Produced by Tom Cosmas from materials made freely available
on The Internet Archive. All derived products are placed
in the Public Domain.









Transcriber Note

Text emphasis is denoted as _Italics_ and =Bold=. Whole and fractional
parts of numbers as 123-4/5.




THOUGHTS ON A PEBBLE.

[Illustration]

REEVE, BENHAM, AND REEVE, PRINTERS AND PUBLISHERS OF SCIENTIFIC WORKS,
KING WILLIAM STREET, STRAND.

[Illustration: GIDEON ALGERNON MANTELL, L.L.D. F.R.S

_Vice-President of the Geological Society &c. &c._]




                               THOUGHTS

                                 ON A

                                PEBBLE,

                                  OR,

                      A FIRST LESSON IN GEOLOGY.


              BY THE AUTHOR OF "THE WONDERS OF GEOLOGY."


[Illustration: _The Nautilus and the Ammonite._ _Vide_, p. 57.]


"There is no picking up a pebble by the brook-side, without finding all
nature in connexion with it."

  _Contemplations of Nature._

EIGHTH EDITION; WITH THIRTY-TWO ILLUSTRATIONS.


LONDON:

REEVE, BENHAM, AND REEVE, KING WILLIAM STREET, STRAND.

1849.


                                  TO

                                MY SON,

                   =Reginald Nebille Mantell, C.E.,=

                                 THESE

                        "THOUGHTS ON A PEBBLE"

                        ARE MOST AFFECTIONATELY

                              INSCRIBED.


  LONDON,

  19, CHESTER SQUARE, PIMLICO.

  1849.

"Every grain of sand is an immensity--every leaf a world--every insect
an assemblage of incomprehensible effects in which reflection is lost."

                                                               Lavater.


"To the natural philosopher there is no natural object that is
unimportant or trifling. From the least of Nature's works he may learn
the greatest lessons. The fall of an apple to the ground may raise his
thoughts to the laws which govern the revolutions of the planets in
their orbits; or the situation of a _pebble_ may afford him evidence of
the state of the globe he inhabits, myriads of ages before his species
became its denizens."

                                                 Sir J. F. W. Herschel.




TO THE READER.


Deeply impressed with the conviction that it is of the highest
importance the young and inquiring mind should have a correct idea
of natural phenomena--that it should not be left to its own unaided
efforts to unravel the mysteries of the beautiful world in which this
first state of being is destined to be passed--or have its curiosity
stifled or misled by unsatisfactory or erroneous conjectures--I have
endeavoured in this little work to explain in a simple and attractive
guise, some of the grand truths relating to the ancient physical
history of our planet, which modern geology has established.

The favourable reception of these desultory "_Thoughts_" which
were originally penned for the amusement and instruction of an
intelligent boy, is a gratifying proof that the attempt has not been
unsuccessful; and I would fain indulge the hope, that this "_First
Lesson in Geology_" may still be productive of good, by exciting in
some youthful minds a desire for the acquisition of natural knowledge;
and inculcating the important truth, that He who formed the Universe
has created nothing in vain; that His works all harmonize to blessings
unbounded by the mightiest or most minute of His creatures; and that
the more our knowledge is increased, and our powers of observation are
enlarged, the more exalted will be our conception of His wondrous works.

  Chester Square,
  Pimlico.




CONTENTS.


                                                          Page.

  Thoughts on a Pebble: Part I.                              5

  More Thoughts on a Pebble: Part II.                       33

  "The Nautilus and the Ammonite"                           57

  Supplementary Notes                                       61

  Note I.    _Shells in Chalk_                              61

  ---- II.   _Wood in Flint_                                66

  ---- III.  _Whitby Ammonites_                             69

  ---- IV.   _Fossil Nautili_                               72

  ---- V.    _Brighton Cliffs_                              75

  ---- VI.   _Rotaliæ in Chalk and Flint_                   79

  ---- VII.  _Isle of Wight Pebbles_                        82

  ---- VIII. _Zoophytes of the Chalk_                       87

  ---- IX.   _Minute Corals from the Chalk_                 92

  ---- X.    _Infusorial Earths_                            97




LIGNOGRAPHS.


                                                          Page.

   1. Vignette of Title-page.

   2. Fossil Turban-echinus (_Cidaris_), with spines.        9

   3. Bivalve with spines (_Plagiostoma spinosum_) in
        chalk; from Lewes.                                  11

   4. Teeth of several species of the Shark tribe, in
        chalk; from Lewes.                                  12

   5. Chalk-dust highly magnified, consisting of minute
        shells.                                             13

   6. Shells (_Rotaliæ_) from the chalk, highly magnified.  14

   7. Ammonite (_A. communis_) from the Lias, at Whitby.    20

   8. Nautilus (_N. elegans_) from the chalk-marl, Lewes.   22

   9. View of the Cliffs east of Brighton.                  27

  10. Fossil animalcules (_Xanthidia_) in flint.            35

  11. _Xanthidium palmatum_, in flint.                      37

  12. Rotalia in flint.                                     39

  13. Minute scales of fishes in flint.                     40

  14. Choanites from the chalk; near Lewes.                 44

  15. A branch of fossil coral attached to the pebble       46

  16. Coral-polype in flint.                                47

  17. Minute Corals from chalk.                             50

  18. Fossil cases or shields of animalcules from
        Richmond, Virginia; highly magnified.               53

  19. Several species of Lamp-shells (_Terebratulæ_) from
        the chalk, near Brighton.                           63

  20. Silicified Oyster from the chalk.                     65

  21. Coniferous wood in flint, from Lewes Priory.          68

  22. Several species of Ammonite.                          69

  23. The body of a recent microscopic animalcule
        (_Nonionina_), the shell having been removed by
        immersion in acid.                                  81

  24. A branch of Sponge in flint; a minute Coral from
        chalk; and a section of a pebble enclosing a
        zoophyte (_Siphonia Morrisiana_).                   85

  25. Flints deriving their shapes from Zoophytes
        (_Ventriculites_).                                  89

  26. Ventriculites in chalk; from Lewes.                   90

  27. Portions of three kinds of recent corals.             94




LITHOGRAPHS.

                                                          Page.

  Plate I. A rolled flint pebble, having a Choanite as a
    nucleus, and the remains of an echinus and spine,
    shell, and coral, apparent on the surface.               5

  Plate II. A longitudinal section of the pebble, showing
    the structure of the enclosed _Choanite_.               42

  Plate III. A polished section of an Ammonite, having
    the septa or chambers filled with variously coloured
    spar, &c.                                               70

  Plate IV. Polished sections of two pebbles from the
    Isle of Wight; in the upper specimen, the transition
    from opaque flint to cloudy chalcedony and
    transparent quartz crystals, is beautifully shown;
    the lower specimen is richly tinted; the dark
    appearance is derived from manganese.                   86

[Illustration: _Plate I._

"THE PEBBLE"


_Page 5_]




                               THOUGHTS

                                 ON A

                                PEBBLE.

  "Honoured, therefore, be thou, thou small pebble, lying in the lane;
  and whenever any one looks at thee, may he think of the beautiful and
  noble world he lives in, and all of which it is capable."

                                  Leigh Hunt's _London Journal_, p. 10.




PART I.


Well might our immortal Shakspeare talk of "_Sermons in stones_;" and
Lavater exclaim, that "_Every grain of sand is an immensity_" and the
author of 'Contemplations of Nature' remark, that "_there is no picking
up a pebble by the brook-side without finding all nature in connexion
with it._"

I shall confine my remarks to a _flint_ pebble, as being the kind of
stone familiar to every one. The pebble I hold in my hand was picked
up in the bed of the torrent which is dashing down the side of yonder
hill, and winding its way through that beautiful valley, and over those

  Huge rocks and mounds confus'dly hurl'd.
  The fragments of an earlier world,

which partially filling up the chasm, and obstructing the course of
the rushing waters, give rise to those gentle murmurings that are so
inexpressibly soothing and delightful to the soul.

[Sidenote: ORIGIN OF THE PEBBLE.]

Upon examining this stone I discover that it is but the fragment of a
much larger mass, and has evidently been transported from a distance,
for its surface is smooth and rounded, the angles having been worn
away by friction against other pebbles, produced by the agency of
running water. I trace the stream to its source, half way up the hill,
and find that it gushes out from a bed of gravel lying on a stratum of
clay, which forms the eminence where I am standing, and is nearly 300
feet above the level of the British Channel. From this accumulation of
water-worn materials the pebble must have been removed by the torrent,
and carried down to the spot where it first attracted our notice; but
we are still very far from having ascertained its origin. The bed of
stones on the summit of this hill is clearly but a heap of transported
gravel--an ancient sea-beach or shingle--formed of chalk-flints, that
at some remote period were detached from their parent rock, and
broken, rolled, and thrown together, by the action of the waves. We are
certain of this because we know that flints cannot grow;[A] that they
were originally formed in the hollows or fissures of other stones; and
upon inspecting the pebble more attentively, we perceive, not only that
such was the case, but also that it has been moulded in _Chalk_, for it
contains the remains of certain species of extinct shells and corals,
which are found exclusively in that rock. Here then a remarkable
phenomenon presents itself for our consideration; this flint, now so
hard and unyielding, must once have been in a soft or fluid state,
for the delicate markings of the case and spine of an _Echinus_, or
Sea-Urchin, are deeply impressed on its surface;[B] and a fragile shell
with its spines, is partially imbedded in its substance.[C] Nay more,
upon breaking off one end of the pebble,[D] we find that a sponge, or
some analogous marine zoophyte, is entirely enveloped by the flint;
and also that there are here and there portions of minute corals, and
scales of fishes. What a "_Medal of Creation_" is here--what a page of
nature's volume to interpret--what interesting reflections crowd upon
the mind!

[A] "_Flints cannot grow._"--Here I would digress for a moment to
notice an opinion so generally prevalent, that perhaps some of my
young readers will not be prepared at once to answer the question--_Do
stones grow?_ The farmer who annually ploughs the same land, and
observes a fresh crop of stones every season, will probably reply in
the affirmative; and the general observer who has for successive years
noticed his gardens and plantations strewn with stones, notwithstanding
their frequent removal, may possibly entertain the same opinion; but
a little reflection will show that stones cannot be said to grow or
increase, in the proper acceptation of the term. Animals and plants
grow, because they are provided with vessels and organs by winch they
are capable of taking up particles of matter and converting them
into their own substance; but an inorganic body can only increase in
bulk by the addition of some extraneous material; hence stones may
become incrusted, or they may be cemented together and form a solid
conglomerate, but they possess no inherent power by which they can
increase either in size or number--_they cannot grow_.

[B] Plate I, _a_.

[C] Plate I, _b_.

[D] Plate I, _c_.

[Sidenote: FOSSIL ECHINUS WITH SPINES.]

[Illustration: Lign. 2:--Fossil Turban Echinus, with its
spines; in limestone.

(See '_Medals of Creation_', p. 340.)]

[Sidenote: FOSSIL SHELLS IN CHALK.]

[Illustration: Lign. 3:--Shell with spines, imbedded in Chalk;
from Lewes. (See '_Medals of Creation_,' 1 p. 390.)]

To avoid confusion, we will reverse the order of our inquiry, and first
contemplate the formation of the flint in its native rock. The Chalk,
that beautiful white stone, which (as an American friend, who saw it
for the first time, observed), is so like an artificial production,
abounds in marine shells and corals, and in the remains of fishes,
crabs, lobsters, and reptiles, all of which differ essentially from
living species; although a few of the corals and shells resemble, in
some particulars, certain kinds that inhabit the seas of hot climates.
These remains are found in so perfect a state--the shells with all
their spines and delicate processes (_Lign. 3_), and the fishes with
their teeth (_Lign, 4_), scales, and fins, entire--that no doubt can be
entertained of the animals having been surrounded by the chalk while
living in their native sea, and that many of them were entombed in
their stony sepulchres suddenly, when the rock was in the state of mud,
or like liquid plaster of Paris.[E]

[E] See Note I. _Shells in the Chalk._

[Illustration: Lign. 4:--Fossil teeth of Fishes of the Shark
family, in Chalk; from Lewes. (See '_Medals of Creation_.' p. 625.)]

[Sidenote: SHELLS AND FISHES IN CHALK.]

But besides the fossils which are obvious to the unassisted eye, the
Chalk teems with myriads of minute forms that may readily be detected
with a lens of moderate power; and even when these have been extracted,
the residue, which appears to be merely white calcareous earth, is
found, when examined under the microscope, to consist almost wholly of
bodies yet more infinitesimal--of perfect shells and corals, so minute,
that a cubic inch of chalk may contain upwards of a million of these
organic remains (see _Lign. 5_)!

