calcareous cases, or coverings, of a more highly organized class of
molluscous animals, than the inhabitants of the bivalves (see p.
366), for they possess a head and mouth with jaws, eyes, and feelers;
and while the _Acephala_, with but few exceptions, are incapable of
locomotion, the _Encephala_ are almost all of them furnished with
organs of progression, and can creep, climb, and swim, or float on the
surface of the water. Their shells are for the most part formed of
one valve, hence the name of _univalve_; but in some species it is
composed of several pieces. The most simple form of shell is that of
the hollow cone, of which the _Patella_, or limpet, affords an example;
and in the more complicated modifications, the cone is twisted, or
convoluted spirally, either in the same plane as in the _Planorbis_
of our rivers, or obliquely, as in by far the greater number of
species. The direction of the spire is generally from left to right,
the aperture being dextral to the observer when the shell is placed
with its apex uppermost, as in _Lign. 133, figs. 1, 2, 3_; but in a
few species the spire turns in the opposite manner, and the mouth or
aperture is to the left, or sinistral, as in _Lign. 133, fig. 4_.
In consequence of the form of the aperture of the shell, the entire
or notched condition of its margin, and the presence or absence of a
canal or siphon always having relation to the soft parts of the animal,
these characters afford data by which the genera and species of the
shells may be determined, and information obtained as to the structure
and economy of the originals.
The Gasteropoda generally creep by means of a fleshy disk, or foot,
which is situated under the belly. Some kinds are terrestrial, others
inhabit trees, many live in rivers and streams, others in stagnant and
brackish waters; but the greater number are denizens of the sea.
[Sidenote: FOSSIL GASTEROPODA.]
The Common Snail, River Snail, and Periwinkle, are instances of
terrestrial, fluviatile, and marine forms. The organs of respiration
are situated in the last whorl of the shell; and in some genera
the border of the mantle, or integument surrounding the body, is
prolonged into a siphon, by which the water is freely admitted,
without the head or foot being protruded: in these mollusks the shell
has a corresponding channel to receive the siphon, as in the Whelk,
or Buccinum, and in the fossil shell _Lign. 133, fig. 4_. The
Gasteropoda are generally provided with an operculum, or movable valve,
by which the aperture is closed and defended when the animal retreats
within its shell. In some species the operculum is a mere horny
pellicle; in others it is a solid calcareous plate of considerable
relative thickness. These mollusca, as is but too well known of the
terrestrial species, consume large quantities of food. Some are
herbivorous, and others carnivorous; many prey on living, and others
on decaying animal and vegetable substances.[378] As in a fossil state
the shells alone remain to afford any clue as to the structure and
economy of the originals, characters have been sought for, by which
the fluviatile or marine nature, and the carnivorous or herbivorous
habits of the living mollusca may be determined. As a general rule,
it will be found, that the shells of terrestrial and fresh-water
Gasteropoda have the aperture entire, as in the Garden Snail, and in
the fossil shell, _Lign. 133, fig. 1_; and that a large proportion
of the marine species have the opening notched or channelled, as in
the Whelk, and _Lign. 133, figs. 3, 4_; and most of the species with
entire apertures are herbivorous. But these inferences must be regarded
in a very general sense, and it will require corroborative evidence to
establish the marine or fresh-water nature of those fossil shells which
do not bear a close analogy to known living species.[379]
[378] "All _Gasteropoda_ commence life under the same form, both of
shell and animal, namely, a very simple helicoid shell, and an animal
furnished with two ciliated wings or lobes, by which it can swim freely
through the fluid in which it is contained. At this stage of existence
the animal corresponds to the permanent state of the _Pteropod_, and
the form is alike, whether it be afterwards a shelled or a shell-less
species."--Prof. E. Forbes, Edin. Philos. Journal, vol. xxxvi. p. 326.
The well known Tiger Cowry (_Cyprcea tigris_) in its earliest stage has
a minute helicoid (snail-like) shell.
[379] See _Ly._ p. 30.
The various conditions in which the remains of univalve shells occur in
the mineral kingdom have already been so fully explained, that but a
few additional remarks on that subject are required (see p. 382).
The Gasteropoda are found to progressively diminish in number with
the antiquity of the deposits, and it was once supposed that this
type of molluscous organization was not contemporaneous with the
ancient Cephalopoda. My discovery of several genera associated with
Ammonites in the chalk (see _Foss. South D._ pl. xviii, xix) first
tended to invalidate this hypothesis; and the subsequent researches
of Dr. Fitton, Professor Phillips, and other geologists have shown
that the presence or absence of Gasteropoda in a stratum may generally
be ascribed to the circumstance of the deposit having been formed
in shallow, or in deep water. Thus when simple univalves largely
predominate under circumstances that indicate they were imbedded in
their native habitats, it may be safely concluded that the rock is of
littoral formation; or, in other words, was deposited in shallow water,
near the sea-shore; and, on the contrary, when Nautili, Ammonites,
and the shells of other mollusca known to live in deep waters abound
in a formation, it may be presumed that the strata were formed in the
tranquil depths of the ocean. The number of described species from
the British strata is nearly eight hundred; and these are distributed
throughout the sedimentary formations, from the Silurian to the newest
Tertiary; the latter containing by far the greater proportion.
[Sidenote: FOSSIL FRESH-WATER UNIVALVES.]
Fresh-water Univalves.--The fossil shells of Gasteropoda that are
undoubtedly fluviatile, comprise but few genera and species, and are
confined to those deposits, which, from the corroborative proofs
afforded by other organic remains, are unquestionably of fresh-water
origin. Such are the intercalated beds of clay and limestone in the
London and Paris basins, the Wealden formation, and certain strata in
the Carboniferous system. The most numerous specimens are principally
referable to the common fluviatile genera, _Paludina_, _Limnæa_,
_Planorbis_, and _Melanopsis_ (see _Ly._ p. 29).
Paludina. _Lign. 133, fig. 1._ (_Wond._ p. 401, _Ly._ p. 29.)--This
common river shell is of a conoidal form, and the whorls of the spire,
and the aperture, are rounded. Eleven British species are known. In
the tertiary fresh-water beds of Headon Hill, at Alum Bay, Paludinæ
with the shells perfect, and of a dull white colour, are abundant;
and also in the limestone at Shalcombe, in the Isle of Wight, in the
state of casts. In both these localities the Paludinæ are associated
with other fresh-water shells. But the grand deposit of shells of
this genus is the Wealden formation; throughout which there are
extensive beds of marble, coarse limestone, and clays, almost wholly
composed of Paludinæ, and minute fresh-water Crustaceans, of the
genus _Cypris_, which will be described in a subsequent chapter. The
compact paludina-limestone of Sussex, called Petworth or Sussex marble,
is principally made up of one species, the _P. fluviorum_, _Lign.
133, fig. 1_, and is an aggregation of Paludinæ, held together by
crystallized carbonate of lime; the cavities of the shells, and their
interstices, being often filled with white calcareous spar. A polished
slab, displaying sections of the enclosed shells, is figured in _Wond._
p. 402. Upon examining slices of this marble with the microscope, the
cavities of the shells are found to contain myriads of the cases of
Cyprides.[380] The Wealden limestone of the Isle of Purbeck, _Lign.
134_, known as Purbeck marble, is, in like manner, composed of Paludinæ,
but of a much smaller species. Both these marbles were in great
repute with the architects of the middle ages, and there are but few
of our cathedrals and ancient churches which do not still contain
examples, either in their columns, monuments, or pavements, of one or
both varieties. The polished marble columns of Chichester Cathedral,
and those of the Temple Church, in London, are of Purbeck marble; in
other words, they are composed of the petrified shells of snails, that
lived and died in a river, flowing through a country inhabited by the
Iguanodon and other colossal reptiles, all of which have long since
become extinct. With the exception of the _mussel-band_ limestone of
the Carboniferous system, previously described, these are the only
British fresh-water marbles[381] There are four species of Paludina in
the Wealden, and four in the Tertiary strata of Hants.
