributed to the action of
this river, but are of higher antiquity, probably, than the river
itself, and proceeded from the waves of an ancient sea, existing in a
state of the surface of the globe very different from that of the
present day.

In 1834, tracks were discovered near Hildberghausen in Saxony, to
which Prof. Kaup, of Darmstadt, gave the name of Chirotherium, from
the resemblance to the impressions of the human hand. On a subsequent
examination, Prof. Owen preferred the name of Labyrinthodon, from the
resemblance of the folds in the teeth to the convolutions of the
brain.

Various other instances of impressions were seen; and, in the year
1835, Dr. Deane and Mr. Marsh, residents of Greenfield, noticed
impressions resembling the feet of birds in sandstone rocks of that
neighborhood. These observations having come to the knowledge of
President Hitchcock, of Amherst College, that gentleman began a
thorough investigation of the subject, followed it up with unremitted
ardor, and has, since 1836 (the date of his first publication), laid
before the public a great amount of ichnological information, and
really created a new science. Dr. Deane, on his part, has not been
idle: besides making valuable discoveries, he has written a number of
excellent papers to record some portion of his numerous observations.

In 1837, at the request of my friend Dr. Boott, I carried to London,
for the Museum of the Royal College of Surgeons, various scientific
objects peculiar to this country; among which were a number of casts
of Ornithichnites.

These casts were kindly furnished me by President Hitchcock, and the
Government of the Royal College thereon voted to present to President
Hitchcock and Amherst College casts of the skeleton of the famous
Megatherium of South America. These casts were packed, and sent to be
embarked in a ship destined for Boston, but were unluckily delivered
to a wrong shipping house in London, and I lost sight of them for some
time. They were at length discovered. After remaining in this
situation for more than a year, they were sold at public auction; and,
notwithstanding many efforts on my part, I was unable to obtain and
transmit them to Amherst College.

The fossil impressions which have been distinguished in various places
in the new red sandstone are those of birds, frogs, turtles, lizards,
fishes, mollusca, crustacea, worms, and zoophytes. Besides these, the
impressions made by rain-drops, ripple-marks in the sand, coprolites
or indurated remains of fæces of animals, and even impressions of
vegetables, have been preserved and transmitted from a remote
antiquity. No authentic human impressions have yet been established;
and none of the mammalia, except the marsupials.(?) We must, however,
remember that, although the early paleontology contains no record of
birds, the ancient existence of these animals is now fully
ascertained. Remains of birds were discovered in the Paris gypsum by
Cuvier previous to 1830. Since that time, they have been found in the
Lower Eocene in England, and the Swiss Alps; and there is reason to
believe that osseous relics may be met with in the same deposits which
contain the foot-marks. Most of the bird-tracks which have been
observed, belong to the wading birds, or Grallæ.

The number of toes in existing birds varies from two to five. In the
fossil bird-tracks, the most frequent number is three, called
tridactylous; but there are instances also of four or tetradactylous,
and two or didactylous. The number of articulations corresponds in
ornithichnites with living birds: when there are four toes, the inner
or hind toe has two articulations, the second toe three, the third toe
four, the outer toe five. The impressions of the articulations are
sometimes very distinct, and even that of the skin covering them.

President Hitchcock has distinguished more than thirty species of
birds, four of lizards, three of tortoises, and six of batrachians.

The great difference in the characters of many fossil animals from
those of existing genera and species, in the opinion of Prof. Agassiz,
makes it probable that in various instances the traces of supposed
birds may be in fact traces of other animals, as, for example, those
of the lizard or frog. And he supports this opinion, among other
reasons, by the disappearance of the heel in a great number of
Ornithichnites.

D'Orbigny, to whom we are indebted for the most ample and systematic
work on Paleontology ("Cours Elémentaire de Paléontologie et de
Géologie," 5 vols. 1849-52), does not accept the arrangement of
President Hitchcock. He objects to the term Ornithichnites, and
proposes what he considers a more comprehensive arrangement into
organic, physiological, and physical impressions. _Organic
impressions_ are those which have been produced by the remains of
organized substances, such as vegetable impressions from calamites,
&c. _Physiological impressions_ are those produced by the feet and
other parts of animals. _Physical impressions_ are those from
rain-drops and ripple-marks; and to these may be added coprolites in
substance. This plan of D'Orbigny seems to exclude the curious and
interesting distinctions of groups, genera, and species; in this way
diminishing the importance of the science of Ichnology.

Fossil impressions have been found on this continent in the
carboniferous strata of Nova Scotia, and of the Alleghenies; in the
sandstone of New Jersey, and in that of the Connecticut Valley in a
great number of places, from the town of Gill in Massachusetts to
Middletown in Connecticut, a distance of about eighty miles.

