A MONOGRAPH

OF THE

CRAG MOLLUSCA,

WITH

DESCRIPTION OF SHELLS

FROM THE

UPPER TERTIARIES OF THE BRITISH ISLES.

SEARLES V. WOOD, F.G.S.

VOL. II.

BIVALVES.

LONDON:

PRINTED FOR THE PAL£)ONTOGRAPHICAL SOCIETY.
1851—1861.

EARTH

SCIENCES

LIBRARY

PEINTED BY
•J. E. ADLARD, BAETHOLOMEW CLOSE.

NOTE

TO

THE CRAG MOLLUSC A.

IN the Appendix to the ' Crag Mollusca,5 p. 323, is the notice of a fossil which I
have there assigned, with doubt, to the Genus Aplysia, conceiving it to have been the
calcareous portion of an internal shell ; and as it is important that errors of this kind
should not remain unconnected, I take the earliest opportunity of making the correc-
tion. In the living Aplysia there is a shell or shield situated on the back of the animal,
encysted in the mantle, covering the branchial region ; and although this internal
shell in the recent state is thin and coriaceous, I thought it possible there might be
sufficient calcareous matter in the shell of some species of that genus to permit its
being preserved in a fossil state. In this I have been mistaken. Considerable doubt
was entertained by me at the time of publication, but it was my desire to have
everything figured that appeared to be in any way connected with the Mollusca of the
Crag.

In the course of my examination of the Eocene Bivalves, now preparing for
publication, my attention has been directed to the Genus Anomia, and I find there
that the right or under valve is sometimes so small as almost to be obsolete or useless
as a protection to the living animal, the diameter of the upper valve being in some
instances three times that of the lower, and the construction of this latter is often
so thin and fragile as to permit the greater part of it to be easily destroyed. From
the umbonal region of this valve, proceeding towards the larger side in the interior
of the shell, are two thickened ridges, one forming the dorsal margin and the other
extending downwards to the body of the shell immediately on the hinder edge of the
foramen, which gives a strength and protection to this part of the valve over the

87491

2 NOTE TO THE CRAG MOLLUSCA.

other, and this is the state and condition of the specimens of my little Crag fossil,
the correct position of which I had been unable to determine ; the figure, therefore
(fig. 24, PI. XXXI) will serve as an illustration of the under valve of what probably
was the young state of the Crag A. ephippium.

There is every reason to believe that the Genus Aplysia existed during the Tertiary
Period, but as yet it appears we have no well-attested specimens of their remains
having been preserved in a fossil state.

S. V. WOOD.

May, 1860.

A MONOGRAPH

OF THE

MOLLUSCA FROM THE CRAG.

BIVALVIA, Linnaus, 1767.

BIVALVIA. Bonanni, 1661. Lister, 1686. Flem. 1828.

DITHYRA. Arist. Turt. 1822. Swains. 1840.

DITOMA. Tournefort, 1742.

ACEPH ALA TE STAGE A (part). Cuv. 1/89.

LAMELLIBRANCHIATA. De Blainv. 1814.

CONCHIFEKA (part). Lam. 1818.

CONCHA. Leach. 1819.

PELECYPODA. Goldfuss, 1820.

ENDOCEPHALA (part). Lot. 1825.

ELATOBRANCHIA. Menke, 1830.

CORMOPODA. Burm. fide Herrm.

ANIMALS of this Division of the Linnean Testacea have no proper head, their most
vital parts are enveloped in a mantle, or pallium, as it is called, which surrounds them
on all sides ; the edges of this mantle are sometimes plain, at others fringed, and are
more or less united : what is called the foot, is generally a large and powerful muscular
mass, capable, in some species, of being protruded beyond the shell to a considerable
distance. The respiratory organs, or branchiae, are usually four in number, and are
arranged in the form of ruffles enveloping the abdominal mass, but entirely included
within the mantle ; in some few of the species, the number of these feathery append-
ages is less, while in others there are more, than four. The animal is protected by
two portions of shelly matter called valves, these are secreted by and formed upon the
mantle, and are articulated together by a cartilage and ligament, by which the two
pieces are held in position, and move, as it were, like a door upon its hinge, or rather

1

2 MOLLUSCA FROM THE CRAG.

like the two covers of a book, this is furthermore often strengthened by prominences
and depressions in a part of the shell kept thickened for the purpose, interlocking each
other, preventing, in most instances, the possibility of any material inconvenience
arising from lateral motion without a fracture. The common action of the valves in
their separation or opening is from the relaxation of the adductor muscles, when from
the natural elasticity of the ligament the valves are drawn apart, and again closed by
the contraction of the muscle or muscles that pass from one valve to the other, strongly
adhering: to the inner surface of the shell on which, in most cases, a distinct, and often

O

a deep indentation is left.

The muscular fibres by which the edges of the mantle are withdrawn adhere to,
and leave a linear impression somewhat within the margin of the shell ; and, in some
of the Bivalvia, at the posterior side of the animal, are two siphonal tubes, formed by
the prolonged portions of the mantle, the lower one is called the inhalent, the upper
one the exhalent siphon, these tubes are capable of being protruded by the animal with
the assistance of muscles for that purpose, and again withdrawn under the protection
of the shell. In animals possessed of these tubes, the withdrawal of them is indicated
in an impression on the body of the shell by the retractor muscle, leaving what is
called a siphonal scar, or palleal sinus, which generally denotes, by its depth, a cor-
responding proportion in the length of the tubes ; and where the muscular fibres of
the mantle adhere to the interior leaving the impression without an inflection, the
animal either has no prolongation of the mantle, or that the tubes are so short as
scarcely to be capable of extension beyond the margin of the valves, and the im-
pression in that case formed by the mantle is parallel, or nearly so, to the outer edge
of the shell.

These marks, therefore, are of essential service to the Palaeontologist, as they
afford the only indications of the form possessed by the animal inhabitant, thus im-
pressed upon the interior of the valves. It is however to be feared, that a perfectly
strict reliance cannot always be placed upon the peculiar magnitude of this siphonal scar,
even in specific determination, as a marked deviation from what might otherwise be
considered its typical form may occasionally be detected, but it is in those species
which are most subject to variation in the outward forms of the shell ; as a general
rule, this line, when visible, is of the greatest assistance, and at all times a good
auxiliary character in the determination of a species. The length of the siphonal
tubes, or the consequent indenture or sinuation of the mantle mark in the shell,
points out a difference in the animal from those in which the sinus is wanting, or at
least nearly so, where it indicates a mantle either without or with very short siphons,
giving fair grounds for generic separation ; but occasionally, species are met with that
are otherwise very closely allied, having a similar dentition, and bear the same general
relationship in regard to the shell, although very unlike in the form of the mantle-
mark, such as Leda and Nucula, Cardium and Adacna, Lucina and Lucinopsis, and
cannot, without violence to a natural arrangement, be removed to any distant position,

BIVALVIA. 3

merely, in consequence of a difference in the length of the tubes or depth of the

sinus.*

Some Malacologists seem disposed almost entirely to reject the shell, as unworthy
of consideration in a Zoological arrangement, viewing it in the light of an inert or
inorganic mass, unconnected with the animal, or at least merely formed by and used
as a protection to its more vital parts, and have based their superstructure upon the
mantle itself, and upon the difference in length of its siphonal tubes. In the ' History
of British Animals/ by Dr. Fleming, published in 1828, the Bivalvia were separated
into two sections, called SIPHONIDA and ASIPHONIDA, a division subsequently
adopted by some continental authors under the denominations SINUPALEALIA and
INTEGROPALEALIA, as founded upon a portion of the animal more highly organised than
its dermal covering, and, consequently, supposed to give a more scientific basis to its
classification. Investigations by the microscope have shown a high degree of organi-
sation, and the possession of a considerable amount of vitality in the shell, essential to
the existence, depending upon, and modified by the exigencies of the animal ; and in
this outer coating of the mantle there is preserved a relationship apparently more con-
stant than is exhibited by its fleshy interior ; and whatever other organs, in the more
vital parts may be supposed to furnish a basis for Ordinal division, it is very doubtful
if the form of the mantle alone will be sufficient.

The number and position of those parts of the hinge called teeth are essential
distinctions, as there is a permanence of form in the dentition of all genera, although,
in a few instances, these characters which are prominent and distinctive in some
species, will be diminished and become nearly obsolete in others ; but they do not
vary in form or position in the same genus. f That portion of the hinge called the
ligament, performs an important office in the animal economy, as it is by this the
valves are bound together, and kept in their true position. This uniting and elastic
substance is called cartilage, when it is placed within the edges of the valves, and is
consequently compressed when they are closed, and by its tendency to expand at the
relaxation of the adductor muscle or muscles, assists in the separation of the shells at
the ventral margins : that portion which is external, is called ligament, and is generally
placed on a prominent fulcrum, or projecting portion of the shell, and by its elasticity
or contraction draws back and opens the valves when the opposing power of the
adductors is relaxed ; although this substance is of a cartilaginous nature, and con-
tains but a small portion of lime, and is consequently not often preserved in a fossil
state, its position is always indicated where it has been, either by a pit or depression
for its reception, or by the fulcrum to which it was attached. In the smaller portion
of the Bivalvia, the animal is furnished with only one adductor muscle, and constitutes

* Great differences also exist between the mantles of some of the members of the Leptonidae.

f There is a slight exception to this rule in the hinge of the Polyodonts, Leda, Pectunculus, fyc., where
the number of teeth will vary, even in individuals of the same species at different periods of existence,
but their general character is not altered.

4 MOLLUSCA FROM THE CRAG.

that division or section called Monomyaria, or Unimusculosa, by some authors. In this,
the muscle is placed in the centre, or nearly so, and is generally large and powerful,
adhering strongly to the interior, leaving often a deep indentation which is sometimes
of a different colour to the rest of the shell ; the form of this muscle mark is variable
in different genera, but is not of much assistance in specific determination. Some of
these have the hinge ligament on the exterior, like the Oyster, &c., where it acts by
contraction and elongation ; in others, Pecten, &c., its action is by expansion and com-
pression ; in this group, the edges of the mantle are generally disunited and not pro-
longed into siphons, and the impression formed by its muscles within the shell, is
without any inflection, and parallel to the margins of the valves. In the much larger
portion, called Dimyaria, or Bimusculosa, the animal has two distinct adductor muscles,
one of which is situated near the anterior margin, while the other occupies generally a
corresponding position on the posterior side.

As these muscular impressions are relatively situated in the same position, and
always of the same form,, a great alteration takes place during the growth of the
animal by a gradual progression, as it increases in size and the shell enlarges ; the
successive advancement of these impressions is indicated in many species by distinct
lines of growth : and as this enlargement necessarily increases outwardly, the animal
possesses the power of making fresh additions to the exterior portion of the muscle,
while at the interior part, the now becoming useless or inconvenient portion, is
detached from its former place of adherence, and absorbed by the animal ; while in
most species, a fresh layer of calcareous matter, secreted from the whole surface of
the mantle, is deposited upon the interior of the shell, and covering the deserted
portion of the muscle mark, leaving untouched that part only against which is
attached its powerful adductor. In the Oyster, more especially, these successive
layers are distinctly visible, showing the enlargment of the shell by the extension
of the mantle in the lines of growth upon the exterior, as also by the generally
rugose or lineated surface of the ligamental area. The same may be said of the
dental characters of the shell which are always relatively placed in regard to the
specimen, whether in the young or in the adult ; and the alteration, therefore, of their
position in the growth of the shell, can only be effected by the removal of one part,
while fresh deposition is formed on the other, unless the whole be sufficiently organised
to partake of the varying changes of the animal itself: a question as yet not satis-
factorily determined.

Dr. Carpenter gives in his ' Report on the Microscopic Structure of Shells,' as the
true history of the Conchiferous Acepkala, the following account :— " The margin only
of the mantle has the power of giving origin to the outer layer of the shell, while the
whole surface may generate the inner. Every new production of shell consists of an
entire lamina of the latter substance, which lines the whole interior of the old valve,
and of a broader margin of the former which thickens its edge. So long as the
animal continues to increase in dimensions, each new exterior layer of shell projects so

BIVALVIA. 5

far beyond the preceding, that the new border composed of the outer layer, is simply
joined on to the margin of the former one, so that the successive formations of the
outer layer scarcely underlie each other. But when the animal has arrived at its full
growth, the new laminae cease to project beyond the old, and as each is composed of
a marginal band of the external substance attached to the edge of an entire lamina of
the inner, these bands must now underlie each other, being either quite free as in
Ostrea, or closely united to each other as in Unio, and most other Bivalves ; and the
additions to the shells of the Gasteropoda are made upon the same plan, although it
has commonly been supposed that they are only attached to the edge of the old shell,
instead of being continued over its entire surface."

The figure and size of the foot materially influences the form of the anterior part
of the shell, while the posterior depends upon the modification of the siphons.
The degree of development of the nervous system is said to be very variable in
these animals, and the organs of sense dependant thereon variously distributed, im-
perfect organs of sight are present in some species, and rudimentary organs of hearing
have been detected in others, and are possibly present in all : while in some, the sexes
are separate and distinct, in others they are united or hermaphrodite, microscopic
animals and plants constitute their principal food.

Species of this class have been found in the seas of every clime, and inhabit the
waters of all depths, some few are left dry by the retiring tide, while others frequent
the bottom of seas, to the depth of 200 fathoms ; and the vertical range of many
species is so extensive, as to render doubtful the allocation of strata from the presence
of a few fossil forms, with whose habits we are but indifferently acquainted ; more-
over, the habits of all recent species are not, perhaps, necessarily the same as those
of their prototypes that lived in times long past, and probably, under different
conditions.

The authors of the beautiful work upon the 'British Mollusca,' now in the course of
publication, have given many interesting details respecting the range in depth at
which most of these animals have been obtained, and occasionally, the nature of the
ground they had selected for their habitation ; the generality of species prefer clear
water and a sandy bottom, but others are frequenters of mud. The bottoms of the
Crag Seas, judging from the deposits now remaining upon the Eastern Coasts of
England, appear to have been principally of sand or gravel, with comminuted frag-
ments of shells ; that of the Coralline Crag Sea being generally fine in its particles,
formed at a depth varying, perhaps, from 20 to as much as 40 fathoms, if the habits of
the then existing animals were the same as their homologues of the present day. The
Red Crag Sea appears to have been subject to greater agitation, and was probably
less in depth, while much of its bottom was of a gravelly character, or of coarser sand.
The deposits of the Mammaliferous Crag Period present us with characters rather
more variable ; that which is found near Norwich, being what is called Fluvio-marine,
formed probably, in a shallow estuary, and composed of sand, gravel, and shells,

6 MOLLUSCA FROM THE CRAG.

while the Bridlington bed was more purely marine, with a bottom apparently of sandy
mud, similar to what is exhibited by the newly discovered tranquil deposit resting
upon the Red Crag at Chillesford, where the water may have been of some con-
siderable depth.

In estimating the dimensions of the shell in the following descriptions, the pro-
portions are given only as an approximation ; in most species, these are more or less
variable. The length is taken from the anterior edge of the shell to the outermost
portion of the posterior side, that being considered as anterior where the foot is pro-
truded, while the position of the ligament and the siphonal tubes, where they exist or
their presence shown in the shell by the sinuated form of the pallial impression, is on
the posterior side. Presuming, therefore, the animal to move with the foot foremost,
it will have its dorsal or hinge-part of the shell uppermost, and the diameter from the
umbo to the ventral margin is called its height, while the depth is measured from the
most tumid part of one valve to the corresponding place in the other.

ANOMIA.* Linn. 1767.

ANOMIA. Miiller. 1776.

GLYCIMEEIS. Browne, 1756.

LAMPADES (sp.). Gevers. 1787, fide Gray.

FENESTELLA. Bolton. 1798, fide Herrmansen.

ECHION and ECHIODERMA. Poll. 1791.

CEPA. Humphries, 1797.

ANOMYA. Agass. 1839.

Generic Character. Shell irregular, inequivalved, subequilateral, ovate or sub-
orbicular, and fixed : lower or inferior valve more or less flattened, with a large
foramen or perforation, through which passes a bony or calcareous appendage for the
attachment of the animal ; upper valve, convex smooth or irregularly laminated,
sometimes striated, costated or muricated, often assimilating the body of the shell to
that on which it is fixed ; one muscular impression in the lower or fixed valve, with
three in the upper or convex one ; ligament internal, placed a little within the umbo of
the upper or larger valve, in a somewhat triangular pit, with a projection near the
edge of the foramen in the opposite valve, to which it is attached ; hinge without
teeth.

The animal of this genus, is said to have the edges of the mantle disconnected,
the margins bearing a double fringe of short scirrhous appendages, without ocelli or
rudimentary eyes. No siphonal tubes, and foot very small, nearly obsolete. The
adductor muscle is divided into three parts, making three distinct impressions on the

* Etym. 'Avojuoios, unlike or unequal.

BIVALVIA. 7

upper, while one only is formed upon the lower valve, the other two passing into the
calcareous operculum by which it is fixed. Sexes distinct.

As the individuals of this genus are always attached, they are seldom of a regular
form, but generally more or less distorted, modified by, and often assuming the shape
and characters of the body to which they adhere ; and as they are frequently attached
to the shells of the Pecten, an individual of this genus, which in its natural state is
nearly smooth, will become, in consequence, rayed or pectinated, partaking of the
characters of the body it has been living upon. If, therefore, it be attached near the
umbo of the Pecten, its regular increase will assume the form of that genus ; but if its
attachment be upon the wider rays, these ribs will not represent the regular form, but
the impress of its place of attachment will be shown, as in fig. 3 b, in parallel or nearly
parallel ridges across the shell. In order to produce this appearance, the addition
that is made by the mantle to the edges of the shell are carried over the ribs of the
Pecten down into the interspaces, by which means a costated form is given to a shell,
otherwise smooth. This character, however, according to Mr. Clark, appears to be
eclectic, or at the will of the animal. Thus, whenever the under or lower valve has
its edges elevated above the ribs of the Pecten, so as not to be influenced by those
inequalities, then the upper valve retains its original form. The lower valve is
generally thin, often papyraceous, so that in the fossil state, the upper valve is
the most numerous.

The Anomia is closely allied to the Pectens, and the perforation in the lower valve*
is said by the authors of the ' Hist, of Brit. Mollusca,' to be chiefly a greater extension
of the auricular sinus of that genus ; and that the young fry will be probably found
attached by means of a byssus, which as the animal increases, eventually becomes
converted or transformed into the calcareous opercular process of the older shell, this
organ of attachment being merely the extension and indurated portion of the lower
part of the adductor.

A large number of detached valves are found in the Coralline Crag, but their
specific appropriation is a matter of great difficulty from their excessive variability of
form, as well as great irregularity in their external ornament ; and as their correct
assignment, even in a recent state, with " all appliances and means to boot" by the
aid of their animal inhabitant, as well as by assistance given in the colouring matter of
the shell, is still a doubtful matter, the appropriation of the fossil species may be looked
upon with suspicion.

Mr. Clark in the examination of this genus, has arrived at the conclusion, that
there is but one species now found in the British Seas ; and that the extraordinary
variation both in form and sculpture, exhibited by individuals, is so fluctuating in
character, as not to be depended upon for specific distinction. As, however, there
are generally some marked differences in these shells by which the variations may be
separated, I have followed the authors of ' British Mollusca,' in considering them for
the present so many distinct species.

8 MOLLUSCA FROM THE CRAG.

This genus is found in the Secondary Rocks ; one species has been described by
Mr. Bean, from the Cornbrash ; ( Mag. Nat. Hist.' 1839. And some from the Green-
sand by Dr. Fitton.

1. ANOMIA EPHIPIUM, Linnceus. Tab. I, fig. 3, a — d.

ANOMIA EPHIPPIUM. Linn. Syst. Nat. ed. 12, p. 1150, No. 218, 1767.

— SCIUAMULA. Id. p. 1151, No. 221.

Turt. Brit. Biv. p. 229, pi. 18, fig. 5-7, 1822.
Broc. Conch. Foss. Subap., p. 461, 1814.

Dekay. Nat. Hist. New York (Zool.), p. 168, pi. 12, fig. 209, 1843.
Middendorff". Malacozoologia Rossica (Mem. de 1'Acad. des Sc. Imp*
de St. Petersb.), p. 519, t. 11, fig. 18-21, 1849.

— SULCATA. Poli. Test. Sic. vol. ii, p. 186, t. 30, fig. 12.

— MARGAKITACEA. Id. t. 30, fig. 11.

— CCEPA. Id. t. 36, figs. 1, 25-8.
LENS ? Goldf. Pet. vol. ii, p. 40, t. 88, fig. 8, a— e.

— EPHIPPIUM. S. Wood. Catalogue, 1840.

— COSTATA. Broc. Conch. Foss. Subap., p. 463, t. 10, fig. 9, 1814.

— KADI ATA? Id. - t. 10, fig. 10.

— SULCATA? Id. - - t. 10, fig. 12.

Spec. Char. Testa polymorpld, crassd vel tenui, plerumque lavigatd, forma valde
irregulari.

Shell many shaped, thick and strong, sometimes thin and fragile, generally smooth,
form very irregular.

Diameter, f ths of an inch.

Locality., Cor. Crag, Sutton, Sudbourn.

Recent, Mediterranean, Britain, Scandinavia, North America.

The variety of this species, called squamula, is exceeding abundant in the Coralline
Crag, and like the recent shell, is subject to great distortion, depending upon the
body to which it has been attached ; a large number of these specimens have taken the
characters of the genus Pecten, to which, in the living state they were attached, but it
is only in the upper or free valve that I have been able to observe the costated form, the
lower or adherent one was probably much thinner, and less capable of preservation.

A few specimens of the lower or perforated valve are occasionally met with, and in
all that I have seen, the valve is externally smooth, at least, free from striae or costae,
and its place of attachment was some smooth or even surface. This variety does not
appear to have attained the size of more than f ths of an inch in diameter, and the
majority of specimens have not reached above half those dimensions. In those
which have the upper valve quite flat and smooth, the place of attachment was
probably the interior of some shell, from which the lower valve would take the
convex form, giving room between the two for the occupation of its inhabitant. The
beak or umbo of this species, is almost immediately at the margin or projecting a
little beyond it.

BIVALVIA. 9

The variety called cylindrica or cymbiformus (fig. 3, c), is also occasionally found in
the Coralline Crag, though by no means abundantly. It has been determined by
British Conchologists, that this form is produced from its place of adherence being the
stem of the seaweed, or some such cylindrical body,* while the variety fornicata
is said to be merely a deformity from some similar cause ; this I have not yet seen
in the fossil state. The exterior of some of the Crag specimens indicate their place
of rest to have been upon a Bryozoon, the shell being prettily and distinctly marked by
that animal.

Some idea may be formed of the Protean character of this species, as no less than
eighteen different specific names are introduced by the authors of the ' Hist, of Brit.
Moll.' into their synonyma, while these, with several others by them, considered
as distinct, are included as mere varieties by Mr. Clark.

2. ANOMIA ACULEATA, Mutter. Tab. I, fig. 2, a — b.

ANOMIA ACULEATA. Miill. Zool. Dan. Prod., p. 249, 1766.

Mont. Test. Brit., p. 157, pi. 4, fig. 5, 1803.
Brown. Brit. Conch. Illust., pi. 34, fig. 6, 1827.
8. Wood. Catalogue, 1840.
Gould. Invert. Massach., p. 139, fig. 90, 1841.
Philippi. En. Moll. Sc., vol. ii, p. 214, t. 28, fig. 1, 1841.
Thorpe. Brit. Mar. Conch., p. 123, fig. 73, 1844.
Loven. Ind. Moll. Scand., p. 30.

Dekay. Nat. Hist. New York (Zool.), p. 168, pi. 12, fig. 210.
STRTOLATA. Turt. Brit. Biv., p. 233, 1822.

W. Wood. Ind. Test., p. 54, pi. 11, fig. 7, 1825.

Flem. Brit. An., p. 396, 1828.

Thorpe. Brit. Mar. Conch., p. 123, 1844.

Spec. Char. Testa suborbiculari vel ovatd ; striatd, striis plurimum numerosis, radian-
tibus, squamoso-aculeatis ; umbone submarginali, Itevi.

Shell suborbicular or ovate ; striated, striae generally numerous, with fine elevated
or squamose prominences, rendering the surface rough or prickly ; umbo, submarginal,
and smooth.

Diameter, \ an inch.

Locality. Cor. Crag, Sutton, and Ramsholt.

Recent, Mediterranean, Britain, Scandinavia, and North America.

This species, called the prickly Anomia, is very abundant in the Coralline Crag at
Sutton, whence all my numerous specimens were obtained. I have not yet seen it
from the newer formations. It closely resembles the young of the preceding in most

* This, however, was not the position of our shell, which is the upper or imperforate valve, and is
quite flat, the lower or adherent one, was probably convex externally, and fixed to the interior of some
cylindrical body, and to which our specimen must have acted as a lid.

2

10 MOLLUSC A FROM THE CRAG.

of its characters, but may be distinguished, if not specifically, certainly as a variety,
by its sculpture, which is in the form of spinous or squamose radiations. In the
recent state, the lower or perforated valve, is said to be generally thin and fragile, and
destitute of the aculeated striae. As the shells found in the Crag are separated or
detached, they would not be recognised, if this were always the case ; but many of the
lower valves are alike ornamented with these markings, though they are less con-
spicuously so than upon the upper ones. The umbo of this is placed very near the
margin, and is generally slightly recurved ; the striae are numerous, although in
some specimens they are more distant ; but in all they have more or less, the
vaulted or raised, and slightly reflected edges, which as it grows produce the
series of aculeated or fimbriated striae upon the exterior, though very faintly
exhibited in the variety called striolata. In the very young of some of my speci-
mens, the shell appears to be free from sculpture of any kind, and this may favour the
opinion of Mr. Clark.

3. ANOMIA PATELLIFORMIS, Linnaus. Tab. I, fig. 4, a — b.

ANOMIA PATELLIFORMIS. Linn. Nov. Act. Upsal., vol. i, p. 42, pi. 5, figs. 6, 7, 1773.

Loven. Ind. Moll. Scandin., p. 30, 1846.
Alder. Cat. Moll. North, and Durh., p. 75, 1848.
Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 334, pi. 56,

figs. 5, 6, 1849.

Middendorff. Malac. Eoss. (Mem. de 1'Acad. des Sc. St. Petersb.),
p. 521, 1849.

— UNDULATIM STRiATA. Chem. Conch. Cab., t. viii, p. 88, tab. 77, fig. 699.

— UNDULATA. Gmel. Syst. Nat., p. 33, 46.

Mont. Test. Brit., p. 157, pi. 4, fig. 6, 1803.
Turt. Brit. Biv., p. 230, pi. 18, figs. 8, 9, 10, 1822.
Brown. Illust. Conch. Gr. Brit., pi. 34, figs. 2, 3, 1827.
Flem. Brit. An., p. 395, 1828.
S. Wood. Catalogue, 1840.

OSTREUM STRIATUM. Dacosta. Brit. Conch., p. 162, pi. 11, fig. 4.
OSTREA STRIATA. Donov. Brit. Shells, vol. ii, tab. 45, 1801.
Mont. Test. Brit., pp. 153, 580, 1803.
List. Hist. Conch., fig. 36.
Ency. Meth., pi. 171, fig. 16, and pi. 184, figs. 5, 6.

Spec. Char. Testa suborbiculari, plicis 20 — 30 convexis, undulati-radiatis ; striis
concentricis crebris, sublaminaceis ; umbone subprominulo a margine remotiusculo.

Shell suborbicular, ornamented with 20—30 radiating and undulating ribs ; con-
centric striae or lines of growth thick and sublaminated ; umbo slightly prominent,
a little distant from the margin.
Diameter, 1^ inch.
Locality. Cor. Crag, Sudbourn and Sutton.

Red Crag, Sutton, Bawdsey, Walton Naze.

Recent, Britain and Scandinavia.

BIVALVIA. 11

A few specimens resembling the figure, and corresponding with the description of
what the authors of ' Brit. Moll.' have considered as distinct, are in my cabinet, from
the Coralline Crag : they consist of the upper valve only, which is somewhat finely
striated over the earlier formed part of the shell, while the latter or outer portion is
covered with larger and coarser radiations. The umbo is rather more prominent, and
placed at a greater distance from the margin than in Ephippium, a broad triangular
fossette beneath the umbo received the ligament, and the upper valve in my Cor. Crag
specimens is nearly flat. A number of specimens of the upper valve, from the
Red Crag, present characters by which they may be referred to the above recent
species, and are uniform in their exterior markings, having large and undulating ribs
or broad and elevated striae (fig. 4, a). This is the only species or variety, that I have
been able to obtain from the Red Crag, and those specimens, as might be expected, in
that deposit, consist of the upper or thicker valve only ; this is pretty uniform in
shape, which is nearly orbicular, though the diameter in some is greater from the
umbo to the ventral margin, in others it is the reverse.

4. ANOMTA STRIATA ? Brocchi, Tab. II, fig. 3.

SQUAMA MAGNA ? Chem. Conch. Cab., t. viii, p. 87, pi. 77, fig. 697.
ANOMIA STRIATA? Broc. Conch. Foss. Subap., p. 471, t. 10, fig. 13, 1814.
? Loven. Ind. Moll. Scand., p. 29.
? Gold/. Pet. Germ., t. ii, p. 39, tav. 88, fig. 4, a—c.