[380] For a particular account of this marble, see Geol. S. E. pp.
182-187.
[381] The collector may obtain specimens, and polished slabs of these
limestones, of Mr. Martin, mason, Lewes, Sussex.
[Illustration: Lign. 134.
Polished Slab of Purbeck Marble.]
Limnæa. _Lign. 133, fig. 2._--Several species of these fresh-water
mollusks inhabit our lakes and ponds, and may be known by their pointed
spire, elongated oval body, and delicate thin shell: on the inner lip
of the aperture there is an oblique fold. Fossil shells of this genus
are found with Paludinæ in the fresh-water tertiary deposits. Headon
Hill and other localities in the Isle of Wight abound in these shells;
and in the limestone of Calbourn beautiful casts are very numerous.
The Paris basin yields several species; and there are six species in
the Isle of Wight Tertiary; I have not observed any decided examples
in the Wealden. In the sands and clays the shells are well preserved;
in the limestones the casts only remain. Shells of another genus of
fresh-water spiral univalves, termed _Bulimus_ (_Ly._ p. 30), are found
associated with the above. A large species (_B. ellipticus_, _Min.
Conch._ tab. 337), occurs in the limestone at Binstead, near Ryde,
and at Calbourn; I have collected specimens two inches long from the
former locality; they are generally in the state of casts, with a white
friable coating of the shell.[382]
[382] A very large species of _Limnæa_ from Bavaria (labelled _L.
maxima_) is in the British Museum. It is a cast six and a half inches
long, and is placed with the recent shells. Prof. E. Forbes has
discovered a Limneïd (_Physa_) in the Purbeck strata.
Planorbis. _Ly._ p. 29. _Wond._ p. 400.--The shells of this genus
are also numerous in our rivers and lakes, and may be distinguished
by their discoidal form, the shell being coiled up in a nearly
vertical plane. There are about twenty living species; and sixteen are
enumerated as fossil in the British tertiary; five occur in the Isle
of Wight basin, in the localities of the fresh-water genera already
mentioned; Headon Hill, in particular, yields shells of this genus in
great abundance and perfection.
Melanopsis. _Ly._ p. 29.--These are spiral univalves, the appearance
of which will be better understood by the figures, than by any
description. I allude to this genus because a small species is very
numerous, with the other fresh-water shells, at Headon Hill; and two or
more species are found in the argillaceous strata of the Wealden (see
_Geol. S. E._ p. 249, and _Lign. 132_).
[Sidenote: FOSSIL MARINE UNIVALVES.]
Marine Univalves.--Of the fossil marine Gasteropoda there are no less
than eighty genera in the strata of the British Islands, and the
species amount to several hundreds. To distinguish the species and
genera, reference must, of course, be made to works expressly devoted
to fossil conchology, as Sowerby's _Mineral Conchology_, and _Genera
of Fossil Shells_; or to the works of French authors, particularly
those of Lamarck, edited by M. Deshayes, and of M. Blainville. The
_Penny Cyclopedia_ contains admirable notices of fossil shells, under
the respective heads of the classes, orders, and genera, of the recent
Mollusca.
Buccinum, of which the common Whelk is an example.--Fusus, _Lign.
133, fig. 4_. _Wond._ p. 244.--Pleurotoma, _Ly._ p. 31. _Wond._ p.
244.--Cerithium, _Lign. 133, fig. 3_. _Wond._ p. 244.--Ancilla,
_Wond._ p. 244. _Ly._ p. 31.--Voluta, _Ly._ p. 202, _fig._ 180.--Murex,
_Ly._ p. 164.--Rostellaria, _Ly._ p. 201.--To the eight genera here
enumerated a very large number of the marine simple univalve shells
belong; and they are principally found in Tertiary strata.
The animals of these shells are characterized by their respiratory
organs, which are formed of one or two pectiniform gills, with a tube
or siphon more or less elongated, for the free admission of sea-water
to the branchial apparatus. This organization is indicated in the
shell, either by a notch, or by a prolonged tubular canal. All the
species are, with scarcely any exceptions, inhabitants of the sea, and
carnivorous.
I have selected for illustration of the genus _Fusus_, a celebrated
shell of the Crag, known among collectors as the "_Esssex reversed
Whelk_," _Lign. 133, fig. 4_; the spire is twisted in the opposite
direction to the usual mode, and the mouth is consequently to the left
of the observer; the same species occurs with the spire in the common
direction. The shells of the genus _Pleurotoma_ are distinguished by an
incision, or notch, in the side of the right or outer lip; and those
of _Cerithium_, by the form of the mouth, see _Lign. 133, fig. 3_.
The latter is a very numerous genus, and more than two hundred
fossil species are enumerated; it contains many elegant forms. The
Tertiary strata at Grignon are particularly rich in these fossils;
the shells are of a pearly whiteness, and as perfect as when recent.
Some Cerithia are of considerable size; the _C. giganteum_ is from ten
to fourteen inches in length. The genus Potamides comprehends shells
closely resembling the Cerithia in form, but which are inhabitants of
fresh-water.[383] This is an instance of the difficulty which sometimes
exists of arriving at certain conclusions as to the habits of the
mollusks, from their testaceous coverings alone.
[383] Mr. Woodward informs me that they can only be distinguished when
_fossil_, by the absence of _varices_, or "periodic mouths." The recent
species are known to be inhabitants of fresh-water, by their dark
epidermis, corroded points, and horny multi-spiral _opercula_.
The Plastic Clay beds at Castle Hill, Newhaven, and in the vicinity
of Woolwich, abound in two species of shells, which were originally
described by Mr. Sowerby, as _Cerithia_ (viz. _C. funatum_ and _C.
melanoides_),[384] but are now referred to the fresh-water genus,
Melania; by some conchologists to _Potamides_. At Castle Hill they
are accompanied by fresh-water bivalves, and leaves of dicotyledonous
plants.
[384] Foss. South Downs, tab. xvii. figs. 3, 4.
Of the genus _Rostellaria_, there is a remarkable species in the London
Clay, called _R. macroptera_, from the large wing-like expansion of its
outer lip, in adult specimens; see _Ly._ p. 201. An elegant Rostellaria
is found in the Galt, at Folkstone,[385] (_Foss. South D._ tab. xix.
figs. 12, 14,) and other localities; and also in the Chalk Marl.
[385] "This shell belongs to the recent genus, _Aporrhaïs_, and is
related to Cerithium, not to Strombus."--_Mr. Woodward._
* * * * *
Casts of a large ventricose, globular univalve, called Dolium,[NV]
have been found in the Chalk Marl, at Clayton, near Hurstpierpoint, in
Sussex. This species is distinguished by its transverse tuberculated
bands; it is a very rare production of the lower chalk of Sussex
(_Min. Conch._ tab. 326). Turbinated shells related to _Trochus_, and
belonging to several genera, occur in the Cretaceous deposits. As is
the case generally with the univalves of this formation, but slight
traces of the shells remain; the thin internal nacreous lining is
sometimes found adhering to the cast.
[386] This Chalk fossil is not a _Dolium_: it is probably related to
_Ringinella incrassata_ (Geol. Suss. t. xix. _fig._ 3), one of the
_Tornatellidæ_, a family largely developed in the chalk.