A slab from Turner's Falls, obtained for me by Dr. Deane in 1845,
measuring two feet by two and a half, and two inches in thickness,
contains at least ten different sets of impressions, varying from five
inches in length to two and a half, with a proportionate length of
stride from thirteen inches to six. All these are tridactylous, and
represent at least four different species. In most of them the
distinction of articulation is quite clear. The articulations of each
toe can readily be counted, and they are found to agree with the
general statement made above as to number. The impressions are
singularly varied as to depth; some of them, perfectly distinct, are
superficial, like those made by the fingers laid lightly on a mass of
dough, while others are of sufficient depth nearly to bury the toes;
some of the tracks cross each other, and, being of different sizes,
belong to animals of different ages or different species. There is one
curious instance of the tracks of a large and heavy bird, in which,
from the softness of the mud, the bird slipped in a lateral direction,
and then gained a firm footing; the mark of the first step, though
deep, is ill-defined and uncertain; the space intervening between the
tracks is superficially furrowed; in the settled step, which is the
deepest, the toes are very strongly indicated. On the same surface are
impressions of nails, which may have belonged to birds or chelonians.

The inferior surface of the same slab exhibits appearances more
superficial, less numerous, but generally regular. There are three
sets of tracks entirely distinct from each other; two of them
containing three tracks, and one containing two,--the latter being
much the largest in size. In addition, there is one set of tracks,
which are probably those of a tortoise. These marks present two other
points quite observable and interesting. One is that they are
displayed in relief, while those on the upper surface are in
depression. The relief in this lower surface would be the cast of a
cavity in the layer below; so the depressions in the upper surface
would be moulds of casts above. The second point is the
non-correspondence of the upper and lower surfaces; i.e. the
depressions in the upper surface have not a general correspondence
with the elevations on its inferior surface. The tracks above were
made by different individuals and different species from those below.
This leads to another interesting consideration, that in the thickness
of this slab there must be a number of different layers, and in each
of them there may be a different series of tracks.

To these last remarks there is one exception: the deep impression in
which the bird slipped in a lateral direction corresponds with an
elevation on the lower surface, in which the impression of these toes
is very distinctly displayed, and even the articulations. Moreover,
one of the tracks on the inferior surface interferes with the outer
track in the superior, and tends in an opposite direction, so that
this last-described footstep must have been made before the other. It
is also observable, that, while all the other tracks are superficial,
this last penetrates the whole thickness of the slab; thus showing
that the different deposits continued some time in a soft state.

On the surfaces of this slab, particularly on the upper, there are
various marks besides those of the feet, some of which seem to have
been made by straws, or portions of grass, or sticks; and there is a
curved line some inches in length, which seems to have arisen from
shrinkage.

In the collection of Mr. Marsh,[B] there were two slabs of great size,
each measuring ten by six feet, having a great number of impressions
of feet, and about the same thickness as the slab under examination.
One of these presented depressions; and the other, corresponding
reliefs. These very interesting relations were necessarily parted in
the sale of Mr. Marsh's collection; one of them being obtained for the
Boston Society of Natural History, and the other for the collection of
Amherst College.

  [Footnote B: Mr. Marsh was a mechanic of the town of Greenfield,
  and procured his subsistence by his daily labor. Being employed by
  Dr. Deane in obtaining the sandstone slabs of Ornithichnites, he
  acquired a taste for the pursuit, entered into it with
  extraordinary ardor, and accumulated by his own labors a great
  collection of fine specimens. He unfortunately fell into a
  consumption, and died in 1852. The collection was sold at public
  auction for a sum between two and three thousand dollars. The
  specimens were purchased by the Boston Society of Natural History,
  by Amherst College, and by varioud colleges and scientific
  associations in this country.]

The _Physical Impressions_, according to Professor D'Orbigny, are
of three kinds, viz.: 1st, Rain-drops; 2d, Ripple-marks; and 3d,
Coprolites. I have a slab which exhibits two leptodactylous
tracks very distinct, about an inch and a half long, surrounded
by impressions of rain-drops and ripple-marks. Another specimen
exhibits the impressions of rain in a more distinct and remarkable
manner. The imprints are of various sizes, from those which might
be made by a common pea to others four times its diameter; some
are deep, others superficial and almost imperceptible. They are
generally circular, but some are ovoid. Some have the edge equally
raised around, as if struck by a perpendicular drop; and others
have the edge on one part faintly developed, while another part is
very sharp and well defined, as if the drop had struck obliquely.
It has been suggested, that these fossil rain-drops may have been
made by particles of hail; but I think the variety of size and
depth of depression would have been more considerable if thus
made.

Although we have necessarily treated the subject of fossil
footmarks in a very brief way, sufficient has been said to show
that this new branch of Paleontology may lead to interesting
results. The fact that they are, in some manner, peculiar to this
region, seems to call upon our Society to obtain a sufficient
number of specimens to exhibit to scientific men a fair
representation of the condition of Ichnology in this quarter of
our country; and we have therefore great reason to congratulate
ourselves, that, through the vigilance and spirit of our members,
the Society has the expectation of obtaining a rich collection
of ichnological specimens.




                     FOSSIL IMPRESSIONS.--II.


Since writing the preceding article, I have been able to obtain,
through the kindness of President Hitchcock, a number of additional
specimens of fossil impressions. By the aid of these, I may hope to
give an idea of the system of impressions, so far as it has been
discovered, without, however, attempting to enter into minute details.
For these, I would refer to the account of the "Geology of
Massachusetts," by President Hitchcock; to his valuable article
published in the "Memoirs of the American Academy;" and to his
geological works generally.