[Illustration: Lign. 5:--A few grains of Chalk-dust highly
magnified, and shown to consist of shells, &c.

  _a, a_, Shells called Rotalia.

     _b_, ------------- Textularia.

  (See '_Medals of Creation_,' p. 232.)

]


The Chalk is stratified--that is, divided into _strata_ or layers--as
if a certain quantity of mud had sunk to the bottom of the sea, and
enveloped the shells, corals, &c., which fell in its way, and had
become somewhat solid before another layer was deposited upon it.

[Sidenote: FLINT NODULES AND VEINS.]

The mineral substance termed _silex_ or _flint_, is variously
distributed in the chalk. It most commonly occurs in the state of
nodules of an irregular or spheroidal, globular figure, which are
arranged in rows parallel and alternating with, the cretaceous strata;
it is likewise disposed in continuous thin layers, which are spread
over considerable areas; and it often forms horizontal, vertical, and
oblique veins, that fill up the fissures and interstices of the chalk.
The siliceous nodules frequently enclose corals, shells, sponges,
and other organic remains, as in the pebble before us; and in many
instances these fossils are found partly imbedded in the chalk and
partly invested with flint. But though flints contain in abundance
relics of the same species of marine animals as the chalk, they are not
like that rock composed of an aggregation of fossil remains; on the
contrary, the siliceous earth, which is their constituent substance,
was evidently once in a state of complete solution in water, and
precipitated into the chalk before the latter was consolidated, the
organic bodies serving as nuclei or centres around which the silex
concreted; for the deposition of the flint, like that of the chalk,
appears to have taken place periodically.[F]

[F] Note II. _Wood in flint._

[Illustration: Lign. 6:--Minute fossil shells from Flint and
Chalk, very highly magnified, and seen by transmitted light.

  1, 2, 3, 6, Rotaliæ;

  4, Portion of a Nautilus;

  5, Rotalia composed of flint.

  (See '_Medals of Creation_,' p. 232.)

]

[Sidenote: ANIMALCULES IN CHALK.]

The composition of the Chalk, and the prevalence throughout that rock
of the relics of animals that can only live in salt-water, prove
incontestably that the chalk and flint were deposited in the sea;
and that our beautiful South Downs, now so smooth and verdant, and
supporting thousands of flocks and herds, and the rich plains and
fertile valleys spread around their flanks, were once the bed of an
ocean. It is also evident not only that such must have been the case,
but also that the Chalk was deposited in the basin of a very _deep_
sea--in the profound abyss of an ocean as vast as the Atlantic.

[Sidenote: AMMONITES AND NAUTILI.]

From the absence of gravel, shingle, and sea-beach, it is certain that
the white chalk-strata were formed at a great distance from sea-shores
and cliffs; and this inference is confirmed by the swarms of shells
termed _Ammonites_ and _Nautili_, which we know from their peculiar
structure were, like the recent pearly Nautilus, inhabitants of deep
waters only. For these are chambered shells; that is, are divided
internally by thin transverse shelly septa or plates, into numerous
cells; the body of the animal occupied only the outer compartment,
but was connected with the entire series of chambers by a tube or
siphuncle, which passed through each partition. This mechanism
constituted an apparatus which contributed to the buoyancy of these
animals when afloat on the waves; for the Ammonites and Nautili were
able to swim on the surface, or sink to the depths of the ocean at
pleasure.

    The fragile Nautilus that steers his prow,
    The sea-born sailor of his shell canoe,
    The Ocean Mab, the fairy of the sea,
    O'er the blue waves at will to roam is free.
    He, when the lightning-winged tornadoes sweep
    The surf, is safe, his home is in the deep;
    And triumphs o'er the Armadas of mankind,
    Which shake the world, yet crumble in the wind.

                              Byron, _The Island_.

[Sidenote: WHITBY SNAKE-STONES.]

[Illustration: Lign. 7:--Ammonite from Whitby.]

The Ammonites, so called from the supposed resemblance of their shells
to the fabled horn of Jupiter Ammon, are only known in a fossil state;
but they must have swarmed in the ancient seas, for several hundred
species have been discovered in the Chalk and antecedent strata, though
none have been found in any deposits of more recent formation; at the
termination of the chalk epoch the whole race, therefore, appears to
have perished. The Ammonites are commonly termed _snake-stones_, from
the origin ascribed to them by local legends; those of Whitby are well
known (see _Lign. 7_).[G]

[G] Note III. _Whitby Ammonites._

    Thus Whitby's nuns exulting told--
    How that of thousand snakes, each one
    Was changed into a coil of stone,
        When holy Hilda prayed:
    Themselves, within their sacred bound,
    Their stony folds had often found.

                              Scott's _Marmion_.

[Illustration: Lign. 8:--Nautilus from the Chalk, near Lewes,
(one-eighth the natural size.)]

The Nautili were the contemporaries of the Ammonites, and many kinds
are found associated with those shells, in strata far more ancient than
the Chalk; and several species of both genera, as we have previously
shown, were inhabitants of the cretaceous ocean. When the Ammonites
became extinct, the Nautili continued to flourish, and numerous
examples occur in the strata that were deposited during the vast period
which intervened between the close of the Chalk formation, and the
dawn of the existing condition of the earth's surface. At the present
time two or three kinds only are known in a living state, and these are
restricted to the seas of tropical climes, and so seldom approach the
shores, that but few specimens of the animals that inhabit the shells
have been obtained.

The Nautilus, therefore, is one of those types of animal organization
that have survived all the physical revolutions to which the surface of
the earth was subjected during the innumerable ages that preceded the
creation of the human race.[H] This remarkable fact is portrayed with
much force and beauty by Mrs. Howitt, in the following stanzas:

[H] Note IV. _Fossil Nautili._

TO THE NAUTILUS.

    Thou didst laugh at sun and breeze
    In the new created seas;
    Thou wast with the reptile broods
    In the old sea solitudes,
    Sailing in the new-made light,
    With the curled-up Ammonite.
    Thou surviv'dst the awful shock,
    Which turn'd the ocean-bed to rock;
    And chang'd its myriad living swarms
    To the marble's veined forms.
    Thou wert there, thy little boat,
    Airy voyager! kept afloat,
    O'er the waters wild and dismal,
    O'er the yawning gulfs abysmal;
    Amid wreck and overturning,
    Rock-imbedding, heaving, burning,
    Mid the tumult and the stir,
    Thou, most ancient mariner!
    In that pearly boat of thine,
    Sail'dst upon the troubled brine.

[Sidenote: THE SEA-SHORE.]

We have thus acquired satisfactory proof that the flint of which our
pebble is composed, was once fluid in an ocean teeming with beings, of
genera and species unknown in a living state, and that it consolidated
and became imbedded in the chalk, which was then being deposited at
the bottom of the sea; hence the shells, corals, and other organic
remains, which we now find attached to its surface, and enclosed in
its substance. Thus much for the origin of the pebble; let us next
inquire by what means it was dislodged from its rocky sepulchre, cast
up from the depths of the ocean, and transported to the summit of the
hill whence it was dislodged by yonder torrent. If we stroll along the
sea-shore, and observe the changes which are there going on, we shall
obtain an answer to these questions; for

    There is a _language_ by the lonely shore--
    There is society where none intrudes,
    By the deep Sea, and music in its roar!

                              Byron.

The incessant dashing of the waves against the base of the
chalk-cliffs, undermines the strata, and huge masses of rock are
constantly giving way and falling into the waters. The chalk then
becomes softened and disintegrated, and is quickly reduced to the state
of mud, and transported to the tranquil depths of the ocean, where it
subsides and forms new deposits; but the flints thus detached, are
broken and rolled by attrition into the state of boulders, pebbles, and
gravel, and ultimately of sand.

[Illustration: Lign. 9:--View of Brighton Cliffs; looking
eastward from Kemp Town.[I]

  _a. Cliff's composed of chalk rubble._

  _b. Ancient elevated sea-beach._

  _c. Chalk forming the base of the Cliffs._

]

[I] Note V. _Brighton Cliffs._

[Sidenote: BRIGHTON CLIFFS.]

Now we must bear in mind, that had the chalk remained at the bottom of
the deep sea in which it was originally deposited, it would not have
been exposed to these destructive operations. It is therefore manifest,
that at some very distant period of the earth's physical history, the
bed of the Chalk-ocean was broken up, extensive areas were protruded
above the waters, lines of sea-cliffs were formed, and boulders, sand,
and shingle accumulated at their base. Subsequent elevations of the
land took place, and finally, the sea-beach was raised to its present
situation, which is several hundred feet above the level of the sea!

Every part of the earth's surface presents unequivocal proofs that the
elevation of the bed of the ocean in some places, and the subsidence
of the dry land in others, have been, and are still, going on; and
that, in truth, the continual changes in the relative position of the
land and water, are the effects of laws which the Divine Author of
the Universe has impressed on matter, and thus rendered it capable of
perpetual renovation:--

    Art, Empire, Earth itself, to change are doomed;
    Earthquakes have raised to heaven the humble vale,
    And gulfs the mountain's mighty mass entombed,
    And where the Atlantic rolls wide continents have bloomed.

                              Beattie.

[Sidenote: IMMUTABILITY OF THE SEA.]

Our noble poet, Lord Byron, in his sublime apostrophe to the Sea,
has most eloquently enunciated the startling fact revealed by modern
geological researches,--namely, that if the character of immutability
be attributable to anything on the surface of our planet, it is to the
ocean and not to the land!--

      Roll on, thou deep and dark blue ocean--roll!
      Ten thousand fleets sweep over thee in vain;
      Man marks the earth with ruin--his controul
      Stops with the shore:--upon the watery plain
      The wrecks are all thy deed, nor doth remain
      A shadow of man's ravage, save his own.
      When, for a moment, like a drop of rain.
      He sinks into thy depths with bubbling groan,
    Without a grave, unknell'd, uncoffin'd, and unknown!

      Thy shores are empires, changed in all save thee,--
      Assyria, Greece, Rome, Carthage, what are they?
      Thy waters wasted them while they were free,
      And many a tyrant since; their shores obey
      The stranger, slave, or savage,--their decay
      Has dried up realms to deserts:--not so thou,
      Unchangeable, save to thy wild waves' play--
      _Time writes no wrinkle on thine azure brow:_
    _Such as Creation's dawn beheld, thou rollest now!_

      Thou glorious mirror, where the Almighty's form
      Glasses itself in tempests; in all time,
      Calm or convulsed--in breeze, or gale, or storm,
      Icing the Pole, or in the torrid clime
      Dark-heaving, boundless, endless, and sublime--
      The image of Eternity--the throne
      Of the Invisible; even from out thy slime
      The monsters of the deep are made; each zone
    Obeys thee: thou goest forth, dread, fathomless, alone!

                              Childe Harold. _Canto IV._

[Sidenote: APOSTROPHE TO THE OCEAN.]

I will conclude this "first lesson" with the following beautiful
remark of an eminent living philosopher:[J]--"To discover order and
intelligence, in scenes of apparent wildness and confusion, is the
pleasing task of the geological inquirer; who recognises, in the
changes which are continually taking place on the surface of the globe,
a series of necessary operations, by which the harmony, beauty, and
integrity of the Universe are maintained and perpetuated; and which
must be regarded, not as symptoms of frailty or decay, but as wise
provisions of the Supreme Cause, to ensure that circle of changes, so
essential to animal and vegetable existence."

[J] Dr. Paris.

[Illustration]




                             MORE THOUGHTS

                                 ON A

                                PEBBLE.

  "Not a mote in the beam, not an herb on the mountain, not a pebble
  on the shore, not a seed far-blown into the wilderness, but contributes
  to the lore that seeks in all the true principle of life--the
  beautiful--the joyous--the immortal."

                                       Sir E. Bulwer Lytton's _Zanoni_.




PART II.


More thoughts on a pebble!--is not the subject exhausted? have not
all the hieroglyphics impressed on the flint been interpreted?--can
Science, like the fabled wand of the magician, call forth from the
stone and from the rock their hidden lore, and reveal the secrets they
have so long enshrined?--Gentle Reader! but one page of the eventful
history of the pebble has been deciphered; I proceed to transcribe this
natural record of the past, explain its mysterious characters, and
present to thy notice the marvels they disclose.