Phil. En. Moll. Sic., vol. ii, p. 66, 1844.
— ? Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 336, pi. 55, figs. 1, 6, and

pi. 53, fig. 6, 1849.

RUGOSA. Nyst. Coq. Foss. de Belg., p. 312, pi. 24, fig. 6, 1844.
— SQUAMA? W. Wood. Ind. Test., p. 55, pi. 11, fig. 11, 1825.
? Brocchi. Conch. Foss. Subap., p. 462, No. 4, 1817.
? Ency. Meth., pi. 171, fig. 22.

Spec. Char. Testa variabile, orbiculata, vel transverse ovatd, discoided, radiatd; striis
creberrimis, imbricato-squamulatis ; umbone submarginali.

Shell variable, ovate, orbicular or discoidal ; sometimes transversely ovate, covered
with numerous radiating, rather rough or imbricated striae ; umbo submarginal.

Diameter, 2 inches.

Locality. Cor. Crag, Button, Sudbourn, and Gedgrave.

Recent, Britain and Scandinavia.

A large number of loose valves in my cabinet, from the Coralline Crag, correspond
with the figures and description as given of the recent shell under this name, which is,
probably, the same as the fossil one figured by Brocchi, although that shell appears to
have the umbo rather nearer to the margin. Ours may be described as variable in
form, the upper valve sometimes flat, in others convex, covered over with numerous
subimbricated strise, with the umbo a little distant from the edge.

12 MOLLUSCA FROM THE CRAG.

Anomia striata, J. Sow., Min. Conch., t. 425, differs from our shell, in having more
numerous and much finer striae without the roughness of the Crag specimens, and is in
all probability distinct ; the umbo of the Eocene shell extends to the edge, or very
nearly so, and was, probably, not so thick in substance.

These, as before remarked, have been separated into different species by recent
Conchologists, but their correct specific distinction cannot be expected in fossils,
when the recent forms are so perplexing as to defy determination, or at least to pro-
duce great diversity of opinion ; it is, therefore, only attempted with the Crag species,
to assign them to what is believed to be identity of form or correspondence with those
shells which are found in recent seas.

OSTREA, Linn. 1758.*

OSTREA. Lister, 1686.

OSTREA. Defrance. Swains. Reeve and Catlow.

OSTREUM. Rumph. 1705. Adanson, 1757.

MYA. Scopoli, 1777,

PELORIS and PELORIDEUMA. Poli. 1791.

DENDOSTR^EA. Swains. 1840.

Gen. Char. Shell attached by a part of the larger or lower valve, generally thick
and strong, lamellated or foliated, variously shaped, irregular, inequivalved, inequi-
lateral ; upper or free valve flat or slightly concave ; under or adherent one convex,
sometimes strongly marked with radiating, lamellated costae ; hinge without teeth,
ligament lodged in a linear depression in each valve semiexternal. Impression
of the adductor muscle, large subcentral, that by the mantle entire, generally indis-
tinct, and ill defined.

The animal has the mantle disunited on all sides, with its edges bordered by
short tentacular fringes ; foot obsolete. Sexes distinct.

The shells of this genus have only one muscular impression, which is always a little
inclined to the posterior side. These animals fix themselves by the exterior of the
left valve, and the space upon the shell denoting the place of adherence is exceedingly
variable in size, depending, probably, upon external causes ; in some individuals, the
greater part of the entire surface is employed, while in others, this place of attachment
is scarcely to be discerned, and occupies only a small portion of the pointed umbo of
the shell. The ligament may be considered as external, separating the valves by its
contraction when the adductor is relaxed. This ligament takes its rise at the extreme

* Etym. oorpeov, a fish, (o<rreo»') ?

BIVALVIA. 13

point or umbo of the shell, and advances with the increase of the animal, apparently
in an opposite direction to that of the Dimyaria, the additions being made in a some-
what sloping direction inclining towards the anterior side, the successive advance is
denoted by the lines of increase, as the fresh layers of calcareous matter are deposited
by the animal, most distinctly visible in this ligamental area, which may be called
tripartite.

The general substance of the shells of this genus is thick, though they are ex-
ceedingly variable in that character, some specimens of the common Oyster possess a
solidity of nearly an inch, while others, quite as large, have not a fourth of that
thickness.

This is a Marine genus, though many are inhabitants of estuaries, and some will
live where the water, at low tide, is not very salt. Its presence, in any formation, is
considered to be indicative of its marine nature ; none have yet been found as true
inhabitants of freshwater. It is a genus of great antiquity, species having been
figured from various secondary formations from the lias to the chalk, while sonie
were natives of the Seas during the Eocene Period, all of which have become extinct.

1. OSTREA EDULIS, LinncBus. Tab. II, fig. 1, a — c.

OSTREA. Lister. Hist. Conch., lib. iii, fig. 30, A, and fig. 31, 1687.

Knorr. Delices des Yeux, pi. 24**, fig. 2, and pi. 25**, fig. 2, 1766.
EDULIS. Linn. Syst. Nat, ed. 12, p. 1148, No. 211, 1767.
Poli. Test. Sicil., vol. ii, p. 169, t. 29, fig. 1, 1795.
Mont. Test. Brit, p. 151, 1803.
Broc. Conch. FOBS. Subap., p. 562, 1814.
G. B. Sowerby. Genera, No. 6, fig. 1.
De Blamv. Man. Malac., pi. 60, fig. 1, 1825.
Crouch. Int. Lam. Conch., pi. 12, fig. 8, 1827.
Gold/. Pet. Germ., vol. ii, p. 19, t. 78, fig. 4, a—h.
S. Wood. Catalogue, 1840.
G. Sow., Jr. Conch. Man., fig. 180, 1842.
Phil. En. Moll. Sic., vol. i, p. 90 ; vol. ii, p. 64.
Nyst. Conch. Foss. de Beige, p. 327, pi. 31, fig. 2, a, b, and pi. 33,

fig. 2, a', b', 1844.

Loven. Ind. Moll. Scand., p. 30, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 307, pi. 54, and pi. T,
fig. 1, 1850.

— PSETJDO-EDULIS ? Desk. Exp. Sc. de. Morde, p. 231, pi. 5, figs. 3, 4.
DEFOEMIS. Parkinson. Org. Rem., vol. iii, pi. 14, fig. 3, 1811.

Desh. 2d ed. Lam., torn, vii, p. 229, 1835.

— HIPPOPUS. Desh. 2d ed. Lam., torn, vii, p. 219, 1835.
BOBLAYEI? Desh. Exped. Scient. de Morea, pi. 3, figs. 6, 7, 1833.
PAHASITICA. Turt. Brit. Biv., p. 204, pi. 17, figs. 6, 7, 1822.

Flem. Brit. An., p. 392, 1828.

Thorpe. Brit. Mar. Conch., p, 120, fig. 108, 1844.

— DENTICULATA? Born. Mus. Goes. Vindobon., p. 113, t. 6, figs. 9, 10, 1780.

14 MOLLUSCA FROM THE CRAG.

OSTREA DENTICULATA. Desk. 2d ed. Lam., torn, vii, p. 225.
Broc. Conch. Foss. Subap., p. 568, 1814.

— FOLIOSA. Broc. Conch. Foss. Subap., p. 563, 1814.

— UNGULATA. Nyst. Coq. Foss. de Belg., p. 325, pi. 24, fig. 8 ; pi. 26, fig. 8 ; and

pi. 34, fig. 1, a, 0, b, 1844.

— BOREALIS ? Desk. 2d ed. Lam., torn, vii, p. 220.
— Gould. Inv. Massach., p. 137, 1841.

SPECTRUM. (Leathes, M. S.) Woodward Synop. Tab. Brit. Org. Rem., p. 20, 1830.

_ — S. Wood. Catalogue, 1840.

— LAMELLOSA. Goldf. Pet. Germ., vol. ii, p 18, t. 78, fig. 3, a, b.
OSTRETJM VTJLGARE. Dacostci. Brit. Conch., p. 154, pi. 11, fig. 6, 1778.
AURICTJLARIA MAXIMA. Dale. Hist, and Antiq. of Harwich, p. 291, t. xii, fig. 2, 1730.

Ency. Method., pi. 183, figs. 3, 4 ? pi. 184, figs. 7, 8.

Spec. Char. Testa variabile, plerumque ovato-rotundatd, basi subattenuatd, concen-
trice lamettosd, interdum radiato-costatd, costis imbricatw, undulatis ; valvd superiori
pland.

Shell variable, for the most part of a roundedly ovate form ; base of the shell,
slightly attenuated, concentrically lamellated, sometimes costated with imbricated and
undulated ribs ; upper valve flat.

Diameter, 3 inches.

Locality. Cor. Crag, Ramsholt, Sudbourn, Gedgrave.
Red Crag, Passim.

Recent, Britain. North America ? Mediterranean ?

The earliest appearance of the true edible Oyster seems to have been in the
Coralline Crag Period, so far as it is possible to determine a species in this truly
variable genus, and its diversified forms were then as great as we see them in the
recent shell of the present seas. In the same deposit, at Ramsholt, and in the same
bed in close proximity, are two very distinct varieties, from which, as well as from a
great dissimilarity of form, solidity of shell, and other differences, it was presumed at
the time my Catalogue was drawn up, that they were specifically distinct ; but the
variety then considered different, and which passed under the provisional name of
spectrum, corresponds with the recent shell that is now determined by British Con-
chologists to be only a local variation, and they are, therefore, here united into one
species. At Ramsholt there is a complete bed of this shell (parasiticd), sometimes
attached to each other in clusters, or often to the large species of Balanus, so abun-
dant in that locality ; at this place, also, the thick and ponderous variety (fig. 1, a), is
occasionally met with, but not in any great profusion ; the latter shell is at this place
more isolated in its habits and regular in form, and is sometimes marked with nearly
obsolete radiating costse, with a very rugose exterior to the lower or adherent valve,
while in the upper valve there are no markings, except the regular lines of growth ;
in the other variety, there is less appearance of the radiating ribs with a more
lamellated exterior, and the shell is much thinner, and less regular in shape, partaking

BIVALVIA. 15

of irregularities produced by its often confined position, the edges of the lower valve
of this variety have sometimes a fimbriated character, like what has been called
denticulata, parts of the larger valve projecting considerably beyond the upper, more
especially on each side of the hinge, where the shelly matter is pushed up or elevated,
so as to have, in some specimens, the fanciful resemblance to a spectral appearance
produced by a person with extended arms beneath a cloth, which suggested the name
to the late Rev. G. R. Leathes. The more common variety of the present day, and the
one by which our markets are supplied, does not appear in this deposit, at least, there
is no specimen in my cabinet strictly resembling that shell, although there is no doubt
the specimens figured are mere modifications of the same species.

A detailed description of this common and well-known shell is unnecessary, as the
form and appearance of almost every specimen will present some diversity. It may,
however, be observed, that in the interior of the upper valve of some specimens of
the thick variety, a little within the hinge, is a small indentation or puncture not
present in all, and may be often seen in the common variety of the recent shell : for
what purpose this is intended or how produced Malacologists have not informed us, as
it appears to have been overlooked, probably, as of no importance ; it certainly is of no
use as a specific determination, as the same may be seen in specimens of a very dif-
ferent species from the deposits of the older Tertiaries. The form of the impression pro-
duced by the adhesion of the adductor muscle, it is to be feared, is a character of no
great dependence, assuming, as it often does, a variation in shape conforming, in some
slight degree, to the outward form or contour of the shell : in the thick variety, this is
generally more or less ovate, its longer axis being from the anterior to the posterior
side, and slightly contracted in the middle of the upper part, ascending and some-
what pointed towards the posterior ; rounded on the lower side, and rather broader
on the anterior, or towards the middle of the shell ; in the var. spectrum or para-
sitica, this mark is as broad as it is long, and of nearly an orbicular or roundedly
quadrate form.

A long and interesting history of this species, and of its commercial value, is given
by the authors of the ' Hist, of Brit. Moll.,' who consider the English coast as its
peculiar province, and although it has a very considerable geographical range, it is
nowhere obtained in such great perfection as in our own seas ; there is not in
that work any notice of this shell, as an inhabitant of the Mediterranean Sea, and it is
certainly not given as a living species by Philippi in his fEn. Moll. Sic.,' nor by
Payraudeau in his ' Catalogue of Corsican Shells ;' but in Poli's splendid work ' Test,
utrius. Sicil. 1795,' is figured and described a group of shells, as well as the animal, of
what appears to belong to this species, and from the general accuracy of that obser-
vant author, there is very little doubt the specimens were procured in those seas.
From the List of Synonymes, it will be seen, that several authors have given this as a
fossil from the newer Tertiary formations of that part of the world, where it has been
considered by many to be no longer in existence ; and the fossil from the Morea,

16 MOLLUSCA FROM THE CRAG.

described by Deshayes as a new species, under the name of 0. Boblayei, does not
appear from the representation to be more than a modified form of our very variable
shell ; and for my own part, I am much inclined to believe, that Poli was correct, and
that it is still an inhabitant of the Mediterranean, as a specimen evidently of this
species was lately shown to me by Professor E. Forbes, said to have been obtained
by Mr. M' An drew, very near to Gibraltar. The common Oyster of North America,
called 0. borealis, by Lamarck, which differs very materially in its varieties, is still con-
sidered by some Conchologists as doubtfully distinct. Dr. Gould says, 'Invert.
Massach./ p. 138, "The Oystermen maintain that our shell is identical with the English
Ost. edulis, and there are certainly forms in which the American and European speci-
mens could not be distinguished ;" and although this is described by that gentleman
under the name of borealis, it was evidently his impression also, that it was not
specifically distinct, as Ost. edulis, Linn, is enumerated in his synonyma. A fossil
species, also, from the upper Tertiaries of America, figured and described by Conrad
under another name, so strongly resembles our species, as to excite suspicion that it is
not really different. It is, however, exceedingly difficult in this, perhaps, more so
than in most others, to determine its specific limitation, and every species in this
genus seems to possess the character of deviating in a great degree from what
might be called its typical form. Sir Charles Lyell, in his ' Second Tour to the
United States,' vol. i, p. 312, speaks of the Virginian oyster (Ost. Virginica), as
resembling the British shell, when it lives isolated and grows freely under water, but
that it loses this more rounded form, and becomes greatly lengthened, when living
gregariously on banks between high and low water-mark. Our own oyster will
assume a variety of forms, dependent principally upon its peculiar position, but no
amount of confinement or lateral pressure will train it into the elongated shape of the
Virginian shell.

I believe, however, the range of this species in the living state may be said to
extend from the Mediterranean to the North-Eastern Coast of the United States,
although it appears to have selected, for its more favoured abode at the present day,
the seas of our own Island.

The portions of the formation belonging to the Mammaliferous Crag Period have
not, to my researches, yielded this species, nor is it enumerated as amongst the Estnary
shells of the Norfolk Beds, by Woodward.

BIVALVIA. 17

2. OSTREA PRINCEPS, S. Wood. Tab. I, fig. 1, a — b, and Tab. II, fig. 2, a — b.

OSTREA UNDULATA. Nyst. Coq. Foss. de Belg., p. 324, pi. 24, fig. 7 a, and pi. 26, fig. 7 4,
1844, (not J. Sowerby).

Spec. Char. Testa magnd, crassd. rotundatd; valvd sinistrd convexd, costatd, costis
numerosis elevatis,radiantibus, divaricates, concentrice undato-plicatis ; valvd superiori pland,
obsolete costatd.

Shell large, thick, and rounded ; left or lower valve convex, ornamented with
numerous, elevated, radiating and bifurcating costae, lines of growth or concentric
laminae of an undulate or waving form, slightly reflected over the ribs ; upper valve
flat, with faint depressed, or nearly obsolete rays.

Diameter, five inches.

Locality, Cor. Crag, Sutton, Ramsholt, and Sudbourn.
Red Crag, Sutton, Newbourn, and Bawdsey.

This elegant shell was obtained by my friend, W. Whincopp, Esq., of Woodbridge,
who has kindly permitted me to have it figured ; a similar specimen, though not quite
in so great perfection, is in the handsome museum recently erected by the liberal
inhabitants of the town of Ipswich ; two or three more of the same dimensions are in
the possession of E. Acton, Esq., of Grundisburgh, and these with another in the
Cabinet of J. S. Bowerbank, Esq., constitute the whole that I have seen of that
magnitude.

Such specimens appear to be very rare, as it was never my lot to find so large a
one during my researches in the Crag of Suffolk, although the same shell, in its
younger state (fig. 2 b}, has been for many years in my cabinet, and from its presenting
characters in that condition, by no means distinct, it was considered only as a variety
of ednlis, but the deeply sculptured markings, so well displayed in the specimen
figured, seem to justify its being considered as a different species, although it
must be confessed, the gradations of alteration between the young of this, and some
of the varieties of the common edible species, are so trifling, that the line of
separation cannot satisfactorily be pointed out. There are, in this genus particularly,
perplexities in specific determination, so that no diagnosis can be given of any one
species that is not liable to serious deviation, and the present name is assigned
provisionally, from the apparently marked difference in the adult state, and which, if
it be not specifically distinct, its elegance, a rather uncommon character in this genus,
will entitle it to be ranked as a marked and peculiar variation, worthy of a dis-
tinguishing appellation.

A slightly sinuated form is visible on the posterior side, where the costae also
appear more particularly to have a divaricating character. Upon the young shell the
radiating ridges or costae are but few in number, and by no means prominent or
distinct, appearing then strongly to resemble the edulis ; as it enlarges, the differences
become more visible, the rays being prominent and regular. The edge or inner margin
of the shell is deeply indented with a slightly reflected edge, thus producing the sub-

3

18 MOLLUSCA FROM THE CRAG.

lamellated costse of the exterior. One peculiarity, observable in this shell, is the very
small portion of surface by which it was attached, its own substance and weight
seeming sufficient security against displacement by the movement of the water.

The form of its muscular impression is elongato-ovate across the shell, differing in
no respect in that character from the form displayed by the same muscle in specimens
undoubtedly belonging to edulis. The upper valve is quite flat, very thick, and only
faintly marked with radiations, scarcely visible in the younger state, and on each side
of the ligamental area, upon the edge of the shell, are some denticulations like those
visible upon the same valve of edulis in the same place.

HINNITES.* De France, 1821.

HINNITA. Ferussac. 1821. Gray, 1826.
HINNITES. J. Sow. 1827.
HINNUS. J. Sow. 1835.
HYNNITES. Herrn. 1846.

Generic Character. Shell inequivalve, sub equilateral, more or less ovate, thick, and
strong, covered externally with somewhat irregular, squamose, or radiating costse.
Valves eared with a deep and elongated area for the ligament or cartilage, which is
wholly internal ; a large ovate impression by the adductor muscle, that by the mantle
entire.

ANIMAL UNKNOWN.

This genus was first established by M. de France, in the ' Diet, des Sci. Nat.,'
torn, xxi, p. 169, upon a fossil species, which appeared to unite the characters of the
two genera, Ostrea and Pecten, differing from the former in adhering by its outer
surface, only in its older state, and by the opposite valve : while in the young it was
probably fixed by a byssus. It has, by some authors, been united with Pecten since one
species of that genus (P. pusio], is in the young state fixed by a byssus, but when more
grown, becomes attached by the outer surface of its right valve in the same manner.
This peculiar habit is here considered as alone insufficient for excluding the present
genus, as the extreme solidity of two or three fossil species of typical characters, with
a peculiar form in the muscle mark, seem to indicate a difference in the animal

•

inhabitant sufficient to remove them from Pecten.

In the juvenile state the form of the shell is very similar to that of Pecten with
its projecting auricles, and an opening or sinus beneath the anterior one in the right
valve through which, in all probability, there issued a byssus ; as it advanced in age
its habits became altered, when it fixed itself by the outer surface of its valve. This
same habit is adopted by P. pusio in the recent state, though not so in the fossil form
of what is considered as the same species in the Crag Formations, where they never

* Etym. "twin, hinnus, vel uv»os, vomer, sec, Herrm.

BIVALVIA. 19

became attached by the exterior of the shell, but always preserve their regularity or
partial freedom. The exterior of the shells in this Genus have not the regularly
radiating form of striae or costse, so characteristic of the Pectens or fans, but they are
ornamented with arched or lamellated fringes or squamose appendages, more re-
sembling the exterior of Spondylus, to which they appear to have considerable affinity,
and, indeed, may be considered as a connecting link between Ostrea and that Genus,
differing from the former in having distinct auricles in the young state, and in adhering
by a different valve ; and from the latter, in the absence of those dental characters
prominently exhibited in Spondylus.

A few species only are at present known, and those all in a fossil state ; two or
three are peculiar to the Tertiary Formations, and one has been figured by Mr. Sowerby
in ' Min. Conch.,' from the Inferior Oolite of this country.

I. HINNITES CORTESYI, De France. Tab. III.

HINNITES CORTESYI. De France. Diet, des Sci. Nat., t. 21, Art. Hinnites, p. 169, Atlas,

fig. 1, la, 1821.

De Blainv. Malac., pi. 61, fig. 1, 1825.
Desk. 2d edit. Lam., torn, vii, p. 150, 1836.
Chenu. 111. Conch. Hinnites, pi. 1, fig. 4.

CORTESIANUS. De Blainville. Die. des Sci. Nat., t. 32, 311, 1824.
DUBUISSONI. J. Sowerby. Min. Conch., t. 601, 1829.

Woodward. Syn. Tab. of Org. Rem., p. 20, 1830.

Id. Geol. of Norf., p. 44, 1833.

HINNUS DUBUISSONI. J. Sow. Syst. Ind. to Min. Conch., p. 244, 1835.
S. Wood. Catalogue, 1840.
J. Morris. Catal. Brit. Foss., p. 110, 1843.

Spec. Char. Testa magnd, ovatd, depressd, crassd, radiatim et undulatim costatd ;

fransversim squamoso-lamellosd ; auriculis inaqualibus ; sulco cardinali,pr<elon(/o, et prof undo.

Shell large, ovate, depressed, thick, and strong, with radiating and undulating costae ;

ribs covered with squamose projecting lamellae ; auricles unequal ; and a deep and

elongated sulcus for the ligament.

Length, 5 inches. Height, 6 inches.

Locality ', Cor. Crag, Ramsholt.

Although a shell of great strength and solidity, it is by no means abundant as a
British fossil, and I have seen it only from one locality, and that in the Coralline Crag.
The specimen now figured was from a less disturbed part of that deposit, where the
two valves of many of the Bivalvia are found in their natural position ; while the one
figured in ' Min. Conch.' was from a single valve. A few other specimens were
obtained by W. Colchester, Esq., from the same spot, and these constitute all that
I have as yet seen.

A perfect representation of the Genus Pecten is exhibited in the young shell, and
it must then have been difficult to have pointed out a character by which it could be

20 MOLLUSCA FROM THE CRAG.

considered as belonging to any other ; there is, however, even in that state an irregu-
larity in the arrangement of the rays, which are at rather unequal distances, and have
indications of the squamae that so prominently ornament the adult shell.

When full grown its true characters are displayed, and no mistake can, I think,
then arise respecting its generic distinction from that of Pecten. Our shell is nearly
of an oval form, having its height or diameter from the umbo to the ventral margin,
one sixth more than in a contrary direction. The lower or adherent valve is rather
the deeper of the two, while the upper or left valve is nearly flat ; the latter is orna-
mented with numerous undulating rays at somewhat irregular distances, amounting
to as many as forty in one specimen, and these are elevated and arched at different
periods of growth, giving a roughened file-like appearance to the exterior ; on the other
valve the rays are fewer, less regular, and the imbricated squamose appendages larger
and more prominent, resembling in that character the common Oyster. The hinge-line
in the adult shell is nearly straight, having an elongated and deep sulcus for the
ligament, enlarging downwards, and slightly visible externally at the umbo ; this is
placed a little on the posterior side of the centre, giving a slight inequality to the
auricles, the anterior one being of course the larger ; the muscle mark is of an enor-
mous size, occupying nearly half the length of the shell, while the diameter of it in the
other direction is rather less.

In assigning the Crag shell to H. Dubuissoni, Mr. J. Sowerby says he was guided
to that determination by the description only, and having seen but one valve, thought
the comparison suited better with the shell from the older Tertiaries than with the
other species described by M. De France. I regret exceedingly not having been able to
obtain, for comparison, a specimen of either of the two species described by M. De France,
and the dependence here is also based upon an insecure foundation. I feel, however,
more disposed to refer our shell to H. Cortesyi, as well from what appears a greater
correspondence in their external characters having both valves for our guidance, as
also from the age of the formations in which they were obtained ; and as no new name
is imposed, the simple alteration is a matter of no great importance should it hereafter
be found to be erroneous.

PECTEN.* Pliny , Aldrov, &c.

PECTEN. Chem. 1784. Bolten, 1798.

PANDORA. Meyerle, 1811.

JANIRA. Schum. 1817.

NEITHEA. Drouet. 1824.

JANERA. G. E, Sow. Jr. 1842. — P. maximus.

PECTEN. Rumphius, 1705. Browne, 1756. Chem. 1784.

OSTREA (sp.). Linn.

ARGUS (sp.). Poll. 1795.

CHLAMYS (sp.). Bolten, 1798.

* Etym. :— Pecten, a comb.

BIVALVIA. 21

AMUSIUM (sp.). Chem. 1784.

PALLIOLUM. Id.

PYXIS. Id.

PERA. Id. - — P. opercularis.

PALLIUM. Martini, 1773. Schum. 1817.

DENTIPECTEN. Eiippell, sec. Gray.

DECADOPECTEN. Ruppell, sec. Swains.

PSEUD-AMUSIUM. Chem. 1784.— P. tigerinus.

AMUSIUM. Rumph. 1705. Chem. 1784. Schum. 1817.'

PLEUEONECTES. Schlotth. 1820.

PLEURONECTIA. Swains. 1840. — P. Gerardii.

Generic Character. Shell ovate, or suborbicular, subequilateral, inequivalve, with
a projecting, generally unequal auricle, on each side of the umbo, surface rayed with
striae, or more or less elevated costse ; beaks approximate and acute. Hinge with a
linear groove across the dorsal part of the auricles for the ligament, and a triangular
pit or fossette beneath the umbo for the cartilage. Muscular impression of the mantle
entire but ill denned ; adductor large, excentric.

Animal resembling the shell without the auricular appendages, its mantle dis-
connected on all sides ; the margins bearing generally two rows of tentacular filaments,
at the base of which are arranged a series of ocelli or rudimentary eyes ; foot small,
subcylindrical, containing a groove from which is spun a byssus for its attachment ;
one large and powerful adductor muscle : no siphonal tubes. Sexes united.

This is a well and strongly-marked genus, generally ornamented with rays, like the
expanded sticks of a lady's fan : these in some species are large and highly elevated,
while in the more aberrant forms they are nearly obliterated, merging into some which
are perfectly smooth, the gradations from the one to the other are so imperceptible as
to be without any definable line of demarcation, and although this group has been
separated into several Genera, there is no good or permanent character by which they
can be distinguished.

In some, the valves are very unequal in size, while in others there is scarcely a
perceptible difference, though in most species, by close observation, a trifling
inequality may be detected. Those, in which one valve is very convex, while the
other is flat, or even concave in its young state, have mostly the larger one buried in
the sand, resting in a horizontal position, so that the flat one opens upwards, like the
lid of a box, these, when young, are furnished with a byssus, the opening for which
is visible in the smaller shell, but becomes obliterated in the adult. The animal
probably, in all the species, is capable of producing a byssus for attachment, this,
however, is mostly made use of by the young, as when more advanced in growth it
appears to be possessed of a considerable degree of locomotive power, which is often
employed so as to make considerable progress through the water by means of its large
and powerful adductor after opening the valves, and flapping them suddenly together
with great rapidity ; some species are probably always stationary, as we find at all

22 MOLLUSCA FROM THE CRAG.

ages an opening in one valve through which a byssus of considerable magnitude
might have passed ; others fix themselves to rocks or foreign bodies by the spinous or
imbricated processes of their valves ; when fixed like P.pusio, it is by the right valve,
which is also the one wherein is left an opening for the byssus, and the one also like
P. maxima, which the animal buries in the sand, it may, therefore, always be considered
the lower valve : this is sometimes the most convex, while in those that are free, the
greater convexity is generally in the left or upper valve, which, in the living shell, is
the more highly coloured.

This is purely a marine genus, and in the recent state has a very extended
geographical distribution, being found in almost all parts of the world, while its
vertical range is also considerable, inhabiting the seas at various depths ; it is also of
great antiquity, species having been found as low in the Secondary Series as the Lias,
and are continued upwards through nearly every period to the present time ; it is
largely developed in the newer Tertiaries, and is exceedingly abundant as an existing
genus, upwards of a hundred species being already known. It has been quoted as an
inhabitant of the Palaeozoic Period, but the specimens found in the Coal Measures and
Mountain Limestone Rocks, present differences that are considered as generically
distinct, and they have been separated by Prof. M'Coy under the name of Aviculopecten
differing from the true Pectens in the absence of a cartilage-pit, and in the inequalities
of the auricles being reversed, thereby connecting it with Avicula.

It is to be feared, that many of our Tertiary specimens have been erected into
species without sufficient claim to such distinction, and that several will be found upon
further examination to be merely variations of form and sculpture of those which are
perhaps more than commonly disposed to deviate from what may be considered as the
typical form of long and well-known recent species.