The numerous tracks which have been assembled together in the
neighborhood of Connecticut River have afforded an opportunity of
prosecuting these studies to an extent unusual in the primitive rocky
soil of New England. These appearances are not, indeed, wholly new.
Such traces had been previously met with in other countries; but, in
their number and variety, the valley of the Connecticut abounds above
all places hitherto investigated.

Twenty years have elapsed since the study of Ichnology has been
prosecuted in this country; and, in this period of time, about
forty-nine species of animal tracks have been distinguished in the
locality mentioned, according to President Hitchcock; which have been
regularly arranged by him in groups, genera, and species.

I propose now to lay the specimens, recently obtained, before the
Society, as a slight preparation for the more numerous and more
valuable articles which they are soon to receive.

The traces found on ancient rocks, as has been shown in the previous
article, are those of animals, vegetables, and unorganized substances.
The traces of animals are produced by quadrupeds, birds, lizards,
turtles, frogs, mollusca, worms, crustacea, and zoophytes. These
impressions are of various forms: some of them simple excavations;
some lines, either straight or curved, and others complicated into
various figures.

President Hitchcock has based his distinctions of fossil animal
impressions on the following characters, viz.:--

     1. Toes thick, pachydactylous; or thin, leptodactylous.
     2. Feet winged.
     3. Number of toes from two to five, inclusive.
     4. Absolute and relative length of the toes.
     5. Divarication of the lateral toes.
     6. Angle made by the inner and middle, outer and middle toes.
     7. Projection of the middle beyond the lateral toes.
     8. Distance between tips of lateral toes.
     9. Distance between tips of middle and inner and outer toes.
    10. Position and direction of hind toe.
    11. Character of claw.
    12. Width of toes.
    13. Number and length of phalangeal expansions.
    14. Character of the heel.
    15. Irregularities of under side of foot.
    16. Versed sine of curvature of toes.
    17. Angle of axis of foot with line of direction.
    18. Distance of posterior part of the foot from line of direction.
    19. Length of step.
    20. Size of foot.
    21. Character of the integuments of the foot.
    22. Coprolites.
    23. Means of distinguishing bipedal from quadrupedal tracks.

By these characters, President Hitchcock has distinguished
physiological tracks, or those made by animated beings, into ten
groups provisionally. To these may be added, "organic impressions,"
made by organized bodies; and the impressions made by inanimate
bodies, called "physical impressions."

The specimens under our hands enable us to give some notion of the
distinctions which characterize the greater part of these groups.

       *       *       *       *       *

                     GROUP FIRST--STRUTHIONES.

The ostrich-tracks present a numerous natural and most remarkable
group; remarkable from the great size of some species,--all of them
tridactylous and pachydactylous. The ostrich of the Old World has only
two toes, but this family exists in South America at the present time
under the name of Rhea Americana; and tracks of an animal, probably of
the same family, are found in the numerous impressions near
Connecticut River,--all of them having three toes in front, and the
rudiment of a fourth behind.

This group contains a number of genera. The FIRST GENUS, denominated
_Brontozoum_, presents the tracks of a most extraordinary bird. These
tracks appear less questionable since the discovery in Madagascar of
the eggs of the Epyornis.

The tracks of the largest species, the BRONTOZOUM GIGANTEUM, are
four times the magnitude of those made by the existing ostrich of
Africa. They are very numerous, and congregated together. The foot of
the Brontozoum Giganteum, including the inferior extremity of the
tarso-metatarsal bone, which makes a part of the foot, measures in our
specimen twenty inches; in the Mastodon Giganteus, the foot measures
twenty-seven inches; the width also is less, being ten inches across
the metacarpals, while that of the Mastodon is twenty-two: but the one
is a bird, the other a quadruped. The toes are three in number, and
present the same divisions with existing birds; the inner toe having
three, the middle four, the outer five phalanges. Some of the
articulations of the toes of this noble specimen are remarkable for
the manner in which they illustrate the mode of formation of the
tracks. These phalanges have become separated from the solid rock in
which they were encased, so as to be removable at pleasure; and they
thus show that the whole foot is not a simple impression in the rock
which contains it, but a depression filled by foreign materials, i.e.
by sand, clay, and other relics of pre-existing rocks. These materials
had been gradually deposited in the mould formed by the bird's foot,
and are therefore independent of this rock, in the same way as the
plaster-of-Paris cast of a tooth, or any other body, is independent of
the mould to which it owes its form. The impressions are in gray
sandstone.

On the reversed surface of the slab is seen a small piece of broken
quartz, about half an inch square. This piece forms a beautiful
illustration of a part of the process by which the sandstone rocks are
formed.

The second species of the same genus is the BRONTOZOUM SILLIMANIUM.
Of this we have three specimens; the tracks have the same general
character with the preceding, but are smaller.

The third species of this genus is styled the BRONTOZOUM LOXONYX,
from _loxos_, a _bow_, and _onyx_, a _nail_,--a curved nail. It is
smaller than the Sillimanium, and has the nail set to one side.

The fourth species, still smaller, is the Brontozoum Gracillimum. On
this slab the impressions are in relief; viz.: 1st, of Brontozoum
Gracillimum; 2d, of Brontozoum Parallelum; 3d, of the track of a
tortoise, fourteen inches long, and two wide. Other extensive
eminences and depressions, with rain-drops, may be observed on the
same surface.