Our previous examination of the specimen showed that the flint had
once been in a fluid state, and had consolidated in a sea inhabited by
shells, echini, fishes, corals, sponges, and other zoophytes; and the
appearance of the fractured end (_Plate I, c_), indicated that some
organic body had formed the nucleus of the pebble, and that traces of
the structure of the original still remained. To ascertain if this
inference is correct, it will be necessary to divide the stone in a
longitudinal direction--but I will first strike off a small fragment,
and examine it by the aid of a microscope.

[Sidenote: FOSSIL ANIMALCULES.]

[Illustration: Lign. 10:--Fossil animalcules (_Xanthidia_) in
Flint.]

By a sharp blow of a hammer, a very thin and minute portion of the
flint has been detached (see _Lign. 10, fig. 1_); it is translucent,
and when held between the eye and a strong light, appears like a slice
of horn; and a few extremely minute specks may with difficulty be
detected. Under the microscope, five of these almost invisible points
are well defined, and present a radiated appearance (see _fig. 3_); but
I will substitute a higher power, and lo! they are seen to be distinct
globular or spherical bodies beset with spines (_fig. 3_); and with a
still more powerful lens, one which magnifies many hundred times, their
nature is completely displayed. The whole five possess this general
character--a central globular case or shell, from which radiate tubes
or hollow spines, that terminate in fringed or divided extremities
(_figs. 4, 5, 6_); but these bodies differ from each other in the
relative proportions of the shell and spines, and in the number,
shape, and length of the tubular appendages. The group, in short, is
separable into three distinct species, of the same kind of fossil
remains; and several other varieties occur in the chalk and flint. .

[Sidenote: XANTHIDIA IN FLINT.]

[Illustration: Lign. 11:--_Xanthidium palmatum_ in flint:
highly magnified.]

But what are these bodies?--They are the durable cases of animalcules,
many species of which swarm in our seas, and are so minute, that
thousands may be contained in a drop of water! In a living state,
the case is flexible and filled with a granular jelly, which is the
soft body of the animalcule, and the tubes and the outer surface are
invested with a similar substance. After death the soft parts dissolve;
but the case and its spines often remain unchanged.

In another magnified portion of the pebble, a specimen of the
microscopic discoidal shells which we have already seen compose the
greater part of the white chalk (_Lign. 5_, p. 14), is beautifully
displayed when viewed by transmitted light, under a highly magnifying
power (_Lign. 12_).[K] Our investigation has thus shown, that a great
part of the pebble is actually composed of the aggregated fossil
remains of animalcules, so minute as to elude our unassisted vision,
but which the magic power of the microscope reveals to us, preserved,
like flies in amber, in all their original sharpness of outline and
delicacy of structure.

[K] Note VI. _Rotaliæ in chalk and flint._

[Sidenote: ROTALIA IN FLINT.]

[Illustration: Lign. 12:--Rotalia in flint: highly magnified.]

On another fragment of this stone two glittering specks, not larger
than a pin's head, are discernible (_Lign. 9_): these with a magnifier
of moderate power, are seen at a glance to be scales of fishes. But
they differ from each other; both have the surface smooth, and without
enamel: in the one the margin or edge is simple (_fig. 3_); in the
other, it is divided like the teeth of a comb (_fig. 2_);--trifling as
this difference may appear, it is sufficient to enable the naturalist
to determine that the fishes which furnished these scales belonged to
two distinct orders, of which the Salmon and the Mullet are living
examples.

[Illustration: Lign. 13:--Scales of Fishes in flint.

  Fig. 1.--A fragment of the pebble with the scales of the natural size.

       2.--One of the Scales (of a species of _Beryx_) highly magnified.

       3.--The other Scale (of a species of _Salmo_).

]

[Illustration: _Plate II._

_Longitudinal section of the Pebble._

_Page 41._]




[Sidenote: SECTION OF THE PEBBLE.]

SECTION OF THE PEBBLE.

_Plate II._


We will now avail ourselves of the assistance of the lapidary, and
divide the pebble in a longitudinal direction;--what a beautiful and
interesting section is thus obtained! The markings observable on the
fractured portion of the stone (see Plate I, c), are thus
shown to have originated, as we surmised, from some organic body,
which the flint, when fluid, had penetrated and enveloped. The enclosed
fossil was obviously one of those soft marine zoophytes, allied to the
_Actiniæ_ or _Sea-Anemones_, which are of a globular, spherical, or
inversely conical shape, and consist of a tough, jelly-like substance,
permeated with tubes, disposed in a radiated manner around a central
cavity, or digestive sac; a structure admitting of that constant supply
and circulation of sea-water, which the economy of these curious forms
of animal existence requires.

[Sidenote: ISLE OF WIGHT PEBBLES.]

The surface exposed by the division of the pebble, is an oblique
vertical section of the petrified zoophyte. It shows a central canal
filled with bluish-grey flint (_Plate II, c_), in a mass traversed by
tubes or channels, which possess considerable beauty and variety of
colour from an impregnation of iron.[L] A transverse section (see
_Lign. 14._ fig. 1) would, of course, have a central spot, with rays
proceeding thence to the circumference, as in the oblique fracture
(_Plate I, c_).[M]

[L] Specimens of this kind form beautiful objects when polished, and
are mounted as brooches by the lapidaries of Brighton, Bognor, and
the Isle of Wight, who term them petrified sea-animal flowers. Mr. G.
Fowlstone (4, Victoria Arcade) of Ryde, has many splendid examples, and
also agates and jaspers, the genuine productions of the Island.

[M] Note VII. _Isle of Wight Pebbles._

[Sidenote: CHOANITES KONIGI.]

The form of the original zoophyte when living, must have been that of
an inverted cone or funnel, (hence the scientific name _Choanite_ or
funnel-like,) with a long cylindrical digestive cavity in the centre,
from which tubes ramified through every part of the mass. It was
attached to a rock, stone, or shell, by root-like fibres which spread
out from its base; and its soft body was strengthened, as is the case
in many sponges and animals of a similar nature, by numerous siliceous
spines or spicula, which are often found in the flint and chalk (see
_Lign. 10._ fig. 5).[N]

[N] Note VIII. _Zoophytes of the Chalk._

[Illustration: Lign. 14:--Choanites _Konigi_: from
the Chalk.

  Fig. 1.--A transverse section.

       2.--Upper portion of the body.

       3.--Vertical section, like the pebble, Pl. II. p. 41.

       4.--A flint, enclosing a Choanite, which is exposed on the
             upper surface.

       5.--Various forms of siliceous spines of Choanites and other
             analogous bodies; magnified slightly.

          (See '_Medals of Creation_,' p. 264.)

]

The _Choanites_ must have swarmed in the Chalk ocean, for in some of
the strata almost every flint exhibits traces of these zoophytes.[O]

[O] The shingle at Brighton and Bognor in Sussex, and in various
localities in the Isle of Wight, abounds in specimens more or less
perfect. I would inform my fair readers who may visit these places, and
be inclined to purchase a brooch, in illustration of these "_Thoughts
on a Pebble_," that by far the greater number of the so-called
Brighton and Isle of Wight moss-agates, jaspers, &c., sold by the
lapidaries and jewellers, are of German or Scotch origin; and that the
_false-emeralds_, and _aquamarines_, are water-worn fragments of common
green glass bottles!

[Sidenote: CORALS IN CHALK.]

[Illustration: Lign. 15:--Branch of Coral on the
Pebble.

  Fig. 1.--A portion magnified.

       2.--A fragment represented as when alive.
            _a, a_, Two polypes collapsed.
            _b, b_, Two polypes with their tentacula extended.

]

One more character inscribed on the pebble remains to be interpreted;
it is the minute branch of coral partially imbedded in the flint.[P]
The surface of this coral, when seen with a powerful lens, is found to
be studded with small pores or cells. In a recent state, each cell was
inhabited by a living polype or animalcule, which, though permanently
united at its base to the general mass, had an independent existence,
and possessed sensation and voluntary motion; expanding its thread-like
feelers or tentacula to catch its prey, and withdrawing, at will, into
its little cell.[Q]

[P] Plate I. immediately below the shell and spine of Echinus.

[Q] For a popular account of recent and fossil corals, see 'Wonders of
Geology,' 6th Edit., vol. ii. Lecture VI. p. 589.

[Illustration: Lign. 16:--A Coral-polype preserved in flint:
magnified 500 diameters.]

From these investigations, we learn that the Pebble, which has formed
the subject of our contemplation, had its origin in a living zoophyte
that was growing on a rock, in a sea whose boundaries have long since
been swept away; that corals, shells, and echini inhabited the bottom
of the deep; and that fishes related to existing families, sported in
the waters of that ancient ocean. In fine, we have presented to us the
scene so exquisitely described by the American poet:--

[Sidenote: THE CORAL GROVE.]

THE CORAL GROVE.

    Deep in the waves is a coral grove.
    Where the purple mullet and gold fish rove,
    Where the sea-flower spreads its leaves of blue,
    That never are wet with the falling dew.
    But in bright and changeful beauty shine,
    Far down in the green and glassy brine.
    The floor is of sand, like the mountain drift.
    And the pearl-shells spangle the flinty snow;
    From coral rocks the sea-plants lift
    Their boughs, where the tides and billows flow;
    The water is calm and still below.
    For the winds and the waves are absent there,
    And the sands are bright as the stars that glow
    In the motionless fields of upper air:
    There with its waving blade of green,
    The sea-flag waves through the silent water,
    And the crimson leaf of the dulse is seen.
    To blush like a banner bathed in slaughter.
    There with a light and easy motion
    The fan-coral sweeps through the clear deep sea;
    And the yellow and scarlet tufts of ocean,
    Are bending like corn on the upland lea;
    And life in rare and beautiful forms,
    Is sporting amidst those bowers of stone.

                              Percival.

[Illustration: Lign. 17:--Minute Corals from the Chalk;[R]
_highly magnified_.]

[R] Note IX. _Minute corals from the Chalk._

[Sidenote: MICROSCOPIC CORALS.]

Our previous examination of the pebble had prepared us for these
results; but the microscope, that mighty talisman of wisdom, has shown
us, that even those infinitesimal creatures to whom a drop of water
is an unbounded ocean--those living atoms of that world of being which
is for ever concealed from the uninstructed mind--the inhabitants of
that universe beneath us, which the eye of science can alone penetrate,
existed in ages incalculably remote, and were, like their gigantic
contemporaries, the living instruments by which a large proportion
of the solid materials of the surface of our planet was elaborated;
their imperishable siliceous and calcareous skeletons, constituting no
inconsiderable amount of the crust of the earth.[S]

[S] See _"Thoughts on Animalcules, or a Glimpse of the Invisible World
revealed by the Microscope_," by the Author. Published by Mr. Murray,
London, 1846.

Fossil animalcules and corals similar to those we have discovered in
the pebble and in the chalk, and hundreds of other genera and species
equally minute, occur in such prodigious numbers, as to warrant the
conclusion, that this class of animal existence has contributed more
largely than any other, to the formation of the sedimentary strata.

Not only the Chalk hills, but whole mountain-ranges formed of other
deposits of great thickness and extent, are found to consist almost
entirely of similar remains. In the state of rock, of sand, of clay,
of marl--in the coarsest limestone, and in the purest crystal, the
petrified skeletons of animalcules alike abound. The town of Richmond,
in Virginia, is built on a bed of stone twenty feet thick, which is
wholly composed of the fossil skeletons of different kinds of marine
animalcules. The polishing slate of Bilin, in Germany, is wholly made
up of the siliceous shields of similar beings, disposed in layers
without any connecting medium; and these belong to species so minute,
and are so closely compressed together, that in a cubic inch of the
stone, weighing but two hundred and twenty grains, there are the
remains of _forty-one thousand millions_ of animalcules![T]

[T] See '_Medals of Creation_,' p. 221.

[Illustration: Lign. 18:--Animalcules from the Richmond earth:
very highly magnified[U]]

[U] Note X. _Richmond Infusorial earth._

                   *       *       *       *       *


[Sidenote: REFLECTIONS.]

Here we must bring our "_Thoughts on a Pebble_" to a close; but not
without adverting to the pure and elevating gratification which
investigations of this nature afford, and the beneficial influence
they exert upon the mind and character. In circumstances where the
uninstructed and incurious eye can perceive neither novelty nor beauty,
he who is imbued with a taste for natural science will everywhere
discover an inexhaustible mine of pleasure and instruction, and new
and stupendous proofs of the power and goodness of the Eternal! For
every rock in the desert, every boulder on the plain, every pebble by
the brook-side, every grain of sand on the sea-shore, is fraught with
lessons of wisdom to the mind which is fitted to receive and comprehend
their sublime import.