In the Chalk of Touraine, species of the genera _Conus_ (_Lign. 135,
fig. 1_) and _Solarium_ (_Lign. 135, fig. 2_) are found with the
shells preserved. The specimens figured, _Lign. 135_, are selected to
familiarize the student with the difference so commonly observable,
between the outer surface of the casts, and that of the shells: in
both these fossils the shells are marked externally with lines and
tubercles; but the casts present only the smooth surface of the
interior of the shell in which they were moulded.
[Illustration: Lign. 135. Univalves, from the Chalk of Touraine.--_nat._
Fig. 1.--Conus tuberculatus, with part of the shell remaining
attached to the cast.
2.--Solarium ornatum, with the shell.
2_a_.--Specimen of the same species, deprived of the shell.
]
In the most ancient fossiliferous formations, the Carboniferous;
Devonian, and Silurian, many species and genera of Gasteropoda have
been discovered. Professor Phillips enumerates more than ninety in
the mountain limestone of Yorkshire (_Phil. York._), belonging to the
genera _Turbo_, _Pleurotomaria_, _Natica_, _Euomphalus_, _Loxonema_,
_Macrocheilus_, _Platyceras_, and _Metoptoma_. Thirty-four species from
the Silurian rocks are figured and described in _Murch. Sil. Syst._ p.
706.
The _Natica_, _Lign. 136, fig. 3_, sometimes attains thrice the size
represented, and has been found in many localities in England and
Ireland.
Pleurotomaria. _Lign. 136, fig. 4._--This is an extinct genus,
distinguished from Trochus by a fissure on the right lip, the position
of which is indicated by the band along the back of the whorl in
_Lign. 136_; several species occur in the Mountain Limestone; the
markings of the original shell are sometimes preserved, as in the
example delineated This genus is common in the Oolite; a splendid
species, with the shell entire, is found in the Kimmeridge Clay, at
Hartwell; limestone casts of the same species are abundant in the
Portland stone at Swindon, in Wiltshire.
[Illustration: Lign. 136. Univalves from the Mountain Limestone.
Fig. 1.--Euomphalus pentangulatus; Upper surface.
2.--Polished section of the same species.
3.--Natica plicistria. _Yorkshire. Mt. L._
4.--Pleurotomaria flammigera. (_Phil. York._) _Mt. L._
]
There are two species of this genus (formerly named _Cirrus_ by Mr.
Sowerby) which are of frequent occurrence in the White Chalk of
England, in the state of casts, and are figured in my _Foss. South D._
tab. xviii., under the names of _Cirrus perspectivus_, and _Trochus
linearis_. The Chalk Marl of Sussex yields in some localities (Hamsey,
Middleham, Clayton) fine casts of Pleurotomaria, which appear to be
distinct from those of the upper cretaceous strata.
[Sidenote: EUOMPHALUS.]
Euomphalus.[387] _Lign. 136, figs. 1, 2._--The shells of this extinct
genus are deeply umbilicated, discoidal, spiral univalves, having the
innermost whorls of the shell divided by imperforated partitions. The
internal structure of these shells will serve to prepare the student
for those more complicated forms of the testaceous apparatus presented
by the Cephalopoda, which will form the subject of the next chapter.
There are several recent univalves the animals of which retreat in the
progress of growth from the apex of the spire, and the vacated portion
is shut off by a shelly plate. In some genera a series of concave septa
are thus formed; but in others (as _Magilus_) the deserted cavity
is filled by a compact accretion of calcareous matter, and a solid
elongated shell is produced. The _Euomphalus_, of which there are many
species in the Silurian, Devonian, and Carboniferous strata, belongs
to the former group. As the animal increased in size, it deserted the
smaller and innermost portion of the spire, and a nacreous partition
was secreted by the posterior part of the mantle, the interspace
remaining hollow; as this process was repeated at different periods,
several cells were successively formed. This chambered structure is
shown in the specimen _Lign. 136, fig. 2_, in which the cells are
filled with spar, but the outer cavity is occupied by limestone like
that in which the shell was imbedded; a proof that no communication
existed between the chamber occupied by the body of the animal, and
the space from which it had withdrawn. The calcareous spar, as in
the vegetable remains previously described (p. 71), has percolated
the substance of the fossil, and crystallized in the innermost
cells. We shall again have occasion to refer to this interesting
fact, when investigating the chambered cells of the Cephalopoda. It
may be necessary to remark, that it does not appear that the vacant
interspaces in the Euomphalus served the special purpose of the
air-chambers of the Nautilus and Ammonite.
[387] So named by Mr. Sowerby, in allusion to the deeply umbilicated
character of the disk.
[Illustration: Lign. 137.
Murchisonia angulata.
_Devonian; Eifel_.]
Murchisonia. _Lign. 137._ An elongated spiral shell, having the outer
lip deeply notched, as in the Pleurotomaria (_a, Lign. 137_). There
are upwards of 50 species of this genus, which are characteristic of
the palæozoic rocks. They occur in the Permian, Devonian, and Lower
Silurian deposits; the specimen figured is from the Devonian, or Old
Red of the Eifel.
Chiton. Valves of Chitons have been found in the Magnesian limestone,
near Sunderland, by Prof. King, (_Permian Fossils_, _Pal. Soc._ p. 202,
pl. xvi.), and in the Silurian rocks of Ireland, by Mr. Salter, _Geol.
Journal_, vol. iii. p. 48.
[Sidenote: SPHÆRULITES.]
Sphærulites.[388] _Lign. 138._--No vestiges of a shell of this genus
had been noticed in the English strata, until my discovery of some
fragments in the Lewes Chalk in 1820; from the lamellated structure of
these fossils, I mistook them for corals, until specimens were obtained
sufficiently perfect to show the form of the originals; these were
described in the _Geol. S. E._ (p. 130), under the name of Hippurites.
But these fossils are more nearly related to the _Sphærulites_, which
differ from the shells of the former genus in having only one internal
longitudinal ridge, and in the external surface being roughened by
irregularly raised plates, as in _Lign. 138, fig. 1_, which is a
specimen from the Pyrenees, collected by M. Alex. Brongniart; the
operculum is seen at _a_.
[388] This genus has been referred by some conchologists to the
Bivalves, and by others to the Univalves.
[Illustration: Lign. 138. Sphærulites from the Chalk of France and
England.
Fig. 1.--Sphærulite, with its _operculum_, _a_.
2.--Sphærulites Mortoni (G. A. M.), _from Lewes_: 1/2 _nat._
2_a_.--Cellular structure of _fig._ 2, in a transverse section: ×
2_b_.--Structure, as seen in a vertical section: ×
]
The species found in the Sussex Chalk, _Lign. 138, fig. 2_, is
characterized by the longitudinal striæ on the outer surface. In some
examples there is an external longitudinal furrow, and a corresponding
internal ridge.[389]
[389] The specific name is in honour of Dr. George Morton, of
Philadelphia, author of the "Synopsis of the Cretaceous Group of the
United States."
The Sphærulites sometimes occur in groups in the Sussex chalk; I
had a large water-worn mass, consisting of five or six individuals,
anchylosed together. Some beautiful specimens collected by the late Mr.
Dixon from the Chalk, near Worthing, are now in the British Museum.[390]
The structure of the Sphærulite is accurately delineated in _Lign.
138, figs. 2a 2b_. The cavities of these shells are occasionally
filled with flint, but in general with chalk, which may be entirely
cleared away, as in _fig. 2_. The Hippurites of the limestone of the
Pyrenees are frequently occupied by calcareous spar, and the substance
of the shells is occasionally transmuted into the same mineral.
[390] Petrifactions, p. 468.
* * * * *
[Sidenote: MOLLUSKITE.]