The fifth species is called BRONTOZOUM PARALLELUM, from the tracks
being on a line with each other. Of this there are two specimens, one
of them, however, being a single track. On the surface of the other
slab there are at least five distinct tracks, one of them being a
small new and undescribed species,--thus making the whole number of
species of Brontozoum which we possess to be at least six.

The SECOND GENUS of Struthiones is called _Æthyopus_, from
_aithuia_, a _gull_, and _pous_, a _foot_,--gull-footed. This genus
is smaller than the Brontozoum Giganteum; and we have two species,
viz. the ÆTHYOPUS LYELLIANUS, which is the larger, and two specimens
of ÆTHYOPUS MINOR. All of these are distinguished from the preceding
genus by the winged foot, and in the Lyellianus by the shallowness of
the impression. The Æthyopus Minor is not always distinguished by the
superficiality of its impression. This is sometimes deep. Therefore
this character may not be considered a distinctive one, or the
Æthyopus Minor might be referred to another genus. Of the two
specimens of this latter species, the first is in depression,
tridactylous. The depressions are deep with rain-drops, marks of
quadrupeds and zoophytes over the whole surface. The ornithichnic
impressions are two in number; one superficial, the other very deep.
The reversed surface of this slab contains one tridactylous impression
in relief. The second specimen has three depressions; two of which are
superficial, and the third is quite deep, displaying, by a depressed
surface, the webbed character of the foot.

       *       *       *       *       *

                            GROUP SECOND.

We shall take, to characterize this group, the _Argozoum_, from
_argês_, _swift_, _winged_.

Of this genus there are two species, the larger of which is the
ARGOZOUM DISPARIDIGITATUM. It is leptodactylous, and remarkable for
the length of the middle toe. We have another species, which is
smaller than the last named, and in which the toes are nearly of equal
length; hence called ARGOZOUM PARIDIGITATUM.

The other genus of this group is the PLATYPTERNA, and our specimen
is named _Deaniana_. This genus is remarkable for the width of the
heel; hence the name, from _platys_, _broad_, and _pterna_, _a heel_.
It has three toes like the other genera of this group.

       *       *       *       *       *

                             GROUP THIRD.

This and the succeeding group are tetradactylous; having one toe
behind, three forwards.

The third group is leptodactylous; foot usually small, but sometimes
of medium size. Of it we have two specimens, viz.: ORNITHOPUS
GALLINACEUS, and ORNITHOPUS GRACILIS. The former is so called from the
resemblance to the domestic fowl: for convenience sake, in this and
other instances, we use the whole for a part. It is about three inches
in length, and the Ornithopus Gracilis about two.

This latter specimen is particularly interesting. It consists of two
parts, which open like the covers of a book. These covers present four
impressions: first, the superficial, which is distinct, slender, and
beautiful--the heel is broad; second, corresponding with this
depression and on the inside, is a figure in relief as distinct as the
depression; third, on the inside of the second cover is a depression
corresponding with the relief last mentioned; fourth, on the outer
side is a second relief corresponding with the second depression, but
less distinct than either of the other three, still, however,
exhibiting three toes pointing anteriorly, but the hind toe is
wanting. The whole of this double slab forms a series of cameos and
intaglios, measuring four inches by three, and in thickness an inch
and a quarter.

       *       *       *       *       *

                            GROUP FOURTH.

Of the fourth group we have five specimens. The _Triænopus_, so called
from its resemblance to a trident, has besides three leptodactylous
toes pointing forwards, a fourth extending backwards in a remarkable
way, like the handle of a trident; the impression, however, being
expanded so as to show an extensive displacement of the mud. All the
specimens of Triænopus are in a beautiful red shale, very thin and
fragile, but presenting well-defined impressions, generally about
three inches long.

There are two species to this genus. Of the TRIÆNOPUS EMMONSIANUS we
notice three impressions in relief. In another specimen there is the
appearance of a part of the toes of the Anomoepus Scambus, and on the
upper side are seen two excavations corresponding with the three
impressions. In the last slab, the track of the TRIÆNOPUS BAILEYANUS
appears to have been made by two feet placed successively in the same
spot, which led President Hitchcock to suspect it might have been made
by a quadruped. One of the specimens has the Triænopus tracks
intermixed in a peculiar way with other impressions.

The specimen representing the genus HARPEDACTYLUS is larger than the
preceding; and, though leptodactylous, the toes are much broader and
also more curved, whence the name Harpedactylus, _sickle-finger_, from
_harpê_ and _daktylos_.

       *       *       *       *       *

                             GROUP FIFTH.

The fifth group differs much from the four previous ones. In this and
the following groups we pass from the vestiges of birds to those of
other animals, some of which are bipeds, some quadrupeds. Many
impressions are without any distinct character, belonging probably to
the lower animals, to vegetables, and unorganized bodies.

The fifth group comprehends the tracks of an extraordinary animal, the
OTOZOUM.[C] The name which has been given to it is taken from that
of an ancient giant, Otus, who with his brother Ephialtes, according
to heathen mythology, made war with the gods. These fabled giants
were, at nine years of age, nine cubits in width and nine fathoms in
height.

  [Footnote C: The specific name of Moodii has been attached to the
  Otozoum, from its having been discovered by Mr. Moody.]