    "From millions take thy choice,
      In all that lives a guide to God is given;
    Ever thou hear'st some guardian angel's voice,
      When nature speaks of heaven!"

Amidst the turmoil of the world and the dreary intercourse of common
life, we possess in these pursuits a never-failing source of delight,
of which nothing can deprive us--an oasis in the desert, to which
we may escape, and find a home "wherever the intellect can pierce,
and the spirit can breathe the air."[V] For like the plant which the
Prophet threw into the waters of Marah,[W] that changed the bitterness
of the wave into sweetness, a branch from the tree of knowledge thrown
into the turbid stream of life, purifies its waters, and imparts to
them a healing virtue, which sheds a hallowing and refreshing influence
over the soul!

[V] Sir E. Bulwer Lytton.

[W] Exod. XV. 23.




THE

NAUTILUS and the AMMONITE.

(_See Page 22._)



FROM SKETCHES IN PROSE AND VERSE,

By the late G. F. Richardson, Esq.

    The Nautilus and the Ammonite
        Were launch'd in storm and strife;
    Each sent to float, in its tiny boat,
        On the wide, wild sea of life.

    And each could swim on the ocean's brim,
        And anon, its sails could furl;
    And sink to sleep in the great sea deep,
        In a palace all of pearl.

    And their's was a bliss, more fair than this,
        That we feel in our colder time;
    For they were rife in a tropic life,
        In a brighter, happier clime.

    They swam 'mid isles, whose summer smiles
        No wintry winds annoy;
    Whose groves were palm, whose air was balm.
        Where life was only joy.

    They roam'd all day, through creek and bay,
        And travers'd the ocean deep;
    And at night they sank on a coral bank,
        In its fairy bowers to sleep.

    And the monsters vast, of ages past.
        They beheld in their ocean caves;
    And saw them ride, in their power and pride,
        And sink in their billowy graves.

    Thus hand in hand, from strand to strand,
        They sail'd in mirth and glee;
    Those fairy shells, with their crystal cells,
        Twin creatures of the sea.

    But they came at last, to a sea long past,
        And as they reach'd its shore,
    The Almighty's breath spake out in death,
        And the Ammonite liv'd no more.

    And the Nautilus now, in its shelly prow,
        As o'er the deep it strays,
    Still seems to seek, in bay and creek,
        Its companion of other days.

    And thus do we, in life's stormy sea,
        As we roam from shore to shore;
    While tempest-tost, seek the lov'd--the lost--
        But find them on earth no more!

Geology, in the magnitude and sublimity of the objects of which it
treats, ranks next to Astronomy in the scale of the sciences.

                                                 Sir J. F. W. Herschel.

[Illustration]




SUPPLEMENTARY NOTES.




Note I. Page 13. _Shells in Chalk._


The shells of mollusca, in consequence of their durability, are the
most abundant fossils in the sedimentary strata;[X] entire layers
of marble and other limestone, of great thickness and extent, are
wholly composed of an aggregation of a few species or genera: in some
instances of fresh-water snails--as, for example, the Sussex and
Purbeck marbles;[Y] in others, of marine bivalves and univalves, as the
oyster-conglomerate of Bromley, and the shelly limestones of Portland,
Dorsetshire, &c.

[X] For an account of the geological value of fossil shells, see
'_Medals of Creation_,' vol. i. p. 363.

[Y] See '_Wonders of Geology_,' 6th Edition, p. 402.

The cretaceous strata contain many hundred species of bivalves and
univalves, by far the greater part of which belong to extinct genera;
and the species, with but four or five exceptions, are unknown in more
recent deposits. In loose sandy strata, fossil shells are oftentimes
beautifully preserved, and may be obtained in as perfect a condition
as if gathered from the sands on the sea-shores: such is the state of
the specimens which abound in the sandy clays near Barton in Hampshire,
and in the "_Crag_" of Essex and Suffolk. In certain beds of clay,
shells are also found entire; sometimes retaining the epidermis, and
the cartilaginous ligament of the hinge. The bivalves in the white
chalk are generally perfect; but the univalves, probably from the more
delicate structure of the originals, seldom retain any vestiges of the
shell, excepting portions of the internal nacreous coat adhering to the
chalk casts, which have been moulded in the interior of the shells.

[Illustration: Lign. 19:--Bivalve shells (_Terebratulæ_) from
Chalk (_natural size_).

  1, 2. Plicated species. 1. _T. octoplicata._ 2. _T. subplicata._
  3, 4. Smooth species. 3. _T. semiglobosa._ 4. _T. subrotunda._

]

[Sidenote: TEREBRATULÆ FROM CHALK.]

In some of the cretaceous strata several extinct species of _Oyster_,
_Scallop_, _Arca_, _Tellina_, and other well-known marine bivalves
abound; and with them are associated many genera of which no living
species have been observed. Among the bivalves that prevail in the
English chalk, are three or four kinds of _Terebratulæ_: which are
small, elegant, subglobular shells, belonging to a family of which
nearly 500 species, referable to several genera, have been obtained
from the British strata.[Z] Certain genera are restricted to the most
ancient sedimentary rocks, in which they occur in almost incredible
numbers; others have a wider range and are met with in the later
secondary deposits; while a few are found in the newest beds, and
have living representative species in the seas of warm climates. From
the immense antiquity of their lineage, these _Terebratulæ_ have been
humourously termed the "_fossil aristocracy_." Some of the most common
chalk species are figured of the natural size in _Lign. 19_. When
living the animal was attached to a rock or other body by means of a
_byssus_ or peduncle, exserted through the aperture in the beak or
curved extremity of the largest valve.[AA] The shells of the smooth
_Terebratulæ_ are full of minute holes or perforations, which may
readily be distinguished with a lens of moderate power.

[Z] See '_Wonders of Geology_,' 6th Edit. p. 329.

[AA] In the Conchological Gallery of the British Museum there is a
group of thirty or forty recent _Terebratulæ_ attached to a stone by
their peduncles; from Australia.

[Sidenote: PETRIFIED OYSTER.]

[Illustration: Lign. 20:--Oyster from the Chalk, near Brighton
(natural size).]

Occasionally the soft body of the mollusk completely silicified--that
is, transmuted into flint--is found in its natural position in the
shell. A beautiful example of this kind is represented in _Lign. 20_.
It is an extinct species of oyster: both valves were entire when I
removed the chalk and cleared the specimen; part of one valve has
been broken away to expose the petrified body of the animal. I have
seen a _Trigonia_[AB] from the oolite of Tisbury in Wiltshire, in
which the entire body of the mollusk was transformed into flint, and
the _branchiæ_ or lamellated gills were beautifully defined, though
converted into semi-transparent chalcedony.

[AB] _Trigonia:_ a genus of bivalves, of which there are many extinct
species in the chalk and oolite; some bands of Portland stone are an
aggregation of _Trigoniæ:_ a few very small species, inhabitants of the
seas of Australia and New Zealand, are the only known living forms of
this once prevailing type of mollusca. See '_Medals of Creation_,' p.
407.




Note II. Page 17. _Wood in Flint._


[Sidenote: WOOD IN FLINT.]

I would remind the reader that the white chalk, together with the
various strata of sand, clay, and limestone, comprising the cretaceous
formation of England, must be regarded as an ancient ocean-bed; in
other words, an accumulation of earthy sediments, formed in the
profound depths of the sea, in periods of long duration and of
incalculable antiquity, and more or less consolidated by subsequent
chemical and mechanical agency. These deposits are made up of organic
and inorganic materials: the former consist of the debris of the cliffs
and shores which encompassed the ancient ocean, of the spoils of the
land brought into the waters by floods and rivers, and of mineral
matter thrown down from chemical solutions. The organic substances
are the durable remains of the animals and plants which lived and
died in the sea, and of terrestrial and fluviatile species that were
transported from islands or continents by rivers and their tributaries.
The whole constitutes such an assemblage of strata as would probably be
presented to observation, if a mass of the bed of the Atlantic 2,000
feet in thickness, were elevated above the waters, and became dry land;
the only essential difference would be in the generic and specific
characters of the imbedded animal and vegetable remains.

The vestiges of terrestrial and fluviatile animals and plants found in
the chalk are comparatively but few: I have collected from Kent and
Sussex, bones of gigantic land lizards, (the _Iguanodon_), of flying
reptiles, (_Pterodactyles_), and of fresh-water Turtles, and water-worn
fragments of stems of coniferous trees allied to the _Araucaria_ or
Norfolk Island Pine; fruits or aments of coniferse; and stems and
foliage of plants related to the _Cycas_ and _Zamia_.

[Illustration: Lign. 21:--Fragment of coniferous wood in flint.]

A fragment of silicified wood imbedded in a flint, is represented in
_Lign. 21_. It was obtained from a wall in Lewes Priory in Sussex; and
though it has been exposed to the atmosphere seven or eight centuries,
still exhibits the characteristic internal structure.




Note III. Page 20. _Whitby Ammonites._


[Sidenote: AMMONITES.]

[Illustration: _Lign. 22_:--Ammonites from the cretaceous formation.

  1. _Ammonites varians_, from Hamsey.

  2. _A. Dufresnoyi_: 2_a_, part of the same.

  3. _A. lautus_: 3_a_, keel and septum of the same.

]

The Ammonites differ from the Nautili in having the margins of the
septa or internal shelly partitions (which in the latter are smooth),
foliated or wrinkled; and the siphunculus or tube placed along the
back of the shell, whereas in the Nautilus it is central. The sides of
the shell in the Ammonites are very generally more or less ornamented
with arched elevations and depressions, and studded with spines and
tubercles, as in the specimens above figured.

There are several kinds of Ammonites found in the Lias at Whitby and
other places in Yorkshire; the most common species is figured in
_Lign. 7_. p. 20; the dark colour of this fossil is produced by the
argillaceous stone with which it is now filled. The internal structure
of these Ammonites is generally well preserved, the chambers being
lined with spar or other mineral matter; transverse polished sections
are often very beautiful from the several cells being occupied by
variously coloured marble, susceptible of a high polish. (Pl. III.) In
some examples the entire shell is transmuted into brilliant pyrites
(sulphuret of iron), and the chambers are filled with white spar; a
specimen of this kind in my possession, collected by Lady Murchison, is
the most elegant fossil imaginable.

[Illustration: _Plate III._

_Polished section of an Ammonite._

_Page 70._]

[Sidenote: AMMONITE-MARBLE.]

It is not unusual for the visitors at Whitby to inquire of the
collectors how it is that the head of the animal is never found?
and the crafty dealers, willing to accommodate the taste of their
customers, carve the extremity of an Ammonite into the semblance of
a serpent's head, and affix two red eyes; thus producing a veritable
proof of the truth of the legend of St. Hilda! My young readers will
not be duped by this trick-of-trade, if they reflect but a moment on
the real nature of a fossil Ammonite: they will remember that it is a
shell which, when empty, became filled with what was then soft mud, but
is now stone; in like manner as if liquid plaster of Paris were poured
into an empty snail-shell and consolidated.

In some parts of Somersetshire, a beautiful marble composed of an
aggregation of two or three small species of Ammonites, is used for
sideboards and other ornamental purposes: the polished slabs are
diversified by the numerous sections of the shells.

Some of the clays of the Lias abound in a species of Ammonite of
extraordinary beauty from the iridescent lustre of the pearly coat of
the shell: a slab of stone from Watchett, on which a hundred or more
Ammonites of this kind are displayed, may be seen in the British Museum.




Note IV. Page 23. _Fossil Nautili._


The beauty, elegant form, and remarkable internal structure of the
shell of the Nautilus, have rendered it in all ages an object of
curiosity and admiration: yet an accurate knowledge of the organization
of the animal to which it belongs, has but recently been obtained. The
Nautili may be regarded as Cuttle-fish or _Sepiæ_, inhabiting shells
furnished with an apparatus to impart buoyancy, and enable the animals
to swim on the surface, or sink to the profound depths of the ocean.
A few explanatory remarks on the nature of the recent Sepia may be
necessary to render the subject intelligible to the unscientific reader.

[Sidenote: RECENT NAUTILUS.]