Molluskite; or the carbonized remains of the soft parts of
mollusca.--Before proceeding to the consideration of that numerous and
important division of the mollusca the _Cephalopoda_, I will offer a
few remarks on a carbonaceous substance resulting from the gelatinous
matter of which the soft bodies of these animals are composed, and for
which I have proposed the name of _molluskite_, to indicate its nature
and origin.
[Illustration: Lign. 139. Coprolites and Molluskite. _Chalk and
Greensand._
Fig. 1.--Coprolite of a fish (_Macropoma_). _Chalk, Lewes._
2.--Coprolite of a fish (_Squalus_). _Chalk marl. Ramsey._
3.--Molluskite of a _Rostellaria_. (_Mr. Bensted._) _Kentish Rag,
Maidstone._
]
This substance is of a dark brown or black colour, and occurs either
in shapeless masses, which are irregularly distributed among the
shells and other organic remains, in sandstone, limestone, &c., or
as casts of shells, or occupying their cavities, as in the specimen
_Lign. 139, fig. 3_, which is a vertical section of a spiral univalve
(_Rostellaria_), filled with the soft parts of the animal, converted
into molluskite. Upon analysis this substance is found to contain
a large proportion of animal carbon.[391] The rocks of firestone at
Southbourne, on the Sussex coast, are mottled with brown molluskite
and hard amorphous concretions, consisting of carbon and phosphate of
lime, mixed with sand and other extraneous matter. Casts of shells,
of the genera Venus, _Arca_, &c., entirely composed of the same kind
of materials, are also abundant in those rocks. The lowermost bed of
Galt, at its line of junction with the Greensand beneath, at Folkstone,
and in many other localities, is largely composed of similar matter,
resembling in appearance the fossils called Coprolites, hereafter
described. The outer chamber of the Ammonites and other shells, so
abundant in the Galt, are often filled with this substance. But the
most interesting deposit of molluskite is in the Kentish Rag of Mr.
Bensted's quarry, near Maidstone. This phenomenon had not escaped
the notice of that intelligent and accurate observer, who liberally
placed at my disposal numerous shells, particularly of _Trigoniæ_ and
_Terebratulæ_, which were filled with molluskite, and large slabs of
the sandstone, full of concretionary and amorphous masses of the same.
The latter, Mr. Bensted suggested, may have been derived from the soft
bodies of the dead Mollusks, which, having become disengaged from their
shells and aggregated together, had floated in the sea, until they
became enveloped in the sand and mud, which have gradually consolidated
into the arenaceous stone termed Kentish Rag, In illustration of this
opinion, Mr. Bensted directed my attention to the following remarkable
fact, related in the _American Journal of Science_:--In the year 1836,
a fatal epidemic prevailed among the shell-fish of the Muskingum River,
in the state of Ohio. It commenced in April, and continued until June,
destroying millions of the mollusca that inhabited the beds of the
tributary streams, and the river. As the animals died, the valves
of the shells opened, and, decomposition commencing, the muscular
adhesions gave way, and the fleshy portions rose to the surface of
the water, leaving the shells in the bed of the river. As masses of
the dead bodies floated down the current, the headlands of islands,
piles of drifted wood, and the shores of the river, in many places,
were covered with them; and the air in the vicinity was tainted with
the putrid effluvium exhaling from these accumulations of decomposing
animal matter. The cause of the epidemic was unknown.
[391] Some of this _molluskite_ has, at my request, been analyzed by Mr.
Rigg, who obliged me with the following remarks:--"After removing the
lime by means of hydrochloric acid from ten grains of this substance,
there remained 1.2 grain of dark powder, which gave, by analysis with
oxide of copper, .16 of a cubic inch of carbonic acid, and a small
portion of nitrogen. On subjecting to the same kind of analysis two
grains of the darker body, without previously acting upon it by any
acid, .054 of a cubic inch of carbonic acid was obtained; so that
from these results there is no doubt but the darker portion of the
molluskite contains about .35 per cent, of its weight of carbon in an
organized state."
"Now nearly the whole of the shells in the beds of Kentish Rag," Mr.
Bensted remarks, "have their shells open, as if they were dead before
their envelopment in the deposit. And, from the large quantity of
water-worn fragments of wood perforated by Pholades imbedded with them,
it seems probable that this stratum had originally been a sand-bank
covered with drifted wood and shells, thus presenting a very analogous
condition to the phenomenon above described." The gelatinous bodies of
the _Trigoniæ_, _Ostreæ_, _Rostellariæ_, _Terebratulæ_, &c., detached
from their shells, may have been intermingled with the drifted wood in
a sand-bank; while, in some instances, the animal matter would remain
in the shells, be converted into molluskite, and retain the form of the
original, as in the spiral univalve, represented in section, _Lign.
139, fig. 3_.
* * * * *
A microscopical examination of the Maidstone molluskite detects, with
a low power, innumerable portions of the nacreous laminæ of shells,
intermingled with the carbonaceous matter, many siliceous spicula of
Sponges, minute spines of Echinoderms, and fragments of Corals; these
extraneous bodies probably became entangled among the floating animal
matter. A large proportion of the shelly laminæ, examined with a high
power, displays the peculiar structure of the _Terebratulæ_ (see
_Lign. 126, fig. 2a_), of which several species are abundant in
the Kentish Rag.
The dark masses and veins so common in the Sussex and Purbeck marbles
are produced by molluskite. If at the period of their envelopment
the shells were empty, they became filled either with grey marl and
limestone, or with white calcareous spar; but if they enclosed the
bodies of the Mollusks, the soft mass was changed into carbonaceous
matter; and in polished sections of the marble, the _molluskite_
appears either in black or dark brown spots, or fills up the cavities
of the shells. The dark blotches and veins observable in the fine
pillars of Purbeck marble in the Temple Church, London, are produced
by molluskite; and the most beautiful slabs of Sussex marble owe their
appearance to the contrast produced by this black substance in contact
with white calcareous spar.[392]
[392] See a "Memoir on the Carbonized Remains of Mollusca," by the
author. Read before the Geological Society of London, February, 1843;
and published in the American Journal of Science.
Carbon, resulting from animal remains, is of frequent occurrence
in many strata; and the fetid emanations from certain limestones,
upon being broken or rubbed, are attributable to the evolution of
sulphuretted hydrogen, from the animal matter which they contain.
* * * * *
[Sidenote: GEOLOGICAL DISTRIBUTION OF SHELLS.]
Geological Distribution of the Bivalve and Univalve Mollusca.--If the
more rare and splendid organic remains may be regarded as the "Medals
of Creation," the fossil testaceous mollusca, from their durability,
numbers and variety, may be considered as the current coin of Geology.
Occurring in the most ancient fossiliferous strata in small numbers,
and of peculiar types,--becoming more abundant and varied in the
secondary formations,--and increasing prodigiously, both numerically
and specifically, in the tertiary, these relics are of inestimable
value in the identification of a stratum in distant regions, and in
the determination of the relative age of a series of deposits. To the
solution of the former problem the sagacity of the late Dr. William
Smith first suggested their applicability;[393] while the idea, so
happily conceived, and so philosophically candied out, by Sir C. Lyell,
of arranging that heretofore chaotic mass of deposits, termed the
Tertiary, into groups, by the relative number of recent and extinct
species of shells, demonstrated the important aid to be derived from
this class of organic remains, in the determination of some of the most
difficult questions in geological science.
[393] See an interesting memoir of Dr, Smith, from the pen of his
distinguished nephew, Professor Phillips.