The foot is divided into four toes; the two outer of which seem to be
connected by a common basis. The inner toe has three phalanges; the
second toe, also three; the third and fourth toes, four each. The
first is the shortest, the second longer, the third longest, the
fourth shorter than the third. It will appear, then, that this track
differs from that of birds in the number of toes pointing forwards;
these being four, while in birds the forward toes are only three.
There is a difference also in the number and arrangement of the
articulations.

The track in our possession is twenty inches long by thirteen and a
half inches broad. The rock in which it is imbedded is a dark-colored
sandstone. President Hitchcock has a slab showing a regular series of
tracks of this animal; the distance between the steps being about
three feet, and the tracks equidistant and alternate, which would not
be the case if the animal had been quadrupedal. In a quadruped, the
horse for example, the hind feet are set down near the fore feet, and
sometimes even strike them. Hence it must be inferred that the track
in question was that of a biped, or of a quadruped which did not use
its fore feet in progression, like a kangaroo. We naturally ask, What
kind of biped could this have been? Evidently not a man, the size of
the foot being too large to admit such a supposition; nor could it
have been a bird, the number of toes and their direction not admitting
this hypothesis.

Tetradactylous birds, or those which have four toes, have only three
of them directed forwards, and the fourth backwards, generally. There
are, however, exceptions; some birds have four toes directed forwards:
this is the fact with the Hirundo Cypselus and the Pelicanus Aquilus
of Linnæus, or Man-of-war Bird. But the articulations are different in
the two animals, birds having regularly two, three, four, and five
phalanges, and the spur, where it exists, supported by a single
osseous phalanx; whereas the Otozoum has three phalanges in the inner
and second toe, four in the third and fourth toes. In this last
arrangement, the Otozoum is decidedly different from all known birds.
It is not likely to have been a tortoise or a lizard. The kangaroo has
four feet, and uses only two in progression, moving forward by leaps;
also, like the Otozoum, it has four toes; but the size of the toes
does not accord with that of the Otozoum, nor is the structure of the
foot the same, so far as we know. It has been suggested by Professor
Agassiz, that this animal might have been a two-footed frog. Nature
had, in those days, animal forms different from those we are
acquainted with; and this might have been the fact with the Otozoum.

       *       *       *       *       *

                             GROUP SIXTH.

We have in this group a specimen of the track of a four-footed animal,
which may have been a frog, though different from ours. The feet are
unequal in size, and present a different number of toes. In existing
frogs there are four toes in the fore feet, and five in the hind; but,
in the specimen before us, the front toes are five in number, and the
back toes three. It is called, therefore, ANOMOEPUS, _unequal-footed_.
These impressions are in the red shale of Hadley, and very distinct.
In some of them the lower leg is indicated, forming an impression six
or seven inches long. The feet being smaller than the legs, the
impression made by the latter is more expanded, superficial, and
broader, yet still very definite. The opinion of President Hitchcock
and Dr. Deane is, that the different impressions of five and three
toes are those of the anterior and posterior extremities of one animal,
which, from the size of the limbs, might be a frog three feet high.

On the same schist with these footmarks, are other curious
impressions. The back of the slab is almost covered with the imprints
of rain-drops. In the midst of these is a tridactylous impression,
probably of a quadruped, crossed at its root by a single depression,
nearly an inch broad, and two and a half long: this seems to form part
of another broad superficial impression of about seven by four inches,
which is probably also quadrupedal. Other parts present the
impressions of nails and worm-tracks. At the opposite end is a deep,
smooth, regular excavation, which might have been made by a Medusa.

       *       *       *       *       *

                            GROUP SEVENTH.

The seventh group contains the impressions of the feet of Saurians or
lizards. We have a specimen of quadrupedal marks, with five toes to
each foot, about an inch long, which may have been made by these
animals. The impressions are small, but very distinct. There are
lizards of the present day with five toes, about the size of these
impressions; and these may, therefore, be set down as belonging to
this order of reptiles. Like a number of the last-named specimens,
they are in red shale.

       *       *       *       *       *

                            GROUP EIGHTH.

The eighth group is assigned by President Hitchcock to the Chelonian
or turtle tribe. The slab bearing impressions of Brontozoum
Gracillimum has a mark about fourteen inches long and two wide, which
may be attributed to the plastron or breast-plate of the tortoise. On
the slab from Turner's Falls there is a longitudinal furrow, which
might have been made by the tail of a turtle; and in various of our
slabs are impressions which we think belong to this tribe. We shall
have occasion to notice hereafter remarkable tracks of these animals
in the old red of Morayshire, in Scotland.

The most distinct of the traces of chelonians are on the large slab
lately obtained for me by President Hitchcock from Greenfield. (_Vide_
Plate.) This interesting slab contains the traces of quadrupeds,
various birds, and two trails of chelonians: the largest of these is
nearly five feet long, and four inches in diameter. The trail is
composed of a number of parallel elevations, comparatively
superficial.

       *       *       *       *       *

                             GROUP NINTH.

Of the ninth group, containing the marks of Annelidæ, Crustacea, and
Zoophytes, we have various specimens.