The _Sepia_ or Cuttle-fish of our seas is of an oblong form, and
composed of a soft substance covered with a tough integument or skin:
it varies from a few inches to a foot or more in length. The mouth
is placed in the centre of one extremity of the body, and has a
pair of powerful, curved, horny mandibles, much resembling the beaks
of a parrot: it is surrounded by eight long arms like the rays of a
star-fish, and these are beset with rows of little cups which act as
suckers, and enable the animal to secure its prey, and attach itself
with great firmness to any object.[AC] It has a distinct head, with
two eyes as perfect as in the vertebrated animals, and complicated
organs of hearing: and below the head there is a tube or funnel which
acts as a locomotive instrument, and propels the animal backwards by
the forcible ejection of the water which has served the purpose of
respiration, and can be thrown out with considerable force by the
contraction of the body. The soft parts are supported by a large
internal bone or osselet of a very curious structure, which, when dried
and reduced to powder, forms the substance used by scriveners, termed
_pounce_. These naked mollusca also possess a membranous bag or sac,
containing a dark-coloured fluid resembling ink in appearance, which
they eject into the surrounding water upon the approach of danger, and
by the obscurity thus induced foil the pursuit of their enemies. This
fluid, when inspissated, forms the base of the colour termed _sepia_ by
artists.

[AC] From this arrangement of the organs of prehension around the head,
this order of mollusca is termed the _Cephalopoda_; _i. e._, the feet
around the head.

The body of the Nautilus resembles in its essential characters that of
the Cuttle-fish, and occupies the large outer receptacle of the shell;
maintaining a connection with the inner compartments by means of the
membranous siphunculus or tube, which is only partially invested with
shell. The internal chambers are air-cells, and the animal can fill
the siphunculus with fluid, or exhaust it at will; the difference thus
effected in its specific gravity enables it to rise to the surface or
sink to the bottom with facility. Now if' we imagine a Cuttle-fish
placed in the outer chamber of a Nautilus-shell, and provided with a
siphuncule, but having neither ink-bag nor osselet--these organs being
unnecessary to an animal possessing a chambered shell--we shall have a
general idea of the nature of the recent species.

The Nautilus is essentially an inhabitant of deep water: it creeps
along the ground at the bottom of the sea, with its shell upwards like
the snail; and by means of its arms can proceed with considerable
speed.[AD]

[AD] See '_Conchologia Systematica_,' vol. ii. p. 302, and '_Elements
of Conchology_,' p. 22, by Mr. Lovell Reeve, F.L.S., for an admirable
description of the recent Nautilus, with illustrations.

A large and splendid species of fossil Nautilus is not uncommon in the
London Clay of the Isle of Sheppey, Sussex, and Hampshire. The chambers
are often lined with spar or other brilliant mineral matter; and
polished sections, like those of the Ammonites, admirably display the
internal structure.[AE]

[AE] See Dr. Buckland's '_Bridgewater Treatise_' for numerous figures
of Ammonites and Nautili; _plates_ 31 to 34. Consult also '_Medals of
Creation_,' vol. ii. p. 457.




Note V. Page 27. _Brighton Cliffs._


[Sidenote: BRIGHTON CLIFFS.]

The stranger who approaches Brighton by the railroads through deep
tunnels and cuttings in the chalk, and perceives the town spread
over the plain and on the sides of a valley of the South Downs, will
naturally expect to find the sea-shore bounded by chalk-cliffs. But
a wall of admirable construction, extends from the Steyne to beyond
Kemptown, and effectually conceals from view the materials that
compose the site of that part of Brighton; a ramble along the shore to
Rottingdean is therefore necessary to reveal to the inquiring observer,
the nature of the strata that flank the southern border of the Downs.

The sketch given in page 27, represents the appearance of part of the
coast to the east of Kemptown. The base of the cliff to the height of a
few feet, is seen to consist of the white chalk with its usual layers
of flint nodules, forming a low wall or terrace, which slopes seaward,
and extends far into the British channel--probably to the opposite
coast of France: at low-water a considerable expanse of modern shingle
and sand is spread over, and in a great measure conceals, the chalk,
at a few yards distance from the cliff. Upon the terrace of chalk, at
the height of from ten to fifteen feet above the modern beach, there
is a bed of pebbles and sand, containing also a considerable number
of boulders of granite, porphyry, and other crystalline rocks foreign
to the south-east of England: in fact, a sea-beach, which must have
been formed at some remote period, in the same manner as the modern
shingle. Upon this ancient beach are strata of loam, and chalk-rubble,
with flints partially water-worn, and boulders of sandstone, breccia,
granite, &c., constituting the upper sixty or eighty feet of the cliff.
In these beds, and also in the ancient shingle, many teeth and bones of
mammoths (extinct species of elephant), horse, deer, oxen, and other
ruminants, and bones of whales, have been discovered.[AF]

[AF] See '_Medals of Creation_,' p. 914.

[Sidenote: THE SUSSEX COAST.]

A few hundred yards beyond Kemptown the inroads of the sea have
destroyed all vestiges of the strata above described, and the cliffs
consist of a perpendicular wall of chalk; if we extend our walk to
Rottingdean, we shall perceive here and there isolated patches of the
ancient shingle, and of the calcareous strata containing elephants'
bones.

The appearances described demonstrate the following changes in this
part of the Sussex coast. _Firstly_, the chalk terrace (_Lign. 9, c_;
p. 27) on which the ancient shingle (_b_) rests, was on a level with
the sea for a long period; for this beach must have been accumulated,
like the modern, by the action of the waves on the then existing chalk
cliffs. But there must also have been some cause not now in operation,
by which pebbles, and boulders of granite and other rocks foreign to
this coast, with bones of extinct mammalia, &c., were thrown up on
the strand, and imbedded in the beach then in progress of formation.
These materials were probably brought from some distant part of the
then continental shores by floating ice: an agency by which delicate
bones and shells may be transported and deposited without injury amidst
pebbles and boulders.

_Secondly._ The whole line of coast with the ancient shingle must
have subsided to such a depth as to admit of the deposition of the
calcareous materials forming the "Elephant bed;" and from the absence
of beach and shingle in these strata, it may be inferred that this
deposition took place in tranquil water: possibly at that period this
part of the Sussex coast formed a sheltered bay.

_Lastly._ The land was elevated to its present level, and the formation
of the modern sea-beach and cliffs commenced.[AG]

[AG] See '_Medals of Creation_,' "On the Geological structure of
Brighton Cliffs," p. 913.




Note VI. Page 38. _Rotaliæ in Chalk and Flint._


[Sidenote: FOSSIL FORAMINIFERA.]

The shells called _Rotaliæ_ (see _Lign._ 5 and 6, p. 14 and 16) belong
to a group of marine animals of very simple organization, and which
present great variety in the form and markings of their testaceous
coverings; but they all agree in having the sides of the shell pierced
by numerous holes or foramina; whence the scientific term of the
Order, _Foraminifera_, is derived: these openings are for the egress
of delicate filaments, which appear to be organs of progression and
respiration.

The _Foraminifera_ are, with but few exceptions, exceedingly minute;
in an ounce of sea-sand, between three and four millions have been
detected. The body of these animalcules consists of uniform granules
enclosed in a skin or integument, having one or more digestive sacs
or cavities; these creatures appear, in fact, to be mere polypes,
protected by testaceous coverings. Some have but a single cell; others
have many, disposed in a conical or cylindrical form; many kinds, of
which the _Rotaliæ_ are examples, are discoidal involutes, and divided
internally by septa into distinct chambers:[AH] they resemble in this
respect the shell of the Nautilus, but are readily distinguished by the
perforations.

[AH] See '_Wonders of Geology_,' 6th Edit. p. 322.

All the various kinds of _Foraminifera_ swarm in the present seas,
and were not less numerous in the ancient ocean. We have seen that
the white chalk almost wholly consists of a few genera of these
animalcules; and in many strata of sand they are so abundant, that
a cubic inch of the mass contains upwards of sixty thousand. In the
_Rotalia_, the body is entirely enclosed within the shell, and occupies
all the cells; and long, soft, tentacula are sent off through the
foramina. The shell, therefore, though resembling in form that of
the Nautilus, is essentially different; for in the latter, the outer
chamber only is occupied by the body of the animal, the internal ones
being successively quitted empty dwellings; whereas, in the _Rotaliæ_
and analogous _Polythalamia_,[AI] all the cells are contemporaneously
filled by the soft parts of the animalcule.

[AI] _Polythalamia, many-chambered_, is a general term applied to these
shells.

[Sidenote: RECENT FORAMINIFERA.]

When the shell is removed, which is readily effected by immersion in
diluted hydrochloric acid, the body is exposed, and found to consist
of a series of lobes or sacs, united by a tube corresponding somewhat
in its position with the siphuncle of the Nautilus, but which is the
digestive canal. The body of a recent animalcule of this kind, deprived
of the shell, is figured in _Lign. 23_.

[Illustration: Lign. 23:--The body of a recent animalcule
allied to the _Rotalia_, deprived of its shell; _highly magnified_.]

Not only the characters of fossil shells of such infinite minuteness
can be revealed by the microscope, but even the soft parts of the
animalcules which inhabited them; for these are occasionally preserved,
and may be demonstrated with as much distinctness as the recent
examples.[AJ] In flint the soft parts of _Rotaliæ_, _Textulariæ_,
&c., are abundant, and may be seen, with but little preparation, like
insects in amber: the specimen figured in _Lign. 12_, p. 39, shews
the body of a _Rotalia_ well defined; the only preparation this atom
of flint has undergone, is immersion in Canada balsam. To detect such
delicate structures in chalk requires, however, some experience in
microscopic manipulation, as the calcareous matter must be dissolved
in hydrochloric acid, and the animal substance separated from the
residuum.[AK]

[AJ] See '_Wonders of Geology_,' 6th Edit., p. 322.

[AK] See my '_Memoir on the fossil remains of the soft parts of
Foraminifera in Chalk, &c._' Philosophical Transactions, 1846, p. 465.




Note VII. Page 43. _Isle of Wight Pebbles._


[Sidenote: ISLE OF WIGHT PEBBLES.]

The nodules and veins of flint that are so abundant in the upper
chalk, have probably been produced by the agency of heated waters
and vapours; the perfect fluidity of the siliceous matter before its
consolidation is proved, not only by the sharp moulds and impressions
of shells and other organisms retained by the flints, but also by the
presence of numerous remains in the substance of the nodules, and the
silicified condition of the sponges and other zoophytes which abound in
the cretaceous strata.

Now although silex, or the earth of flint, is but sparingly soluble in
water of the ordinary temperature, its solution readily takes places
in vapour heated a little above that of fused cast iron, as has been
proved by direct experiment;[AL] and similar effects are being produced
at the present moment by natural causes. The siliceous deposits thrown
down by the intermittent boiling fountains, called the Geysers, in
Iceland, are well known;[AM] and in New Zealand this phenomenon is
exhibited on a still grander scale. From the crater of the volcanic
mountain of Tongariro,[AN] which is several thousand feet above the
level of the sea, jets of vapour and streams of boiling water highly
charged with silex, are continually issuing forth, and dashing down
the flanks of the volcano in cascades and torrents, empty themselves
into the lakes at its base. As the water cools, siliceous sinter is
deposited in vast sheets, and incrustations of flint form around the
extraneous substances lying in the course of the thermal streams. Silex
is also precipitated by the boiling waters in stalagmitic concretions,
and in nodules resembling in colour and solidity the flints of the
English chalk. The complete impregnation and silicification of
organized bodies is attributable to an agency of this kind; and
although the origin of the siliceous waters that deposited the nodules
and veins of flint in the chalk is still involved in obscurity, the
mode in which the latter were formed is satisfactorily elucidated.

[AL] See '_Wonders of Geology_,' p. 100.

[AM] Ibid., p. 95.

[AN] Ibid., p. 98.

[Illustration: Lign. 24:--Zoophytes in Chalk and Flint.

  1. A minute coral from chalk and flint; the lower figure is of the
       natural size.

  2. Branch of a sponge in flint. 3. Pebble enclosing a zoophyte.

]

Of the perfect transmutation into flint of the most delicate organic
structures, the pebbles strewn along the sea-shore of the south coast
of England, afford a beautiful illustration; those from the Isle of
Wight are especially celebrated for their rich and varied colours.
The most common and interesting are those which exhibit sections of
Choanites, as in the specimen which suggested the reflections embodied
in these pages. Other allied forms are scarcely less beautiful; the
petrified zoophytes called _Siphonia_, which, when living, consisted
of a soft mass traversed by tubes, for the free ingress and egress of
the water, often display the internal structure of the original: as
in the polished transverse section figured above, _Lign. 24, fig. 3_.
Other bodies of this class occur in the flint, and present interesting
examples of the zoophytes of the chalk ocean.