Many useful tables have been constructed by Professor Phillips,[394]
Sir C. Lyell, M. Deshayes, M. D'Orbigny, Prof. E. Forbes, and other
eminent observers, to illustrate the geological distribution, in the
several formations, of the genera and species of fossil shells hitherto
described. To the English student, Mr. Morris's "Catalogue of British
Fossils," of which an enlarged edition is in the press, will be the
most valuable for reference. In the works which we have especially
recommended for reference (_ante_, p. 10), figures are given of some of
the characteristic shells from each formation, as follow; commencing
with the most ancient deposits.
[394] A Treatise on Geology; and Art. _Geology_, Encyclopæd.
Metropolitana.
Silurian System. _Ly._ p. 350.
Orthis orbicularis; _Ly._ fig. 409.
------ grandis;--fig. 427.
Terebratula navicula;--fig. 410.
------------ Wilsoni;--fig. 413.
Pentamerus Knightii;--fig, 411.
---------- lævis;--fig. 426.
Atrypa reticularis; fig. 414. _Wond._ p. 786.
Lingula Lewisii; _Ly._ fig. 412.
Strophomena depressa;--fig. 421.
Devonian System. _Ly._ p. 342.
Calceola sandalina; _Ly._ fig. 403.
Stringocephalus Burtini;--fig. 404.
Megalodon cucullatus;--fig. 405.
"The Silurian System," by Sir R. I. Murchison, a splendid work on the
rocks and fossils of the above formations, contains numerous figures
of the shells peculiar to each group of strata; and many other species
are delineated in the Memoir on the Devonian deposits of Devonshire
and Cornwall, by Sedgwick and Murchison, _Geol. Trans. New Series_,
vol. v. plates lii-lvii. A Memoir on the Palæozoic Rocks of Germany and
Belgium, by the same distinguished geologists, is also accompanied by
many figures of fossil shells belonging to the same geological epochs.
_Geol. Trans. New Series_, vol. vi.
See also Prof. M'Coy's "Silurian Fossils of Ireland," and his
Description of the British Palæozoic Fossils in the Woodwardian Museum
at Cambridge, in Prof. Sedgwick's "Synopsis of the Classification of
the British Palæozoic Rocks," of which two Parts are already published.
Carboniferous System. _Ly._ 308. _Wond._ p. 736.
Producta punctata; _Wond._ p. 736.
-------- Martini; _Ly._ fig. 390.
Pleurotomaria flammigera; _Lign._ 136, fig. 4.
Euomphalus pentangulatus; _Lign._ 136, fig. 1.
Natica plicistria; _Lign._ 136, fig. 3.
Spirifera trigonalis; _Wond._ p. 736.
--------- triangularis; _Wond._ p. 736.
--------- glabra; _Ly._ p. 389.
Serpula carbonaria; _Ly._ fig. 375.
Avicula papyracea;--fig. 378.
For the shells of the Mountain Limestone, reference should be made to
the second vol. of Prof. Phillips's "Geology of Yorkshire;" to Prof.
M'Coy's "Carboniferous Limestone Fossils of Ireland;" and to Prof,
de Konick's "Anim. Foss. Belg." The fossils of other portions of the
Carboniferous System are illustrated in Phillips's "Palæozoic Fossils
of Devon;"[395] and in Prestwich's Memoir on Coalbrook Dale (_Geol.
Trans._).
[395] To prevent confusion, it may be necessary to state that Professor
Phillips, in the work referred to, terms the Silurian strata the
"_lower palæozoic_" and the mountain limestone, the "_upper palæozoic_"
Magnesian Limestone and Trias. _Ly._ p. 301.
Producta calva; _Ly._ p. 203, fig. 337. } Permian.
Spirifera undulata;--fig. 338. }
Posidonia minuta;--p. 288, fig. 321. } Triassic
Avicula socialis;--fig. 322. }
Prof. King's elaborate Monograph on the Permian Fossils (published by
the Palæontographical Society) should be consulted by the student.
Lias. _Ly._ p. 273.
Pleurotomaria Anglica; _Ly._ p. 39.
Avicula inæquivalvis; _Ly._ fig. 302.
Plagiostoma giganteum; _Ly._ fig. 303.
Gryphæa incurva; _Lign._ 127.
Oolite. _Ly._ p. 257.
Gryphæa virgula; _Ly._ fig. 268.
Ostrea deltoidea (Kimmeridge Clay);--fig. 269.
Trigonia gibbosa;--fig. 270.
-------- clavellata; _Lign._ 127.
-------- costata; _Lign._ 127.
Nerinæa Goodhallii; _Ly._ fig. 274.
Diceras arietinum;--fig. 275.
Pleurotomaria;--fig. 299.
Terebratula spinosa;--fig_ 297.
----------- digona;--fig_ 283.
Ostrea Marshii;--fig. 300.
Phasianella Heddingtonensis;--fig. 58.
Many of the characteristic shells of the Oolite and Kimmeridge Clay,
are figured in Plates XXII. and XXIII. of Dr. Fitton's Memoir on the
Strata below the Chalk; _Geol. Trans. New Series_, vol. iv.
The fossil shells of the Great Oolite are figured and described by
Messrs. Morris and Lycett, in the Memoirs of the Palæontographical
Society; and valuable Papers on the Brachiopods of the Oolite and Lias,
by Mr. Davidson, have been published by the same Society.
Wealden and Purbeck. _Wond._ vol. i. _Geol. S. E._, _Foss. Tilg.
For._, and _Ly._ p. 225.
Melanopsis; _Wond._ pp. 401 and 404.
Cyclas;--p. 404.
Paludina Sussexiensis;--p. 401.
Neritina Fittoni;--p. 401.
Mytilus Lyellii;--p. 405.
Unio antiquus; _Geol. S. E._ p. 250, fig. 1.
---- compressus;--fig. 2.
---- aduncus;--fig. 3.
---- porrectus;--fig. 4.
Valdensis;--_Min. Conch._ pl. 646, and _Lign._ 131.
Corbula alata; _Ly._ p. 229.
Ostrea distorta;--p. 232.
The shells of the Wealden are also figured by Dr. Fitton, _Geol. Trans.
New Series_, vol. iv. Pl. XXI.
Chalk Formation.
I.--Shanklin, or Lower Greensand. _Ly._ p. 219.
Dr. Fitton's Memoir, previously quoted, contains numerous figures of
the characteristic shells of this division of the Chalk, particularly
of the species which abound in the celebrated Whetstone of Devonshire.
_Geol. Trans. New Series_, vol. iv. Pl. XIII-XVIII. See also Prof. E.
Forbes's Catalogue of Lower Greensand Fossils, in the Quart. Geol.
Journal, vol. i.
II.--Galt and Upper Greensand. _Wond._ p. 307; _Ly._ p. 218.
Inoceramus concentricus; _Wond._ p. 330, fig. 1.
---------- sulcatus;--fig. 3.
Terebratula lyra; _Ly._ fig. 219.
Pecten quinquecostatus;--fig. 203.
Ostrea carinata;--fig. 204.
In Plates XI. and XII. of Dr. Fitton's Memoir, there are figures of
more than twenty characteristic shells of this division of the Chalk.
III.--White Chalk. _Ly._ p. 211, _Foss. South D._, _Geol. S. E._
Some cretaceous species are delineated in _Lign. 125, 126, 128, 129,
130, 138_; and Sir C. Lyell figures other species; but I must refer the
student to the _Foss. South D._, _Geol. S. E._, and Dixon's _Fossils
of Sussex_, as accessible works containing numerous figures of the
fossil shells of the Chalk. Accurate descriptions and representations
of all the British chalk shells, however, are still much required.
Mr. Davidson has done much towards the illustration of our Cretaceous
Brachiopods; and the shells of the Cretaceous strata of the United
States are figured and described in an elegant work by Dr. Morton, of
Philadelphia.