The impressions of insects do not seem as yet to have been
distinguished on the ancient rocks. There is reason to believe,
however, that many of the marks we discover in the rocky beds might
have been made by the feet and bodies of large insects; and small
species of the same tribes have been found imbedded in, and actually
constituting, immense masses of calcareous and siliceous rocks.

The tracks of worms are numerous. No doubt these worms drew together a
concourse of birds to the shores on which they rolled. On various
slabs we find long cylindrical furrows, about the eighth of an inch in
diameter, and of different lengths; one of them, in the slab from Dr.
Deane, being eight or nine inches long. To these impressions the name
of HERPYSTEZOUM, from _herpystês_, _crawling_, has been given. They
vary, however, and some of them are very likely to be the tracks of
the common earth-worm, or of some species of worm which existed when
these rocks were formed. These impressions vary in length and in
diameter; some of them are moderately regular, and others irregularly
curved.

Very interesting tracks have been found in the ancient Potsdam white
sandstone of Beauharnais, on the St. Lawrence, by Mr. Logan, an
excellent geologist of Canada, and determined by Professor Owen to
belong to Crustacea, crabs. The number of impressions made by each
foot is sometimes seven, sometimes eight, and even more. This track,
showing the traces of Crustacea, goes to form another link in the
chain of fossil footsteps.

The Medusæ, commonly called jelly-fish, dissolving as they do under
the influence of the sun and air, would hardly be expected to leave
their traces impressed on ancient rocks. Professor D'Orbigny, however,
has watched the dissolution of these animals on the sea-shore, and
found that, after wasting, they may leave their impressions on the
sand; which, not being disturbed by a high tide for nearly a month,
retains the impression of the zoophyte, and serves as a mould to
receive materials which take a cast and transmit it to subsequent
ages. We find one of these impressions on the slab of the Anomoepus
Scambus; and President Hitchcock, having examined it, is of opinion
that it retains the traces of a Medusa. The impression is about five
inches in diameter, of a darker color and smoother texture than the
rest of the rock. Its edges fade away gradually in the surface of the
subjacent sandstone. A similar impression is found on the superior
surface of the slab containing the Argozoum.

       *       *       *       *       *

                             GROUP TENTH.

The tenth group contains the HARPAGOPUS, a name derived from
_harpagê_, _seizure_, _rapine_. It is represented by President
Hitchcock as having the form of a drag. The figure given by him
resembles in a degree the foot of the African ostrich; being a long
thick toe, with a shorter one, not unlike a thumb, on the side. An
impression approximating this, but of small size, may be seen on the
slab of the Anomoepus Scambus.

       *       *       *       *       *

The formation of bird-tracks is well represented by a clay specimen,
about an inch thick, and ten inches long. This is a piece of dried
clay, obtained by President Hitchcock from the banks of the
Connecticut, and produced by washings from clay on the shore above,
covered with foot-impressions of a small tridactylous bird, and dried
in the sun. This piece shows, in a way not to be questioned, the
manner in which the ancient vestiges were produced. Sir Charles Lyell
noticed a similar fact on the banks of the Bay of Fundy.




                         ORGANIC IMPRESSIONS.


The _second_ great division of fossil impressions is called ORGANIC,
meaning impressions made by organized bodies; the bones of animals,
fishes, and vegetables.

Near one extremity of the slab of the Ornithopus Gallinaceus is an
elevation, about a foot long, and between one and two inches wide,
projecting from the surface nearly half an inch. It has the appearance
of a round bar of iron imbedded in the rock, which is clayey
sandstone. This apparent bar of iron was probably a bone, buried in
the stone, now silicified and impregnated with iron; the animal matter
having entirely disappeared. In the slab of the Brontozoum Sillimanium
is a projection about seven or eight inches long, and half an inch
wide; probably the bone of an animal, perhaps a clavicle of the
Brontozoum Giganteum.

The vestiges of fishes are very numerous in the sandstone rocks of
Connecticut River. We have not less than two dozen specimens from this
locality; a number equal to all the other specimens in our collection.
These impressions of fishes are generally from three to six inches
long, and three or four inches wide. They are of the grand division
denominated by Professor Agassiz "heterocercal," having their tails
unequally bilobed, from the partial prolongation of the dorsal spine;
and they are considered to be of lower antiquity than the fishes which
are entirely heterocercal. The most remarkable of the fish-specimens
in our collection is a CEPHALASPIS (?): this fish is found in the
specimen containing tracks of the Brontozoum Gracillimum, and traces
of a turtle or tortoise. This fossil was discovered in the upper layer
of the old red sandstone of Scotland, and had been mistaken by some
for a trilobite: to us it appeared to be a Limulus, but further
observation leads us to believe it to be a _Cephalaspis_. It exhibits
a convex disc, four inches across, by two inches from above downwards,
and a tail at right angles with the disc, the uncovered part of which
is three inches long. The animal has been described by Professor
Agassiz as being composed of a strong buckler, with a pointed horn at
either termination of the crescent, and an angular tail.