But many of the Isle of Wight pebbles exhibit no traces of animal
structure, yet are valuable and instructive as mineralogical specimens:
such are the clear and transparent pebbles with bands and veins of
quartz and chalcedony. Some specimens are as pellucid as rock-crystal;
others are of a bright yellow, amber, dark-brown, and bluish-black
colour, and are often mottled with dendritical or arborescent
manganese. (_Plate IV._) The moss agates, as they are called by the
lapidaries, are silicified sponges. Small pebbles of pure transparent
rock-crystal are often found among the shingle in Compton and Sandown
bays, and have probably been washed out of the wealden strata; for
similar stones occur in the Tilgate grit, and at Tunbridge Wells: in
the latter place, they are cut and polished for rings, brooches, &c.

[Illustration: _Plate IV._

_Polished sections of Pebbles._

_Page 86._]

[Sidenote: ZOOPHYTES OF THE CHALK.]

On the shores of the Isle of Wight, pebbles of jasper, resembling those
from Egypt, and of banded quartz, with arborescent markings, or with
zones of rich brown, are also met with; these do not appear to have
originated from the chalk strata.

Pebbles of silicified wood have been collected in Sandown bay by Mr.
Fowlstone; and water-worn boulders and pebbles of petrified wood,
bones, &c., are common in Brook bay; rolled masses of the fresh-water
shelly limestones (Sussex and Purbeck marbles) are also abundant in the
same localities.[AO]

[AO] All these varieties may be obtained of Mr. Fowlstone, 4, Victoria
Arcade, Ryde.




Note VIII. Page 45. _Zoophytes of the Chalk._


Zoophytes, especially sponges, occur in such prodigious numbers in some
of the chalk strata, that the nucleus of almost every flint nodule is
an organic body. In many instances the silex has completely permeated
the animal substance, as in the pebbles before described; but sometimes
the sponge is a white calcareous mass, occupying a hollow in the flint:
a branched specimen of this kind, exposed on breaking a small nodule,
is represented at _Lign. 24, fig. 2_.

In describing sponge as an animal substance, it may be necessary to
explain that the sponge in ordinary use is the flexible skeleton of
a living zoophyte, and was originally invested with a gelatinous or
slimy matter, which lined all the pores and channels. When alive in
the water, currents constantly enter the outer pores, traverse all
the internal inosculating canals, and issue from the larger orifices
which often project above the surface in perforated papillæ. By
the circulation of the sea-water through the porous structure, the
nutrition of the animated mass is effected; and the modifications
observable in the number, size, form, and arrangement of the pores,
canals, and apertures, in the different kinds of this type of
organization, are subservient to this especial function.

But associated with the true _Poriferæ_ or sponges, are numerous
zoophytes which resemble them in form, but are of an entirely distinct
nature; for they are the fossilized remains of _Polyparia_, that is, of
the frame-work of an aggregation of polypes, each individual of which
had an independent existence, although the whole were united by one
common living integument, like the _Alcyonium_, or dead-men's fingers,
of our coasts.[AP]

[AP] See '_Medals of Creation_,' p. 251.

[Illustration: Lign. 25:--Flints deriving their forms from the
zoophytes they enclose.]

[Sidenote: FUNGIFORM FLINTS.]

Among the flints whose forms depend on the organic bodies they enclose,
are some which bear so close a resemblance in shape to _Fungi_, that
they are provincially called in Sussex "_petrified mushrooms_;" several
of them are figured above (_Lign. 25_). In these fossils there are
openings at the base, and a groove on the margin of the upper part, in
which the structure of the enclosed body is generally more or less
distinctly seen; and upon breaking one of these bodies, a section of
a funnel-shaped zoophyte is obtained. The origin of these flints will
be understood by reference to the four interesting specimens here
delineated, one-sixth of the natural size in linear dimensions.

[Illustration: Lign. 26:--Ventriculites from the Chalk, Lewes.

  1. A perfect specimen in Chalk, shewing the external net-like surface.

  2. An expanded specimen, displaying the inner surface studded with cells.

  3. A Ventriculite with the lower part enveloped in Flint.

  4. Part of a Ventriculite; the base invested with Flint: the root-like
       fibres are seen at a.

]

[Sidenote: VENTRICULITES.]

This zoophyte, to which the name of _Ventriculite_ has been given to
denote its usual shape, was a hollow inverted cone, terminating at
the base in a point, whence radicles or root-like processes were sent
off, by which the animal was firmly attached to the rock. The outer
integument was disposed in meshes like a net (see _Lign. 26, fig.
1_), and the inner surface was beset with regular circular openings,
the orifices of tubular cells (_fig. 2_); each of which was probably
occupied by a polype. The substance of the _Polyparium_, or general
support of this family of animalcules, which alone occurs in a fossil
state, appears to have been analogous to that of the soft _Alcyonia_,
and to have possessed a common irritability; the entire mass
contracting and expanding, as is the case in many recent zoophytes.[AQ]

[AQ] See '_Wonders of Geology_,' 6th Ed., p. 610; '_Medals of
Creation_,' p. 273-276; and '_Geological Excursions round the Isle of
Wight_,' pp. 179-184, for an account of the silicification of these and
other Zoophytes.

The flints, _figs. 3, 7, 8, 9, Lign. 25_, were evidently formed
in the manner exemplified in _fig. 3, Lign. 26_; _figs._ 2, 4, 6,
are illustrated by _fig. 4, Lign. 26_; for the chalk specimens,
_Lign. 26_, shew that all these flints have been moulded around
_Ventriculites_, and that their diversity of figure has arisen from
the quantity of silex that happened to permeate the substance of the
zoophyte; if but a small portion, flint like _figs._ 2 and 4, were
the result; if the quantity were considerable, the larger fungiform
examples were produced.




Note IX. Page 50. _Minute Corals from Chalk._


Some layers of chalk are composed of an aggregation of many kinds of
delicate corals, the interstices being filled up with _Rotaliæ_ and
other foraminiferous shells. In the cliffs near Dover there are several
beds of this nature, well known to collectors for the profusion of
exquisite specimens they yield to the experienced investigator. _Lign.
17_, p. 50, represents several varieties from different localities;
the small figures shew the natural size, and the enlarged ones their
appearance when magnified. Attached to the surface of shells, and
sometimes standing erect in crannies of flint nodules, beautiful corals
may often be detected by the aid of a lens of moderate power. By
brushing chalk in water, and examining the deposit, delicate fossils of
this kind may also be obtained.[AR]

[AR] Refer to '_Medals of Creation_,' p. 284, and to '_Wonders of
Geology_,' _Lecture VI._ p. 588, for a comprehensive view of Recent and
Fossil Corals.

[Sidenote: NATURE OF CORALS.]

From the close analogy of the fossil corals to existing forms, it would
not be difficult to give restored figures of the originals. Every
little branch might be represented fraught with living polypes: in some
cells the agile inmates might be shown with the mouth expanded, and
the tentacula in rapid motion; in others withdrawn into their stony
recesses, and devouring the infinitesimal atoms that constitute their
food: even their varied hues might be introduced, and thus a vivid
picture be presented of the microscopic beings which peopled the waters
of the ancient chalk ocean.

That the Corals, which from their elegance and beauty are preserved in
almost every cabinet, have been fabricated--or, in other words, built
up--by polypes, in the same manner as the honey-comb of the bee and
wasp, is so prevalent yet erroneous an opinion, that I am induced to
point out its fallacy, by giving a brief account of the formation of
these substances. The three recent specimens represented in _Lign. 27_
will serve to illustrate my remarks.

[Illustration: Lign. 27:--Recent Corals.

  1. _Oculina ramea._

  2. _Madrepora muricata._

  3. _Isis hippuris._

]

The coral, _fig. 1_, was an internal axis or skeleton, deposited by the
soft fleshy integument with which, when living, it was wholly invested;
in the same manner as are the bones of animals, by the special membrane
(_periosteum_) that secretes them. This integument lined every cell,
and the polypes were permanently united to it. When the live coral is
taken out of the water, the animalcules shrink up and quickly perish;
their soft parts and the external investing substance putrefy, and the
stony axis beset with the radiated cells alone remains.

[Sidenote: RECENT CORALS.]

In the example of _Oculina ramea_, or May-blossom Coral, _fig. 1_, from
the Mediterranean, the cells are large and distinct; in the _Madrepore_
from the West Indies, _fig. 2_, they are small and very closely
aggregated.

The specimen of _Isis_ (_fig. 3_) belongs to a group of coral-zoophytes
in which the polype-cells consist of a substance that is durable, but
not so hard as coral, and invests an axis composed of a tough flexible
material, which is exposed at the base of _fig 3_, by the removal of
the external or cortical part in which the polypes were situated. The
_Gorgonia_, or Venus's fan, has a similar structure and composition.[AS]

[AS] See '_Wonders of Geology_,' vol. ii. p. 616.

In the _Red Coral_, so largely employed in the manufacture of beads,
brooches, and other ornaments, not only the animalcules, but also
their receptacles, are composed of a soft perishable substance. When
alive, the polypes, as well as the investing fleshy integument, are of
a delicate bluish tint; the internal calcareous axis alone possesses
the peculiar red colour. Upon being taken out of the sea, vitality
quickly ceases, the soft parts decompose, and the beautiful crimson
stone commonly known as the _true coral_, is obtained free from all
traces of the soft mass by which it was secreted. Although an actual
investigation of the facts described can only be instituted near the
seas of warm climates, yet our coasts abound in certain coral-zoophytes
in which similar phenomena may readily be observed. Most persons in
their rambles by the sea-side must have noticed on the fuci, algæ,
shells, pebbles, &c., patches of a white earthy substance, which
when closely examined resemble delicate lace-work. These apparently
calcareous incrustations are clusters of the zoophytes termed
the _Flustra_, or sea-mat.[AT] When removed from the water, this
aggregation of polypes seems coated over with a glossy film or varnish;
and with a lens of moderate power the surface is seen to be full of
pores, disposed with much regularity. If viewed under the microscope
while immersed in sea-water, a very different appearance is presented.
Every pore is found to be the opening of a cell whence issues a tube
fringed with several long feelers or arms; these expand, then suddenly
contract and withdraw into the cell, and again issue forth; the whole
surface of the Flustra being covered with these hydra-like animalcules.
The Flustra, therefore, like the corals, constitutes an assemblage of
polypes, each individual being permanently fixed in a durable cell,
and the whole attached to a common integument by which the calcareous
frame-work was secreted and maintained.[AU]

[AT] See '_Wonders of Geology_,' Plate 5.

[AU] See Dr. Johnson's beautiful work on '_British Zoophytes_,' in
which are numerous figures of various species of Flustra.






Note X. Page 53. _Infusorial earth from Richmond in Virginia._


[Sidenote: INFUSORIAL EARTHS.]

The greatest natural operations are produced by the most simple
and apparently inadequate agents: for as the illustrious Galileo
emphatically remarked, "_La nature fait beaucoup avec peu, et ses
opérations sont toutes également merveilleuses._" The profound thinker
Hobbes, in the same spirit observes, "The majesty of God appeareth no
less in small things than in great, and as it exceedeth human sense in
the immensity of the universe, so also doth it in the smallness of the
parts thereof." This sublime truth is strongly impressed on the mind
of the geological inquirer, who perceives that whole countries and
mountain ranges of great elevation and extent, are wholly composed of
the aggregated remains of beings of such infinite minuteness that but
for the powerful optical instruments of modern times, their presence
would never have been suspected.

A few years only have elapsed since the sagacious Ehrenberg first
drew attention to this subject, and pointed out the proper method of
investigation;[AV] and so rapid has been the progress of discovery in
this department of science, that _infusorial deposits_, as these beds
of fossil animalcules are designated, have been detected in every
quarter of the globe. A fact equally unexpected and remarkable has also
been established, namely, that at the present moment similar minute
living agents are largely contributing to the increase of the solid
materials of the crust of our planet.

[AV] See '_Medals of Creation_,' p. 244, for instructions for the
microscopical examination of earths, chalk, &c.

[Sidenote: RICHMOND EARTH.]

The infusorial earth of Virginia, alluded to in the text, is a
yellowish siliceous clay, forming a deposit from twelve to fifteen
feet in thickness, upon which the towns of Richmond and Petersburgh
are built. The surface of the country over which it extends is
characterized by a scanty vegetation, owing to the siliceous nature of
the soil dependent on the minute organisms of which it almost entirely
consists. When a few grains of this earth are properly prepared for
microscopic examination, immense numbers of the shields or cases of
animalcules are visible under a magnifying power of 300 diameters; in
fact, the merest stain left by the evaporation of water in which some
of the marl has been mixed, teems with these fossil remains.[AW]

[AW] Specimens of Infusorial earths, prepared for the microscope, may
be obtained of Mr. Topping, 4, New Winchester Street, Pentonville Hill,
New Road, London.