Tertiary Formations.
I.--Eocene. _Ly._ p. 174; _Wond._ p. 226.
II.--Miocene. _Ly._ p. 168.
III.--Pliocene. _Ly._ p. 161.
The specimens figured by Sir C. Lyell have been so carefully selected,
and are so well engraven, as to present a _coup-d'œil_ of the most
characteristic shells of the three grand divisions of the Tertiary
Deposits.
I have reserved for especial mention in this place, the work, which
will afford the student of British fossil Conchology the most important
aid in the identification of specimens, namely, the "_Mineral
Conchology of Great Britain_," by the late eminent naturalist, Mr.
James Sowerby, and continued by his son, Mr. James De Carle Sowerby; in
six volumes 8vo., with several hundred coloured plates. Unfortunately,
this work has long been discontinued; and the rapid progress of
discovery, and the numerous foreign publications on every department
of fossil conchology, almost forbid the hope that it will be resumed
by the present proprietor. Although the high price of this work places
it beyond the reach of many individuals, it will be found in most
libraries of Natural History.
* * * * *
[Sidenote: ON COLLECTING FOSSIL SHELLS.]
On the Collection and Arrangement of Fossil Shells.--The instructions
already given for the collection of corals, echinoderms, &c., will
have familiarized the student with the methods generally adopted,
and render it unnecessary to enter into much detail. The shells in
arenaceous deposits, particularly in those of the Tertiary formations,
are commonly so perfect, as merely to require careful removal: those in
the clays are more fragile, and must be extracted with great caution;
and, when very delicate, should be left attached to the clay or shale.
The specimens extracted entire may be kept either in paper trays, lined
with wadding, or fixed to pieces of card or thin board covered with
paper, by thick gum-water; three or four specimens being attached in
different positions, so as to expose the essential characters, as the
aperture, spire, and back of the univalves, and the hinge, muscular
imprints, &c. of the bivalves. Where only casts remain, search should
be made for an impression of the outer surface of the shell, and a cast
taken of it in wax, kneaded bread, or plaster of Paris. In indurated
clays, sometimes both shells and casts may be obtained; and a specimen
of each should be preserved. Mastic varnish, or solution of gum
tragacanth, delicately applied to fragile shells, tends to preserve
them, and improves their appearance. It is desirable to collect the
same species in various states of growth; the form of the young shell
(as in _Rostellaria ampla_, of Solander) often differing essentially
from that of the adult. It will be found convenient to have trays or
boards of different colours; and to select one tint for the shells
collected from a particular formation, or deposit; for example, the
newer Tertiary may be placed on yellow paper; the older, or Eocene
fossils, on light-blue. It is also desirable to separate the marine
from the fresh-water species.
Shells imbedded in chalk, limestone, &c., often require much labour
to display their more delicate and important characters. For clearing
chalk specimens, a stout penknife, and a few gravers or gouges of
various sizes, will be necessary; and by a little practice, the spines
of the Spondylus (_Lign. 128_), and the beaks and hinge of Inocerami
(_Lign. 129_), &c., may be readily exposed. A small stiffish brush,
used with water, is also serviceable. The shells in compact stone,
as those of the mountain limestone, must generally be cleared with
the hammer and chisel. Common species may be broken out, and, from
several examples, probably one or two will be found perfect; but choice
and rare specimens should not be thus risked; they will amply repay
the trouble of the less expeditious method of chiselling away the
surrounding stone. Casts may be taken in gutta percha, &c.
To determine the names of the specimens that he has collected should be
the next care of the student. No method will so readily initiate the
young collector in fossil conchology, as the careful examination of
a small series of the common species, with their names attached.[396]
By the geological map,[397] the nature of the deposit in which the
locality of the specimens is situated, may be ascertained; and the
remarks previously advanced on the prevailing shells of each formation,
will afford a general idea of the genera to which they belong; and, by
referring to the figures quoted, the specific names may be determined.
[396] Such a series may be obtained, at very little cost, of dealers in
objects of natural history; as, Messrs. Tennant, Sowerby, the British
Natural History Society, &c. See Appendix.
[397] A Geological Map of England and Wales, coloured by Mr. Woodward,
under the direction of Sir R. I. Murchison, has been published by the
Society for the Diffusion of Useful Knowledge, at the low price of
5_s._ Although on a very small scale, and therefore not to be compared
for utility and convenience with that by Prof. Phillips, much less with
Greenough's large map, or with Knipe's, it will be found serviceable.
I subjoin a list of some localities of fossil shells, to direct
research in places which are likely to be productive.
* * * * *
BRITISH LOCALITIES OF FOSSIL SHELLS.
[Sidenote: BRITISH LOCALITIES OF FOSSIL SHELLS.]
Aldborough, Suffolk. The usual shells of the Crag.
Alum Bay, Isle of Wight. Eocene tertiary; marine and fresh-water
shells.
Ancliff. Great variety of minute shells of the Oolite.
Arundel, Sussex. Chalk-pits in the neighbourhood.
Atherfield, Isle of Wight, Shells of the lower beds of the Lower
Greensand, in great variety and abundance.
Aylesbury, Bucks. Kimmeridge Clay: near Hartwell.
Aymestry. _Pentamerus_, and other Silurian shells.
Barnstaple, North Devon. Numerous Devonian shells.
Barton Cliff, Hants. Eocene shells in profusion.
Bedford. Lower Oolite, _Terebratulæ_, _Ostreæ_, _Myadæ_, &c.
Binstead, near Ryde, Isle of Wight. Tertiary: in the stone-quarries,
terrestrial and fresh-water shells, as _Bulimus_, _Helix_,
_Limncæ_, and _Planorbis_.
Blackdown, near Collumpton, Devon. Greensand. Numerous silicified
shells, of great beauty. _Trigonia_, _Venus_, _Corbula_,
_Rostellaria_, &c. &c.
Bognor Rocks, Sussex. Eocene Tertiary. _Vermetus_, _Pectunculus_,
_Pinna_, _Voluta_, &c.
Bolland. Numerous shells of the Mountain Limestone.
Bradford, Wilts. Numerous Oolitic shells. _Avicula._
Bramerton Hill, near Norwich. Shells of the Norfolk Crag.
Brighton. _Strondylus_, _Terebratula_, _Ostrea_, _Pecten_,
_Inoceramus_, &c. Many species in the chalk.
Bromley, Kent. Eocene Tertiary. Oyster conglomerate.
Brook-point, Isle of Wight: about one mile east of the Chine.
Wealden: _Unio valdensis_, _Cyclades_, _Paludinæ_, &c.
Brora, Scotland. Oolite. _Pholadomya_, _Sanguinolaria_, &c.
Calbourn, Isle of Wight. Tertiary. Fresh-water Univalves.
Cambridge. In the Galt and Chalk-marl, the usual shells.
Castle Hill, near Newhaven, Sussex. In the Tertiary strata, on the
summit of the hill. Numerous _Potamides_, _Cyclades_, and other
fresh-water shells, _Ostreæ_, with pebbles.
Chardstock, Devon. The fossils of the Lower Chalk.
Cheltenham. Fine shells of the Oolite and Lias.
Chute, near Longleat, Wilts. Greensand shells, in abundance.
Clayton, near Hurst, Sussex. In Chalk-marl, many rare shells; as,
_Dolium nodosum_ (_Min. Conch._ tab. 326.)
Clifton. Carboniferous Limestone. _Spirifera_, _Producta_, &c.
Coalbrook Dale. Silurian and Carboniferous fossils.
Cork. In the vicinity. Carboniferous limestone shells.