This genus flourished most abundantly in the Crag Seas, and the modifications in
the ornamental portions of most of the species render their correct appropriation a
task of no ordinary difficulty.

1. PECTEN MAXIMUS, Linnaeus . Tab. IV, fig. 1, a— b, and Tab. VI, fig. 7, a — b.
Lister. Hist. Conch., lib. iii, par. 1, fig. 1 A, 1687.
OSTREA MAXIMA. Linn. Syst. Nat., p. 1144, No. 185, 1767.

Enorr. Delices des Yeux, xiv*, fig. 1, 1766.

Donov. Brit. Shells, pi. 49, 1800.

W. Wood. Ind. Test., p. 47, pi. 10, fig. 1, 1825.

Broc. Conch. Foss. Subap., p. 572, No. 16, 1814.
PECTEN MAXIMUS. Mont. Test. Brit., p. 143, 1803.

Chem. Conch. Cab., vii., p. 268, pi. 60, fig. 585, 1782.
— Crouch. Int. Lam. Conch., p. 20, pi. 12, fig. 13, 1827.

Brown. Illust. Conch. Gr. Brit., pi. 32, fig. 1, 1827.

Desk. 2d ed. Lam., t. vii, p. 129, 1836.

Payr. Cat. Moll. Cors., p. 71, No. 132, 1826.

S. Wood. Catalogue, 1840.

BIVALVIA.

23

PECTEN MAXIMUS. Chenu. Illust. Conch. Pecten, pi. 2, figs. 1—3, and pi. 29, figs. 1—18.
Loven. Ind. Moll. Scand., p. 30, 1846.
Alder. Cat. Moll. North., p. 76, 1848.

Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 296, pi. 49, 1849.
Sismond. Syn. Meth. An. Invert. Pedem. Foss., p. 13, 1847.
G. B. Sow. Jr. Thesaur. Conch., vol. i, p. 45, pl.xv, figs. 98-100, 1847.
— VULGAKIS. Da Costa. Brit. Conch., p. 140, pi. 9, fig. 3.
COMPLANATUS. J. Sow. Min. Conch., t. 586, 1828.
S. Wood. Catalogue, 1840.
J. Morris. Cat. Brit. Foss., p. 114, 1843.
Nyst. Coq. Foss. de Belg., p. 285, pi. 22 bis, fig. 1, b, V, 1843.
G. B. Sow. Jr. Thes. Conch., p. 46, pi. 16, figs. 116, 117, 1847.
Chem. Conch. Cab., t. vii, p. 272, t. 60, figs. 586, 587, 589.
Desk. 2d ed. Lam., t. vii, p. 130, 1835.
Phil. En. Moll. Sic., vol. ii, p. 59, 1844.
Chenu. Illust. Conch., pi. 4, figs. 2 — 6.
Sismonda. Syn. Meth. Ped. Foss., p. 13, 1847.
GRANDIS. J. Sowerby. Min. Conch., t. 585, 1828.

8. Woodward. Syn. Tab. Brit. Org. Hem., p. 19, 1830.

S. Wood. Catalogue, 1840.

J. Morris. Catal. Brit. Foss., p. 114, 1843.

Nyst. Coq. Foss. de Belg., p. 284, pi. 21, fig. 6, b, b, and pi. 22,

fig. 1, a, b, 1844.
Ency. Meth., pi. 209, fig. 1, a, b.

SIMILIS.
MEDIUS.

Spec. Char. Testa intsguivalvi, suborbiculari ; valvd dextrd vel inferiori convexd,
superiori planulatd ; radiis magnis, 13 — 14 rotundatis, longitudinaliter striatd ; marginibus
lati-crenulatis ; auriculis tequalibus.

Shell inequivalved, suborbicular ; right or inferior valve convex ; left or upper
valve flat, or very slightly inflated ; ornamented with 13 or 14 large, rounded, and
striated ribs or rays ; margin broadly indented ; ears equal.

Length, 5f ; height, 4f inches.

Locality, Cor. Crag, Sutton, Aldbro', Ramsholt, Gedgrave.
Red Crag, Sutton, BaWdsey.
Northern Drift, Ireland (Forbes).

Recent, Britain and Northern Seas, Mediterranean t Red Sea :

This is very abundant in some localities of the Coralline Crag, and particularly
variable in its exterior ornament. The peculiar arrangement of the striated portion of
the rays,, which some of the specimens have assumed, induced authors who have
described the Crag shell, to consider it as wholly distinct from the recent British
species, and I was long of the same opinion ; but the examination of numerous speci-
mens in the cabinets of my Crag collecting friends, has shown a union between the
extremes of sculpture, as represented in the variety grandis, and that which is commonly
exhibited in the generality of recent specimens, by small and almost imperceptible
variations, so as to prevent a distinct line of demarcation to be drawn between

24 MOLLUSCA FROM THE CRAG.

them, and as such, they are here considered only in the light of varieties of the living
British shell.

M. Nyst, seems to consider the variety grandis as a modified form of P. Jacobaus,
from which opinion I must dissent, believing it to be, as above stated, specifically
united with our own species P. maccimus. In P. Jacobtsus, the costse or rays are
broader in proportion to the intermediate depression, and are more quadrate : those
upon the Crag shell are often as much elevated, but always more or less rounded,
without the abrupt or sharp edges, which distinguish the Mediterranean shell. The
most prominent character in the var. grandis, is the distinct ray in the centre of the
depression, while a corresponding kind of sulcus or furrow runs down the centre of the
large ray, dividing it into two parts ; this character, which in some specimens appears
so strongly marked, that it alone would be quite sufficient for specific distinction, be-
comes in var. complanatus scarcely discernible with the rays very much depressed, and in
those specimens with this division in the rays, each side appears to be again divided
by a less distinct line, or arranged in pairs. P. medius. Chemn. is said, by its author, to
be intermediate between Jacobceus and Maximus, partaking, in some degree, the characters
of both, but from the figure and description appears to be only a variety of the latter.

A species from Australia, somewhat resembles our Crag fossil, in having the inter-
mediate small ray, but it has no bipartite division of the large rays, while they are
rounded and simple on the flatter or upper valve, and may, therefore, only be looked
upon as the representative of our species. In the young state, our shell is nearly
smooth, while the upper or left valve is concave on the upper surface, in which stage of
its existence it was probably furnished with a byssus, as an opening is then visible beneath
the auricle of the convex or right valve, but entirely obliterated in the adult shell.

In the Coralline Crag at Ramsholt, many beautiful specimens have been found with
the valves united, in what was, probably, a deeper portion of the sea at that period,
in association with Pyrula, PJioladomya, Lingula ; forms, now found only in Tropical
or Sub-Tropical Seas, while at the same locality are numerous individuals of species,
whose homologues are living at the present day upon the Scandinavian Coast.

The range of this species (maoeimus), in the living state, is given by the authors of
the ' Hist of Brit. Moll.,' from the Coast of Norway to Gibraltar. Payraudeau quotes
it as found, though rarely, on the West Coast of Corsica ; and Born speaks of it also
as from the Mediterranean.

2. PECTEN GERARDII, Nyst. Tab. V, fig. 5, a—b.

PECTEN GERARDII. Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 19, No. 75, pi. 3, fig. 75,

1835.

Potiez. et Mich. Cat. des Moll, de Douai, t. 11, p. 78, No. 32, 1844.
Nyst. Coq. Foss. de Belg., p. 300, pi. 18, fig. 11, 1844.
SUBDIAPHANUS. S. Wood. Catalogue, 1840.

Spec. Char. Testa orbiculari, subhyalind, intequivalvi, equilaterali, radiatim striatd,
et divaricatim insculptd ; auriculis incsqualibus; margine tenuissime crenulatd.

BIVALVIA. 25

Shell orbicular, subpellucid, inequivalved or somewhat plano-convex, equilateral,
externally covered with fine longitudinal rays, visible only near the margin, and beau-
tifully sculptured with diverging or divaricating striae, auricles unequal.

Diameter, 2 inches.

Locality. Cor. Crag, Ramsholt, Sudbourn, and Gedgrave.

This beautiful species is exceedingly abundant at the latter locality, where, how-
ever, the valves are always separated. At Ramsholt, they are somewhat less abun-
dant, and the valves are there found in their natural position.

From the figure and description given by M. Nyst, above referred to, there is little
doubt, that the English Crag shell is the same as the one found in the Campinian
beds of Belgium. Our shell is very thin, but strong, with irregularly-marked lines of
increase ; the right valve always more or less flattened, while the opposite one is
tumid or convex. Auricles very unequal and rayed, or costated, with a moderate
sized opening beneath the anterior one of the right valve, this is almost obliterated in
the adult shell, a rather large triangular cartilaginous area overhanging or projecting
into the interior. The impression formed by the edge of the mantle parallel with the
margin, and extending to about two thirds the length of the shell, that by the
adductor, less distinctly defined. The contour of the shell is nearly circular, a little
interrupted with a pair of rather high shoulders. A dark line diverges from the umbo,
within which the shell is of a lighter colour, like that in P. corneus, being, however,
perfectly distinct from that species. The beautifully curved or divaricating striae
(from the absence of longitudinal or radiating ribs), are visible upon the smooth sur-
face of the shell with the naked eye. An American fossil, Pecten Virginianus,
Conrad. 'Foss. of the Med. Tert. of the United States,' p. 46, pi. 21, fig. 10, 1838,
appears to resemble our shell in many characters, but from the representation it differs
in being longer than high, and has the ears more equal and larger.

3. PECTEN SIMILIS, Laskey, Tab. V, fig. 4, a — c.

PECTEN SIMILIS. Laskey. Mem. Wern. Soc., vol. i, p. 387, pi. 8, fig. 8, 1811.
Brown. Illust. Conch. Gr. Brit., pi. 32, figs. 5, 6, 1827.
Flem. Brit. An., p. 384, 1828.
Forb. Rep. on Egean Invert., p. 183, 1848.
Alder. Cat. Moll. North, and Durh., p. 77, 1848.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 293, pi. 52, fig. 6, and

pi. S, fig. 1, 1849.

OSTREA TUMIDA. Turt. Conch. Diet., p. 132, 1816.
PECTEN TUMIDUS. Turt. Brit. Biv., p. 212, pi. 17, fig. 3, 1822.
Flem. Brit. Anim., p. 384, 1828.
Thorpe. Brit. Mar. Conch., p. 117, 1844.
S. Wood. Catalogue, 1840.
loven. Ind. Moll. Scand., p. 36, 1846.

G. B. Sow., Jr. Thes. Conch., vol. i, p. 57, pi. 13, figs. 27—29, 1847.
PYGM.EUS? Phil. En. Moll Sic., vol. ii, p. 61, 1844, (not Gold/.}

4

26 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa minutd, suborbiculatd, aquivalvi, subcequilaterali, tenui, subhyalind,
planulatd, glabrd ; auriculis subcequalibus, in valvd decctrd antice longiori, rotundatd, postice
rectangulatd ; sinu brevi, acuto.

Shell small, suborbicular, equivalved, subequilateral, thin, subpellucid, flattened,
smooth ; auricles nearly equal ; the anterior one of the right valve rather the longer
and rounded, on the posterior side it forms a right-angled triangle, with a short and
acute sinus.

Diameter, j inch.

Locality. Cor. Crag, Button. Recent Britain, Finmark, J^gean Sea.

This pretty little shell is particularly abundant at Sutton, in the Coralline Crag, to
which formation, as far as is at present known, it is restricted : its minuteness and
fragility may, however, be one cause why it has not yet been found in the Red Crag,
as it appears to be a species possessed of capabilities to endure a considerable range in
temperature, being quoted by Dr. Loven as having been obtained on the coast of
Finmark, while Professor Forbes procured it in considerable numbers from a great depth
in the JSgean Sea, some specimens of which he has obligingly given me, for the pur-
pose of comparison with the British fossil.

There are some slight differences between the recent shell and the fossil, but
which can hardly be considered of sufficient importance to justify it being ranked
as more than a variety; the living species in several characters is subject to
variation. The specimens from the .ZEgean, which were obtained at the depth of
100 fathoms, are rather larger than any I have from the Crag, measuring a little
more than a quarter of an inch in its longitudinal diameter, and a trifle less in
the height, with the auricles unequal, the anterior one, more especially in the
right valve, less than the posterior, but this is not a permanent character, as in
some specimens they are equal in size. The Crag shell does not exceed in
diameter a quarter of an inch, very rarely attains this magnitude, and the dorsal
margin, or rather the ears of the shell, extend to 5-6ths of its entire length. In
the right valve the anterior auricle is as large as the posterior one, and completely
rounded with a small sharp sinus beneath it, as if the shell, in the living state, had been
supplied with a byssus. There is a slight peculiarity in this species in the right valve,
attributable probably to the presence and size of the byssus ; the diverging line from
the umbo is on the posterior side rather convex, while on the opposite, or beneath the
projecting ear, it is distinctly concave ; in the left valve the auricles are equal in size,
and the divergence of the edge of the shell more regular, forming an angle of 90° ;
this valve is, in the recent state, ornamented with coloured markings of a zigzag,
or what is called Vandyke shape, traces of these colours are still remaining in some of
the Crag specimens, one of which has only a single line of divergence from near the
centre, somewhat like the ornaments upon Lucina divaricata. There is also a slight
inequality in the depth or convexity of the valves, the right or lower one being a little
more tumid than the other.

BIVALVIA. 27

P. Groenlandicus, Loven and G. B. Sow., Thes. Conch., p. 57, PL 13, fig. 40,
appears to differ from our shell only in being somewhat larger.

4. PECTEN TIGRINUS, Mutter. Tab. V, fig. 2, a—g.

PECTEN TIGRINUS. Mull. Zool. Dan., ii, p. 26, pi. 60, figs. 6—8, 1776.
Desk. 2d ed. Lam., t. viii. p. 155, 1835.
Nyst. Coq. Foss. de Beige, p. 303, pi. 23, figs. 4—10, 1844.
Lov6n. Ind. Moll. Scand., p. 31, 1846.
Alder. Cat. of Moll. North, and Durh., p. 77, 1847.
Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 285, pi. 50, figs. 8—11.
OBSOLETUS. Penn. Brit. Zool., vol. iv, p. 322, t. 64, fig. 3.
Don. Brit. Shells, vol. i, t. i, fig. 2, 1799.
Mont. Test. Brit., p. 149, and sup., p. 57, 1808.
Turt. Brit. Biv., p. 213, pi. 9, fig. 6, 1822.
Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 6, 1827.
J.Sowerby. Min. Conch, t. 541, figs. 1—8, 1828.
Nyst. Rech. Coq. Foss. d'Anv., p. 19, No. 74, 1835.
S. Wood. Catalogue, 1840.
J. Morris. Cat. of Brit. Foss., p. 115, 1843.
Thorpe. Brit. Mar. Conch., p. 118, 1844.
PARVUS. Da Costa. Brit. Conch., p. 155, 1778.
L^VIS. Penn. Brit. Zool., vol. iv, p. 102.

Mont. Test. Brit., pp. 150, 579, pi. 4, fig. 1, 1803.
Turt. Brit. Biv., p. 212, 1822.
Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 7, 1827.

DOMESTICUS. Chem. Conch. Cab., t. xi, p. 261, pi. 207, figs. 2030—2036, 1783.
OSTREA OBSOLETA. Turt. edit. Linn., vol. iv, p. 266, 1806.

W. Wood. Ind. Test., p. 50, pi. 10, fig. 37.
Mawe. Linn. Conch., pi. 14, fig. 6.
TIGERINA. Turt. edit. Linn., vol. iv, p. 268, 1806.

L^EVIS. Mat. and Back. Linn. Trans., vol. viii, p. 100, pi. 3, fig. 5, 1807.
W. Wood. Ind. Test., pi. 10, fig. 38.

Spec. Char. Testa tequivalvi, aqnilaterali, suborbiculari ; radiatd, radiis variis,
inter dum obsoletis, striis subtilissimis arcuatim divergentibw ornatd; auriculis valde
inaqualibus.

Shell equivalve, equilateral, suborbicular ; costated costee variable, sometimes
obsolete, or small and numerous, sometimes arranged in fives ; ornamented with fine
curved and diverging striae, ears very unequal.

Diameter, 1 inch.

Locality. Cor. Crag, Sutton, Ramsholt, Gedgrave, Sudbourn.
Red Crag, Sutton, Bawdsey, and Walton Naze.

Recent, Britain and North Seas.

This is a very abundant species in the Coralline Crag, with as great a range in

28 MOLLUSCA FROM THE CRAG.

variation as is exhibited by those obtained in our own seas at the present day. In the
Red Crag, specimens are much more scarce, although var. 8 I have seen only from
this Formation.

From the great diversity of forms displayed by this animal, it is not to be
wondered at, that it should have been separated into several species : with variations
exceeding in appearance what are generally considered as sufficient for specific dis-
tinction, there is no permanent character that will justify their separation. In the
Crag as well as in the recent state, specimens may be obtained presenting every
minute gradation, and these apparently different forms are now justly included under
one name.

In var. a the shell is nearly smooth (Itevis, Penn.), or at least without any distinct
longitudinal ribs or striae, or with the edges only presenting these radiations ; this
may be considered as one extreme of the species, while the other variety exhibits five
large elevated ridges or ribs ; these are generally separated, and in pairs, though they
are sometimes simple, the intermediate spaces are filled up with three or more rays.
Var. |3 may be called lenticular, with numerous fine rays covering the entire surface,
sometimes single, sometimes in pairs ; var. 7 has four or five raised ribs, as before
described ; var. 8 has from seven to nine rays, which are themselves faintly striated,
while the intermediate spaces are also filled with radiating lines ; but these forms are
not permanent, and specimens uniting some of the characters of each may be commonly
obtained. Every specimen is strongly marked with fine divaricating striae, in a curving
direction from the umbo to the sides. In the young state the shell is often very scabrous,
the rays being covered with regularly raised imbrications. The general form may be
described as suborbicular, though the greater diameter is from the umbo to the ventral
margin. The auricles may be considered its most distinguishing character ; these are
very unequal, the posterior one small, nearly obsolete, while that on the anterior side
is large, generally costated, or coarsely rayed. In the early stages of its growth, the
shell is always regularly convex or lenticular, but in some specimens, when at a certain
size, its form is altered by the enlargement of the shell on the inner edge of the margin
instead of outwardly, so as to give a greater space to the interior without much in-
creasing the diameter of the shell, and this character is exhibited in both valves.
Fig. 2, g, is what in my Catalogue was enumerated with doubt as a new species, under
the name exoletus, but which probably is only a giant monstrosity of this species, as
the ordinary form is well displayed on the outside, beyond which, by apparently an
extra effort of growth, it has induced a deposit of calcareous matter, till it has
reached a diameter of \\ inches, thus much exceeding the general size of this species,
which is rarely more than one inch. Fig. 2, #, is from a specimen belonging to Mr
Bridgman, obtained in the Mammaliferous Crag, near Norwich.

The animal in the recent state is said to range from 12 to 80 fathoms, while 18 or
20 is its most favorite depth.

BIVALVIA. 29

5. PECTEN BRUEI, Payraudeau. Tab. V, fig. 3, a — b.

PECTEN BRUEI. Payr. Cat. Moll, de 1'Ile de Corse, p. 78, pi. 2, figs. 10—14, 1826.
Desk. Append. Lyell's Princ., vol. iii, p. 14, 1833.
G. B. Sow., Jr. Thesaur. Conch., vol. i, p. 70, pi. 20, figs. 241-2, 1847.
Chenu. Illust. Conch. Pecten, pi. 39, fig. 6, a — c.

— PICTUS. Goldf. Pet. Germ., vol. ii, t. 97, fig. 4, a— c, 1830 (not Da Costa).

— STRIATUS ? Goldf. Pet. Germ., vol. ii, t. 96, fig. 3, a— b.

— LAMALII. Nyst. Coq. Foss. de Belg., p. 305, pi. 22, fig. 5, a — b, and pi. 24,

fig. 5, 1844.
PANDORA? Desk. Exped. Scient. de Morea, pi. 2, figs. 12 — 14, 1833.

Spec. Char. Testa suborbiculari, cequivalm? (squilaterali, convexiusculd ; radiatim
costatd, costis 18 — 20 convexis inaequalibus, lonyitudinaliier tenuissime lineatis, in juventd
nodosis vel subimbricatis ; auriculis alteris minimis, radiantibus.

Shell suborbicular, equivalve ? equilateral, slightly convex ; costated with 1 8 to 20
unequal rounded ribs, finely striated longitudinally ; and nodose or imbricated in the
young state ; auricles unequal and rayed.

Diameter, ^ an inch.

Locality, Coralline Crag, Sutton. Recent, Mediterranean.

Five or six separated valves are all that I have obtained, and these appear to cor-
respond with the recent species above referred to. Four localities are given by
Payraudeau, of recent habitats, who says it is " peu abondant." The shell figured
by Nyst is presumed to be the same, from the disposition of the rays; but he speaks
of irregular and oblique striae upon the sides of the shell, like those upon tiyrinus;
these I have not been able to detect in my specimens, which, however, may but ill
display such sculpture, as they are, probably, only young individuals, not measuring
more than half the diameter of the Belgian fossil; but from the representation
there is a slight difference, the auricles of his shell are rather more rounded, and
more unequal, and approach nearer in that character to one of the varieties of
tigrinus.

Our shell may be further described as having rounded rays generally single, some-
times arranged in pairs, but in no regularity in either the right or left valve, while the
whole surface, as well on the costae as between them, is covered with radiating
striae, these appear like linear markings in the shell, and not upon it, the line being
alternately of a light and dark colour, that upon the centre of each rib, larger or
broader than the rest.

In the young shell, the rays are ornamented with nodose protuberances, and the
interstices have then also a raised portion of the shell, so that, in its young state, the
surface is prettily cancellated. The auricles are unequal, the anterior one being the
larger of the two, though not displaying so great a disparity as in tigrinm ; they are
sharp and rectangular, and not the least rounded, covered with prominent rays, which
are strongly decussated by raised lines of growth : there is a small byssal sinus under
the anterior auricle.

30 MOLLUSCA FROM THE CRAG.

This is quite distinct from any of the varieties of P. tigrinus, the larger or more
rounded form of the rays, as well as less inequality in the auricles, will distinguish
it; and in all the varieties of that species, strongly marked divaricating striae, or
curved lines radiating from the umbo, may easily be observed, but I have been unable
to detect such markings upon my specimens of this species, although individuals of
tiffrinus, much less in size, exhibit them distinctly ; and it seems also to be specifically
different from P. Dumasii, in which the rays are larger, fewer, and more prominent,
and the auricles of our shell are comparatively larger than those in that species. In
the recent state, this is, probably, a deep water species, as Payraudeau speaks of his
specimens having been obtained by means of the dredge.

6. PECTEN DANICUS, Chemnitz. Tab. IV, fig. 2.

PECTEN DANICUS. Chem. Conch. Cab., t. xi, p. 265, pi. 207, fig. 2043, 1795.

G. Sow. Thesaur. Conch., vol. i, p. 61, pi. 12, figs. 16 & 187.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 288, pi. 52, figs. 1, 2, 7—10.

— GLABRIS. Brown. 111. Brit. Conch., pi. 32, figs. 3, 4, 1827.

DUMASII. Payr. Cat. Moll, de 1'Ile de Corsi., p. 75 pi. 2, figs. 6, 7, 1826.
Desk. Append. LyelTs Princ., vol. iii, p. 15, 1833.
Forbes. Eept. jEgean Invert., p. 183, 1843.
Jeffreys. Ann. Nat. Hist., vol. xix, p. 313.

— ASPERSUS. Desk. 2d ed. Lam., t. vii, p. 136, 1836.

Phil. En. Moll. Sic. vol. i, p. 82. 1836; and vol. ii, p. 57, 1844.

— JAMESONI. Smith. Mem. Wern. Soc., vol. viii, p. 58, pi. 2, fig. 1, 1838.

Brown. Illust. Conch. Gr. Brit., 2d edit, p. 73, pi. 25, fig. 7.

— SEPTEMRADIATUS. Loven. Ind. Moll. Scand., p. 31, 1846.

— TRIRADIATUS. MiilL Zool. Dan., vol. ii, p. 25, pi. 60, figs. 1, 2, (fide Loven and Desk.)
OSTREA HYBRIDA. Gmel. Syst. Nat., p. 3318, 1788 (fide Loven).

W. Wood. Ind. Test., p. 48, pi. 10, fig. 10, 1825.

— TRIRADIATA. Turt. ed. Linn., vol. iv, p. 268, 1806.

W. Wood. Ind. Test., p. 50, pi. 10, fig. 39, 1825.

SEPTEMRADIATA. Id. - p. 268, 1806.

— INFLEXA. Poll. Test. Sicil., vol. i, p. 160, t. 28, figs. 4, 5.

— CLAVATA. Id. - - p. 161, t. 28, fig. 17.

PECTEN PSEUD-AMUSIUM. Desk. Exped. Scient. de Morea, p. 231, pi. 2, figs. 9—11, 1833.
Ency. Meth., pi. 212, fig. 6.

Spec. Char. Testa subrotundatd, aquilaterali, radiis 5 — 6 rotundatis inaqualibus,
striatis ; auriculis inaqualibm.

Shell subcircular, equilateral, thin, with rounded or convex rays varying in number
from 5 to 6 striated ; auricles unequal.

Diameter, 1 inch.

Locality. Clyde Beds. Recent, ^Egean, and Scandinavia.

Although this species, in the recent state, has been obtained in the ^Egean, as
well as in the Mediterranean Sea, and is quoted also by Philippi as an abundant fossil

BIVALVIA. 31

in the Sicilian Beds, I have not yet seen it from any of the three Crag Formations of
Essex, Suffolk or Norfolk. As it is a fossil in the Clyde Beds, and may, probably, be
hereafter found in the Crag, it ought not to be here passed over in silence. The
specimen figured (which is the right valve) was given to me by James Smith, Esq.,
of Jordan Hill, and is undoubtedly identical with the British shell recently obtained in
considerable plenty by Mr. George Barlee.

Our specimen contains a good deal of animal matter, with some slight remains of
colour, as indicative of its comparatively modern origin. The shell like that of
P. tigerinus., is ornamented with curved radiating or diverging striae, but less promi-
nent and distinct, and most visible at the lateral edges. A specimen of P. Dumasii,
given to me by Professor Edward Forbes, which he obtained from a great depth in the
vEgean Sea, does not appear to differ specifically from the British shell, and I have
followed his example in uniting the two. Our fossil, however, appears to agree with
the recent British specimens better than with the Dumasii from the Mediterranean, in
having a rather larger posterior auricle ; but my specimen from the YEgean differs also
in that character from the Mediterranean shells, in having as large an auricle com-
paratively as the British specimens. The number of ribs is a variable character;
sometimes the right valve has six, when the left one has only five, the depressions of the
one valve corresponding to the elevations of the other, and vice versa.

In this, as in most of the species of this genus, the auricles are comparatively
larger in the younger shell than in the adult ; my specimen, is a full grown shell, with
six ribs or elevations, and the whole surface rayed or striated longitudinally, made
rough or scabrous by elevated lines of growth, and the diverging or curved striae
visible only at the sides.*

7. PECTEN PRINCEPS, /. Sowerby, Tab. VI, fig. I.

PECTEN PRINCEPS. J. Sow. Min. Conch., t. 542, fig. 2, 1826.
Woodward. Geol. of Norf., p. 44, 1833.
S. Wood. Catalogue, 1840.
Morris. Cat. of Brit. FOBS., p. 115, 1843.
CLINTONITJS? Say. Journ. Acad. Nat. Sci., vol. iv, p. 135, pi. ix, fig. 2, 1824.

? Conrad. Foss. of the Med. Tert. of the United States, p. 47, pi. 23,

fig. 1, 1838.
SUBL^VIGATUS ? juv. Nyst. Coq. Foss. de Beige, p. 298, pi. 24, fig. 4, 1844.

Spec. Char. Testa, orbiculari, subintsquivalvi, convexd, longitudinaliter costatd, costis
numerosis confertis, subsquamosis, interstitiis divaricatim striatis ; auriculis magnis sub-
cequalibus ; valvd dextrd minori.

Shell orbicular, slightly inequi valve, convex, externally ornamented with numerous
close set, rounded and slightly squamose or imbricated striae, with a small inter-

* A specimen much worn, and without its auricles, very recently found in the Red Crag, is in my
Cabinet, and may possibly be of this species, but it is too much mutilated for fair examination.

32 MOLLUSCA FROM THE CRAG.

mediate ray in the aged shell, and fine diverging strise visible between the rays ; ears
large, nearly equal, and rayed ; right valve the smaller of the two.

Length, 5f . Height, 5£ inches.

Locality. Cor. Crag, Ramsholt.

This noble shell appears not to have lived beyond the Period of the Coralline Crag,
at least, I have not seen it from any more recent deposit, although Woodward, in his
' Geol. of Norf.' has included it in his List of Fossils from the Mammaliferous Crag at
Thorpe, with the letter a at the end of the locality, denoting its abundance, but
I have not been able to see a specimen, or ascertain that it was even found in that
formation, perhaps, fragments or imperfect specimens of P. Islandicus may have been
mistaken for it.