To the vegetable impressions discovered among the sandstone rocks a
peculiar name has not yet been assigned. When, however, we consider
the strong probability that many impressions of stalks, leaves,
fruits, and other parts of vegetables, may be hereafter discovered in
these rocks, it will be found convenient to have a distinctive
denomination. Vast numbers of vegetable impressions of a distinct and
beautiful appearance, and in great variety, have been found in the
coal-formation, which is nearly allied to the sandstone: such are the
Sigillaria, Stigmaria, Equisetaceæ, Lycopodiaceæ, Coniferæ, Cycadeæ,
&c. It is sufficient to say that the number of these has been already
swelled to many hundreds: we must also believe, that some of the
impressions in sandstone rocks which have been assigned to other
substances ought to be attributed to vegetables. We may, therefore,
venture to call the vegetable impressions "phytological."

A number of our slabs bear impressions of vegetables; either twigs of
trees, or spires of plants. In a fragment broken from one of the toes
of the Brontozoum Giganteum, we see a cylindrical depression, three
inches long, and half an inch in diameter, marked by transverse lines,
about the sixth of an inch apart, and presenting an unquestionable
appearance of a fragment of a twig of an ancient vegetable, which had
been trodden under the foot of the mighty Brontozoum. On the reversed
surface of the same slab are found impressions, which were produced by
a number of fragments of sticks, five or six inches long, lying at
right angles, or nearly so. One of these sticks has been broken, and
its pieces are slightly displaced from each other. Various other
specimens contain the marks of sticks, or twigs of trees. The striæ,
so distinctly discernable in a number of these portions, having been
compared with twigs of the existing coniferæ (?), were found to
resemble them. Some of these sticks show the appearance of incipient
carbonization; yet the rock is sandstone, presenting, as already
mentioned, distinct appearances of quartz, and other substances of
which the arenaceous rocks are composed.




                        PHYSICAL IMPRESSIONS.


The _third_ great division of impressions in the sandstone rocks is
called PHYSICAL, meaning those made by inanimate and unorganized
substances; such are rain-drops, ripple-marks, and coprolites.

1. Marks of rain-drops, described on page 20, appear to be quite
common. We have two or three specimens in relief, and as many in
depression. They occur as follows: 1st, on the upper surface of the
slab first described; 2d, on that of the Platypterna; 3d, on that of
the Æthyopus Lyellianus; 4th, on that of the Brontozoum Gracillimum;
5th, on that of the Æthyopus Minor; 6th, on that of the Anomoepus
Scambus; 7th, on the recent clay; also in one small hand-specimen, and
in a second containing two fishes. They show that, in those ancient
periods when the Brontozoum Giganteum and the Otozoum resided in these
parts, showers were frequent, and probably abundant for the supply of
the wants and the gratification of the appetites of these animals,
then common, but which now appear to us so extraordinary.

2. Ripple-marks are seen in a number of these pieces; for example, on
the slab first described, on the Brontozoum Sillimanium slab, on the
Brontozoum Gracillimum slab, on one of the Triænopus, and on the upper
surface of the Greenfield slab. These marks are represented by
parallel curves, or straight lines, distant from each other from half
an inch to an inch, and presenting a slight degree of prominence.
There is another form of ripple-marks(?), differing from those above
described. These are of a circular and mammillary form: they are
strewed thickly, like little islets, approximating to each other. They
are seen distinctly on one of the slabs of the Brontozoum Sillimanium,
on that of the Æthyopus Lyellianus, and some others. Whether they are
to be considered as accumulations of sand and clay, formed by the
action of the sea, we are uncertain; but there seems to be no other
cause to which they can be assigned with so great probability.

3. _Coprolites_, the fossilized ejections of animals, are intermixed
with other animal vestiges in the sandstone of Connecticut River, and
afford additional proof of the former existence of animals about these
rocks.

       *       *       *       *       *

The latest accounts of fossil footprints we have had occasion to
notice are those of the Crustacea, already mentioned, as found in
Canada, and of the Chelonian in Scotland. The Canadian impressions,
called by Professor Owen Protichnites, were discovered in the year
1847, and were laid before the London Geological Society in 1851. The
most remarkable circumstance about them was their existence, as
already stated, in a white sandstone, near the banks of the River St.
Lawrence, at Beauharnais. This sandstone, which has been described by
New York geologists under the name of Potsdam, is thought to belong to
the Silurian system, and to have a higher antiquity than even the "old
red."

The Scotch footsteps are situated in the old red sandstone, and are
those of a Chelonian. So that we have now two series of tracks, the
Crustacea in Canada and the Chelonian in Scotland, of higher antiquity
than any which had been previously discovered.

       *       *       *       *       *

On a review of the labors of President Hitchcock, we are struck with
admiration at the immense details that, in the midst of arduous
official and literary duties, he has been able to go through with in
the period since the foot-tracks were discovered on Connecticut River.
Although his labors should be modified by succeeding observers,
Science must be ever grateful to him for laying the foundation, and
doing so much for the completion, of a work so great, novel, and
interesting.

This inquiry seems to us to promise a rich variety; and we hope that
President Hitchcock and other observers will continue to explore and
cultivate it with undiminished zeal.




                       DESCRIPTION OF THE PLATE.


We are indebted to Photography for enabling us to represent the
remarkable slab from Greenfield, and its numerous objects, in a small
space, yet with perfect accuracy. This slab is four feet seven and
one-half inches in one direction, and four feet one inch transversely
to this; in thickness it measures about an inch. It is composed of
gray sandstone, in which the micaceous element is conspicuous, and
contains many interesting impressions on both surfaces.