Crich Hill, Derbyshire. The usual shells of the Mountain Limestone.
Cuckfield, Sussex. In the Sandstone and Grit, fresh-water shells of
the Wealden.
Dudley. Profusion of shells of the Silurian strata.
Dundry, near Bristol. Beautiful shells in the Inferior Oolite.
Earlstoke, Wilts. Many shells of the Greensand.
Faringdon, Berks. The usual shells of the Oolite in the Coral Rag,
&c.; and of the Greensand, in the Gravel-pits.
Folkstone, Kent. Galt. _Inoceramus_, _Arca_, _Rostellaria_,
_Dentalium_, &c. Lower Greensand, _Gryphæa_, _Ostrea_, &c.
Gravesend. Beautiful shells of the White Chalk.
Hampstead Cliff, Isle of Wight. Fresh-water Tertiary shells.
Hampton Quarry, near Bath. Abounds in Oolitic shells.
Hartwell, Bucks. On the estate of Dr. Lee, beautiful shells of the
Kimmeridge Clay.
Harwich Cliff, Essex. The Crag shells. _Voluta Lamberti_.
Hastings, Sussex. Fresh-water shells of the Wealden.
Headon Hill, Isle of Wight. Fresh-water Tertiary shells in profusion.
Heddington. Oysters in Kimmeridge Clay (_Ostrea deltoidea_). _Perna_,
_Gervillia_, _Trigonia_, &c.
Highworth, Wilts. Very fine Trigoniæ, and other Oolitic, shells, in
the stone-quarries.
Hollington, near Hastings. Wealden. Fresh-water bivalves, &c.
Holywell, near Ipswich. Shells of the Crag, abundantly.
Hordwell Cliff, Hants. The usual shells of the Eocene deposits, in
immense quantity, variety, and perfection.
Horningsham, near Frome, Wilts. Oxford Clay. _Terebratula_, _Pecten_,
&c. in great numbers.
Horsham, Sussex. Fresh-water shells of the Wealden, in the
stone-quarries.
Humbleton Hill, Sunderland. Permian fossils.
Hythe, Kent. Greensand. _Trigonia_, _Gryphæa_, _Pecten_, &c.
Ilminster, Somerset. _Brachiopoda_, &c. Inf. Oolite and Marlstone.
Ipswich. The usual Crag shells.
Langton Green, near Tunbridge Wells. Wealden. In the sandstone
quarries, _Uniones_, _Cyclades_, &c.
Leckhampton Hill, near Cheltenham. Numerous shells of the Inferior
Oolite and Lias.
Lewes. _Inoceramus_, _Pecten_, and usual shells of the White Chalk
and Chalk Marl.
Ludlow. _Pentamerus_, _Spirifera_, &c. and other Silurian shells.
Lyme Regis. Lias. _Plagiostoma_, _Gryphæa_, _Trochus_.
Malton. Beautiful shells of the Oolite.
Matlock, Derbyshire. The mountain limestone in the vicinity abounds
in the characteristic shells _Leptæna_, _Spirifer_, &c.
Minchinhampton. Numerous shells of the Great Oolite.
Osmington, near Weymouth. Purbeck; fresh-water and marine shells:
Oolite; _Trigonia_, _Gervillia_, _Perna_, _Pholadomya_, and many
other genera.
Portland, Isle of. Oolite. In the stone-quarries immense numbers of
the genera _Trigonia_, _Venus_, _Ostrea_, _Pecten_, &c.
Pluckley, Kent. Lower Greensand. _Trigoniæ_, _Terebratulæ_, &c.
Radipole, near Weymouth. _Trigonia_, _Pholadomya_, &c. in Oxford Clay.
Sandgate, near Margate. In the Greensand, the usual shells.
Scarborough. In the cliffs along the shore, a profusion of Oolitic
and Liassic shells.
Selbourne, Hants. In the firestone, _Ostrea carinata_ and other
characteristic shells.
Shalfleet, Isle of Wight. In tertiary fresh-water limestone, shells
of various genera, as _Bulimus_, _Helix_, _Planorbis_, &c.
Shanklin Chine. Greensand. In the cliffs along the shore,
_Terebratidæ_, _Gryphites_, _Gervilliæ_, and many other shells.
Sharnbrook, Bedfordshire. The usual shells of the Cornbrash and Lower
Oolite.
Sheppey, Isle of. Eocene. London Clay shells, in abundance.
South Petherton, Somerset. _Terebratulæ_, _Pholadomya_, _Ostreæ_,
_Pleurotomariæ_, &c. of the Marlstone.
Stamford, Lincolnshire. Lower Oolite. Univalves and bivalves in
profusion.
Stonesfield, Oxfordshire. _Trigoniæ_ and other shells of the Lower
Oolite.
Stubbington Cliff, near Portsmouth. Eocene shells.
Swanage. In the quarries in the vicinity, the prevailing fresh-water
shells of the Purbeck limestone.
Swindon, Wilts. Oolite. The Portland limestone abounds in the usual
shells of that deposit. _Trigoniæ_, _Gervilliæ_, &c.
Taunton, Somersetshire, (Pickeridge Hill, &c.) _Lima_, _Pecten_, and
other Liassic shells.
Tisbury, Wilts. Beautiful _Trigoniæ_, and other shells of the
Portland Oolite.
Vincent's, St., near Clifton. The rocks abound in the usual shells of
the mountain limestone.
Walton, Essex. Shells of the Crag, in great variety.
Weymouth. The Oxford Clay and other strata in the vicinity contain
great variety of fossil shells.
Whitecliff Bay, Isle of Wight. Eocene. Marine and fresh-water shells.
Worthing. The chalk quarries in the neighbourhood are remarkably
prolific in the usual species; and yield Sphærulites.
Note.--A comprehensive list of the localities for _Lower Palæozoic_
shells, &c. is given by Prof. M'Coy in the second Fasciculus of the
"British Palæozoic Fossils;" and in the little "Stratigraphical List,"
published by Mr. Tennant, reference is carefully made to the localities
for the fossils of every formation.
END OF VOL. I.
R. CLAY, PRINTER, BREAD STREET HILL.
* * * * *
BOHN’S SCIENTIFIC LIBRARY.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
MANTELL’S
MEDALS OF CREATION.
VOL. II.
[Illustration: _Pl. 2_
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
THE
Medals of Creation;
OR,
FIRST LESSONS IN GEOLOGY,
AND
THE STUDY OF ORGANIC REMAINS.
BY
GIDEON ALGERNON MANTELL, LL.D. F.R.S. V.P.G.S.
PRESIDENT OF THE WEST LONDON MEDICAL SOCIETY, ETC.
AUTHOR OF THE WONDERS OF GEOLOGY, ETC.
[Illustration: INCLINED STRATA OF MILLSTONE GRIT, CRICH HILL.]
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
IN TWO VOLS.--VOL. II.
CONTAINING
Fossil Cephalopoda, Crustacea, Insects, Fishes Reptiles,
Birds, and Mammalia.
WITH NOTES OF GEOLOGICAL EXCURSIONS.
SECOND EDITION, ENTIRELY REWRITTEN.
LONDON:
HENRY G. BOHN, YORK STREET, COVENT GARDEN.
LONDON:
R. CLAY, PRINTER, BREAD STREET HILL.
DESCRIPTION
OF THE
FRONTISPIECE OF VOL. II.
PLATE II.
_Illustrative of the mode of developing Fossil Fishes in Chalk._
Osmeroides Mantelli: a Fossil Smelt; from the _Chalk_, Lewes.
See page 626.
(_One-third natural size._)
Fig. 1.--The two corresponding surfaces of a block of Chalk split asunder. The
irregular oval lines, seen on each surface, are the only apparent indications
that the stone contains an extraneous body.