This is the largest species of the genus belonging to the nearly equivalved section,
equalling in magnitude the common Scallop. Pecten Magellanicm somewhat re-
sembles this shell, and may be considered its representative on the other side of the
Atlantic; but it has not the rays so distinctly marked or elevated as those upon
the Crag shell, and is a flatter or more compressed species, with a few other minor
distinctions sufficient to separate the two.

An American fossil above referred to, as far as can be determined by the figure and
description, appears so closely to resemble our shell, that they are here considered as
probably the same species ; some slight differences may, however, be pointed out, as
our reliance is entirely upon the representation, without the opportunity of comparison.
Our shell has the auricles large and unequal, those on the posterior side being much
the smaller, while in the American fossil they appear more equal, and somewhat less,
and the rays are represented as bifurcating, or double in number, on the outer part of
the shell, or its latter growth ; the Crag shell has from 70 to 80 small and convex
rays, rounded and slightly imbricated, but never angulated, the distance between them
about equal to the rays ; at the outer part of my largest specimen is an intermediate
ray, thereby resembling the figure of the American fossil ; between the rays may be
seen fine diverging or divaricating strias, crossing the lines of growth in an oblique
direction. Under the anterior auricle of the right valve is a large opening. The
valves are closed nearly all round, slightly gaping at the shoulders. The same sized
rays ornament the auricles, which are also scabrous. Oysters and Barnacles are
attached to the roughened surface of the shell, and may be seen, sometimes upon the
right, in others on the left valve.

This was found, in situ, in the tranquil deposit at Ramsholt. Pecten sublavigatus
Nyst, so much resembles a small specimen in my possession, that it is probably only
the young state of this species.

Say's name appears to have priority of date, but from the uncertainty of identifi-
cation, the much more appropriate one given by Mr. Sowerby has, for the present,
been retained.

BIVALVIA. 33

8. PECTEN PUSIO, Pennant. Tab. VI, fig. 4, a — c.

Lister. Hist. Conch., lib. iii, par. 1, figs. 9, 18? and 23? 1/89.
PALLIOLUM? Chem. Conch. Cab., vii, p. 333, t. 67, figs. 635-6, 1784.
OSTREA MINIATA. Born. Mus. Cses. Vind., p. 104, t. vii, fig. 1, 1780.

— MULTISTRIATA. Poli. Test. Sicil., vol. ii, p. 164, t. 28, fig. 14, 1795.

— PUSIO. Don. Brit. Shells, vol. i, pi. 34, 17 ".-.'.

SINUOSA. W. Wood. Ind. Test., p. 50, pi. 10, fig. 34, 1825.
PECTEN PUSIO. Penn. Brit. Zool., vol. iv, pi. 61, fig. 65.

Turt. Brit. Biv., p. 215, pi. 17, fig. 2, 1822.
Payr. Cat. Moll, de File de Cors., p. 74, 1826.
G. B. Sowerby. Genera, No. 31, fig. 6.
Phil. En. Moll. Sic., vol. i, p. 84, and vol. ii, p. 58, 1844.
Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 278, pi. 50, figs. 4, 5 ;
pi. 51, fig. 7.

— DISTORTUS. Da Costa. Brit. Conch., p. 148, pi. 10, figs. 3, 6.

Mont. Test. Brit., p. 148, and Sup., p. 61, 1808.
Loven. Ind. Moll. Scand., p. 30, 1846.
SINUOSUS. Turt. Brit. Biv., p. 210, pi. 9, fig. 5, 1822.

Brown. Illust. Conch. Gr. Brit., pi. 32, fig. 2, 1827.
Forbes. Geol. Surv. of Gr. Brit., vol. i, p. 86, 1846.

— SPINOSUS. Brown. Illust. Conch. Gr. Brit., pi. 33., fig. 8, 1827.

— STRIATUS. /. Sowerby. Min. Conch., t. 394, figs. 2 — 4, 1823.

Dujard. Mem. Soc. Geol. de France, t. ii, pi. 2, p. 270, No. 3, 1837.
Nyst. Coq. Foss. de Belg., p. 301, pi. 15, fig. 1, b, b', d, 1843.
SERRATUS. Dubois. Conch. Foss. de Wolhyn. Podol., p. 73, pi. 8, fig. 5, 1831.

— GLORIA MARIS? Id. - p. 72, pi. 8, figs. 6 & 19, 1831.
SQUAMULOSUS. Desk. Exped. Sci. de Morea, pi. 5, fig. 7 — 1 1, 1833.

LIMATUS. Gold/. Pet. Germ., vol. ii, p. 59, pi. 94, fig. 6, a — b.
Chenu. Conch. Illust. Pecten, pi. 49, fig. 5.

— ELONGATUS ? Goldf. Loc. cit., pi. 94, fig. 7, a — c.
HINNITES PUSIO. G. B. Sow., Jr. Conch. Man., fig. 173.

SINUOSUS. Desk. 2d ed. Lam., t. vii, p. 149, 1836.

G. B. Sow., Jr. Thesaur. Conch., vol. i, p. 79, pi. 20, figs. 1—3, 1847.
IRREGULARIS. Desk. Ency. Meth. Vers., t. ii, p. 273, No. 1.

Spec. Char. Testa orbiculato-ovatd, subaquivalvi, aguilaterali, radiatd, radiis confertis,
numerosis, 2 — 3 partitis, irregularibus, lavibus ant scabris ; auriculis intequalibi/s.

Shell orbiculato-ovate, subequivalve, equilateral with numerous close-set rays, in
sets of two or three, irregularly scabrous, with very unequal auricles.
Longitudinal diameter, 2 inches; height, 2fths of an inch.
Locality. Cor. Crag, Sutton, Ramstiolt, and Sudbourn.
Red Crag, Sutton, Bawdsey, Walton Naze.

Recent, Britain, Mediterranean, Bergen.

This shell is abundant in both formations, and in the Coralline Crag at Ramsholt
the two valves are often united. In the young state, the Crag shell so much resembles
the recent specimens of the same size, that it cannot be considered otherwise than

5

34 MOLLUSCA FROM THE CRAG.

identical, as suggested by Philippi, ' En Moll. Sic.,' vol. i, p. 84, notwithstanding a
material change in its habits appears to have taken place in the modern shell, where,
after it has attained a certain age or magnitude, it attaches itself to some stone or
rock, by the entire surface of the right valve adhering by the scabrous or imbricated
portions of the rays, in consequence of which it is often distorted, moulding itself to the
inequalities of the body to which it is fixed, producing great variation in form, from
which circumstance the recent shell has been separated into two or more species.
This does not appear to have been the habit of the Crag shell, as amongst the
numerous specimens I have seen, there is no indication of its having been attached by
the exterior surface, but may have been a fixed species by means of a byssus, as in
all the right valves a large opening exists beneath the anterior auricle, so far
resembling the habits of the recent species in being fixed though by a different process.*
Some of my specimens have attained a diameter of rather more than 2j inches
from the umbo to the ventral margin, but, unlike the full-grown recent shell,
have retained their regularity of form throughout their whole existence. There is
often a slight obliquity in the shell, produced probably from its attached habits, the
large byssus causing the auricle on that side to be more elevated than on the
posterior, which is not only much smaller, but more depressed. The valves are nearly
equal in convexity, though the right one is a little the flatter of the two, and in general
the rays are arranged in pairs, unequal in size, the larger one being scabrous, sometimes
less regular with three of different sizes, and all imbricated, the exterior is, however,
very deceptive in this character, as in one variety which from the entire absence of
these imbrications as well as from a greater regularity in the rays, it was assumed to
be a distinct species, and passed in my catalogue under the name of striaturus, wThich
there is reason now to believe is not entitled to that distinction. At the anterior
opening beneath the auricles, are five or six elevated ridges for the purpose, probably,
of keeping the byssus more spread, or in its place, and the shell appears to have
had a somewhat large cartilaginous area, as well as a broad surface for the attach-
ment of the ligament, the valves opening about five and twenty degrees. In the
young as well as in the adult shell, there is a great inequality in the size of the
auricles.

In this, as in many species of this genus, the exterior is ornamented with fine
divaricating striae, crossing the lines of growth at nearly right angles, visible also in
the recent shell, and between the rays the surface is often subcancellated by the
reflexed or thickened margin of the shell at the varied periods of increase.

The recent shell is stated, by the authors of British Mollusca, to range from near
low water mark to 90 fathoms : most plentiful between 15 and 28. Its lateral range
extends from the Mediterranean to the Norwegian shores.

* Although never being itself fixed by the shell, its roughened exterior is well adapted for parasitical
animals and we, consequently, find Oysters or Barnacles adhering to the valves.

BIVALVIA. 35

9. PECTEN OPERCULARIS, Linnaeus. Tab. VI, fig. 2, a — d.

List. Hist. Conch., lib. iii, fig. 27.
OSTREA OPERCULARIS. Linn. Syst. Nat., p. 1147, No. 202, 1767.

— Born. Mus. Cses. Vindobon, p. 106, 1780.

Schrot. Einleit in die Concbyl., iii, p. 317, t. ix, fig. 3, 1784.
W. Wood. Ind. Test., pi. 10, fig. 43.

— SUBRUFA. Don. Brit. Shells, vol. i, pi. 12, 1799.
LINEATA. Don. Brit. Shells, vol. iv, pi. 116, 1803.

— SANGUINEA. Poli. Test. Sicil., vol. ii, pi. 28, figs. 7-8.

? Knorr. Delices des Yeux., t. iv, fig. 1, 1766.
PLEBEJA. Broc. Conch. Foss. Subap., p. 577, t. 14, fig. 10, 1814.
PECTEN PICTUS. Da Costa. Brit. Conch., p. 144, pi. 9, figs. 1, 2, 4, 5, 1778.

— LINEATUS. Id. - p. 147, pi. 10, fig. 8.

Mont. Test. Brit., pp. 147, 579, 1803.
Chenu. Conch. Illust. Pecten., pi. 30, figs. 1, 2.
OPERCULARIS. Chem. Conch. Cab., vii, p. 341, pi. 67, fig. 646, 1782.
Mont. Test. Brit., p. 145, 1803.
Lam. Hist, des An. Sans. Vert., vi, p. 172, 1822.
Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 1, 1827.
Payr. Cat. des MoU. de la Corse., p. 77, 1826.
Chenu. Conch. Illust. Pecten., pi. 48, fig. 3.
Gold/. Pet. Germ., t. ii, p. 62, tav. 95, fig. 6, 1833.
Phil. En. Moll. Sic., p. 82, t. 6, fig. 2, 1836.
G. B. Sow., Jr. Thes. Conch., p. 53, pi. 17, figs. 141 — 146, 1847.
Loven. En. MoU. Scand., p. 30, 1846.
Forb. and Hani. Hist. Brit. Moll., vol. ii. p. 299, pi. L, fig. 3 »

L i, figs. 5, 6 ; L iii, fig. 7, 1849.

SULCATUS. J. Sowerby. Min. Conch., t. 393, fig. 1, 1823.
Woodward. Geol. of Norf., p. 44, 1833.
Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 19, 1835.
RECONDITUS. J. Sowerby, Min. Conch., t. 575, figs. 5, 6, 1827.

Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 19, No. 73, 1835.
Potiez et Mich. Cat. Moll, de Douai, p. 77, pi. 49, figs. 1, 2.
SUBRUFUS. Turt. Brit. Biv., p. 210, t. 17, fig. 1, 1822.
AUDOUINII. Payr. Cat. Moll, de Cors., p. 77, pi. 2, figs. 8, 9, 1826.
PLEBEIUS. /. Sowerby. Syst. Ind., p. 244, 1835.

Bronn. Leth. Geog., ii, p. 916, t. 39, fig. 16, 1838.

SOWERBYI. Nyst. Conch. Foss. de Belg., p. 293, pi. 22, fig. 3, b', and pi. 22 bis.
MALVIN^E. Dubois de Montp. Conch. Foss. Wolhyn. Podol., p. 71, pi. 8, figs. 2, 3.
FLAVUS? Id. p. 72, pi. 8, fig. 7.

RECTANGULUS? Id. p. 72, pi. 8, figS.10,1 1.

PULCHELLINUS ? Id. - p. 70, pi. 8, fig. 8.

RADIANS? Nyst. Coq. Foss. de Belg., p. 294, pi. 24, fig. 3, 1844.

— 20-suLCATUS. Mull, (fide Loven.}

Description de PEgypt Hist. Nat., pi. 13, figs. 5, 1—4, and pi. 14, fig. 8, 1826.

Ency. Meth., pi. 212, fig. 2.

Dale. Hist, and Antiq. of Harwich, p. 291, t. xi, fig. 1, 1730.

Spec. Char. Testa suborbiculari, subcequwalm, longitudinaliter radiatd radiis \ 8 — 26,

36 MOLLUSCA FROM THE CRAG.

squamosis, squamis crebris, transversis, interradios divercatim striatis ; auriculis sub-
fsqualibus ; valvd sinistrd convexiori.

Shell suborbicular, slightly inequivalved, covered with 18 — 26 imbricated or
squamose rays, squamae numerous and close set, between the rays are visible fine
divaricating strise ; auricles nearly equal ; the left valve, the more convex one.

Diameter, 2J inches.

Locality. Cor. Crag, Passim.
Red Crag, Id.
Mam. Crag, Bramerton and Thorpe.

Recent, Britain, Finmark, and Mediterranean.

This is one of the most abundant shells, in the Coralline, as well as
in the Red Crag Formations, and is exceedingly variable as regards the ornament
and arrangement of its exterior, which has caused it to be separated into
many different species, so greatly, indeed, does it vary in this character, that
scarcely any description can be given of its sculpture, but what some deviation
may be observed, so as almost to induce an opinion, that such difference might
be considered as a specific distinction. The most abundant variety is that which
corresponds with the rough and imbricated shell, now found living in the
Mediterranean, figured and described as a new species by Payraudeau, under the
name P. Audouini. This shell may be found in almost every locality, in the
Coralline as well as in the Red Crag.

Both valves may be described as somewhat convex, though the upper or left valve
is decidedly the more tumid of the two. Our shell is ornamented with more or less
rounded rays, divided into threes, varying in number from 18 to 26, these
are rather wider than the intermediate spaces, and are covered with rough imbricated
squamae, and the spaces between the ribs are generally imbricated in the same way.
In the young shell the tripartite form of arrangement is seldom to be seen, the rays
then being single, and this continues sometimes till the shell has increased to more
than an inch in diameter ; and the division of the intermediate space into three rays,
does not, in some specimens, show itself until even a greater magnitude, by which the
young shell differs so materially in its ornament, as to have been made into new
species. In one variety of my Crag specimens, the rays are so strongly imbricated
with reflexed squamae, that in my Catalogue, it was considered a distinct species,
and intended to have been described under the name scabrotus (fig. 2, c] ; but the pos-
session of more specimens and further examination, give reason to believe it to be only
a modification of the above species : in this, which, is somewhat of a young shell, the
ribs are single, but the imbrications are continuous undulating over and between the
ribs. The var. lineolata, I have seen only from the Red Crag, and that but rarely.
P. reconditus, Min. Conch., is I conceive, to be only that form sometimes met with in
which the rays have preserved their unity until the specimen has attained a magnitude
of an inch and a half in diameter, although in some specimens, they separate into threes

BIVALVIA. 37

long before they attain that size, the separation of the rays generally producing a
corresponding ornament upon the intermediate spaces, although that often depends
upon the width of those spaces. This appears to differ from the London Clay shell
and I doubt its being Ost. recondita, Brander.

In my specimens from Barton, are two varieties, one not having more than 18 or 20
rays, while the other has 30 — 32, these are more rounded than in the Crag shell ; when
perfect, in general they are more or less eroded, they are striated both upon and between
the rays, but never distinctly keeled, the imbricated lines of growth are finer, and the auri-
cles are comparatively larger. Nor could I detect upon them the fine divaricating stride.

The auricles of our shell may be described as unequal, that of the left valve on the
anterior side projecting, so as to form an angle less than 90°. In the right or flatter
valve, the anterior auricle is longer or projects further than the posterior one, leaving
in the full grown shell a considerable opening, even in those which have exceeded two
inches and a half, and on the edge of the shell on that side are prominent denticles'
four or five of which may be seen in the open space beneath the auricle.

The height of most specimens measuring from the umbo to the ventral margin, is
rather less than the diameter of the opposite direction, although in some specimens
these dimensions are reversed. The angle formed by the divergence of the rays from
the umbo may be called a right angle, although it sometimes exceeds, while in the
more elongated specimens, it falls short of that size. In some old shells, the anterior
and posterior sides are extended, so as to give a high-shouldered appearance to the
valve ; and in all the younger specimens, the comparative size of the auricles is greater
than in the larger shells, indeed, in the pullus state, they are equal to the entire
length, and the shell then is nearly smooth.

Under a lens, fine divaricating striae may be seen diverging or curving over the shell.

This species is stated by the authors of the ' Hist. Brit. Mollusca,' to possess a
great vertical range, from five to one hundred fathoms, while its peculiar province in
the British Seas is between fifteen and twenty-five.

10. PECTEN GRACILIS, /. Sowerby. Tab. VI, fig. 5.

PECTEN GRACILIS. J. Sow. Min. Conch., t. 393, fig. 2, 1825.
S. Wood. Catalogue, 1840.
J. Morris. Cat. Brit. Foss., p. 114, 1843.

Spec. Char. Testa gracili, suborbiculari, compressd vel planimctdd, tenui, costatd ;
costis acutis, angustis, inagualibus, tripartitis, concentrice et tenuissime imbricato-striatis ;
auriculis parvis intequalibus.

Shell suborbicular, compressed or flattened, delicate, thin, and fragile, costated,
ribs sharp and fine, unequal in size, arranged in threes ; finely striated concentrically,
with imbricated and slightly elevated lines of growth, ears small and unequal.

Diameter •, 1^ inches.

Locality. Red Crag, Sutton, Holywells, and Bawdsey.

38 MOLLUSCA FROM THE CRAG.

This, as yet, I have seen from the Red Crag only, and in that Formation it is by
no means abundant.

Some varieties of P. opercularis seem to approach this so closely, that it is possible
it may be only a modification of that variable species, with more attenuated and
depressed valves than are commonly seen ; there are, however, some differences which
must, at least for the present, keep them separated, more especially as there is no
necessity for the imp osition of a new name. The variety linearis of that species, in the
form and arrangement of its sculpture, appears to approach the nearest to our shell.

In P. gracilis both valves are much flattened, the right valve rather the more so
of the two ; the auricles appear comparatively less than in opercularis, and the rays
are arranged much in the same manner, but rather more numerous, varying from
twenty to twenty-six, generally tripartite or ranged in threes, the centre one the most
elevated and the most sharp, with an intermediate one between the three, so that
every fourth ray, as stated by Sowerby, ' Min. Conch.,' vol. iv, p. 129, is the most
prominent and the most conspicuous ; the same disposition of the rays may be
observed in opercularis, var. linearis, only in that shell, neither the valves nor the
rays are so much depressed. Our shell is ornamented with fine concentric striae, or
raised and subimbricated lines of growth, giving a roughness to the feeling, more than
to the eye, but the same sculpture is present in linearis.

The most material differences are a greater flatness in the valves, a much
thinner shell, with a slight alteration in proportionate or comparative dimensions, and
smaller auricles ; this last may, perhaps, be looked upon as the most distinguishing
character, if they be really distinct, which more numerous specimens than I possess
may perhaps determine.

A shell from the older Tertiaries at Bracklesham, somewhat resembles this in its
graceful and elegant form, and slightly so in the disposition of the sculpture, but it has
more numerous rays, and the imbricated lines of growth are finer.

11. PECTEN DUBIUS Brocchi. Tab. IV, fig. 3, and Tab. VI. fig. 3.

List. Hist. Conch., lib. iii, p. 1, fig. 29, 1687.

OSTREA DUBIA. Broc. Conch. Foss. Subap., p. 575, t. 16, fig. 16, 1814.
PECTEN SCABRELLUS. Desk. 2d ecL Lam., t. vii, p. 161.

Bast. Bord. Foss., p. 73, 1825.

Gold/. Pet. Germ., t. ii, p. 62, t. 95, fig. 5.

Dujard. Mem. Geol. de France, p. 270.

Bronn. Leth. Geog., ii, p. 917, t. 39, fig. 17, a— c, 1838.

Grateloupe. Cat. Zool. des An. Vert, et Invert. Bord., p. 58, 1838.

Phil. En. Moll. Sic., vol. ii, p. 60, 1844.

— MURICATUS? Risso. Princ. Prod, de 1'Eur., t. iv, p. 304, 1826.

— VENTILABRUM 1 Goldf. Pet. Germ., t. ii, p. 67, t. 97, fig. 2.

— SCWERBYI. Nyst. Coq. Foss. de Belg., p. 293, pi. 22, fig. 3, b, and pi. 22 bis,

fig. 3, a', 1844.

— TUMESCENS. S. Wood. Catalogue, 1840.

BIVALVIA. 39

Spec. Char. Testa suborbiculari, cequilaterali, subaquivalvi, radiatd, radiis 14
—18 sulcatis, plurimum tripartitis, squamoso-denticulatis ; auriculis incequalibus.

Shell suborbicular, equilateral, slightly inequivalved, with 14 — 18 large and elevated
rays for the most part, one large, with a small one on each side, strongly imbricated
ears, unequal, rayed, and squamose.

Diameter, \\ inch.

Locality. Cor. Crag, Sutton, Ramsholt, Sudbourn, Gedgrave.

Red Crag, Sutton, Newbourn, Bawdsey, Walton Naze.

This is by no means rare in the Coralline, but rather more so in the Red Crag ; it
is, however, much less abundant than opercularis, though it may generally be
obtained in those localities in which the shells of either Formation are met with in a
good state of preservation.

The valves of this species may be described as equal in size, at least, as far as can
be determined by the disconnected valves, which appear to present a similar amount
of convexity, although a specimen of the left valve may occasionally be seen a little
more tumid or deeper than the right. The rays are fewer than in P. opercularis, never
exceeding eighteen, while they have sometimes not more than fourteen, but the general
amount is the intermediate number ; these are tripartite, and about an equal width with
the spaces between them ; the centre ray is much larger than the one on each side of
it, and is covered with large and prominent squamae or imbrications, while the smaller
rays are also scabrous, but have more numerous and smaller squamae, not correspond-
ing with those upon the larger ray as if they were not formed at the same time by the
reflexed edge of the mantle. The spaces between the rays in the young shell are
naked or free from longitudinal striae, which, however, become ornamented as the
shell increases with from one to three rough and radiating scabrous lines. The
length of the shell in most specimens is equal to the height, but when it deviates
from this regularity it is in the direction from the anterior to the posterior side, which
becomes greater than from the umbo to the ventral margin. Its most distinguishing
characters appear to be the inequality of the auricles, the anterior one being much
larger than the posterior, particularly in its young state, and much exceeds the
differences observable in P. opercularis. The spread of the auricles at the liga-
mental edge equals 3-5ths the diameter of the shell, while in some small specimens
the hinge area is comparatively larger. On the right valve beneath the anterior
auricle, as in the last species, are some prominent denticulations, and the exterior
of the shell is also ornamented with fine divaricating striae, visible only with the aid
of a magnifier.

One variety of what I have considered as the young of this species, is rather
peculiarly ornamented on the left valve, having every third ray more especially
covered with large and elevated imbrications, while the two intermediate ones are
nearly smooth upon the outer edge (t. vi, fig. 3).

40 MOLLUSCA FROM THE CRAG.

12. PECTEN ISLANDICUS, Mutter, Tab. V, fig. 1.

PECTEN ISLANDICUS. Mull. Zool. Dan. Prod., p. 248, No. 2990, 1776.

Chem. Conch. Cab., vii, p. 314, pi. 65, figs. 615-16, 1782.
_ Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 3, 1827.

— Flem. Brit. An., p. 385, 1828.
Desk. 2d ed. Lam., vii, p. 145, 1836.

Gould. Invert. Massach., p. 133, fig. 87, 1841.

— Mdller. Ind. Moll. Grosn., p. 16, 1842.

G. Sow. Thesaur. Conch., vol. i, p. 75, pi. 17, figs. 159-160, 1843.
Dekay. Nat. Hist. New York Zool., p. 173, pi. 11, fig. 206, 1843.

— Loven. Ind. Moll. Scand., p. 30, 1846.

— Chenu. Conch. Illust. Pecten., pi. 32, figs. 1 — 4.

— Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 303, 1849.
Middendorff. Mem. de 1'Acad. des Sci. St: Petersb., p. 526, t. 12,

figs. 7-8, 1849.
G. B. Sow., Jr. Thesaur. Conch., vol. i, p. 75, pi. 17, figs. 159—161,

1847.

OSTREA ISLANDICA. Gmel. Syst. Nat., p. 3326, 1788.
Turt. ed. Linn., vol. iv, p. 267.
Shaw. Zool. Misc., vol. xxiii, t. 978, 987.
W. Wood. Ind. Test., p. 49, pi. 10, fig. 21, 1825.

— CINNABABJNA. Born. Mus. Goes. Vind., p. 103, 1780.

Dillwyn. Desc. Cat. Rec. Shells, p. 256, 1817.

PECTEN PEALII. Conrad. Amer. Mar. Conch., p. 12, pi. 2, fig. 2, (fide Gould}.
Ency. Method., pi. 212, fig. 1.
Lister. Hist. Conch., pi. 1057, fig. 4.

Spec. Char. Testa suborbiculari, tequilaterali, convecciusculd, subtequivalvi, radiatd,
radiis numerosissimis, bisulcatis, scabriusculis ; auriculis incequalibus.

Shell suborbicular, equilateral, slightly convex, subequivalve, covered with nume-
rous close-set, somewhat scabrous bisulcated rays or costulated striae ; auricles
unequal.

Locality. Clyde Beds.

Recent, Scandinavia, Greenland, and North American Seas.

This handsome shell is rejected by British Conchologists, as a living inhabitant of
our own Seas, it must necessarily, therefore, fall into the hands of the British
Palaeontographist, as a fossil species, it being abundant in the Clyde Beds. Dead
valves have been dredged up in the Scottish and Zetland Seas, from depths varying
from thirty to one hundred fathoms.

It is, essentially, a Boreal species, and is found living upon the Banks of New-
foundland, where it is said by Dr. Gould, to be the favorite food of fishes. I have
not as yet seen a specimen from any of the three Formations into which the Crag has
been separated, although fragments of what may belong to this species have been
found in the Mammaliferous Crag, at Bramerton, and what were considered to

BIVALVIA. 41

have been P. Princeps, by Woodward, were, probably, only portions of specimens
of this shell which sometimes attains a magnitude of four inches in diameter, a size
that might well lead to such an error.

Our figure is taken from a magnificent specimen found in the beds of the Clyde,
and now in the Museum of the Geological Society, presented by James Smith, Esq.,
of Jordan Hill.

13. PECTEN VARIUS, Linnceus.

OSTREA VARIA. Linn. Syst. Nat., ed. 12, p. 1146, No. 199, 1767.

Poli. Test. Sic., vol. ii, p. 163, t. 28, fig. 10, 1793.

Don. Brit. Shells, vol. i, pi. 1, fig. 1, 1799.

Shaw. Nat. Miscel., vol. 23, fig. 993.

Mawe. Linn. Conch., pi. 14, fig. 4, 1823.

W. Wood. Ind. Test., p. 50, pi. 10, fig. 31, 1825.

Burrow. Elem. Conch., p. 144, pi. 9, fig. 2, 1815.
PECTEN VAKIUS. Chem. Conch. Cab., vii, p. 331, pi. 66, figs. 633, 634, 1782.

Crouch. Int. Lam. Conch., p. 12, fig. 4, 1827.

Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 4, 1827.

Phil. En. Moll. Sic., vol. i, p. 84, 1836.

J. Smith. Mem. Wern. Soc., vol. viii, p. 46, 1838.

G. B. Sow. Conch. Man., fig. 171, 1843.

Id. Thesaur. Conch., vol. i, p. 76, pi. 19, fig. 214, 218, 1847.

Thorpe. Brit. Mar. Conch., p. 118, 1844.

Phil. En. Moll. Sic., vol. ii, p. 58, 1844.

Lovtn. Ind. Moll. Scand., p. 30, 1846.

Alder. Cat. Moll. North, and Durh., p. 77, 1848.

Forb. and Hani. Hist. Brit. Moll., vol. 2, p. 273, pi. 50, fig. 1, 1849.
MONOTIS. Dacosta. Brit. Conch., p. 151, pi. 10, figs. 1, 2, 4, 5, 7, 9, 1778.

Spec. Char. Testa rotundato-ovatd, aquivalvi, (squilaterali, radiatd ; rudiis 26 — 30,
subcompressis, squamoso-scabris ; auricula alterd minima.

Shell roundedly ovate, equivalve, equilateral, ornamented with 26 — 30 subcom-
pressed rays, which are covered with squamose imbrications ; ears unequal.

Locality. Clyde Beds. Recent, North Seas, Britain, and Mediterranean.

This is given by Philippi, as a living species in the Mediterranean, and enumerated
by Loven, as an inhabitant of the Coast of Scandinavia ; but it has not yet, that I am
aware of, been found in either of the three deposits of the Crag. As it is undoubtedly
a fossil, in the Clyde Beds, and found frequently in the upper Tertiaries of Sicily, it
may, probably, yet be discovered in the Red or Mammaliferous Crag in our own
country. It would not, however, be here introduced simply upon such anticipation,
but it is claimed as one of the fossils of our upper Tertiaries.