The most interesting surface is the inferior; and the objects are, of
course, presented in relief. They are, first, two Chelonian tracks;
second, four sets of bird-tracks; third, footsteps of an unknown
animal. The _Chelonian tracks_ are two in number: the longest measures
four feet ten inches; the shorter, two feet nine inches. Both of these
impressions are made apparently by the plastron of the turtle. They
are from four to eight inches in width, and composed of elevated
striæ. These striæ are formed by raised lines, pursuing a course
generally regular, but accompanied with some inflections: they are, as
the plate represents, very distinct. The shorter track appeared to me
to be crossed by another; but the photographic impression, though only
a few inches long, enabled me to ascertain that this appearance was
produced by bird-tracks above and below.

The _bird-tracks_ are all tridactylous. The first set lies above and
to the right of the shorter turtle-track, and is composed of only two
steps, proceeding in the course of the plate downwards. The second set
of bird-tracks has five impressions, extending from the right superior
pointed angle of the slab across the small turtle-track to the larger,
in which it is lost. The third set of bird-tracks begins by an
impression larger than any other on the piece at the left extremity of
the longer turtle-track; and the remainder, three in number,
descending towards the right, are the least distinct of any. The
fourth set of bird-tracks begins below the longer turtle-track, and
ascends by four impressions, crossing the track till it meets the
first.

The most curious track, consisting of six digitated impressions, still
remains. The first is seen on the left of the longer turtle-track,
near the largest bird-track; the second is on the track; the third is
above the track; the others cross the slab by fainter impressions.
Each of them is composed by two feet, and each foot contains four
toes, which are seen more distinctly in some impressions than in
others. The largest of these double tracks is about three inches in
diameter. Perhaps it would be useless to speculate upon what kind of
animal they were made by. There is a similarity between these and the
tracks of the Anomoepus Scambus, spoken of in the sixth group. In the
latter, however, the toes are five and three. Some experienced persons
think they are tracks of the mink, Mustela Lutreola, an animal common
at the present day in these parts. This has five toes; but it may be
in this as in some other digitigrades, that one of the toes in each
foot does not make an impression; or perhaps it is safer to believe,
till further investigation is made, that it was an animal of a
construction not now existing.

The direction of these tracks presents a puzzle we are not able to
unravel; it exhibits the impressions of four toes, and we have
supposed it might possess five. In either of these cases, we have no
right to consider it a bird-track, but probably a reptile or a mammal.
Admitting this to be the fact, we are unable to account for the
direction of the steps, which is not alternate, as in the quadruped,
but in straight lines. In other words, this animal, supposed to have
four legs, gives us the impressions of two only, and both of these
placed together.

When the tridactylous tracks are attentively considered, compared with
each other, and with the digitated tracks, they appear to exhibit the
character of the impressions of the feet of birds so very decidedly,
that it would require something more than a philosophic incredulity to
question their ornithic origin.

The other side of this slab contains interesting impressions. In the
first place, this surface is covered with ripple-marks, each about two
inches broad, extending with various degrees of distinctness across
the slab, and having an interval of an inch. The width of the ridges
is greater than in any of the specimens we have seen.

This surface is almost covered by rain-drops. It has also, among other
impressions, one which has been drawn by Mr. Silsbee, our
photographist, and represented by the figure below of its proper size.
This figure, nearly four and a half inches in length, is an exact
resemblance in form, but not in size, of the great Otozoum, as
depicted by President Hitchcock, and shown by the actual impression,
in our hands, of the great foot, twenty inches long, and of
proportionate breadth. The form of the heel, or posterior part of the
foot, is the same in the two figures; the toes are equal in both, viz.
four in number; the two internal toes correspond in their
articulations, and the two external are nearly alike, with a little
allowance for a different amount of adipose texture. Whether this was
the impression of an infant Otozoum, I pretend not to determine: the
drawing was taken by a gentleman who knew nothing of the Otozoum.
There are similar impressions, smaller than that last described, on
the same surface.

The stone, though now very hard and intractable, having resisted all
the chemical agents we could employ, must have remained in a soft
state for some time; for the impressions of the foot shown below
penetrate to the opposite surface.

                [Illustration: Fossil foot impression]

In this description we have not attempted to point out all the objects
worthy of interest on both sides of this curious slab. Every part
of it is full of interest, and presents a field for protracted
observations. The surface represented in the plate may, by the aid of
a magnifier, be studied without the presence of the stone itself; for
the photographic art displays the most minute objects without
alteration or omission.




       *       *       *       *       *


                         Transcriber's Notes.

With the exception of several presumed typographical error which have
been changed as noted below, the text presented is that shown in the
original printed version. The original text included Greek characters.
For this text version these letters have been replaced with
transliterations. Also, the 'AE' and 'ae' ligatures are included (for
examples, Æthyopus and striæ); but the 'oe' ligatures (for example,
Anomoepus) are shown as 'oe' for readability as the ligature character
is not present in many fonts.

Typographical Errors:

    "Alleghanies" => "Alleghenies" (Pg. 18)
    "Mastodon Giganteus." => "Mastodon Giganteus," (Pg. 25)

Emphasis Notation:

     _text_   -   italicized