These organisms are of exquisite structure, and comprise many
species and genera. The most beautiful and abundant are the circular
shields, termed _Coscinodisci_ (sieve-like disks), which are elegant
saucer-shaped cases, elaborately ornamented with hexagonal apertures
disposed in curves, somewhat resembling the engine-turned sculpturing
of a watch; these shells are from 1/1000 to 1/100 of an inch in
diameter. A segment of one of these disks, highly magnified, is
represented in _Lign. 18, fig. 2_. The body of the living animalcule
was protected and enclosed by a pair of these concave shells, the
perforations admitting of the exsertion of filaments or tentacula.
This species of _Coscinodiscus_ abounds in the present seas, and
constitutes no inconsiderable proportion of the food of Pectens and
other testaceous mollusca.[AX]

[AX] See '_Thoughts on Animalcules_,' p. 103.

All the animalcules found in the Richmond earth are marine, and most
of them belong to genera, and many to existing species; although the
position of the American strata proves that they are referable to a
period of immense antiquity.

In Germany, beds of a white infusorial earth, resembling magnesia
in appearance, and termed _Bergh-mehl_, or fossil farina, occur at
Bilin, and several other places: at San Fiora in Tuscany, near Egra
in Bohemia, in the Bermudas, Barbadoes, &c., similar deposits have
been discovered; all being composed of the shields of various kinds of
animalcules. But I must not extend these remarks, and will only add a
few observations on the infusorial earth of Barbadoes, which has but
recently been brought under the notice of geologists by Sir Robert
Schomburgk, and is especially interesting for the exquisite beauty and
variety of its organisms, and the circumstances under which the deposit
occurs.

[Sidenote: FOSSIL INFUSORIA OF BARBADOES.]

Barbadoes, an island of the West Indies, is about twelve miles in
length from north to south, and consists of coral reefs, capped in one
district by tertiary sandstones and limestones, which attain a height
of 1200 feet above the sea. Over the rest of the island, coral reefs
form the entire surface, which is divided by vertical walls of coral,
some of them nearly 200 feet high, into six terraces, indicating as
many periods of upheaval. In the lowest reef, Indian hatchets have
been found twenty feet above high water mark; shewing that the last
movement, at least, took place within the human period. The tertiary
strata are more or less inclined, and in many places vertical, and
contorted. Strata of marl, several hundred feet thick, predominate; and
there are beds of bituminous coal, sandstone, clays, and ferruginous
sands. Arenaceous limestone containing teeth of sharks, spines of
echini, and shells, forms the summit of a hill nearly 1,000 feet high.
The white marls abound in 300 species of the most beautiful siliceous
infusoria; many are peculiar, others the same as occur in the Richmond
earth, and some belong to recent species.[AY]

[AY] Sir R. H. Schomburgk: Brit. Assoc. 1847.




                               THE END.


                   *       *       *       *       *


                       WORKS BY THE SAME AUTHOR.


_In 2 Vols, foolscap 8vo, cloth, lettered, with numerous Illustrations
and Coloured Plates, price 18s. the Sixth Edition of_

                        THE WONDERS OF GEOLOGY;

                                  OR,

            A FAMILIAR EXPOSITION OF GEOLOGICAL PHENOMENA.

            By GIDEON ALGERNON MANTELL, Esq., LL.D., F.R.S,
          Vice-President of the Geological Society of London.

  "Dr. Mantell's _Wonders of Geology_ will continue to be a favourite
  work equally in the Geological schools, in the private study, and in
  the family circle. It may be read and understood by any intelligent
  and educated individual; its exact science, sound logic, and dignity
  of style ensure its acceptance with the learned; its elegance,
  beauty, and perspicuity, with the polite and refined; and its
  comprehensive brevity, with the student of the elements of Geology.
  It realizes, indeed, our beau-ideal of a familiar yet dignified
  philosophical style: being alike condensed and luminous, possessing
  a graceful flowing eloquence, and rising as the subject may require,
  into the sublime as well as the beautiful. We are not aware of the
  existence of any work, on any department of science, which has higher
  claims at once to a place in the library of the philosopher, and on
  the table of a refined family."--_Review of the American Edition of
  the Wonders of Geology._ _American Journal of Science._

  "Dr. Mantell's eloquent and delightful work, the Wonders of
  Geology."--_Sir E. B. Lytton._


_In 2 vols. foolscap 8vo, cloth, lettered, with Coloured Plates, and
several hundred Figures of Fossil Remains, price One Guinea._

                        THE MEDALS OF CREATION;

                                  OR,

    FIRST LESSONS IN GEOLOGY, AND IN THE STUDY OF ORGANIC REMAINS.

  These volumes comprise a Popular Introduction to the study
  of Organic remains, and a general view of Fossil Botany and
  Zoology.

  Geological Excursions to some of the most interesting places
  in England are described, in illustration of the method of observing
  and investigating Geological Phenomena, and of collecting Organic
  Remains.

  Ample instructions are given for the development and arrangement
  of Fossil _Vegetables_, _Corals_, _Shells_, _Bones_, _Teeth_, &c.:
  and practical directions for the microscopical examination of
  rocks composed of Fossil Infusoria, and the intimate structure of
  mineralized Plants, Teeth, &c. In fine, these volumes are offered
  as a popular guide and hand-hook for the Student and Amateur
  Collector of Fossil Remains, and the Reader who may desire a general
  acquaintance with a science replete with objects of the highest
  interest; and for the Tourist who may wish, in the course of his
  travels, to employ profitably and agreeably a leisure hour, in the
  various districts he may visit. Such a work has long been required;
  and the present will be found to comprise all that can reasonably be
  expected in two pocket volumes. The plates are alike beautiful and
  faithful representations of the originals.

  "Very rarely can we find a work which is so perfect an example of
  the art of book, making, in the best understanding of that term; we
  mean technically and _mechanically_ as well as _intellectually_.
  Dr. Mantell's 'Medals of Creation' are, indeed, among the
  _chef d'oeuvres_ of the art; and, being elegantly bound in embossed
  covers, of the still portable size of the larger 12mo, will and
  must take their place as the companions, not only of the geologist
  in his study, but in the field; while they will also accompany
  the intelligent travellers of both sexes as most instructive and
  delightful Mentors in their journeyings among the grand and beautiful
  scenes of our globe. This work is a _classic of high excellence_,
  of great research, and formidable labour; and we cannot close our
  remarks without again expressing our admiration of the perspicuity,
  method, and condensation by which it is distinguished."--_American
  Journal of Science for January_, 1845.


_In one volume square 8vo, with 12 coloured plates; price 10s._

                       THOUGHTS ON ANIMALCULES;


                                  OR,

     A GLIMPSE OF THE INVISIBLE WORLD REVEALED BY THE MICROSCOPE.

  "In this beautiful work Dr. Mantell has presented a vast deal of
  information on the most interesting genera and species of Infusoria,
  and clothed it with that fascinating garb, that persuasive eloquence,
  with which he has been ever wont to impart knowledge."--_Westminster
  and Foreign Quarterly Review._


_In one volume 8vo, with numerous plates, sections, coloured geological
maps, &c.; price 12s._

                    GEOLOGICAL EXCURSIONS ROUND THE
                             ISLE OF WIGHT

                                  AND

        ALONG THE ADJACENT COASTS OF HAMPSHIRE AND DORSETSHIRE.

            Illustrative of the most interesting geological
                    phenomena and organic remains.

This work is a popular guide to the geology of the "beautiful Island,"
pointing out and explaining the most remarkable localities and the
fossils with which they abound; not only of the Isle of Wight, but also
of the Isles of Purbeck and Portland.


_In one volume, with plates; price 5s._

                    A DAY'S RAMBLE IN AND ABOUT THE
                        ANCIENT TOWN OF LEWES;


      ILLUSTRATIVE OF THE OBJECTS OF HISTORICAL, GEOLOGICAL, AND
          ANTIQUARIAN INTEREST OF THE TOWN AND NEIGHBOURHOOD.

  "A charming guide to a charming spot; rich in picturesque scenery,
  and historical associations of the highest interest. A day's ramble
  which every one who visits Brighton and has leisure will not fail to
  undertake with so instructive and delightful a companion."--_Brighton
  Gazette._


_Preparing for Publication._

                 THE PHENOMENA OF THE NERVOUS SYSTEM;

                                  OR,

   A FAMILIAR EXPOSITION OF THE NATURE AND FUNCTIONS OF THE NERVES:

         Being the substance of a course of popular Lectures.

             _In one volume, with numerous illustrations._


                   *       *       *       *       *

                                                        _August, 1850._

                            =LIST OF WORKS=

                            PRINCIPALLY ON

                     NATURAL AND PHYSICAL SCIENCE,

                             PUBLISHED BY

                           REEVE AND BENHAM,

                  5, HENRIETTA STREET, COVENT GARDEN.


                                  1.

                         POPULAR FIELD BOTANY;

                              COMPRISING

  A familiar and technical description of the Plants most common to the
  British Isles, adapted to the study of either the Artificial or Natural
  System.

                           By AGNES CATLOW.

                           =Second Edition.=

        _Arranged in twelve chapters, each being the Botanical
                        lesson for the month._

  "A useful aid to young persons at a loss how to take the first steps
  in Botany. One of the impediments in their way is the uncertainty
  that attends all attempts at making out the names of the objects they
  have to examine, and this impediment can only be removed by drawings
  and very familiar descriptions. Miss Catlow, in the work before us,
  has furnished a clear and concise supply of both. We recommend her
  'Popular Botany' to favourable notice."--_Gardeners' Chronicle._

  "The design of this work is to furnish young persons with a
  Self-instructor in Botany, enabling them with little difficulty to
  discover the scientific names of the common plants they may find in
  their country rambles, to which are appended a few facts respecting
  their uses, habits, &c. The plants are classed in months, the
  illustrations are nicely coloured, and the book is altogether an
  elegant, as well as useful present."--_Illustrated London News._

  [***] In one vol. royal 16mo, with twenty plates of figures.
         Price 7_s._ plain; 10_s._ 6_d._ coloured.

     2. INSTINCT AND REASON. By Alfred Smee, F.R.S., Author of
        'Electro-Biology.' One vol. 8vo. With coloured Plates by Wing,
        and Woodcuts. 16_s._

     3. THE TOURIST'S FLORA. A Descriptive Catalogue of the Flowering
        Plants and Ferns of the British Islands, France, Germany,
        Switzerland, Italy, and the Italian Islands. By Joseph Woods,
        F.A.S., F.L.S., and F.G.S. 8vo.

     4. POPULAR HISTORY OF MAMMALIA. By Adam White, F.L.S., Assistant
        in the Zoological Department of the British Museum. With
        sixteen coloured Plates of Quadrupeds, &c., by B. Waterhouse
        Hawkins, F.L.S. Royal 16mo. 10_s._ 6_d._

     5. VOICES FROM THE WOODLANDS; or, History of Forest Trees,
        Lichens, Mosses, and Ferns. By Mary Roberts. With twenty
        coloured Plates by Fitch. Royal 16mo. 10_s._ 6_d._

     6. THOUGHTS ON A PEBBLE; or, A First Lesson in Geology. By Dr.
        Mantell, F.R.S. Eighth Edition, considerably enlarged. With
        four coloured plates, twenty-seven woodcuts, and a Portrait of
        the Author. Square 12mo. 5_s._

     7. THE POETRY OF SCIENCE; or, Studies of the Physical Phenomena
        of Nature. By Robert Hunt, Esq., Author of 'Panthea.' Second
        Edition. Revised by the Author. With an Index.

  "An able and clever exposition of the great generalities of Science,
  adapted to the comprehension of those who know little of her
  mysteries."--_Athenæum._

  "One of the most readable epitomes of the present state and progress
  of science we have yet perused."--_Morning Herald._

  "This book displays a fund of knowledge, and is the work of an
  eloquent and earnest man."--_Examiner._

  [***] One vol. demy 8vo. Price 12_s._

     8. EPISODES OF INSECT LIFE. First Series.

  "The letterpress is interspersed with vignettes clearly and cleverly
  engraved on stone, and the whole pile of natural history--fable,
  poetry, theory, and fact--is stuck over with quaint apophthegms and
  shrewd maxims, deduced for the benefit of man from the contemplation
  of such tiny monitors as gnats and moths.--Altogether the book
  is a curious and interesting one--quaint and clever, genial and
  well-informed."--_Morning Chronicle._

  [***] One vol. crown 8vo, with 16 illustrations. Price 16_s._ elegantly
        bound in fancy cloth. _Coloured and bound extra, gilt, 21s._

     9. EPISODES OF INSECT LIFE. Second Series.

  [***] One vol. crown 8vo, with 36 illustrations. Price 16_s._ elegantly
        bound in fancy cloth. _Coloured and bound extra, gilt, 21s._

                                  10.