42 MOLLUSCA FROM THE CRAG.

LIMA,* Bmguere, 1797.

PLAGIOSTOMUS. Llwyd. 1698.

RADULA. Chem. 1784.

GLAUCUS and GLAUCODERMA. Poll, 1795.

OSTREA (sp.). Linn.

MANTELLUM. Bolten, 1798.

PECTEN (sp.). Mont.

PLAGIOSTOMA. J. Sow. 1814.

GLAUCION. OJcen. 1815.

LIMATULA. 8. Wood. 1840.

LIMULA. D'Orb. sec. Gray.

Gen. Char. Shell ovate, equivalved, generally oblique, inequilateral, and gaping
at both sides ; sometimes closed and equilateral, externally costated or striated,
radiating from the umbo ; often rough and squamous like a file. Hinge area extended
into auricles, bipartite ; cartilage occupying the central or triangular portion ;
ligament more external and linear. Palleal impression entire, that by the adductor
muscle large, ovate, and eccentric.

The animal of this genus has the lobes of the mantle disunited, the margins fringed
with long tentacular filaments, and without siphonal tubes. A small compressed foot
furnished with a byssal groove.

Some species approach very closely to those of the genus Pecten, in being equi-
lateral, and enclosing the animal within the shells when they are brought together ;
in others, the shells gape widely, both on the anterior and posterior sides, and the
animal is too large to be covered by the valves. A subgenus was proposed by myself,
for those species which are equilateral and closed (under the name Limatuld) ; but
recent examinations of the animals of both sections are said not to present differences
sufficient to justify generic separation. They are, therefore, here united.

The name of Limea was proposed as a genus for those species which are furnished
with teeth or crenulations upon the hinge margin on each side of the cartilaginous
pit, and the name Limoarca was also given in consequence to the same section, but
this character alone, it is to be feared, is not sufficient for generic separation ;
specimens of Lima subauriculata in my own cabinet, are in like manner supplied with
minute crenulations. Dr. Loven, however, states the animal of his Limea Sarsii to
have the margin of its mantle destitute of tentacular appendages. Species, probably
belonging to this genus, from the older Secondary Formations figured and described
under the name of Plagiostoma, have been long known, and were abundant in some of
the older periods. In those shells the gape or opening appears to have been on the
rounded or posterior side, on which, in the recent shell, is placed the large adductor
muscle, while the foot, the organ that secretes the byssus, is on the anterior side,
which appears to have been capable of being quite closed, the opening, therefore, was

* Etym. limus crooked, oblique; limat a file.

BIVALVIA. 43

not, probably, for the organ of attachment, and as in the recent species, their shells
vary much in those characters, the secondary fossils were most likely of this genus.

1. LIMA EXILIS, S. Wood. Tab. VII, fig. 6, a—c.

LIMA EXILIS. S. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 233, Sup., pi. 3, fig. 1,

1839.

S. Wood. Catalogue, 1840.
Morris. Cat. of Brit. Foss., p. Ill, 1843.

Spec. Char. Testa ovatd, valde obliqud, depressd, frayili, exili, utroque latere liiante ;
costato-striatd, striis 25-35 asperimis, undulatis ; cardinis obliqui area angustd ; auriculis
minimis <equalibus.

Shell ovate, very oblique, somewhat depressed, slender, and fragile, gaping largely
on both sides ; striated or costated, striae 25-35, rough, irregular and unequal,
cardinal area large, oblique ears, rather small and equal.

Longitudinal diameter, \\ inch. Height, 1^ inch.

Locality. Cor. Crag, Ramsholt, Sudbourn.
Red Crag, Walton Naze.

This elegant shell does not appear to have been very scarce in the Coralline
Crag Sea, having myself procured a dozen specimens, most of which were from one
locality, Ramsholt ; it is also occasionally found in the more tranquilly deposited portion
of the Red Crag at Walton Naze, but its fragility in proportion to size is against
its preservation in that deposit, as even in the older formation, specimens are not often
obtained in a perfect state.

Messrs. Forbes and Hanley have introduced this fossil into their synonyma of
L. hians, considering it only as a variety of that species, to which opinion I am not
willing to assent as a marked and striking difference is presented by my fossils
sufficient by the ordinary mode of valuation in specific distinction to justify a
separation. It somewhat resembles L. inflata, but is flatter and undeserving of that
name, and a shell in the British Museum called L. scabretta, approaches it in some
respects, but that is also more inflated, and is probably a variety of the injtata ; I
have therefore retained it as distinct, being intermediate between the British and
Mediterranean species, approaching rather nearer to the latter than to the former.

It may be more particularly described thus : the form is irregularly ovate,
very oblique, gaping on both sides, and covered with raised and slightly undulating
costulated striae, these are rough or scabrous, at nearly regular distances, covering
in some specimens the entire surface, but generally a small space is left naked
on the anterior side ; in L. hians the striae are less regular, thicker on the
posterior side, larger and more dissimilar on the anterior, in this they are rather
more distant upon the posterior half; the comparative dimensions of this are very
different, taking the height at lj inch from the umbo to the ventral margin, the
diameter in the opposite direction is equal to 1 \ inch, but in hians the height is at

44 MOLLUSCA FROM THE CRAG.

least one third greater than the length ; the hinge line in this is more oblique, the
ligamental area broader and more shallow, with a smaller gape on both sides. Two
forms of the British shell have been figured by Professor Forbes in the ( Mag. Nat.
Hist.,' one of which is less elongated than the other, and more nearly approaches
our shell, but there is still apparently a sufficient difference to keep them separated.

2. LIMA HIANS, Gmelin. Tab. VII, fig. 2, a — c.
OSTREA HIANS. Gmel. Syst. Nat., p. 3332.

Turt. ed. Linn., vol. iv, p. 273, 1806.
W. Wood. Ind. Test., p. 51, pi. 11, fig. 53, 1825.

LIMA TENERA. Turt. Zool. Journ., vol. ii, p. 362, t. 13, fig. 2 (not tenera Chem.).
Brown. Illust. Conch. Gr. Brit., pi. 31, figs. 8, 9, 1827.
Forbes. Malac. Monen., p. 41, 1838.

Id. Report on .Egean Invert., p. 182, 1843.
Phil. En. Moll. Sic., vol. ii, p. 56, pi. 16, fig. 3, 1844.

— INFLATA. Forbes. Malac. Monen., p. 41, 1838.

— SARSII. Kroyer, fide Loven.

— VTTRINA. Brown. Illust. Conch. Gr. Brit., pi. 31, figs. 10, 11.

— FRAGILIS. Flem. Brit. Ann., p. 388, (partly,) 1828.

Id. Crouch. Corn. Faun., pt. 2, p. 37.

— APERTA. G. B. Sow. Thes. Conch., vol. i, p. 87, pi. 22, figs. 26 & 27, 1847.

Thorpe. Brit. Mar. Conch., p. 249.

— HIANS. Loven. Ind. Moll. Scand., p. 32, 1846.

Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 268, pi. 52, figs. 3—5, and
pi. R (animal), 1849.

— OBLONGA. S. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 234, pi. 3, fig. 2, 1839.
LIM.E. Forbes. Mag. Nat. Hist., vol. viii, pp. 593, 594, figs/ 63 & 64, 1835.

Spec. Char. Testa oblongo-ovatd, obliqud, valde incequilaterd, depressd, gracili, costato-
striatd, striis vel radiis numerosis, asperimis, irregularibus, cardine obliquo, area triangulari
latdt auriculis tsqualibus ; margine denticulate.

Shell elongato-ovate, oblique, very inequilateral, depressed, and slender ; striated
with numerous, rough, irregular, and slightly waved striae, projecting beyond the
ventral margin ; gaping widely on the posterior side, slightly so on the anterior ;
ligamental area large and triangular, umbones prominent and distant.

Height, 1 inch. Length, 6-10ths of an inch.
Locality. Cor. Crag, Ramsholt.

Recent, Britain, Scandinavia, and Mediterranean.

This appears more scarce as a fossil than the preceding, having as yet obtained
only two specimens, and those both of the same value, and from the same locality,
there is, however, little doubt of its identity with the recent British species.

The form of this shell is comparatively much more elongated than the preceding, and
is somewhat natter ; it gapes widely on both sides, that on the posterior is particularly
deep immediately behind the hinge line, while the front gape is near the ventral

BIVALVIA. 45

margin ; the exterior is covered with numerous irregular striae or striated costae,
rough or scabrous, radiating in an undulating direction, extending from the extreme
edge of the posterior side to the anterior, where, for a small space, it is naked or
destitute of striae, those on the posterior are fine and closer set, becoming larger and
more distant as they approach the anterior, where they are rough and project beyond
the margin. The hinge line is less oblique than in exilis, and is narrower, which per-
haps it would be, if not a different species, corresponding thus with the more narrow
form of the shell, but the ligamental area is deeper from the umbo inwardly, while the
gape on both sides is larger than in that shell, and the whole contour in this is so dif-
ferent that, judging from the specimens which I possess, they cannot be united without
an extension of variation greater than is generally permitted to species of this genus.

In the recent state, in the more northern parts of the British seas, it attains a greater
magnitude than is given by the dimensions of our fossil, which may not, possibly, be a
full-grown individual, although its gape is wide, a character of the adult shell ; it is said
one inch and three quarters is not an uncommon size in the recent British specimens,
whilst those found at Guernsey are less, resembling in this peculiar our Crag fossil.

3. LIMA LOSCOMBII, G. Sowerby. Tab. VII, fig. 1, a — c.

PECTEN FRAGILIS. Mont, (not Chemnitz). Test. Brit. Sup., p. 62, 1808.

OSTREA FKAGILIS. Turt. Conch. Diet., p. 131, 1816.

LIMA BULLATA. Turt. (not OSTREA BULLATA, Born.). Brit. Biv., p. 217, t. 17, figs. 4, 5.

Thorpe. Brit. Mar. Conch., p. 114, 1844.

Phil. En. Moll. Sic., vol. ii, p. 56, t. 16, fig. 2, 1844.

— LOSCOMBII. G. Sow. Genera of Shells, No. 17, LIMA, fig. 4.

Reeve. Conch. Syst., pi. 112, fig. 4.

G. Sow. Thesaur. Conch., vol. i, p. 86, pi. 22, figs. 20—22.

Loven. Ind. Moll. Scand., p. 32, 1846.

Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 265, pi. .53, figs. 1—3.

Alder. Cat. Moll. North, and Durh., p. 78, 1848.

— FRAGILIS. Brown. Illust. Conch. Gr. Brit., pi. 31, figs. 6-7, 1827.

Forbes. Mag. Nat. Hist., vol. viii, p. 594, fig. 65.

Id. Malac. Monen. p. 40, 1838.
S. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 235, pi. 3, fig. 3, 1839.

Spec. Char. Testa tumidd, odlique-ovatd, intequilaterd, tenui, fragili ; utroque latere
perparvulum hiante, striatd, striis tenuissimis, alternatis, undulatis, cardine oUiquo.

Shell tumid, obliquely ovate, inequilateral, thin and fragile ; very slightly gaping
on either side, covered with fine striae, slightly undulating, and alternately larger and
smaller ; cardinal area oblique and small.
Greatest Diameter, f of an inch.
Locality. Cor. Crag, Sutton and Ramsholt.
Red Crag, Walton Naze.

Recent, Britain, Norway, and Mediterranean.

46 MOLLUSCA FROM THE CRAG.

This elegant and fragile shell is by no means rare in the Coralline Crag at Sutton,
but rather less so at Ramsholt. Walton Naze is the only locality in the Red Crag
from which I have seen it. There cannot, it is presumed, be any doubt about the
identity of this species, which does not seem to possess even a local variation.

The striae which ornament this shell are sometimes regular in size, but more often
possess an intermediate smaller one ; there is a very slight opening between the valves,
near the hinge line on the posterior side, and the valves do not quite close on the
anterior side towards the ventral margin ; hinge line rather short, with a large and
broad ligamental pit projecting inwards ; a subcircular impression by a large adductor
muscle towards the convex or posterior side of the shell.

,4. LIMA PLICATULA, S. Wood. Tab. VII, fig. 4.

LIMA PLICATULA. S. Wood. Mag. Nat. Hist., New Series, vol.iii, p. 235, pi. 3, fig. 4, 1839.

Spec. Char. Testa minutd,in<equilaterali, oblique-ovata, compressiusculd ; costato-striatd ,
striis 14 — 16 convexis, scabriusculis ; antice recta, postice rotundatd ; auriculis valde
inaqualibus ; cardine obliquo ; area ligamenti minutd ; in auriculis dentibus obtusis.

Shell small, inequilateral, obliquely ovate, slightly compressed ; costated or
striated; striae 14 — 16 rounded and somewhat scabrous; anterior side straight,
posterior rounded ; auricles very unequal ; hinge line oblique ; ligamental area
small, with an obtuse tooth in the centre of the auricles.

Longest diameter, ith of an inch.

Locality. Cor. Crag, Sutton.

About a dozen specimens of this shell are in my cabinet, but none of them in very
perfect condition ; and I have not seen other specimens, since the publication of it in the
' Mag. Nat. Hist./ to give further assistance in its elucidation. It appears, however,
t;o present characters differing from any other species with which I am acquainted,
and it must, for the present at least, be considered as distinct, and may be more
particularly described thus.

The shell is very oblique ; the anterior straight, sloping from the umbo with a
scarcely perceptible auricle on that side; while the posterior is not only rounded, but
has a comparatively large and projecting ear : it appears to have been able almost to
close the valve, or at least to have had a very slight gape, as the edge of the shell
nearly touches all round when laid upon a flat surface with its exterior uppermost ; the
rays are rounded, slightly scabrous, and numbering about 17 or 18, and these are
somewhat broader than the spaces between them, which are prettily ornamented with
elevated ridges, giving it a cancellated appearance. The hinge is rather peculiar,
the central depression or pit being small and very oblique ; and on each side in the
middle of the auricles is a tooth-like projection with a corresponding depression in the
opposite valve ; a similar character may be observed in other species of this Genus,
where interlocking prominences and depressions are formed by the animal as an

BIVALVIA. 47

additional security against any injurious lateral movement of the valves. It
appears to differ from L. plicata of the Touraine Beds in not being so elongated,
and in having a broader ligamental area ; and from L. obliqua, of the Paris Basin, in
somewhat similar characters.

5. LIMA SUBAURICULATA, Montague. Tab. VII, fig. 3, a — c.

PECTEN SUBAURICULATA. Mont. Test. Brit. Sup., p. 63, t. 29, fig. 2, 1808.

Flem. Edinb. Ency., pi. 205, fig. 12.
OSTREA SUBAURICULATA. Turt. Conch. Diet., p. 131, 1816.

W. Wood. Ind. Test. Suppl., pi. 2, OSTREA, fig. 5.
LIMA Turt. Brit. Biv., p. 218, 1822.

Flem. Brit. An., p. 388, 1828.
Thorpe. Brit. Mar. Conch., p. 114, 1844.
G. Sow. Thesaur. Conch., vol. i, p. 84, pi. 22, fig. 23.
Phil. En. Moll. Sic., vol. ii, p. 56, 1844.
Loven. Ind. Moll. Scand., p. 32, 1846.
Alder. Cat. of Moll. North, and Durh., p. 78, 1848.
Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 263, pi. 53,

figs. 4, 5, 1849.
SULCATA. Brown. Illust. Conch. Gr. Brit., pi. 31, figs. 4, 5, 1827.

Mailer. Ind. Moll. Grandl., p. 16, 1842.

OSTREA NIVEA. Broc. Conch. Subap., p. 571, t. 14, fig. 14, 1814.
LIMA — Risso. Europ. Merid., t. iv, p. 306, 1826.

Desk, in Lyell's Princ., 1st ed, vol. ii, App., p. 12, 1833.
Nyst. Rech. Coq. Prov. d'Anv., p. 17, 1835.
Phil. En. Moll. Sic., vol. i, p. 78, 1836.
Nyst. Coq. Foss. de Belg., p. 281, pi. 21, fig. 4, 1844.
SULCULUS ? Lovtn. Ind. Moll. Scand., p. 32, 1846.

— ELONGATA. Forbes. .ZEgean Invert., 1843, Rep. Brit. Assoc., p. 192.
LIMATULA SUBAURICULATA. S. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 236, pi. 3,

fig. 6, 1839.
Morris. Cat. of Brit. Foss., p. Ill, 1843.

/Spec. Char. Testa elongato-ovali, cBquilaterali, fragili, convened, in medio striatd vel
costatd, striis rugosis, scepe obtuse angulatis, mediis binis verticalibus ; cardine recto ; auriculis
aqualibus.

Shell elongato-ovate, equilateral, convex, fragile, and closed all .round ; costated or
striated in the centre, becoming obsolete at the sides ; striae or costae rugose, sometimes
angulated ; hinge line straight ; auricles equal.

Length, \ ; height, \ an inch.

Locality. Cor. Crag, Sutton and Ramsholt.

Recent, Britain, Norway, and the ^Egean Sea.

Small specimens of this species are by no means rare in the Coralline Crag at
Sutton ; this place and Ramsholt are the only two localities from which it has as yet
been obtained ; and there is no doubt about its identity with the recent British species.

48 MOLLUSCA FROM THE CRAG.

Our shell is not strictly ovate, but more of an oblong form, with the angles rounded
off ; the sides being somewhat straight, or of very gentle curvature, it is tumid and
thin ; the whole of the ribs being visible on the inside, they occupy the centre of the
shell, and are distributed over about half the surface, two or three of the middle ones
being the most distinct, and these are more conspicuously so on the inside ; umbones
prominent and divergent, leaving a wide ligamental area between them, thereby
enabling the animal considerably to divaricate the valves ; costse obtusely angulated,
rough, but not imbricated, showing distinct lines of growth ; hinge-line straight ;
cartilage pit concave, projecting inwardly, forming an angle of 90°, and occupying
nearly half the ligamental area. The shell extends on each side of the umbo into
what are called auricles, the greater part of which space is occupied by the ligament ;
on the inside beneath these auricles the shell is thickened and strengthened by a
prominent ridge, diverging from beneath the umbo towards the sides : in some speci-
mens may be seen the impression of the large adductor muscle inclining towards the
centre ; my largest specimens do not exceed half an inch, measuring from the umbo
to the ventral margin, and the transverse diameter about half that size.

A specimen from the ./Egean Sea was given to me by Professor E. Forbes, with the
name of L. elongata, which so much resembles some of the Crag specimens (fig. 3, c),
that I have introduced the name among the synonyma. In the ^Egean shell, which
was obtained from the depth of 100 fathoms, the costated striae are in number
about 20, more distinct and distant on the centre or convex portion, and of course
widest near the margin, not rounded but angulated ; while in the generality of speci-
mens of subauriculata they are rounded, but the same characters of sharpened costse
are visible in some of the Crag specimens, and there is not a distinction between the
two sufficient, in my opinion, for specific separation ; probably with a large number of
individuals of the ^Egean shell, as much difference might be detected as is exhibited
in my Crag specimens.

Upon some of the smaller and most perfect specimens of this species from the
Crag, may be observed a row of fine crenulations, occupying the entire edge of the
hinge-line (fig. 3, 6), being a miniature representation of what has been considered a
good generic character ; these are, however, so small as to be of little service for the
ordinary purposes in which the teeth or prominent portions of the shell about the
hinge are employed by the animal.

LIMA OVATA, S. Wood. Tab. VII, fig. 5.

LIMATULA OVATA. 8. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 235, pi. 3, fig. 5,
1839.

Spec. Char. Testa minutd, ovatd, aequilaterd, undigue clausd, inflatd; in mediis
costatis, utrinque obsoletis, costis angulatis circa septem ; cardine recto, foveo ligamenti
trigond, concavd.

BIVALVIA. 49

Shell small, ovate, equilateral, tumid, and closed, costated, central portion with
7-9 angulated ribs, becoming obsolete or disappearing on the sides ; hinge margin
straight, with a trigonal and concave pit for the cartilage.

Height, -^. Length, -±^. Depth of united Valves, TV of an inch.

Locality. Cor. Crag, Sutton.

This pretty little shell is very abundant in the Coralline Crag, at the above
locality.

It appears to be quite distinct from the preceding, and differs in several
characters, and there is no species recent or fossil known to me to which it can be
assigned.

It has about seven angularly formed costae, which occupy the central portion
of the dorsal area, beyond these are faint traces of striae, and in well preserved
specimens the shell is semi-transparent, rendering these ribs visible in the interior, and
giving about half a dozen rough crenulations to the ventral margin of the shell.

The ligamental area is large, and the central pit diverges from the umbo under an
angle of about 80°, muscular impression subcentral and ovate. It differs from any of
the specimens of the preceding species of the same size, in being thicker and more
regularly ovate, the ventral margin is more pointed, the sides are less straight,
while the costse are more prominent and distinct. I have not seen L. sulculus,
Leach and Loven, but the descriptions do not accord with our Crag shell, as it wants
the "mediis binis verticalibus," mentioned by the latter author, but which character
may be seen in specimens of L. subauriculata.

PINNA.* Linnaeus.

PINNA. Arist. Aldrov. List, Linn. Lam., fyc.

PENNARIA. Browne, 1756.

CHIMERA et CHIM.ERODERMA. Poll., 1795.

PERN A. Adans, 1757."

OXYSMA? Rafinesque, 1819.

CURVULA. Id.

ATRINA. Gray, 1840.

Generic Character. Shell equivalved, inequilateral, oblique, triangular or wedge-
shaped, generally thin and fragile ; umbones terminal, hinge rectilinear, without teeth ;
anterior margin sinuated and slightly gaping for the passage of a byssus ; posterior
truncated. Impression by the mantle entire ; ligament internal.

Animal triangular, in conformity with the shape of the shell ; its mantle open or
disconnected on all sides, except the dorsal edge, while its lobes line the whole
interior of the valves; the lobes are ornamented with a double row of tentacular

* Etyra. ttiwa, Arist., a kind of Pearl Oyster.

50 MOLLUSCA FROM THE CRAG.

cirrhi or fringes round their posterior part ; and a single row upon the anterior ;
foot somewhat small and slender, furnished with a byssal groove ; no projecting
siphonal tubes.

Animals composing this genus have their valves particularly thin, considering
their dimensions, which sometimes attain considerable magnitude. In the recent state
they are generally of a brownish or horny colour, which with their angular form have
obtained for them, in France, the vulgar name of jambonneaux, or little hams. The
shell gapes slightly at the anterior part near the beaks, through which is protruded a
set of fibrous threads or byssus, so long as to have been occasionally manufactured
into gloves and stockings. They are exclusively marine, having a range in depth
somewhat considerable, living often in sand or mud, with their beaks or pointed
extremity buried deep in the ground ; sometimes fixed to submarine bodies, by means
of the byssus, which it is said to be capable of displacing at will by the aid of its foot.
The two valves are closely united or soldered, as it were, together, along the dorsal
edge, and are incapable of much expansion, but they gape widely at their larger or
posterior extremity, opposite the beak.

The number of recent species is somewhat limited, although they have a very wide
geographical distribution, being found in most parts of the world, and the fossil species
date as far back in time as the Oolitic Period, from which Formation there is one
strongly resembling an existing form.

1. PINNA PECTINATA (?) Linnaus. Tab. VIII, fig. 11.

PINNA PECTINATA. Linn. Syst. Nat., ed. 12, No. 264, p. 1160, 1767.
Turt. Brit. Biv., p. 223, pi. 19, fig. 1, 1822.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 255, pi. 43, figs. 1,2, and

pi. 53, fig. 8, 1849.

— INGENS. Mont. Test. Brit., pp. 180, 583, and Sup., p. 72.
S. Wood. Catalogue, 1840.

A few fragments or imperfect specimens of a species of this genus have been
obtained by myself from several localities in the Coralline Crag, but they are not in
sufficiently good condition for instituting a fair comparison ; what there is of them
seem to present recognisable characters, and to correspond with those of the above-
named recent species, and may, at least for the present, be considered as identical.
In my Catalogue it was placed under the name of P. ingens, Mont., which the authors
of the 'Hist, of Brit. Moll.' have determined to be only a variety of pectinate; the
spiny or scaly sculpture of that shell being generally removed by abrasion as it
advances in age.

In the small portion of what remains of our fossil, the radiating lines cover about
half the shell, or from the dorsal edge extending into the middle of the valve ; the
ventral portion being sinuated and much thickened at the edge where the presumed
byssus protruded, and the exterior is on that side ornamented with subconcentric or

BIVALVIA. 51

wavy undulations, like those visible upon the recent shell. This species, in the recent
state, is one of our largest bivalves, and Montague says they are not uncommonly
a foot in length. The specimen to which our fragment belonged, probably did not
exceed half that size. The same authority states, p. 181, " We discovered a bed
of these shells in Salcomb Bay, in Devonshire, where they are called by the fishermen
French muscles or scallops. They lie on a gravelly bottom, covered with mud and
long sea- weeds, and are only to be got at particular times when the sea recedes further
than usual." This shell in its living state is of a sort of double composition, the thin
and broadest, or outer portion, being of a brown and somewhat horny texture, while
the thickened lining, or anterior portion, is of a nacreous substance, composed of
fibrous filaments, causing the shell in the fossil state to separate readily at that part in
a transverse direction ; and pieces of this ' fibrous shell' are often met with in the
Coralline Crag at Sutton, separating like finely attenuated glassy filaments.

AVICULA,* Klein, 1753.

PTERIA. Scopoli, 1777, sec. Gray.
RIPARI/E (sp.). Gevers, 1787. Id.
MARGARITIFERA (sp.). Humph., 1797.
ANONICA. Oken., 1815.
PERLAMATER (sp.). Schum., 1817.

Generic Character. Shell inequilateral, inequivalve, oblique ; upper or left valve
the larger or more tumid ; the lower or right valve with an opening for the passage of
a byssus ; surface sometimes smooth, at others ornamented with squamose appendages,
or furnished with radiating costse ; hinge-line rectilinear, often with the posterior
extremity prolonged into the form of an extended wing ; one obtuse tooth in each
valve ; paleal impression without a sinus ; ligament external.

Animal triangular ; the edges of the mantle disunited, and the margins fringed
with small tentacles ; foot small, subcylindrical, beneath which is a byssal groove ; no
syphonal tubes.

1. AVICULA TARENTINA ? Lamarck.

MYTILUS HIRUNDO. Linn. Syst. Nat., ed. 12, p. 1159 (in part).

? Poll, Test. Utr. Sic., vol. ii, p. 221, t. 32, fig. 17, 1795.
AVICULA HIRUNDO. Turt. Brit. Biv., p. 220, pi. 16, figs. 3, 4, 1822.

— ACULEATA. Risso. Hist. Nat. des Princ. Prod, de 1'Eur., t. iv, p. 308, 1826.
ATLANTICA. Brown. Illust. Conch. Gr. Brit., pi. 10*, fig. 6, 1827.
ANGLICA. "Leach." Id. - pi. 31, fig. 3.

— TARENTINA. Lam. Hist, des An. S. Ver., t. vi, p. 148, 1818.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 251, pi. 42, figs. 1—3,
and pi. S., fig. 4, 1849.

* Etym. Avicula, from its resemblance to a Bird's wing.

52 MOLLUSCA FROM THE CRAG.

Two fragments were found by myself in the Coralline Crag at Gedgrave, which
belong undoubtedly to this genus, and as far as can be determined from their muti-
lated condition, appear to be of the above-named species ; they are introduced here
provisionally until better specimens be procured than what I possess : my specimens
of the left valve have an obtuse tooth immediately under the beak within the
ligamental margin, and are beautifully nacreous within. The area for the ligament
appears somewhat larger than is shown by the recent shell.

MYTILUS,* Linnaus, 1758.

MYTULUS. Rondelet, 1555, sec. Herrm.
MUSCULUS. List. 1687.
MITULUS. Browne, 1756.
PERN A (sp.). Adans, 1757.
Id. Schum., 1817.

CALLITRICHE et CALLITRICODERMA. Poli., 1795.

Generic Character. Shell equivalve, inequilateral, oblique, elongate, wedge-shaped
or subtriangular, more or less tumid, sometimes thin and semitransparent, occasionally
thick and opaque : in the recent state covered with an epidermis : umbones acute,
terminal ; hinge slightly denticulated ; surface generally smooth, sometimes striated.
Ligament linear, internal. Muscular impressions two, unequal, anterior one near the
umbo, elongate, posterior one suborbicular near the posterior part of the ventral
margin ; palleal impression without a sinus and rather obscure.

Animal elongate, with the lobes of the mantle partly fringed, disconnected except
at the posterior, where there is a short anal siphon : adductor muscles very unequal ;
a cylindrically formed foot furnished with a gland and groove.

Animals belonging to this genus are inhabitants of salt-water or estuaries, and are
generally very littoral in their habits ; the common Mussel, as is well known, is more
often found where it is deserted by the retiring tide, but some are inhabitants of the
sea at a considerable depth. The living species are found in various parts of the
world, and in the fossil state have been obtained as low in the secondary series as the
Cornbrash.

MYTILUS EDULIS, Linnaus. Tab. VIII, fig. 9, a — e.

MUSCULUS SUBC.&RULEUS. List. Hist. Conch., lib. iii, fig. A, 200, 168/.
MYTILUS EDULIS. Linn. Syst. Nat., ed. 12, p. 1157, No. 253, 1767.