2.--In this figure the two pieces represented above are shown cemented
together; care having been taken that the oval markings on each
surface were accurately adjusted. The chalk has been chiselled away
in the supposed longitudinal direction of the enclosed extraneous
body, and part of the scaly surface of a fish has been thus brought to
light. A portion of chalk has also been removed towards both ends,
with the view of ascertaining the extent and direction of the fossil;
and at each place indications of its presence are visible.
3.--Represents the specimen completely developed. It proves to be a fish
almost perfect, lying on its back, with the body uncompressed, the
mouth open, the arches and opercula of the gills expanded, and the
dorsal, pectoral, and ventral fins entire. The caudal fin, or tail, is
imperfect. The original is nine inches long, and is one of the most
extraordinary fossil fishes ever discovered. It belongs to the Salmon
family, and is allied to the Osmerus, or Smelt; it is now in the British
Museum. We thus perceive that the oval markings on the surface of
fig. 1 were occasioned by the section of the scales covering the cylindrical
body of the fish (see p. 627). A magnified view of one of the
scales is figured _Lign. 185, fig. 4_, p. 567.
LIST OF LIGNOGRAPHS IN VOL. II.
=======
(_Illustrative of Fossil Zoology._)
LIGN. PAGE
140. Fossil Cuttle-Fish (Kelæno) 447
141. Belemnites, from the Chalk, &c. 451
142. Restored outline of Belemnites 453
143. Restored outline of the Belemnites Puzosianus 454
144. Perfect specimen of Belemnites Puzosianus 455
145. Belemnoteuthis antiquus 460
146. Horny rings and hooks of Belemnoteuthis antiquus 461
147. Osselets of extinct dibranchiate Cephalopoda 463
148. Bellerophon 465
149. Nautilus pompilius in its shell 467
150. Fossil Nautili 470
151. Nautilus elegans 471
152. Nautilus Saxbyi 472
153. Casts of Chambers of Nautilus and Ammonite 473
154. Clymeniæ 473
155. Orthoceratites 475
156. Ammonites from the Cretaceous formation 476
157. Ammonites communis 477
158. Ammonites Jason 479
159. Goniatites 482
160. Shells of the Ammonitidæ 484
161. Hamites, &c. from the Chalk-marl 480
162. Scaphites 488
163. Turrilites 489
164. Turrilites tuberculatus 491
165. Aptychus sublævis 492
166. Fossil impression of Nereis 504
167. Fossil Barnacles and Pholades 507
168. Fossil Crustaceans from the Galt 513
169. Fossil Crustaceans from the Chalk 517
170. Fossil Crustacean from the Oolite 519
171. Archæoniscus Brodiei 521
172. Fossil Limulus, in a Nodule of Ironstone 522
173. Limulus trilobitoides 523
174. Fossil Cyprides 527
175. Trilobites 533
176. Homalonotus delphinocephalus 536
177. Phacops caudatus 538
178. Paradoxides Bohemicus 539
179. Fossil Libellula 551
180. Wings of Neuropterous Insects 553
181. Fossil Wings of Insects 554
182. Insectiferous Limestone 556
183. Fossil Insects from Aix 558
184. A group of Fossil Fish from Aix 562
185. Fossil Scales of Fishes 567
186. Lepidotus 575
187. Amblypterus 576
188. Dorsal Rays of Sharks 578
189. Fossil Teeth of Sharks 585
190. Mandible of Edaphodon Mantelli 589
191. Mandibles of Edaphodon Leptognathus 589
192. Fossil Teeth of Sharks 591
193. Fossil Teeth of Sharks from the Chalk 594
194. Fossil Teeth of Fishes 598
195. Dapedius 603
196. Scales and Fin of Lepidotus Mantelli 605
197. Portion of the Jaw of Lepidotus 606
198. Gyrodus Murchisoni 609
199. Cephalaspis Lyellii 611
200. Cephalaspis Lyellii 611
201. Coccosteus and Pterichthys 613
202. Teeth of Asterolepis 619
203. Smerdis minutus 626
204. Fossil Teeth and Jaws of Fishes 629
205. The Lower Jaw of Iguana 649
206. Fossil Vertebræ of Reptiles 653
207. Dermal Bone of the Swanage Crocodile 658
208. Dermal Bones of Fossil Reptiles 660
209. Eye of Ichthyosaurus 664
210. Teeth of Ichthyosaurus and Plesiosaurus 665
211. Vertebra of Ichthyosaurus 666
212. Pectoral Arch of Ichthyosaurus 667
213. Pectoral Arch of Plesiosaurus 667
214. Paddles of Ichthyosaurus and Plesiosaurus 668
215. Hinder Paddle of an Ichthyosaurus, with its Integument 669
216. Skull and Jaws of Teleosaurus and Steneosaurus 675
217. First Caudal Vertebra of Crocodilus Hastingsiæ 676
218. Portion of Jaw of Megalosaurus Bucklandi 686
219. Tooth of the Megalosaurus Bucklandi 687
220. Jaw of Iguanodon Mantelli 693
221. Lower Tooth of the Iguanodon 694
222. Upper Tooth of the Iguanodon 695
223. Teeth of Iguanodon 696
224. Six Caudal Vertebræ of the Iguanodon 699
225. Left Femur of the Iguanodon 701
226. Bones of the Feet and Claws of Iguanodon 703
227. Mosasaurus Hoffmanni 706
228. Mosasauroid Teeth 707
229. Tooth of Mosasaurus 708
230. Mosasauroid Tooth 710
231. Rhynchosaurus articeps 712
232, 233. Dicynodon lacerticeps 716
234. Dicynodon testudiceps (tooth) 719
235. Telerpeton Elginense 721
236. Telerpeton Elginense (outline) 722
237. Pterodactylus crassirostris 724
238. Chelone Benstedi 733
239. Mandible of a Turtle 734
240. Chelone Bellii 735
241. Tretosternon Bakewelli 737
242. Palæophis Toliapicus 738
243. Cryptobranchus Scheuchzeri 741
244. Archegosaurus Dechenii 747
245. Cheirotherium Kaupii 752
246. Fossil Bird 767
247. Ornithoidichnites from Massachusetts 770
248. Bird-like Footprint, and Impressions of Rain-drops 771
249. Zeuglodon cetoides (teeth) 780
250. Teeth of Zeuglodon 781
251. Teeth of Ruminant 782
252. Leg-bones of Horse, Deer, and Anoplothere 784
253. Elephas Ganesa (skull and tusks) 785
254. Mastodon Tooth 786
255. Anoplotherium (outline) 788
256. Anoplothere and Palæothere (teeth) 790
257. Hyopotamus Teeth 792
258. Tooth of Mastodon Elephantoides 794
259. Elephant Tooth 794
260. Elephant Teeth 794
261. Hippopotamus Teeth 795
262. Rhinoceros Teeth 796
263. Teeth of Horse 797
264. Foot and Tooth of Glyptodon 800
265. Jaws of Phascolotherium and Ampitherium 806
(_Illustrative of Geological Excursions._)
266. Hammers 832
267. Brighton Cliffs 852
268. Section of Brighton Cliffs 854
269. Section at Farringdon 861
270. Section at Derwent Valley 876
271. Crich Hill Quarry 886
272. View of Crich Hill 887
273. Plan of Crich Hill 889
274. Section of Crich Hill 890
275. Diagram Section of Crich Hill 895
TABLE OF CONTENTS.
~~~~~~~~~~
VOL. II.
Description of the Frontispiece of Vol. II. p. v.
List of Lignographs in Vol. II. vii.
Contents of Vol. II. ix.