                            POPULAR HISTORY

                                  OF

                          BRITISH SEA-WEEDS;

            Comprising a familiar and technical description
                of the Sea-weeds of the British Isles.

                By the Rev. DAVID LANDSBOROUGH, A.L.S.,
             Member of the Wernerian Society of Edinburgh.

  "This charming contribution to the study of a very interesting branch
  of Natural History combines scientific correctness with artistical
  beauty."--_Literary Gazette._

  "The book is as well executed as it is well timed. The descriptions
  are scientific as well as popular, and the plates are clear and
  explicit. Not only the forms, but the uses of Algæ, are minutely
  described. It is a worthy sea-side companion--a hand-book for every
  occasional or permanent resident on the sea-shore."--_Economist._

  "A work of much general interest, and one which every dweller by
  the sea-side, who makes a right use of his eyes, would do well to
  procure."--_Edinburgh Witness._

  "Mr. Landsborough's very beautiful volume is meant for young students
  of Sea-weeds. The volume is illustrated with many coloured plates,
  executed in a superb style."--_Glasgow Daily Mail._

  "Profusely illustrated with specimens of the various Sea-weeds,
  beautifully drawn and exquisitely coloured."--_Sun._

  "This elegant work, though intended for beginners, is well worthy the
  perusal of those advanced in the science."--_Morning Herald._

  "Those who desire to make themselves acquainted with British
  Sea-weeds, cannot do better than begin with this elegantly
  illustrated manual."--_Globe._

  [***] In one vol. royal 16mo, with twenty-two plates of figures
        by Fitch. Price 10_s._ 6_d._ coloured.

    11. PANTHEA, THE SPIRIT OF NATURE. By Robert Hunt. Author
        of 'The Poetry of Science.' One vol. 8vo. Price 10_s._ 6_d._

  "A brave attempt to range from the elemental to the universal, from
  the known to the unknown."--_Literary Gazette._

  "There is, throughout, the closeness of matter and eloquence of style
  that distinguish the 'Poetry of Science.'"--_Spectator._

    12. A REVIEW OF THE FRENCH REVOLUTION OF 1848. By Captain Chamier,
        R.N. Two vols. 8vo. Price 21_s._

    13. THE NATURAL HISTORY OF IRELAND. By William Thompson, Esq.,
        President of the Natural History and Philosophical Society of
        Belfast. Birds. Vol. I. Price 16_s._ cloth. Vol. II. Price
        12_s._

    14. THE RHODODENDRONS OF SIKKIM-HIMALAYA. By Dr. J. D. Hooker.
        Second Edition. In handsome imperial folio, with ten
        beautifully coloured plates. Price 21_s._

    15. TRAVELS IN THE INTERIOR OF BRAZIL, principally through the
        Northern Provinces and the Gold and Diamond Districts, during
        the years 1836-41. By George Gardner, M.D., F.L.S. Second and
        Cheaper Edition. 8vo. Plate and Map. Price 12_s._

    16. ILLUSTRATIONS OF BRITISH MYCOLOGY; or. Figures and Descriptions
        of British Funguses. By Mrs. T. J. Hussey. Royal 4to. Ninety
        plates, beautifully coloured. Price 7_l._ 12_s._ 6_d._, cloth.

    17. THE ESCULENT FUNGUSES OF ENGLAND, By the Rev. Dr. Badham.
        Super-royal 8vo. Price 21_s._, coloured plates.

    18. NARRATIVE OF THE VOYAGE OF H.M.S. SAMARANG in the Eastern
        Archipelago during the years 1843-46. By Captain Sir Edward
        Belcher, C.B., F.R.A.S. and G.S. In 2 vols. 8vo, 35 Charts,
        Coloured Plates, and Etchings. Price 36_s._, cloth.

    19. CURTIS'S BRITISH ENTOMOLOGY, being Illustrations and
        Descriptions of the Genera of Insects found in Great Britain
        and Ireland, comprising coloured figures from nature of the
        most rare and beautiful species and of the plants upon which
        they are found. By John Curtis, F.L.S. Sixteen vols. royal 8vo.
        770 copper-plates, beautifully coloured. Price £21. (Published
        at £43 16_s._)

                                  20.

                     POPULAR BRITISH ORNITHOLOGY;

                              COMPRISING

                 A familiar and technical description
                  of the Birds of the British Isles.

                            By P. H. GOSSE,

          Author of 'The Ocean,' 'The Birds of Jamaica,' &c.

  _In twelve chapters, each being the Ornithological lesson for the month._

  "Goes over every month of the year, figures the birds naturally in
  painted colours, describes them and their habits well, and is a
  capital manual for youthful naturalists."--_Literary Gazette._

  "To render the subject of ornithology clear, and its study
  attractive, has been the great aim of the author of this beautiful
  little volume. It contains descriptions of all our British birds,
  with the exception of those which may be considered in the light
  of stragglers, and which are not likely to fall in the way of
  the young naturalist, for whose use this work is intended. It is
  embellished by upwards of 70 plates of British birds beautifully
  coloured."--_Morning Herald._

  "We can answer for this compact and elegant little volume being
  beautifully got up, and written in a manner likely to attract the
  interest of the youthful student."--_Globe._

  "This was a book much wanted, and will prove a boon of no common
  value, containing, as it does, the names, descriptions, and habits of
  all the British birds. It is handsomely got up, and ought to find a
  place on the shelves of every book-case."--_Mirror._

  [***] In one vol. royal 16mo, with twenty plates of figures.
        Price 7_s._ plain; 10_s._ 6_d._ coloured.

    21. THE DODO AND ITS KINDRED; or, the History, Affinities, and
        Osteology of the Dodo, Solitaire, and other extinct birds
        of the Islands Mauritius, Rodriguez, and Bourbon. By H. E.
        Strickland, Esq., M.A., F.R.G.S., F.G.S.; and A. G. Melville,
        M.D., M.R.C.S. One vol. royal quarto, with eighteen plates and
        numerous wood illustrations. Price 21_s._

    22. A CENTURY OF ORCHIDACEOUS PLANTS, the Plates selected from the
        Botanical Magazine. The descriptions re-written by Sir William
        Jackson Hooker, F.R.S., Director of the Royal Gardens of Kew;
        with Introduction and instructions for their culture by John
        Charles Lyons, Esq. One hundred coloured plates, royal quarto.
        Price Five Guineas.

    23. CONCHOLOGIA SYSTEMATICA; or, Complete System of Conchology. 300
        plates of upwards of 1,500 figures of Shells. By Lovell Reeve,
        F.L.S. Two vols. 4to, cloth. Price 10_l._ coloured; 6_l._ plain.

    24. CONCHOLOGIST'S NOMENCLATOR; or. Catalogue of recent Shells. By
        Agnes Catlow and Lovell Reeve, F.L.S. Price 21_s._

    25. FLORA ANTARCTICA; or. Botany of the Antarctic Voyage. By Joseph
        Dalton Hooker, M.D., R.N., F.R.S., &c. Two vols. royal 4to, 200
        plates. Price 10_l._ 15_s._ coloured; 7_l._ 10_s._ plain.

    26. CRYPTOGAMIA ANTARCTICA; or, Cryptogamic Botany of the Antarctic
        Voyage. By Joseph Dalton Hooker, F.R.S., &c. Royal 4to. Price
        4_l._ 4_s._ coloured; 2_l._ 17_s._ plain.

    27. THE BRITISH DESMIDIEÆ; or, Fresh-Water Algæ. By John Ralfs,
        M.R.C.S. Price 36_s._ coloured plates.

    28. CONCHYLIA DITHYRA INSULARUM BRITANNICARUM. By William Turton,
        M.D. Reprinted verbatim from the original edition. Large paper,
        price 2_l._ 10_s._

    29. THE PLANETARY AND STELLAR UNIVERSE. By Robert James Mann. Price
        5_s._, cloth.

    30. ILLUSTRATIONS of the WISDOM and BENEVOLENCE of the DEITY, as
        manifested in Nature. By H. Edwards, LL.D. Price 2_s._ 6_d._,
        cloth.

                                  31.

                                POPULAR

                          BRITISH ENTOMOLOGY;

                              COMPRISING

              A familiar and technical description of the
               Insects most common to the British Isles.

                          By MARIA E. CATLOW.

  _In twelve chapters, each being the Entomological lesson for the month._

  "Judiciously executed, with excellent figures of the commoner
  species, for the use of young beginners."--_Annual Address of the
  President of the Entomological Society._

  "Miss Catlow's 'Popular British Entomology' contains an introductory
  chapter or two on classification, which are followed by brief generic
  and specific descriptions in English of above 200 of the commoner
  British species, together with accurate figures of about 70 of those
  described. The work is beautifully printed, and the figures nicely
  coloured, and will be quite a treasure to any one just commencing
  the study of this fascinating science."--_Westminster and Foreign
  Quarterly Review._

  [***] In one vol. royal 16mo, with sixteen plates of figures.
        Price 7_s._ plain; 10_s._ 6_d._ coloured.


                              =Serials.=

    32. CURTIS'S BOTANICAL MAGAZINE; by Sir William Jackson Hooker,
        F.R.S., V.P.L.S., &c., Director of the Royal Gardens of Kew.
        With observations on the culture of each species, by Mr.
        John Smith, A.L.S., Curator of the Royal Gardens. In monthly
        numbers, each containing six plates, price 3_s._ 6_d._ coloured.

    33. HOOKER'S JOURNAL OF BOTANY, and KEW GARDEN MISCELLANY. Edited
        by Sir William Jackson Hooker, F.R.S., &c. In monthly numbers.
        Price One Shilling.

    34. ZOOLOGY OF THE VOYAGE OF H.M.S. SAMARANG. Edited by Arthur
        Adams, Assistant-Surgeon, R.N. Fishes. By Sir John Richardson,
        M.D., F.R.S. Crustacea. By the Editor and Adam White, F.L.S.
        Mollusca. By the Editor and Lovell Reeve, F.L.S., including the
        anatomy of the _Spirula_, by Prof. Owen, F.R.S.

    35. PHYCOLOGIA BRITANNICA; or, History of the British Sea-weeds. By
        Professor Harvey, M.D., M.R.I.A. In parts, price 2_s._ 6_d._
        coloured; large paper, 5_s._ To be completed in 60 parts. Part
        49 just published.

    36. NEREIS AUSTRALIS; or, Illustrations of the Algæ of the Southern
        Ocean. By Professor Harvey, M.D., M.R.I.A. To be completed in
        Four Parts, each containing 25 coloured plates, imp. 8vo, price
        1_l._ 1_s._ Parts 1 and 2 recently published.

    37. CONTRIBUTIONS TO ORNITHOLOGY. By Sir William Jardine, Bart. In
        parts, each containing 4 plates, price 3_s._

    38. CONCHOLOGIA ICONICA; or, Figures and Descriptions of the Shells
        of Molluscous Animals. By Lovell Reeve, F.L.S. Demy 4to.
        Monthly. Eight plates. 10_s._ coloured. Part 87 just published.

    39. ELEMENTS OF CONCHOLOGY; or, Introduction to the Natural History
        of Shells and their molluscous inhabitants. By Lovell Reeve,
        F.L.S. Royal 8vo. In twelve parts, each containing five plates.
        Price 3_s._ 6_d._ coloured.

    40. CURTIS'S BRITISH ENTOMOLOGY. Re-issued in monthly parts, each
        containing 4 coloured plates and corresponding text. Price
        3_s._ 6_d._

    41. A CENTURY OF ORCHIDACEOUS PLANTS. Published in monthly numbers,
        each containing five plates. Price 5_s._


                                LONDON:

          REEVE and BENHAM, HENRIETTA STREET, COVENT GARDEN.


                   *       *       *       *       *


Transcriber Note

Illustrations may have been moved to prevent splitting paragraphs.
Minor typos were corrected. Produced from materials made available on
The Internet Archive and all derived products are placed in the Public
Domain.













End of Project Gutenberg's Thoughts on a Pebble, by Gideon Algernon Mantell