— VULGATISSIMUS. Chem. Conch. Cab. viii, p. 169, t. 84, figs. 750, 751, 755.
PELLUCIDUS. Penn. Brit. Zool., ed. 4, vol. iv, p. 112, pi. 63, fig. 75.
VULGARIS. Da Costa. Brit. Conch., p. 216, pi. 15, fig. 5, (left-hand fig.)
INCURVATUS. Penn. Brit. Zool., pi. 64, fig. 74.
ELEGANS. Brown. Illust. Conch. Gr. Brit., pi. 29, figs. 14, 15, 1827.

* Etym. fjivriXos (deriv. a /uws, as vavnXos a voDs).

BIVALVIA. ")3

MYTILUS FLAVUS. Poll. Test. Sic., vol. ii, p. 207, pi. 32, fig. 4, 1795.
SAGITTATUS. Id. - - 208, - figs. 2, 3.

UNGTJLATUS. Id. - - 209, - fig. 5.

GALLOPROVINCIALIS. Desk. 2d ed. Lam., t. vii, p. 46.

ABBREVIATES. Id. - p. 47, No. 30.

RETUSUS. Id. - p. 48, - 31.

BOREALIS. Dekay. Nat. Hist. New York Zool., p. 182, pi. 13, fig. 222.

DILATATUS. W. Wood. Ind. Test. Sup., pi. 2, MYTIL., fig. 2.

SUBSAXATILIS. Williamson. Mag. Nat. Hist., 1834, vol. vii, p. 354, fig. 48, a — d

ANGULATUS. Alder. MSS., fide Williamson.

SOLITARIUS. Rev. W. Mark. MSS. Id.

NOTATUS. Dekay. Nat. Hist. New York Zool., p. 182, pi. 13, fig. 223, 1843.

ANTI QUORUM. J. Sow. Min. Conch., t. 275, figs. 1-3, 1821.

Desk. 2d ed. Lara., vii, p. 54, 1836.

Nyst. Rect. Coq. Foss. Prov. d'Anv., p. 17, No. 66, 1835.

Phil. En. Moll. Sic., vol. i, p. 73, and vol. ii, p. 53.

Nyst. Coq. Foss. de Belg., p. 267, pi. 21, fig. 1, a— b.

Basterot. Mem. Geol. des Env. de Bord., p. 78, 1825.

Woodward. Geol. of Norf., p. 44, t. 2, fig. 20, 1833.
AL^EFORMIS. J. Sow. Min. Conch., t. 275, fig. 4, 1821.

Woodward. Geol. of Norf., p. 44, 1833.
AFFINIS. Bean. MSS. (not Sowerby).
PLEBEIUS ? Dubois de Montp. Conch. Foss. de Wolhyn. Podol., p. 69, pi. 7>

figs. 26-28, 1831.

EDULIS. Brocchi. Conch. Foss. sub. Apen., p. 584, 1814.
Bast. Mem. Geol. des Env. de Bord., p. 79, 1825.

Spec. Char. Testa elongato-trigonuld, laemgatd ; (interim curvd, subangulatd ; posterius
retusd ; versus basim tumidd ; dentibus tribus vel quaternis.

Shell elongate, of a subtrigonal form, smooth, anterior part curved, subangulated,
posterior obtuse, tumid towards the base, hinge with three or four denticles.

Greatest diameter, 4 inches.

Locality. ' Red Crag, Button, Bawdsey, Ipswich.
Mam. Crag, Bramerton, Bridlington.

Recent, Mediterranean, Britain, Scandinavia, and North America.

The true edible species is first seen in the Red Crag Deposit, and is found in some
places, as might be expected, in great abundance, but the specimens have become so
thin and fragile, as to be with difficulty procured entire.

What is considered as the normal form of this species, by Messrs. Forbes and
Hanley, is that variety which has been erected into a distinct species by Mr.
Williamson, under the name subsaxatilis. In this the shell is more angular, and the
posterior portion becomes broader, its solitary habits giving free scope to an expansion
at that part, and enabling it to assume what may be called its natural shape. This
variety has not been met with by myself in the Red Crag, but it is by no means
uncommon in the deposit at Chillesford which rests upon it, and which probably
belongs to the mammaliferous or more recent period, and where it is the only

54 MOLLUSCA FROM THE CRAG.

form of this species, the other varieties have all been obtained from the older
formation.

The ligament of this is placed within the margin of the shell, although slightly
visible externally, when the valves are closed, it extends the entire length of the dorsal
edge, and a considerable scope is given to the dilatation of the valves ; four small
teeth are placed on the anterior side of the umbo interlocking each other ; these teeth
are always visible, though somewhat variable in their character, the anterior one being
sometimes the larger, and vice versa. In the increase of the valves a slight curvature
is given to the umbo by the retrocession or retreating of the ligament : while fresh
layers are deposited on the anterior margin, three small ridges are left upon the
exterior, indicating the form and position of these teeth, which are produced internally
by the indentures of the exterior. A small but deeply-seated muscle mark is visible on
the anterior side, or immediately beneath the umbo, and a large subcircular one a little
within the posterior part of the ventral margin. Mr. Alder says, " no species under-
goes a greater degree of variation from locality than the common Mussel. For its
full development, a mixture of fresh with salt water appears to be necessary, it is
therefore met with in the greatest perfection at the mouths of rivers. In such
localities the typical form of the species is to be found, and when left undisturbed
usually forms large beds. On the more rocky and exposed parts of the coast it
assumes a stunted appearance, running into the varieties of form mentioned above,
always small on the exposed surface of rocks, but attaining a larger size in hollows
and crevices."

In the Estuary Deposit of the Eocene Period, at Colwell Bay, as well as upon the
opposite side of the Solent at Hordwell, is found a species of Mussel (M. affinis, ' Min.
Conch.,' T. 532, fig. 1), which very much resembles the var. pellucidus of this species,
but it is decidedly more carinated, and wants the denticles so conspicuous in the
common edible Mussel, near the umbo ; and notwithstanding the extraordinary range
in variation assumed by this species, there is, I think, no doubt of the two shells being
specifically distinct ; a specimen from Bridlington, with this name, was obligingly sent
to me for description by Mr. Bean, but there is every reason to believe it is only a
variable form of our common Protean shell.

It is, in general, of littoral habits, being often found in the living state where left
dry by the retiring tide, and as such, indicative of shallow water, although it is
occasionally met with at considerable depth. Its geographical range is very great,
being undoubtedly an inhabitant of the Mediterranean, as well as of the coast of the
United States of America, and in both of which extremes of longitude it appears to
be subject to the same variable character. This is a long known species, descriptions
or figures of the recent shell having been given by almost every author, ancient or
modern, who has ventured to describe a shell ; and in order to show its range in
variation, a list of names is introduced, under which it has been described, pre-
suming all to belong to one and the same species, a single example of each name
being considered sufficient for the living shell.

BIVALVIA. 55

2. MYTILUS HESPERIANUS, Lamarck. Tab. VIII, fig. 10.

MYTILUS HESPERIANUS. Lam. Hist, des An. Sans. Vert., t. vi, p. 127, 1819.
Desk. 2d ed. Lam., t. vii, p. 48, 1836.
Payr. Cat. Moll. Cors., p. 68, pi. 2, fig. 5, 1826.
DENSATUS. S. Wood. Catalogue, 1840.

Spec. Char. Testa, elongatd, obliqud, incurvatd densatd, crassd ; margine dor soli
arcuatd.

Shell elongate, oblique, incurved, thick and heavy ; dorsal margin convex.

Greatest Diameter, 2^ inches.

Locality. Cor. Crag, Sudbourn. Recent, Mediterranean, and Coast of Spain.

Two specimens only of this shell have yet come into my possession, and these are
both of the right valve, and as they are all that I have seen, it does not appear to have
been abundant during the Cor. Crag period. Fragments of a very thick Mussel,
indicating a considerable curvature, and which I presume to belong to this species,
are not unfrequently met with in various parts of the Red Crag ; and as they have
undergone a considerable deal of bouldering, may possibly have been washed out of
the deposit of the antecedent period. I have given it therefore as a certain inhabitant
of the older formation only.

It appears to present characters different from any of the varieties of the common
edible Mussel, sufficiently it is presumed to entitle it to be considered a distinct species.
The variety called Myt. incurvatus, Mont., approaches nearest in form, but the dorsal
margin is never so convex as in our shell, and the specimens I have seen are much
thinner. The Crag shell is very thick, more especially in the narrow part near the
beaks, and the anterior side curves inwardly, while the dorsal and posterior portions are
particularly convex in outline ; the umbones are eroded, and the outer part of the shell
near the beaks is so thin as to show the white lining through it, while towards the
ventral portion the shell is of a deeper colour, as described by Payraudeau. My
specimens are destitute of hinge-teeth, but their probable habitat in deep and more
tranquil water may have rendered such unnecessary, and they may have thus become
obsolete.

MODIOLA,* Lamarck, 1801.

VOLSELLA. Scopoli, 1777, sec. Gray.

CALLITRICHE et CALLITRICHODERMA. Poll., 1/95.

AMYGDALCM. Megerle, 1811.

CRENELLA. Brown, 1827.

BRACHYDONTES. Swains., 1840.

LANISTES. Id. 1840.

MODIOLARCA. Gray, 1840.

MODIOLARIA. Beck, sec. Loven, 1846.

LANISTINA. Gray, 1847.

MODIOLOPSIS? Hall, 1847.

* Etym. Modiolus.

56 MOLLUSCA FROM THE CRAG.

Generic Character. Shell equivalve, inequilateral, irregularly and roundedly trape-
zoidal ; valves sometimes smooth or slightly sulcated concentrically ; sometimes entirely
covered with radiating striae, sometimes the central portions smooth with the lateral
extremities striated ; anterior side very short ; umbo subterminal ; hinge margin
linear, generally smooth, occasionally crenulated or denticulated ; ligament internal ;
impressions of the adductor muscles different in form and unequal in size ; anterior
one small and elongato-ovate ; posterior one large and subcircular ; impression of
the mantle entire ; shell slightly gaping for the passage of a byssus.

Animal of the form of the shell, and the margins of the mantle without a fringe :
an elongated and cylindrical foot, with a gland at its base for the formation of a
byssus.

This genus has by some conchologists been united with the preceding one, in con-
quence of some similarities between the animals as well as the shells. In this the
animal differs in having a simple margin to its mantle, as well as a marked peculiarity
in the branchial region, these characters are as distinct as are generally employed for
the separation of genera, and in the shells the anterior side is always more or less
pushed beyond the umbo, so as to give it a less triangular or a more trapezoidal form
than in Mytilus. The aberrant species will, it is true, bear a close generic resemblance,
and the line of demarcation is difficult to define, but the same may be said of most
proximate genera. Some modern conchologists have constituted a new genus for those
species which are externally ornamented or striated, a character here considered
insufficient for generic distinction, more especially as in well-determined species of the
preceding genus the shell is sometimes smooth, while in others it is covered with deep
and strongly marked lines of radiating striae.

It is doubtful also whether a line of crenulations upon the dorsal edge of the shell
is a character sufficient alone for generic distinction. The genera Crenella and
Modiolarca have therefore been included in the synonyma. Animals of this genus
generally spin a byssus, by which they are attached, and the shell gapes a little at
the anterior part of the ventral margin for its passage ; several species in the recent
state supply this material so largely, as to wholly invest the shell in a kind of nest ;
while others closely resembling this genus are capable of forming a habitation in the
interior of calcareous rocks. (Mytilus litliophagus, Linn.)

This is truly a Marine genus, and found at various depths, and is known among
the oldest of the Secondary Rocks ; but it is rather sparingly distributed throughout
the Tertiaries.

BIVALVIA. 57

1. MODIOLA MODIOLUS, LinncBus. Tab. VIII, fig. 1, a — d.

MYTILUS MODIOLTJS. Linn. Syst. Nat., ed. 12, No. 256, p. 1158, 1767.

Da Costa. Brit. Conch., p. 219, t. 15, fig. 5, 1778, (right-hand fig.)
Chem. Conch. Cab., vol. viii, p. 178.
Donov. Brit. Shells, vol. i, pi. 23, 1799.
W. Wood. Ind. Test., p. 53, pi. 12, fig. 31, 1825.
Mull. Zool. Danica, pi. 53.
Flem. Edin. Ency., vol. vii, pi. 203, fig. 22.
CURTUS. Penn. Brit. Zool., p. 112, pi. 64, fig. 76, a.
CURVIROSTRATUS. Da Costa. Brit. Conch., p. 220, 1778.
UMBILICATUS. Penn. Brit. Zool., ed. iv, vol. iv, p. 112, pi. 65, fig. 76.
Mont. Test. Brit., p. 164, 1803.
W. Wood. Ind. Test., pi. 12, fig. 49, 1829.
BARBATUS. Don. Brit. Shells, vol. ii, pi. 70, 1800.
PAPUANUS. Nyst. Coq. Foss. de Belg., p. 271, 1844.
MODIOLA PAPUANA? Desk. 2d ed. Lam., t. vii, p. 18.

Brown. Brit. Conch. Illust., pi. 29, figs. I — 4, 1827.
Say. Amer. Conch., pi. 45.
Leach. Zool. Miscel., vol. ii, p. 33.
MODIOLUS. Turt. Brit. Biv., p. 199, pi. 15, fig. 3, 1822.
S. Wood. Catalogue, 1840.

Dekay. Nat. Hist. New York Zool., p. 185, pi. 24, fig. 257, 1843.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 182, pi. 44, figs. 1, 2,

1849.

Midd. Malac. Ross., loc. cit., p. 537, 1849.
VULGARIS. Flem. Brit. An., p. 412, 1828.

Loven. Ind. Moll. Scand., p. 33, 1846.
Alder. Cat. Moll. North, and Durh., p. 81, 1847.
GRANDIS. Phil. En. Moll. Sic., vol. ii, p. 51, t. 15, fig. 13, 1844.
Ency. Meth., p. 219, fig. 1.

Spec. Char. Testa oblongo-ovatd, gibbd, Icevigatd ; margine dorsali antico brevissimo ;
postico producto, subrecto ; margine ventrali subsinuato ; extremitate utraque rotundato.

Shell oblong-ovate, tumid, and smooth ; anterior dorsal margin very short ;
posterior much produced, with hinge-line nearly straight ; ventral margin subsinuated,
and both extremities rounded.
Locality. Cor. Crag ?

Red Crag, Button.

Mam. Crag, Postwick, Bridlington.

Recent, Britain, N. Seas, Boreal, America, Mediterranean ?

A few specimens only of this fine shell have been found by myself in the Red Crag,
where it does not appear to have been abundant, although occasionally fragments have
been met with at distant localities, testifying its somewhat general distribution in that
deposit ; a few fragments also of a Modiola of a similar form are in my cabinet from
the Coralline Crag at Ramsholt, but the hinge-line being imperfect, I am unable to

8

58 MOLLUSCA FROM THE CRAG.

determine its specific character, and it was introduced into my Catalogue as belonging
with doubt to this species.

In the recent state this shell is thick and strong, but my specimens differ
materially in that character, and are particularly fragile. This species exhibits a
very considerable degree of variation in its outward form or proportional dimen-
sions, as may be observed in the specimens figured, but a similar variability is
shown in the living shell : the two forms may be considered as belonging to one
species, and there can be little doubt of its identity with the shell now common in our
own seas. My specimens were all found at one locality in association with a bed of
Myt. edulis. British Conchologists give it vertical range from low water mark to
sixty fathoms.

I have introduced as a synonym M. grandis Phil., believing it not to differ
specifically from the British shell : some fossil specimens from Sicily (for which I am
much indebted to Madame Power) in my cabinet, presumed to be the same as
Philippi's species, have no character whereby they can be justly separated from the
shell found upon the coast of Massachusetts. The size of the Mediterranean fossil is
not sufficient for specific distinction, as a specimen of modiolus, measuring seven
inches, is recorded by Captain Brown to have been obtained by a fisherman near the
Bell Rock, on the coast of Forfarshire.

2. MODIOLA BARBATA, Linn&us. Tab. VIII, fig. 2.

MYTILUS BARBATUS. Linn. Syst. Nat., ed. 12, p. 1156, sec. Forb. and Hani.
Poll. Test. Sicil., vol. ii, p. 210, pi. 32, figs. 6, 7, 1795.
MODIOLA BARBATA. Lam. Hist, des An. Sans. Vert., t. vi, p. 114, 1818.
— Phil. En. Moll. Sic., vol. i, p. 70, and vol. ii, p. 50.

Forbes. Report. ^Egean Invert., p. 180, 1843.

Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 190, pi. 44, fig. 4.
GIBBSII. Leach. Zool. Misc., vol. ii, p. 34, pi. 72, fig. 2, 1815.
Turt. Brit. Biv., p. 200, 1822.
Brown. Brit. Conch. Illust., pi. 29, fig. 7, 1827.
Ency. Meth., pi. 218, fig. 6.

Spec. Char. Testa tenui, ovato-oUongd, extremitate compressiusculd, antice brevissimd,
postice dilatatdy subangulatd ; lineis incrementibus ornata.

Shell thin, of an oblong-ovate form, posterior portion somewhat compressed, dilated
and sub-angulated, anterior extremity very short, concentrically striated, or lines of
increase distinct and prominent.

Locality. Red Crag, Walton Naze. Recent, British and Mediterranean Seas.

About half a dozen specimens from the Red Crag, at Walton on the Naze, appear
precisely in form to resemble what the authors of the ' Hist, of Brit. Mollusca,' seem
to consider as entitled to specific distinction, and presuming they have good data for
their determination, I have separated this from where it had been previously placed,

BIVALVIA. 59

as only a variety of M. modlolus. A greater curvature in the ventral margin, and the
expansion on the posterior side, are deviations from the ordinary form of the larger
and more common species, and these are, I presume, the principal characters relied
upon for separation. On the exterior are a series of ridges or elevated lines of
growth, the probable remains of the support of the bearded or fringed portion of the
epidermis when in a recent state. The beaks in this specimen appear to be terminal,
the anterior side of the shell not projecting beyond them, and in that character
more resembling Mytilus, which it closely approaches in form ; there is, nevertheless,
a projection outwards, like the rest of the genus. The ventral margin is somewhat
incurved, the dorsal portion of the shell a good deal flattened behind, and extending
beyond the ligamental area, while the centre is tumid or inflated ; the dimensions
of the widest part, which is on the posterior side behind the ligament, is twice that of
what it measures across the shell immediately behind the umbo.

3. MODIOLA PHASEOLINA, Pkilippi. Tab. VIII, fig. 4.

MODIOLA PHASEOLINA. Phil. En. Moll. Sic., vol. ii. p. 51, t. 15, fig. 14, 1844.
Jeffreys. An. Nat. Hist., vol. xix, p. 313.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 186, pi. 44, fig. 3,
1849.

Spec. Char. Testa oUongo-ovatd> Icevigatd, tenui, margine ventrali recto ; subsinuato,
dorsali mlangulato, cardine crenulato.

Shell oblong-ovate, smooth and thin ; ventral margin straight or subsinuated,
dorsal margin subangulated ; cardinal area crenulated : shell nacreous.

Locality. Coralline Crag, Sutton, and Ramsholt.

Recent, Britain, and Mediterranean.

The distinguishing character of this species appears to be the finely crenulated margin
of the dorsal edge on the outside of the ligamental area, as the outer form or contour of
the shell is variable like M. modiolus, from the young of which it could not be separated
by any character which might not also be applied to that species ; some specimens have
but a short hinge line, with a somewhat rounded dorsal edge, and a subcylindrical or
ovato-oblong outline, while in others there is a considerable angle on the dorsal edge
at the posterior termination of the ligament, and the ventral margin is nearly straight,
varying sometimes from that line a little, both outwardly and inwardly. The largest
specimens which have a minutely crenulated hinge line do not exceed f ths of an inch,
and all show a pearly texture. The umbo is generally terminal, although the anterior
side will occasionally be seen to project beyond it.

This, as well as the preceding species, have been introduced in deference to the
Malacologists, but it is very doubtful if they will not hereafter have both to be united
with M. modiolus.

60 MOLLUSCA FROM THE CRAG.

4. MODIOLA COSTULATA, Risso. Tab. VIII, fig. 6.

MODIOLUS COSTULATUS. Risso. Hist. Nat. de 1'Europ. Merid., t. iv, p. 324, pi. xi, fig. 165,

1826, non bene.

MODIOLA COSTULATA. Phil. En. Moll. Sic., vol. i, p. 70, t. 5, fig. 11, 1836.
_ Id. vol. ii, p. 50, t. 15, fig. 10, 1844.

PETAGN^E. (Scacchf) sec. Phil. En. Moll. Sic., vol. ii, p. 51.
— COSTULATA. Webb and Bertholet. Nat. Hist, des lies Canaries, p. 103, pi. 7, B,

figs. 23, 25, 1842.

Jeffreys. An. Nat. Hist., vol. xix, p. 313.
CYLINDROIDES. S. Wood. Catalogue, 1840.
CEENELLA COSTULATA. Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 205, pi. 45, fig. 1, 1849.

Spec. Char. Testa minutd, oUongd, subcylindricd, antice angmtata et ultra apicem
productd, medio Icevi ; in utroque latere costato-striatd.

Shell small, oblong, subcylindrical, anterior side somewhat contracted, extending
beyond the umbo, middle smooth, with large costated striae upon both sides.

Longest diameter, -g-ths of an inch. Shortest, -f- ths.

Locality. Cor. Crag, Sutton.

Red Crag, Walton Naze.

Only one specimen in my cabinet has been obtained from the older or Coralline
Crag Formation; but in the Red Crag at Walton it does not appear to be at all scarce,
at least a couple of dozen have fallen to my lot, and in them a considerable range in
variation may be detected.

Our shell appears to agree with the figure and description of M. costulata, in the
first vol. of Philippi, which that author, in his second volume, has assigned to another
species : amongst my specimens also are forms corresponding with what he con-
siders to be specifically distinct, and they are therefore both introduced among the
synonyma, as I am unable to separate into two species those which are found in the
Crag; if, however, there be in the recent shells characters sufficient to justify a
specific distinction, both forms seem to have been present in the seas that deposited
the Red Crag, but from what is exhibited in the fossils, they may be fairly included in
one species.

There can be no mistake in regarding this as distinct from either M. discrepans
or M. marmorata, from both of which it differs in being more cylindrical, with
also a greater curvature in the ventral margin. It is an elegantly-formed shell,
the anterior side slightly projects beyond the umbo, somewhat tumid, with a rounded
angularity crossing the shell diagonally from the beaks to the posterior part of the
ventral margin, the anterior side is rounded, and deeply striated or ridged with about
ten or twelve small ribs ; the middle is plain, or only marked by lines of growth,
while the greater half of the shell on the posterior side is covered with striae in a
radiating manner, these are so conspicuous at the margin as to produce somewhat
large and distinct crenulations on the inner edge, most conspicuous a little behind the

BIVALVIA. 61

ligament, but they extend along the whole line of hinge or dorsal area ; the posterior
side in some specimens is much rounded, so as to give a cylindrical form to the shell,
while in others there is an angular slope on the posterior side, from a little beyond
the termination of the hinge line to the ventral margin, which gives a greater width
to that part, thereby producing a different form, and which, in consequence, were that
a permanent character, might be considered a distinct species, but my specimens are
exceedingly variable, so as to present no marked distinction between the two.

5. MODIOLA SERICEA, Bronn. Tab. VIII, fig. 3.

MODIOLA SERICEA. Bronn. Ital. Tert. Geb., p. 122, No. 649, 1831.

Phil. En. MoU. Sic., vol. i, p. 71, t. 5, fig. 14, 1836.

Id. - vol. ii, p. 52, 1844.

Nyst. Add. a la Faime. Conch., p. 444, No. 38, 1842.
HYALINA. S. Wood. Catalogue, 1840.
MYTILUS SEKICEUS. Gold/. Pet., vol. ii, p. 179, pi. 131, fig. 12, a — c, 1841.

Nyst. Conch. Foss. de Belg., p. 271, pi. 21, fig. 2, b— e, 1844.

JE. Sism. Synop. Meth. An. Invert., p. 15, 1847.

Bronn. Ergeb. meiner. naturh.-6'kon Reise, vol. ii, p. 620, sec. Nyst.

Spec. Char. Testa tenuissime, subhyalind, elliptico-ovatd, tumidd ; valde incequilaterd ;
striatd, striolis exilibus confertis ; umbonibus prominentibus recurvis ; maryine ventrali
subrecto, tenuissime crenulato.

Shell thin delicate, subhyaline, of an elliptical or ovate form, tumid ; very inequi-
lateral ; covered externally with numerous close-set, extremely fine, radiating striae ;
umbo projecting beyond the anterior side ; ventral margin nearly straight and
finely crenulated.

Locality. Cor. Crag, Ramsholt and Sutton.

It is very difficult to obtain specimens of this species in perfection, on account of
its extreme thinness, although they appeared at Ramsholt to be by no means rare, but
they are generally more or less broken or distorted.

This beautiful species is of an ovate or elliptical form, very tumid, excessively
thin and semitransparent ; it is covered over its whole surface with extremely
fine radiating striae, crossed occasionally by irregular lines of growth, but not
regularly decussated ; the ligamental area extends about half the distance of the
dorsal portion, its termination forming a very obtuse angle ; the umbo is terminal and
somewhat prominent, curved, and slightly projecting beyond the anterior margin.

This appears at present to be known only as a fossil. My largest specimen
measures an inch and a quarter in its longest diameter.

62 MOLLUSCA FROM THE CRAG.

6. MODIOLA MARMORATA, Forbes. Tab. VIII, fig. 7.

MYTILUS DISCORS. Da Costa. Brit. Conch., p. 221, t. 17, fig. 1, 1778.
_ — Walker and Boys. Test. Min. Rar., pi. 3, fig. 79, 1789.

— — Poli. Test. Utr. Sic., vol. ii, p. 211, pi. 32, figs. 15, 16, 1795.

— Donov. Brit. Shells, vol. i, pi. 25, fig. 1, 1799.

Mat. and Rock. Linn. Trans., vol. viii, p. Ill, pi. 3, fig. 8, 1807.

— Mawe. Conch., pi. 13, fig. 5, 1823.

— W. Wood. Ind. Test., pi. 12, fig. 39, 1825.
MODIOLA Turt. Brit. Biv., p. 201, pi. 15, fig. 4, 1822.

Brown. Illust. Brit. Conch., pi. 29, fig. 10, 1827.
S. Wood. Catalogue, 1840.
I Gould. Inv. Massach., p. 15, fig. 84, 1841.

— DISCREPANS. Phil, En. Moll. Sic., vol. i, p. 70, 1836.

Id. - - - vol. ii, p. 50, pi. 15, fig. 11, 1844.
Payr. Cat. Moll. Cors., p. 67, 1826.

— EUROP^EA. If Orb. fide Loven.

— TUMIDA. Hanley. Rec. Shells, vol. i, p. 241, pi. 12, fig. 39.

— MARMORATA. Forbes. Malac. Monen., p. 44, 1838.

Brown. Illust. Brit. Conch., 2d ed., pi. 27, fig. 10.

Alder. Cat. Moll. North, and Durh., p. 82, 1848.
MODTOLARIA — Loven. Ind. Moll. Scand., p. 33, 1846.

CRENELLA Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 198, pi. 45, fig. 4, 1849.

Spec. Char. Testa minutd, ovato-ellipticd, tumidd, tenui, fragili ; utroque later e
striatd, spatio submediano l&vigato vel transverse striato ; umbonibus minimis wbter-
minalibus.

Shell small, ovate or elliptical, tumid, thin, and fragile ; both sides radiatingly
striated, with a smooth or rather transversely striated space between them ; umbones
small, subterminal.

Longest diameter, -fths of an inch.

Locality. Cor. Crag, Sutton.

Red Crag, Walton Naze.

Recent, Mediterranean, Britain, Scandinavia, and North America?

Small specimens and fragments of this species are abundant in the Coralline
Crag at Sutton, and it appears to have been one of the commoner shells of that
Period. There is no doubt, of this shell being identical with the recent British
species, now determined not to be the discors of Linnaeus, a name given to a larger
shell (Mytulus impacttts, Herm.} by the Swedish naturalist.

Our shell in the fossil state has become opaque, but it has retained its nacreous
appearance ; it is of an elliptical form, the anterior side being rather broader than the
posterior, which is slightly narrowed off from the dorsal slope ; the umbones are small,
slightly inflected, with the anterior side projecting a little beyond them, the shell is
somewhat regularly tumid, with a very slight flattening on the dorsal portion : the

BIVALVIA. 63

tripartite division of the exterior is of unequal dimensions, the posterior striae covering
nearly but not quite half the surface, while the anterior occupies rather a less space than
the centre or naked compartment ; the striae or rays are large and rounded, number-
ing about a dozen or fourteen on the anterior side, with about double that number on
the posterior portion : the whole shell is covered with transverse striae or regular
lines of increase, which prettily ornament the spaces between the ridges, and
the edge of the shell is deeply crenulated on the anterior and posterior sides, or
those portions which are covered with the radiating ridges ; the tripartite division
of the shell, is visible in the interior, and the number of the external striae may be
counted there. The edge of the ventral margin has a slight convexity, contracting a
little towards the striated parts.

The differences between this species and the following are so evident, there
can be no mistake, that shell being more compressed or less tumid, with the posterior
side broader in proportion. The shell to which this approaches nearest, is
M. semi-nuda, Desk., ' Desc. des Coq. Foss. des Env. de Par.,' vol. i, p. 264, pi. 30,
figs. 20 — 22, a fossil belonging to the Formations of the Older Tertiaries. I have not
been able to obtain a specimen from the Paris Basin ; but what I presume to be the
same species in the Cabinet of Mr. Edwards, from the English Deposits, presents
differences that may be regarded as specific. Mr. Edwards's shell is more regularly
ovate, and is even thinner than our species, with fewer radiations on the anterior
side, not having more than seven or eight, and these are broader, it is also, more
regularly tumid than our own shell, which has somewhat of an obtuse angle on the
posterior portion.

The shell figured and described by Dr. Gould, under the name of M. discors, seems
to present but trifling differences with the British shell, judging from description alone ;
but it is considered to be distinct by British Conchologists, as well as by Dr. Loven.

7. MODIOLA DISCORS, Linnaus. Tab. VIII, fig. 5.

MYTILUS DISCORS. Linn. Syst. Nat., ed. 12, p. 1159, No. 261, 1767.

DISCREPANS. Mont. Test. Brit., p. 169, 1803.
MODIOLA DISCREPANS. Turt. Brit. Biv., p. 202, 1822.

Desk. 2d ed. Lam., t. vii, p. 23, 1835.
Forbes. Make. Monens., p. 44, 1838.
Moller. Ind. Moll. Groenl., p. 19, 1842.
Alder. Cat. Moll. North, and Durh., p. 81, 1848.
MODIOLARIA DISCORS. Loven. Ind Moll. Scand., p. 33, 1846.

CRENELLA DISCORS. Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 195, pi. 45, figs. 5, 6,

and pi. 48, fig. 5, 1849.

Spec. Char. Testa ovato-ellipticd, sudcompressd, valde intequilaterd, tenui ; antice et
postice striatd, spatio mediano l&vigato ; latere postico latiore.

Shell ovato-elliptical, somewhat compressed, very inequilateral, thin ; striated at

64 MOLLUSCA FROM THE CRAG.

both extremities, middle space smooth, posterior side of the shell broader than the
anterior.

Longest Diameter, \ an inch.

Locality. Mam. Crag, Chillesford. Recent, Britain and Seas of Norway.

A specimen strongly resembling this species is in my Cabinet, obtained in the
native bed of the Mammaliferous or Newer Crag Period, at Chillesford. The shells
in that deposit are excessively fragile, and are preserved with difficulty. This
specimen appears also to have lost a portion of its outer surface : there is, however,
upon the exterior, traces of what the sculpture has been, and as far as it can be observed,
it seems to correspond with that upon the recent shell, it is, therefore, appropriated to
the above species without much doubt ; and, as its congeners in the same deposit are
such as we know to be its associates at the present day, it might fairly be expected
in that Formation. In the recent state it is considered more of a Boreal form, with
but a limited range to the Southward. The earliest appearance of this species is
in the upper portion of the Crag, where it seems to have been by no means
abundant. I have found it in the recent state upon the shore of the Coast of Suffolk,
in pools of water, left by the retreat of the tide.

8. MODIOLA RHOMBEA, Berkeley. Tab. VIII, fig. 8.

MODIOLA PRIDEAUXIANA. Leach. Zool. Miscel., vol. ii, p. 35, 1815.

Brown. Brit. Conch. Illust., pi. 29, fig. 9, 1827.

RHOMBEA. Berkeley. Zool. Journ., vol. iii, p. 229, Suppl. pi. 18, fig. 1, 1827.
Thorpe. Brit. Mar. Couch., p. 107, 1844.
Brown. Brit. Conch. Illust., 2d ed., p. 78, pi. 39, fig. 17.
ASPERULA. S. Wood. Catalogue, 1840.

CRENELLA RHOMBEA. Forb. and Hani. Hist. Brit. Shells., vol. ii, p. 208, pi. 45, fig. 3,

1849.

Spec. Char. Testa minutd ovato-oUongd vel trapeziformi, tumidd, inflatd, crassd ;
costulato-striatd, sulcis vel striis divaricatis ; antice abbreviatd, rotundatd, postice majiore,
angnlatd ; margine ventrali sinuato ; natibm prominulis incurvis.

Shell small ovato-oblong or trapeziform, tumid, or inflated, covered all over with
large or costulated bifurcating striae ; anterior side, short and rounded, posterior
larger, and angulated ; ventral margin sinuated, with incurved and slightly projecting
umbones'.

Greatest Diameter, \\h of an inch.

Locality. Cor. Crag, Sutton. Recent, British Seas, and Coast of Sutherland.

This is considered by the authors of the ' Hist, of Brit. Mollusca,' as an extremely
rare shell in the recent state, and somewhat of a modern addition to the Marine
Fauna, of the British Isles. Although noticed by Dr. Leach as early as the year
1815, it has since rarely been met with and seldom seen in the Cabinets of collectors.
It is not so in the fossil, but is very abundant in the rich depot of small shells at Sutton.

BIVALVIA. 65

The recent shell is said to be as much as a quarter of an inch in diameter :
the largest of my fossil specimens, does not exceed the sixth of an inch in its
extreme dimensions, measured diagonally from the umbo to the posterior part of its
ventral margin. There is, nevertheless, but little doubt of their identity, as the
only difference is that of size, the Crag specimens corresponding in all other charac-
ters with the recent shell. It is very much inflated : the two valves when united,
having a greater diameter than is given when measuring from the dorsal to the
ventral margin ; the umbo is terminal, projecting a little beyond the anterior of the
shell, and is slightly curved ; it is somewhat rhomboidal in its contour, with a little
obliquity towards the posterior side, and a slight indentation in the ventral margin,
the posterior side forming an obtuse angle with the edge of the shell that contains the
ligament ; the exterior is ornamented with large prominent striae, or rather small ribs
which bifurcate, and are more numerous in the old than in the young shell, they
are crossed and made somewhat rough by prominent and distinct lines of growth,
at rather irregular distances, sometimes giving a decussated appearance to the shell ;
the prominent costulated striae project beyond the margin, and give a deeply
crenulated edge all round; the ribs are sometimes visible in the interior, although
the specimens are often so thick as not to allow them to be seen on the inside ; and
in that case, the impressions formed by the muscles are deeply indented, that by the
anterior adductor is comparatively very large. The ligament seems to have been
a strong one, as a deep linear depression is formed within the dorsal margin. This
shell has been dredged in the living state, in 20 fathoms water, off Penzance.

PECTUNCULUS,* Lamarck, 1791.

PECTUNCULUS POLYLEPTOGINGLXMUS (sp.) List., 1687. •

MACTRA ? Browne, 1756.

ARC A (spec.). Linn., 1767.

GLYCIMERIS. Da Costa, 1778. Humph., 1797.

AXIN.EA AXIN^EODERMA. Poll, 1795.

TUCETA. Bolton, 1798, sec. Herrm. ,

Generic Character. Equivalve, orbicular, convex or lenticular, subequilateral,
closed, thick and strong ; externally smooth or ornamented with radiating striae or
costse. Hinge teeth small, numerous, forming an arched or curved line, central
denticles becoming obsolete in old shells. Ligament external, attached to a grooved
area in each valve, with distant beaks. Impressions of the adductors two, lateral
and strongly marked, that by the mantle entire, or without a sinus.

* Etym. The diminutive of Pecten.

66 MOLLUSCA FROM THE CRAG.

Animal orbicular, or of the form of the shell and capable of being entirely covered
when the valves are closed, mantle with its margins simple and disconnected, some-
what enlarged in the anal regions ; a large semilunar shaped foot with undulating
edges, permitting an expansion into a subdiscoidal form. No byssus.

This is purely a marine genus, inhabiting waters of various depths, with an
extensive geographical range ; though it does not as yet appear to have been found in
any of the very cold regions of the globe. In a recent state the shells are generally
covered with a velvety epidermis, except about the umbones, where it is often
worn off.

The species are not numerous, either recent or in a fossil state, but appear to
have long been inhabitants of this planet, two or three are described by Colonel
Portlock, from the Silurian Rocks of Tyrone, and others have been found in the
Oolites and Green sand, but the shells are not of any magnitude, until the Tertiary
Periods, in which as individuals they are largely developed, both in Europe and in the
Upper Tertiaries of America.

This is a well-marked genus, and not likely to be confounded with any other,
except Limopsis, from which, however, it may be distinguished by the ligamental
area being simple, or only marked with angular or diverging lines, while in that shell
the cartilage is more distinctly separated from the ligament, and placed in a triangular
fossette immediately beneath the beaks.

The ligament in this genus occupies the entire space between the umbo and the
hinge margin, not equally spread over the surface, but placed in diagonal, or rather in
lines diverging from the beak towards the lateral margins, by which a deep impress or
furrow is formed and left upon that part of the shell.

1. PECTUNCULUS GLYCIMERIS, Linn&us. Tab. IX, fig. 1, a — h.
Bonanni. Recr. Ment. et Ocul., fig. 61, 1684.
CHAMA GLYCIMERIS BELLONII. List. Hist. Conch., lib. iii, pars 11, fig. 82, and fig. 80?

1687.

PECTUNCULUS FOSSILIS. Dale. Hist, and Antiq. of Harw., p. 291, t. xi, fig. 3, 1730.
ARCA GLYCIMERIS. Linn. Syst. Nat., ed. 12, p. 1143, No. 181, 1767.

Poli. Test. Sicil., vol. ii, p. 144, t. 26, fig. 1 ; t. 25, fig. 19, 1795.

Don. Brit. Shells, vol. ii, pi. 37, fig. 2, 1800.

Mat. and Rack. Linn. Trans., vol. viii, p. 94, t. 3, fig. 3, 1807.

W. Wood. Ind. Test., p. 46, pi. 10, fig. 36, 1825.

Mawe. Lin. Syst. Conch., pi. 13, fig. 7, 1823.

Burrow. Elem. of Conch., p. 143, pi. 8, fig. 7.

— PILOSA. Linn. Syst. Nat., ed. 12, No. 182, p. 1143, 1767.

Poli. Test. Sicil., vol. ii, p. 138, t. 26, fig. 2—4, 1795.
Broc. Conch. Foss. Subap., p. 487, 1814.
Mat. and Rack. Linn. Trans., vol. viii, p. 94, t. 3, fig. 4, 1807.
W. Wood. Ind. Test., p. 46, pi. 10, fig. 37, 1825.
ARCA SCRIPTA. Born. Mus. Goes. Vin., p. 93, t. vi, fig. 1, 1780.

— UNDATA. Chem. Conch. Cab., vol. vii, p. 224, pi. 57, fig. 560, 1784.

BIVALVIA.

67

ARCA UNDATA. Broc. Conch. Foss. Subap., p. 489, 1814.
POLYODONTA. Broc. - - p. 490, 1814.

— FLAMMULATA. Renieri. fide Philippi.

GLYCIMERIS ORBICULARIS. Da Costa. Brit. Conch., p. 168, p. 11, fig. 2, 1778.
PECTUNCULUS GLYCIMERIS. Turt. Brit. Biv., p. 171, t. 12, fig. 1, 1822.

Brown. Illust. Conch. Gr. Brit., pi. 25, figs. 8, 9, 1827.

Crouch. Int. Lam. Conch., pi. 8, fig. 11, 1827-

Reeve. Conch. Icon. Pectunc., pi. 3, fig. 12.

Dujard. Mem. Geol. Soc. de Fr., t. ii, par. 11, p. 267, No. 1,

1837.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 245, pi. 46,

figs. 4—7, 1849.
PILOSUS. Turt. Brit. Biv., p. 172, t. 12, fig. 2, 1822.

Schum. Essai d'un Nouv. Syst. des Vers. Test., p. 172, pi. 19,

fig. 3, 1817.

Brown. Illust. Conch. G. B., pi. 25, figs. 10, 11, 1827.
Blainv. Man. Malac., pi. 65 bis, fig. 3, 1825.
Reeve. Conch. Icon. Pectunc., pi. 3, fig. 13.
G. Sowerby, Jr. Conch. Man., fig. 134, 1843,
G. Sow. Genera, No. 5, fig. 1.
S. Wood. Mag. Nat. Hist., 1840, p. 13, fig. 7.
Nyst. Coq. Foss. de Belg., p. 247, pi. 19, figs. 6, 7, 1844.
UNDATUS. Turt. Brit. Biv., p. 173, t. 12, figs. 3, 4, 1822.
DECUSSATUS. Id. p. 173, t. 12, fig. 5.

NUMARIUS. Turt. Brit. Biv., p. 174, t. 12, fig. 6, 1822.
VARIABILIS. J. Sow. Min. Conch., t. 471, fig. 1, 1824.
Woodward. Geol. of Norf., p. 43, 1833.
Id. Coq. Foss. de Belg., p. 249, pi. 20, fig. 1, a— b, 1844.
Phil. En. Moll. Sic., vol. ii, p. 45, 1844.

POLYODONTA. Goldf. Pet. Germ., vol. ii, p. 161, t. 126, figs. 6 & 7, a — d.
PULVINATUS. Brongn. Vincent., p. 77, pi. 6, figs. 15, 16, 1823.
1 Bast. Bord. Foss., p. 77, No. 2, 1825.
? Dubois de Mont. Conch. Foss. de Wolhyn., p. 64, pi. 7,

figs. 7, 8, 1831.

suBOBLiauus. S. Wood. Mag. Nat. Hist., 1840, p. 233, pi. 13, fig. 6.
TRAKSVERSUS. ? Dubois de Mont. Coq. Foss. de Wolhyn., p. 65, pi. 7. fig. 9.
NUMIFORMIS. 1 Id. p. 66, pi. 7, fig. 6.

— LATIAREA. Michelotti. fide Sismonda.

PUSILLTJS? Dujard. Mem. Geol. Soc. de Fr., t. 2, pt. 2, p. 276, 1837.

Ency. Method., p. 310, figs. 2 & 3.
ARCA. Smith. Strat. Identif. Craig, t. 2, fig. 7, 1816.

Spec. Char. Testa variabile, suborbiculatd, subovatd, transversd, s&pe obliqud sub-
(Equilaterd, compressd vel tumidd, costato-striatd ; margine crenulato.

Shell variable, suborbicular, elongate or transverse, often oblique, subequilateral,
compressed or tumid ; striated ; margin crenulated.

Diameter, 3^ inches.

68 MOLLUSCA FROM THE CRAG.

Locality. Cor. Crag, Passim.

Red Crag, Passim. — Var. |3, subobliquus, Walton Naze.
Mam. Crag, Thorpe, Bridlington (Leckenby).

Recent, Britain, and Mediterranean.

This is one of the most common and abundant shells in the Coralline as well
as in the Red Crag Deposits. In the Coralline, the valves, as might be expected, are
often found united.

The determination of this species is exceedingly difficult, and the form which was

figured in the ' Mag. Nat. Hist.' (var. /3), presented characters it was then thought

sufficient for the establishment of a new one, but the recent species has been found to

exhibit the same obliquity ; this variety I have never seen from the Older or Coralline

Crag, but it is one of the commonest shells at Walton on the Naze, where the two

valves are frequently found united ; it is generally thinner, and some specimens

are very oblique, and this may be considered the limit of range in variation in

one direction ; var. a in the other ; between these forms every imaginable gradation

may be pointed out in almost any collection possessing a good series of this abundant

Crag shell, so well named by Mr. J. Sowerby (variabilis). There is scarcely a

possibility of giving a correct diagnosis of this species, but what some deviation may

be pointed out, and in consequence of which the varieties have been made into

several species, as may be seen in the above list of synonyma, all, it is presumed,

belong to this species. Specimens are somtimes longer than they are broad, and vice

versa, some are lenticular, with but little tumidity, others are much inflated. The

exterior is generally more or less ornamented with raised, radiating, and distant striae,

variable in number, producing a like variation in the number of crenulations upon the

interior margin of the valves ; in some they are as many as sixty, while in others they

do not exceed thirty-five ; neither is the number of teeth or denticles of the hinge a

more permanent character, for in old specimens the ligamental area is pushed so

far forward as to have obliterated all the central teeth, and they become almost

toothless, not more than three or four remaining ; while in some specimens as many as

eighteen may be counted on each side of the umbo, they are prominent, somewhat

angular, flattened on the top, and when perfect, generally crenulated on the edges ;

between each is a deep depression for the reception of those in the opposing valve,

and in very young shells the hinge is almost entirely destitute of denticles (fig. 1, e].

Every size may be readily obtained, and my cabinet contains a series varying from

specimens less than the eighth of an inch to those in which the diameter is nearly

three and a half inches, dimensions exceeding those generally obtained in our seas ;

and this magnitude may be seen in shells from the Coralline as well as the Red Crag

Deposits, while the species seems to have been rare in the Norwich beds.

Some American Tertiary shells figured by Conrad under two or three different
names, approach so closely to those of the Crag as to render the distinction doubtful.,
as far as regards representation alone.

BIVALVIA. 69

In some of my specimens from the Coralline Crag, where the two valves are in
their natural state a very perceptible difference may be observed, not only in one
valve having a greater tumidity than the other, but the inflated valve has also a larger
diameter. Perhaps the ovarium in these specimens occupied a position not quite
central, thereby giving a little inequality to the valves.

There are nodules of indurated sandstone in my cabinet, which contain casts of
what appear to be the interior of this species, and also those of Isocardia cor. where the
shell has been absorbed or abstracted ; these nodules were obtained on the beaches of
Walton Naze and Felixstow, and were in all probability washed out of the Red Crag.

LIMOPSIS, Sassi. 1827.

ARC A (spec). Brocchi.
TRIGONOCCELIUS. Nyst et Galeotti, 1835.
LIMNOPSIS. Gray, 1840.
PECTUNCULINA. D'Orb, 1844.
CRENELLA. Herrmansen, 1846.

Generic Character. Shell orbicular or obliquely ovate, convex or lenticular, equi-
valved, subequilateral, and closed. Hinge composed of numerous teeth, arranged in
a more or less curvilinear direction, projecting and interlocking. Umbones distant.
Cardinal area large and external, divided by a triangular fossette immediately beneath
the umbo. Impression of the mantle entire, or without a sinus ; those by the adductors
subovate, and deeply impressed.

ANIMAL UNKNOWN.

The characters by which this Genus is distinguished from the preceding one is
the triangular fossette in the centre of the ligamental area, separating the cartilage
from the ligament ; first proposed as of generic importance by Sassi, in 1 827,
according to Bronn, and his name has priority over that by MM. Nyst and Galeotti,
which bears a date several years later. This peculiar character of the hinge
was observed and pointed out by Brocchi in 1814, but of course considered by him
as of specific value only, his shell being placed in the genus Area. The separation
of the ligament into two distinct portions, although both of these are placed exterior
to the hinge line, appears equivalent to the otherwise more general distinction of this
ligature, one portion being within the hinge line, while the other is on the outside.
Eighteen species are enumerated by M. Nyst, one of which is recent from the
Red Sea.

70 MOLLUSCA FROM THE CRAG.

1. LIMOPSIS AURITA, Brocchi. Tab. IX, fig. 2.

ARCA AURITA. Broc. Conch. Foss. Subap., p. 485, t. xi, fig. 9, a — 6, 1814.
PECTUNCULUS AURITUS. Defr. Diet. Scien., t. xxxix, p. 224.

Goldf. Pet. Germ., v. ii, p. 163, t. 126, fig. 14, a— b.
Phil. En. Moll. Sic., vol. i, p. 63 ; vol. ii. p. 45.
Risso. Hist. Nat. des Princip. Prod. del'Europ., t. iv, p. 318, 1826,
SUBL^VIGATUS. S. Wood. Catalogue, 1840.

Morris. Cat. Brit. Foss., p. 97, 1843.
LIMOPSIS AUUITA. Sassi. Giorn. Ligust. (ex. Bronn), 1827.

Bronn. Leth. Geo., vol. ii, p. 935, t. 39, fig. 7, a — b, 1838,
Sismonda. Syn. Meth. Ped. Foss., p. 15, 1847.
TRIGONOCCELIA SUBL^EVIGATA. Nyst. et West. Nouv. Rech. Coq. Foss. d'Anv., p. 12, pi. 2,

fig. 15, 1839.
Nyst. Coq. Foss. de Belg., p. 244, pi. 26, fig. 2, a— b, 1844.

Spec. Char. Testa obliqud, rotundato-ovatd, incequilaterd, sublcevigatd, auriculatd ;
exilissime striatd, et tenuissime decnssatd; car dine arcuata, dentibus 10 — 18; margine
integerrimO) acuto.

Shell oblique, rounded ovate, inequilateral, nearly smooth, and glossy, with small
auricles ; externally ornamented with very fine striae, crossed by distinct lines of
growth; hinge line curved, with about 10 to 18 teeth; margin sharp and smooth.
Longest diameter, \ an inch.
Locality, Cor. Crag, Gedgrave.

This species has recently been found in abundance in one locality of the Coralline
Crag, but it appears restricted to that spot, it may possibly have lived on into the Red
Crag period, as my cabinet contains one specimen from that Formation, which however
is much waterworn.

It is subject to a good deal of variation in its outward form, but is always
more or less obliquely oval, generally becoming especially so in the older speci-
mens, while in some young shells the valves are nearly equilateral. The hinge is
composed of a row of denticles, varying from ten to sixteen, those on the shorter or
rounded side being the greater number, amounting to about nine, the outermost are
angular and somewhat distant, while the inner ones are close set and vertical ; on the
other side they are fewer, not exceeding seven, sometimes not more than four, these
are distant, much inclined, and nearly parallel to the hinge line, furthermore they are
often rough and crenulated upon their edges. The exterior of the shell is smooth and
even glossy when perfect, with faint but distinct radiating striae and visible lines of
growth, and the hinge line projects a little beyond the otherwise oval contour of the
shell, giving it the appearance of auricles, hence its name ; the inner margin is
flattened, smooth, and perfectly free from crenulations, and the impressions by the
adductors deeply seated ; that on the shorter side small and ovate placed near the
hinge, the other is larger and more distant ; the fossette for the cartilage diverges from
the umbo at an angle of about 90°.

BIVALVIA. 71

In the young state the specimens have fewer teeth, and the shell, as before stated,
is less oblique, resembling the young of Pectunculus, from which it may be distinguished
by its smooth and acute margin at all ages ; while in the very small or young specimens
of P. glycimeris the crenulated edge may be always seen. Some specimens are more
tumid than others, but none are much inflated, and the exterior is smooth and perfect,
except where it has been eroded, when the rays are more displayed, giving it there a
granulated or decussated appearance, like Area aurita of Brocchi, from which it appears
to differ only in size.

The remains of red-coloured bands may be seen upon some specimens as if the
shell had been so ornamented when in a living state, or perhaps it was of one
uniform colour, a part of which only has been abstracted.

Trigonoccelia Gold/ussii, Nyst, from Kleyn Spauwen, much resembles our shell, but
is probably specifically distinct; it has its margin obsoletely crenulated, and the
denticles are more numerous, with a slight difference in their arrangement.

LIMOPSIS PYGM.EA, PUlippi. Tab. IX, fig. 3.

PECTUNCULUS PYGM^EUS. Phil. En. Moll. Sic. vol. i, p. 63, t. 5, fig. 5, 1836 ; not Lamarck.

Id. - - - vol. ii, p. 45, 1844.

S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 234, pi. 13,
fig. 5, 1840.
Id. Catalogue, 1840.

Goldf. Pet. Germ. vol. ii, p. 162, t. 126, fig. 11, a—c.
Morris. Cat. Brit. Foss., p. 97, 1843.
TRIGONOCCELIA DECUSSATA. Nyst et West. Nouv. Rech. Coq. Foss. d'Anv., p. 12, No. 29,

pi. 2, fig. 16, 1839.

Nyst. Coq. Foss. de Belg., p. 245, pi. 18, fig. 7, a— d, 1844.
LIMOPSIS PYGMJEA. Sism. Syn. Meth. Ped. Foss., p. 15, 1847.

Spec. Char. Testa minutd, obliqud, intsquilaterd, subtrapeziformi, gibbosd, crassd,
auriculatd ; transversim sulcatd, striis radiantibus tenuissimis, subobsoletis ; margins
crenulato, dentibus circa decem.

Shell small, oblique, inequilateral, sub trap eziform, gibbous, thick, and strong;
hinge line straight, furnished with about ten teeth ; externally covered with fine and
nearly obsolete radiating striae, crossed by more distant and distinct lines of increase ;
margin crenulated.

Longest diameter, \ of an inch.

Locality. Cor. Crag, Sutton.

This species, as far as I know, is restricted to a single locality, where it is one of
the most abundant shells, and the two valves are often found united. I have little
doubt it is the same as Philippi's Sicilian fossil, judging from the figure he has given '•>
the Belgian shell appears rather larger or badly represented, but from description it is
probably the same. Our shell may be further described as being very tumid, the
depth of the valves united equals the width of the hinge line ; its dental formula

72 MOLLUSCA FROM THE CRAG.

consists of about ten teeth, six upon the anterior or rounded side, these are placed
nearly vertical, or forming an obtuse angle, and very prominent in the centre, the four
teeth on the posterior or produced side are much inclined and nearly parallel with the
hinge line, they are also obtusely angular, interlocking between those of the opposite
valve, and by their prominence keeping the two portions united ; hinge margin with a
row of crenulations deeper, larger, and more visible within upon the posterior side :
when the shell is perfect the exterior is finely decussated, the radiating stria3 not
being more prominent than the lines of growth, but when the exterior coating is
removed, which is generally the case more or less, the surface is strongly rayed or
costated. In the young state the shell is less tumid than when full grown and less
oblique. The muscular impressions are unequal in size and suborbicular, the anterior
one or that upon the shorter side is situated close up to the hinge line ; the one
on the posterior or opposite side is larger and much nearer to the ventral margin.

This shell in form and magnitude bears a resemblance to Pectunculus nanus,
Deshayes, an Eocene fossil from the Paris Basin, figured and described in his ( Hist,
des Coq. Foss. des Env. de Paris, vol. i, p. 226, t. 36, figs. 4, 5, 6 ; but judging from the
figure as well as from the description, there appears a different arrangement of the
teeth or denticles, those of the French shell have the greater number upon the larger
or produced side, amounting to as many as six, with only three or four upon the other
or shorter side, and are less oblique, thus reversing the dental arrangement of the Crag
shell ; and the French fossil is said to be thin and fragile, while ours is thick and strong.
The triangular fossette of the Crag shell is deep, and forms an angle less than 90°,
and the margin of the shell is perfectly closed all round.

NUCINELLA, S.

NUCULA (sp.). Deshayes, 1829.
PLEURODON. S. Wood, 1840.
NUCULINA. D'Orbigny, 1845, sec. Gray.

Gen. Char. Shell equivalve, inequilateral, closed, ovate or subtrigonal ; anterior
side short, truncate; posterior produced, ovate or subangular; hinge line broad
slightly curved, furnished with few teeth : one large lateral tooth on the posterior
side. Ligament external.

ANIMAL UNKNOWN.

The diagnosis of this was drawn up from what may be considered as scarcely
sufficient materials for the distinction of a group of animals, denominated a Genus,
being founded upon but one species; it presents, however, such marked differ-
ences in character from any genus hitherto established, that I was unable to find
a position for my little shell when it was first described. The outward trigonal

BIVALVIA. 73

form, as well as possessing a linear series of denticles, seem to point out its place
as near to Nucula from which it differs essentially, in having an external ligament,
and one large lateral tooth upon the anterior side.

The shell is of a nacreous texture within, and was, probably, covered with an
epidermis in the recent state. The ligament is placed on the posterior side of the
umbo, upon a small projecting portion of the shell, and the animal was without
prolonged siphonal tubes, the line impressed by the edge of the mantle being like
that of Nucula, without any indentation. There are no recent species, that I am
acquainted with, possessing such a dental arrangement, and its true position is of
course conjectural. The linear teeth and external ligament resemble Pectunculus, with
a form like that of Nucula.

1. NUCINELLA MILIARIS, Deshayes* Tab. X, fig. 4, a — c.

NUCULA MILIARIS. Desk. Coq. Foss. des Env. de Par., torn, i, p. 225, pi. 36, figs. 7-9,

1829.
PLEURODON OVALTS. 5. Wood. Illust. in Mag. Nat. Hist., 2d Series, vol. iv, p. 231, pi. 13,

fig. 1, 1840.
MILIARIS. S. Wood. Catalogue, 1840.

Spec. Char. Testa minima, sulovatd, l&vigatd, politd, tumidd ; postice subtruncatd,
antice productiore, rotundato-ovatd : dentibus 5 — 6 magnis, (Musis.

Shell minute, subovate, smooth, glossy, and tumid ; posterior side short, subtrun-
cate, anterior large, roundedly ovate ; teeth 5 — 6, large and obtuse.

Diameter, T^- of an inch.

Locality. Paris Basin, Grignon.

Cor. Crag, Ramsholt, and Sutton.

This pretty little shell is by no means rare at either of the above British localities,
and at the former (Ramsholt), the valves are often found- united, the large and pro-
minent teeth with which they are furnished having kept them in their natural position.

It is one of the very few of our Crag Molluscs, that dates its existence from the
Older Tertiaries, or what is called the Eocene Period ; as there is reason to believe
the species left in the Paris Basin is the true progenitor of our little shell, while it
appears to have died out before the severer conditions of the Red Crag Period had set
in : although so small a shell, it would not readily be found, unless abundant, in a
deposit so disturbed.

As, however, some differences exist between the Crag Fossil, and what is here
considered its specific parent, it may be necessary to give a more detailed description
and to point out what, perhaps, might be regarded by some Conchologists as of
sufficient importance to keep them distinct.

Our little shell in its outward form, slightly resembles a minute specimen of
Nucula nucleus, except, that it is more tumid ; the anterior side constitutes nearly
the whole of the shell, the posterior being cut off by an almost straight line from the

10

74 MOLLUSCA FROM THE CRAG.

umbo to the ventral margin. The hinge is composed of five or occasionally six
teeth in the right valve, with six or sometimes seven in the left, these are arranged
in a slightly curved line extending on both sides of the beak, three on each side ;
those on the posterior or shorter side are placed rather closer together than those
on the anterior one, they are prominent, obtuse, and large compared with the
size of the shell; those in the centre standing nearly perpendicular to the line of
hinge, while the outer ones on both sides have their widest portion in an opposite
direction, all placed, of course, so as one set can be interposed between those of
the opposite, when the valves are closed. The lateral tooth of the right valve
has a deep depression between it and the margin for the reception of a large tooth
of the left valve. In a specimen of the French Eocene Fossil in my own cabinet, the
teeth do not appear to be quite so obtuse as in the Crag shell, and the umbo is somewhat
sharper and more terminal, with a rather more angular outline, the posterior side is
apparently more truncated or straight, while the shell is nearly transparent.

A species passing out of one Period, where the animals or the remains of them, are
of a nature to indicate conditions differing materially from those of another Period into
which it is supposed to have had its existence prolonged, and so far removed as
to have almost its entire Fauna formed upon a different type, would in all pro-
bability be affected in some degree by the change, so as to produce a slight alteration
in its calcareous covering, such as would constitute what is called a variety, and these
characters might become permanent under the continuance of those altered conditions ;
but should we not be permitted so to undermine specific integrity, we may at least be
allowed a latitude in variation, that is ordinarily conceded to the examination of
existing forms, and the differences between the shells of the two periods, which are
here considered as identical, is less than is oftentimes presented to us by individuals
of undoubtedly the same species in the Crag deposits ; even in those recent species
that appear to be admitted by almost general consent, as having originated in the
earliest Tertiary Periods, a difference may be detected between the older and the more
recent specimens, showing those animals that are apparently possessed of capabilities
of endurance beyond their contemporaries, have not been able to maintain in strict
integrity the supposed unvarying characters originally impressed upon them ; all, how-
ever, that is contended for here is, that no greater restriction in regard to the limits of
variation ought to be imposed upon the line of specific demarkation, merely from
differences in Geological Periods, than is granted to deviations among specimens from
the same deposit.

BIVALVIA.

75

ARCA,* Linnaus, 1758.

PARALLELOPIPEDUM. Klein, 1753.
ANOMALOCARDIA. Id. (not Schum).

CIBOTA. Browne, 1/56.
PECTUNCULUS. Adanson, 1/57.
ARCA. Linnaeus, 1758.
AMYGDALUM. Chemnitz, 1784.
DAPHNE and DAPHNODERMA. Poll, 1795.
TRISIDOS. Bolten, 1798.
CucuLL(EA. Lam., 1801.
ARCITES. Martin, 1809.
TRISIS. O£ra, 1815.
CYPHOXIS. Rafinesque, 1819.
ARCACJTES. Schlot., 1820.

BYSSOARCA. Swainson, 1820.

NAVICULA. Blainv., 1825.

RHOMBOIDES. 7c?.

SCAPHULA. Benson, 1834, not Swainson.

ARGINA? Gray, 1840.

BARBATIA. 7c?.

LUNARCA ? Id.

LITHARCA. Id. 1844.

SENILIA. Id.

SCAPHURA. Id.

ISOARCA. Munster, 1843.

ANDARA. Gray, 1847.

SCAPHARCA. Id.

Generic Character. Shell inequilateral, generally equivalve, more or less quadrate
or trapezoidal, sometimes closed ; at others, with an opening at the ventral margin,
thick and strong ; externally striated or costated. Umbones distant. Hinge linear,
with numerous close-set interlocking teeth. Ligamental area generally large and
broad, with angular grooves. Palleal impression entire.

Animal oblong, edges of mantle disconnected, simple or fringed, without siphonal
tubes, a large and bent elongated foot with a groove capable of expanding into a disk-
like form, and a gland at its base for the production of a byssus. Byssus compact.

Animals of this genus generally spin a substance for their attachment, but many
are found located in rocks or holes of shells. Some species have a considerable
opening at the ventral margin, in consequence of which, those more strongly marked
with that character were placed in a separate genus, under the name Bysso-arca ;
but in individuals of the same species, this opening is subject to great variation, being
large in some, while in others it is nearly obliterated.

M. Nyst has published a synoptical table of this genus, in which he has enume-
rated 459 species, 162 of these are recent, whilst the others are extended through
almost every Period, commencing with the Upper Silurian, and ranging through all
the intermediate Formations : although some few of these, are probably, only varieties,
such an extensive genus might naturally be expected to have a large geographical
range ; the recent species are found in all parts of the world, though not equally dis-
tributed, nearly one hundred being found in the equinoctial regions ; and its vertical
range, is also very extensive, some being found under stones at low water mark,
while others have been met with attached to rocks as deep as eighty fathoms.

* Etym. So called from its Boat-like form.

76 MOLLUSCA FROM THE CRAG.

1. ARCA TETRAGONA, Poli. Tab. X, fig. 1, a — d.

ARCA TETRAGONA. PolL Test. Sic., vol. ii, p. 137, pi. 25, figs. 12, 13, 1793.
_ Turt. Brit. Biv., p. 166, pi. 13, fig. 1, 1822.

— Payr. Cat. Moll. Cors., p. 61, No. 105, 1826.
Desk. 2d ed. Lara., t. vi, p. 461, 1835.

— — Forbes. Malac. Monen., p. 41, pi. 3, 1838.

_ Id. Report on ^Egean Invert., p. 181, 1843.

— Phil. En. Moll. Sic., vol. i, p. 57, 1836.

— Reeve. Conch. Icon. Monog. Area, pi. 15, fig. 100, a — b.

— ? Menke. Moll. Nov. Roll. p. 37, No. 208, 1843.

— No*. Mont. Test. Brit., p. 139, pi. 4, fig. 3, 1803.

— — Don. Brit. Shells, vol. v, pi. 158, figs. 1, 2, 1804.

— — Brown. Brit. Conch. Illust., pi. 25, figs. 1-3, 1825.

_ _ s. Wood. An. and Mag. Nat. Hist., vol. iv, New Series, p. 231, pi. 13, figs. 2,

& 2a, 1840.
Morris. Cat. of Brit. Foss., p. 78, 1843.

— FUSCA. Mont. Test. Brit. Sup., p. 51, 1808 (not Reeve).

W. Wood. Ind. Test., p. 45, pi. 9, fig. 14, 1825.

Flem. Brit. An., p. 397, 1828.

Thorpe. Brit. Mar. Conch., p. 101, 1844.

— CARDISSA. Desk. 2d ed. Lam., t. vi, p. 463, 1835.

Alder. Cat. Moll. North, and Durh., p. 79, 1848.

— NAVICULARIS. Desk. 2d ed. Lam., t. vi, p. 462, 1835.

— Phil. En. Moll. Sic., vol. ii, p. 42, 1844.

— loven. Ind. Moll. Scand., p. 33, 1846.

— BRITANNICA. Reeve. Conch. Icon. Monog. Area, pi. 15, fig. 98.

— Nyst. Tab. Syn. des Arches. Viv. et Foss., p. 14, No. 47, 1847.

— PAPILLOSA. Smith. Mem. Wern. Soc., vol. viii, pi. 1, fig. 19, 1838.
BALANUS BELLONII. List. Hist. Conch., lib. iii, fig. 207, 1687.

Ency. Meth., pi. 308, fig. 3, a—b.

Spec. Char. Testa oblongd, valde inaquilaterd, costato-striatd, et transversim
decussatd, antics rotundatd, postice angulatd; carind posticd eminente, acutd; apicibus
remotis incurvis ; margine ventrali hiante.

Shell oblong, very inequilateral, with costated striae, decussated by distinct lines
of growth ; anterior side rounded, posterior angulated, with a prominent keel or
ridge from the umbo to the posterior ventral margin ; umbones distant, incurved ;
ventral margin gaping.

Largest diameter, 1 inch.

Locality. Cor. Crag, Sutton, Ramsholt, and Sudbourn.

Red Crag, Sutton. Recent, Scandinavia, Britain, and Mediterranean.

Very small specimens are by no means rare in the Coralline Crag ; but I have met
with very few examples of the adult shell. These small or young specimens are very
regular in form, being much elongated transversely, of a somewhat rhomboidal shape,
the anterior side slopes a little from the extremity of the hinge line, rounding at the
ventral margin, while the posterior side is angular, pointed and projecting ; the ventral

BIVALVIA. 77

margin being nearly straight, or with a very little inflection. A full grown specimen
found in the Red Crag (fig. 1, a — 6), is very regular in form, and all its ornamental
striae beautifully preserved: the rays or costulated striae are close and numerous
upon the posterior half of the outer side of the umbonal ridge, while they are
larger and more distant upon the anterior half; and within the prominent ridge,
that slopes from the umbo to the posterior ventral margin, the rays are large
and few, amounting to about four or five, and are placed in pairs ; they project
beyond the posterior margin, giving it a jagged or indented edge. A long line
of teeth or crenulations occupy the edge of the hinge margin, they are numerous
and vertical on the anterior or shorter side, fewer or more distant, and strongly
inclining on the posterior side. The ligamental area is large and concave removing
the umbones far apart ; this space is ornamented with deep and angular lines diverg-
ing from the umbo, in some they are few and deeply impressed, while in others they
are more numerous. One specimen in my Cabinet, from the Coralline Crag at Gedgrave
(fig. 1, c), precisely resembles the distorted specimens found occasionally upon our
own Coast, in holes or crevices of rocks, and in which the regularity of form has
been interrupted, and the surface much abraded by frequent movements in a con-
fined position, thus producing so great an alteration in the exterior of the shells as to
have induced some authors to consider them distinct. In some of these full grown
and distorted specimens, the ventral margin is deeply indented or sinuated. They
are said by British Conchologists to be regular in form when free, and only distorted
when confined to the crevices of ro cks.

I have entered it among my synonyma upon the authority of Menke, who gives it
as one of the existing species from the North Western Coast, New Holland. He has
enumerated several other European shells from that part of the world.

2. ARCA LACTEA, Linnaeus. Tab. X, fig. 2, a — 6.

ARCA LACTEA. Linn. Syst. Nat., ed. 12, No. 1/3, p. 1141, 1767.
Da Costa. Brit. Conch., p. 1/1, pi. 11, fig. 5.
Chem. Conch. Cab. t. vii, p. 200, t. 55, fig. 547, 1784.
Don. Brit. Shells, vol. iv, pi. 135, 1803.
W. Wood. Ind. Test., p. 45, pi. 9, fig. 24, 1825.
Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 6, 1827.
Mawe. Linn. Syst. Conch., pi. 13, fig. 4, 1823.
Phil. En. Moll. Sic., vol. i, p. 57 ; vol. ii, p. 42.
Forbes. Kept, on ^Igean Invert., p. 181, 1843.
Reeve. Conch. Icon. Area, pi. 17, fig. 116.
Dujard. Mem. Geol. Soc. de France, t. ii, pt. 2, p. 266, 1837.
Hanley. Recent Shells, vol. i, p. 154, pi. 9, fig. 24.

— MODIOLUS. Poli. Test. Sic., vol. ii, p. 137, pi. 25, figs. 20, 21, 1795.

Turt. ed. Linn., vol. iv, p. 251, 1806.

— PERFORANS. Turt. Conch. Diet., p. 9, 1816.

Id. Brit. Biv., p. 169, t. 13, figs. 2, 3, 1822.

— GAIMARDII. Payr. Cat. Moll. Cora., p. 61, pi. 1, figs. 36 — 39, J826.

78 MOLLUSCA FROM THE CRAG.

ARCA GAIMARDII. Desk. Exp. Sci. Algiers Moll., pi. 124, figs. 8 — 11.

— QUOYII. Payr. Cat. Moll. Cors., p. 62, pi. 1, figs. 40—43, 1826.

— - Desk. Append, to Lyell's Princ., 1st ed., vol. iii, p. 10, 1833.

— LACTANEA. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 232, pi. 13, fig. 3,
1840.

— S. Wood. Catalogue, 1840.

— Morris. Cat. Brit. Foss., p. 78, 1843.

— NODTJLOSA? Broc. Conch, Foss. Subap., p. 478, t. ii, fig. 6, a — c, 1814.
_ _ ? Dubois. Wolhyn. Podol., p. 64, pi. 7, figs. 21, 22, 1831.

— STRIATA. Reeve. Conch. Icon. Area, pi. 17, fig. 121.

List. Hist. Conch., lib. iii, fig. 69, 1685.
Dale. Hist, and Antiq. of Harwich, p. 291, 1730.
Adanson. Voy. au Senegal, p. 250, pi. 18, fig. 8, 1757.
not ARCA LACTEA, Brander. Foss. Hant., pi. 8, fig. 106.

Spec. Char. Testa ovato-oblongd, interdum subguadratd, antice rotundatd, postice
oblique truncatd ; decussato-striatd ; striis radiantibus eminentioribus ; area cardinali
mediocre profunda ; margine ventrali subrectd.

Shell ovato-oblong, sometimes nearly square, anterior side rounded ; posterior
obliquely truncated ; covered with striae, crossed by transverse lines of growth ;
radiating striae the most prominent ; cardinal area not large, with a rounded or obtuse
ridge from the umbo backwards ; ventral margin nearly straight.

Longest diameter, f of an inch ; height, ^ an inch.

Locality'. Cor. Crag, Sutton.

Red Crag, Sutton, Walton Naze. Recent, Britain and Mediterranean.

In the sandy portion of the Coralline Crag at Sutton, a locality that has yielded so
many of the smaller and more fragile species of Mollusca, numerous small or young
individuals of this species may be obtained. My largest specimen was found in the
Red Crag at Walton Naze, and measures an inch in its transverse or largest diameter
but it is an old and somewhat mutilated individual.

When my Catalogue was compiled this was considered to be a distinct species, in
consequence of a difference in the size of the ligamental area, as in the Crag shell it is
smaller than in the generality of recent specimens, the resemblance was, however, so
great in all other respects, that the name of lactanea was given from its near
relationship. I have since seen specimens of the recent shell in which this distinction
is lost, and have therefore now united it with the long-known recent species. My
specimens from the Crag are very regular in form, and I have not met with any
fossils resembling the distorted varieties which have been erected into species by
Payraudeau under the names of A. Quoyii and A. Gaimardii, the greatest variation
being slight differences in proportional dimensions, some occasionally being rather
more transverse than others.

Area nodulosa, Miiller, given as an inhabitant of the Seas of Norway, by Dr. Loven,
corresponding probably with the Calabrian fossil A. aspera, Phil., appears to differ
from our shell in being larger and broader on the posterior half, with a more deeply

BIVALVIA. 79

and regularly decussated exterior, but with a small and narrow ligamental area. Area
nodidosa, Brocchi, seems to belong to our present species, as does also, in all probability,
the one figured and described under that name by Dubois, judging from his short
description and small figure.

ARCA PECTUNCULOTDES, Scacchi. Tab. X, fig. 3, a — b.

ARCA PECTUNCULOIDES. Scac. Ann. Civ. delle Due Sicil., vol. vi, p. 82, 1834, fide Nyst.
Scacchi, Notizia, p. 25, t. 1, fig. 12, sec. Phil.
Phil. En. Moll. Sic., vol. ii, p. 44, t. 15, fig. 3, 1844.
Jeff. Ann. Nat. Hist., vol. xix, p. 313.
Lovtn. Ind. Moll. Scand., p. 34, 1846.
? Mich. Free. Faun. Mioc., t. 3, fig. 14, 1847.
Sismonda. Syn. Metli. Pedm. Foss., p. 16, 1847.
Nyst. Tab. Synop. des Arches Viv. et Foss., p. 54, No. 300, 1847.
RARIDENTATA. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 232, pi. 13,

fig. 4, 1840.

Thompson. Ann. Nat. Hist., vol. xviii, p. 385.
S. Wood. Catalogue, 1840.
Morris. Cat. Brit. Foss., p. 78, 1843.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 241, pi. 45, fig. 8,

1849.

PUSILLA. Nyst. Coq. Foss. de Belg., p. 261, pi. 20, fig. 6, 1844.
CUCULLCEA PUSILLA. Nyst. Rect. Coq. Foss. Prov. d'Anv., p. 14, pi. 3, fig. 55, 1835.

Spec. Char. Testa pared, incequilaterd, ovato-rhomboided, gibbd ; striis exiguis,
decmsatis ; area ligamenti parvd, apicibus refleccis ; car dine recto, ntrinque tridentato ;
margine ventrali subsinuato.

Shell small, inequilateral, ovato-rhomboidal, gibbous ; ornamented with fine
decussating striae ; ligamental area small, umbones inflected ; hinge line straight,
furnished with three teeth on each side ; ventral margin subsinuated.

Largest diameter, gth of an inch.

Locality. Cor. Crag, Sutton. Recent, Britain, Mediterranean, and ^Egean Seas.

This elegant little shell is another species, but rarely found in the British Seas, and
which may perhaps be one of those we might consider to be in a specific decline, or
the dying out of what was once largely developed in these latitudes. In the Coralline
Crag at Sutton this is one of the most abundant fossils, and I have obtained the
separated valves by hundreds.

It is stated by the authors of the ' Hist, of Brit. Moll.' to be slightly inequivalved.
In the fossil state I have never been able to obtain a specimen with the valves united.
There does not appear to be any doubt of its identity with the living British species,
and a single valve obtained from a considerable depth in the ^Egean Sea, obligingly
given to me by Professor E. Forbes, corresponds in all respects with the Crag shell.

Where the specimens are so abundant, differences of form may naturally be
expected, some may be selected that are more elongated and less tumid than others,

80 MOLLUSCA FROM THE CRAG.

and my two most extreme variations are here represented : all give indications of an
opening for a byssus by an indentation or sinuosity on the anterior side of the
ventral margin ; this character is imperfectly represented in the Mediterranean fossil
by Philippi, nor is it well shown in that by Nyst, although the probabilities are they
all belong to the same species : both of these authors speak of their shell as being by
no means abundant. When perfect, it is ornamented with distinct radiating striae,
the largest and most prominent at the two extremities ; they are crossed by lines of
growth somewhat irregular, and the surface is imperfectly cancellated. Upon the
hinge line, on the anterior side, are three or four rather large and prominent teeth,
which slope at an angle of about 45°, while those on the posterior, amounting to the same
number and equally prominent, are nearly parallel to the hinge margin; in some
small or young specimens, these teeth or prominences do not amount to more than
two on each side, and all so arranged that when the valves are united, the one set
interlock with those of the opposite valve. The place for the ligament is very small,
and in perfect specimens there may be seen an entire row of crenulations just
within the ventral margin of the shell ; and a prominent ridge slopes down the interior
from beneath the umbo, probably formed by the inner edge of the adductor muscle
on the anterior side. In old specimens the mark of the mantle is deeply impressed,
running parallel to the outer edge.

NUCULA,* Lamarck, 1799.

GLYCIMERIS (sp.). Da Costa, 1778.
TELLINA and DON AX (sp.). Gmel.
ARC A (sp.). Linn.
POLYODONTA. Megerle, 1811.

Generic Character. Shell equivalve, very inequilateral, ovato-trigonal, generally
transverse, closed, nacreous, and in the recent state covered with an epidermis ; often
smooth, sometimes striated, or variously ornamented upon the exterior : hinge line
more or less angular, furnished with a series of sharp, elevated, and angulated teeth,
arranged on each side of the umbones, interrupted by a central and internal spoon-
shaped projection, upon which is placed the ligament. Impression by the mantle
without a sinus.

Animal of the form of the shell, having the edges of its mantle plain dis-
connected, and without siphonal tubes. Foot large, and capable of expanding into an
ovate, pedunculated disc, with fimbriated edges, and by means of this organ it is
capable of a considerable degree of locomotion, creeping like a Gasteropod at the
bottom of the water.

* Etym. Nucula, & little nut.

BIVALVIA. 81

Since the original establishment of the genus by^'Eaniarck, it has been much
curtailed, and is now restricted to those shells with a pectiniform or denticulated hinge,
having the posterior portion, as it were, cut off ; the lines of denticulations forming
nearly a right angle, and the animal being without the posterior siphonal tubes ;
consequently there is no indentation in the impression formed by the muscles of the
mantle.

The genus thus restricted is in a recent state rather sparingly distributed, although
found in the seas of both hemispheres. As fossil, it has been obtained low in the
Secondary Formations.

The species in a living condition are inhabitants of the sea at all depths, some being
found near low water mark, while others are truly pelagian, and have been observed in
the deepest regions Mollusca are known to frequent. Mr. Garner, in his ' History
of the Lamellibranchiata,' says, there is a distinct pinnate process in the mantle of
the animal, for the purpose of secreting the numerous teeth of the hinge ; these teeth
are prominent, sharp pointed, and angular, the angle being directed towards the
umbo from both sides.

1. NUCULA L.EVIGATA, /. Sowerby. Tab. X, fig. 8, a — b.

NUCULA L^EVIGATA. /. Sow. Min. Conch., t. 192, figs. 1, 2, 1818.

Goldf. Pet. Germ., vol. ii, p. 157, pi. 125, fig. 19, a— c.

S. Wood. Illust. Mag. Nat. Hist., New Series, vol. iv, p. 296, 1840.

Id. Catalogue, 1840.
Nyst. Add. £ la Faune Conch, de Belg. (Bull. Acad. de Brux, t. ix,

p. 450), 1842.

Morris. Cat. Brit. Foss., p. 94, 1843.
Nyst. Coq. Foss. de Belg., p. 228, pi. 17, fig. 8, a— b, 1844.

Spec. Char. Testa transversd, ovatd, valde in&qmlaterd, Icevigatd, tenui, mar-
gar itaced, clamd ; antice brevi, subangulatd; postice productiore, rotundatd ; margine
ventrali integerrimo.

Shell, transverse, ovate, very inequilateral, smooth, thin, nacreous, and closed;
anterior side short, sloping, or angulated ; posterior much produced and rounded ;
ventral margin without crenulations.

Longest diameter, l|ths of an inch; height, 1 inch.

Locality. Cor. Crag, Sutton.

Red Crag, Walton Naze.

This is the largest species of the genus that I am acquainted with, either in the
recent or fossil state, it appears to have attained its full development in the Red
Crag, as in the Deposits of that Period at Walton Naze specimens are by no means
rare ; it is found also in the older or Coralline Crag, where, however, they are few in
number and small in size.

M. Deshayes has quoted this as synonymous with N. ovata, an Eocene species from

11

82 MOLLUSCA FROM THE CRAG.

the Paris Basin ; there are, however, marked differences between the two, sufficient to
keep them specifically distinct. The older shell has a crenulated margin, with other
characters of minor importance by which it may also be distinguished, while the
Crag one has its margin perfectly smooth. A shell in the Cabinet of Mr. D'Urban,
found in the Eocene Formation at Bracklesham, strongly resembles our species, in
having its margin free from the slightest appearance of crenulations, but it differs in
being rather less transverse and more tumid, with the posterior ventral margin less
angular and pointed, approaching in the last character the specimens from the
Coralline Crag ; these differences appear to be sufficient for specific distinction, and,
as yet, I have not seen any shell with which it can be fairly identified ; the exterior of
our Crag shell is smooth and glossy in specimens the surface of which has not been at
all eroded, and it was, in a recent condition, most probably covered with an epidermis.
On the anterior dorsal margin there is a rather narrow row of prominent angular teeth,
varying from 20 to 35 ; while on the short or posterior side the teeth are broader and
closer, and in number about 10 or 12, with a deeply impressed lunule on the posterior
or shorter side. There is no other exterior marking than the lines of growth, but
when the glossy surface is removed, the shell appears to have a radiated fibrous
structure, and the interior is often faintly rayed ; a long subangular depression for
the ligament curves inwardly towards the anterior, adhering to the inner edge of the
dorsal margin. The dorsal as well as the ventral margins are rounded, giving an ovate
form to the shell, only truncated on the posterior side, where the ventral margin forms
a sort of incipient rostrum, connecting it in that character with the following genus,
though less so than in some other species.

2. NUCULA COBBOLDI^E, /. Sowerby. Tab. X, fig. 9, a — b.

NUCULA COBBOLDLE. J. Sow. Min. Conch, t. 180, fig. 2, 1818.
Woodward. Geol. of Norf., p. 44, 1833.
Lyell. Mag. Nat. Hist., New Series, vol. iii, p. 328, 1839.

Id. Elem. Geol., p. 299, fig. 113, 2d. ed., 1841.
5. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 295, 1840.

Id. Catalogue, 1840.
G. B. Sowerby. Genera, No. 17, fig. 9.
Forbes. Geol. Surv. Gr. Brit., p. 83, 1846.
Morris. Cat. Brit. Foss., p. 94, 1843.

Spec. Char. Testa transversd, oUique-ovatd, convexd, clausd ; irregulariter radiatd,
aut lineolis flexuosis ornatd ; intus scepe incrassatd; margine integerrimo.

Shell transverse, obliquely ovate, convex, thick and closed ; sculpture on the
exterior, with irregular radiations or lines in a divaricating or zig-zag direction ;
interior often irregularly thickened, margin smooth.

Longitudinal diameter, \± inch. Height, 1 inch.

Locality. Red Crag, Button, Bawdsey, near Ipswich, and Felixstow.
Mam. Crag, Thorpe, Bramerton, Chillesford, Bridlington.

BIVALVIA. 83

This species has not, as yet, I believe, been found in any Formation older than the
Red Crag, in which it does not seem to have been very abundant, but in the Deposits
of the succeeding period it may be obtained in large numbers, in the portion of that
Formation resting upon the Red Crag at Chillesford, where the valves are sometimes
found united, and in their natural position.

There is no species known with which this is likely to be confounded, as its
peculiar sculpture differs from that of any recent Nucula inhabiting the Northern
Hemisphere, or of any of our well-known Tertiary species. Two fossils found in the
Cretaceous Formations (N. bivirgata and ornatissima), possess similar ornament, and a
recent species has been also obtained from a considerable depth off the Cape of Good
Hope, which is covered with zig-zag striae, these however have no specific relationship
with our shell.

This species, although one of the finest belonging to the genus, has not attained
quite so great a magnitude as the preceding one, my largest specimen does not
exceed one inch and an eighth in its transverse or largest diameter, while the
other has reached to an inch and three eighths. Like most of the shells from
the Crag, it varies somewhat considerably in its proportional dimensions. In those
which are most tumid, the diameter is less from the dorsal to the ventral margin, than
it is in those which are more compressed. The number of teeth are generally from
sixteen to eighteen on the anterior side, with about ten upon the shorter or posterior
slope, they are prominent and sharp, of an angular form, and interlocking, and the
fossette for the ligament is large, projecting inwardly, inclining beneath the dorsal
edge towards the anterior side, and the umbo is terminal, and somewhat pointed.
This species is sometimes much thickened internally in aged specimens, forming
deeply indented impressions by the adductors, which are of a sub-circular form
inclining to oval, and the marginal impression of the mantle is then ornamented with
radiations like those in some of the Lucints, but the margin of the shell is smooth,
and free from crenulations.

This pretty shell is ornamented upon the exterior with irregularly divaricating
striae, which generally, in the young state, have only one series of diverging lines, but
in the centre part of the older specimens they are more irregular, and become zig-zag,
with two, three, or more angular points of divergence, the radiations are large and
rounded, and crossed by transverse or very perceptible lines of growth, and the
shell when living was probably covered by an epidermis.

In some specimens the umbo is much eroded, while in others it is quite perfect.

84 MOLLUSCA FROM THE CRAG.

3. NUCULA TENUIS, Montague. Tab. X, fig. 5, a — b.

ARCA TENUIS. Mont. Test. Brit. Suppl., p. 56, t. 29, fig. 1, 1808.
Pennant. Brit. Zool., vol. iv, p. 218, fide Gould.
Dillw. Desc. Cat. Rec. Shells, p. 246, 1817.
Turt. Conch. Diet., p. 11, 1819.

W. Wood. Ind. Test., ARCA, p. 47, pi. 10, fig. 45, 1825.
NUCULA TENUIS. Turt. Brit. Biv., p. 177, 1822.
Flem. Brit. Ann., p. 402, 1828.
Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 13, 1827.
Gould. Inv. Massach., p. 105, fig. 64, 1840.
Moller. Ind. Moll. Groen., p. 17, 1842.
Mac Gill. Moll. Aberd., p. 244, 1843.
Morris. Cat. Brit. Foss., p. 95, 1843.
Thorpe. Brit. Mar. Conch., p. 105, 1844.

• Forbes. Geol. Surv., vol. i, p. 83, 1842.

L . Hanley. Rec. Shells, vol. 1, p. 171, pi. 10, fig. 45.

Alder. Cat. MoU. North, and Durh., p. 79, 1847.
Loven. Ind. Moll. Scand., p. 34, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 223, pi. 47, fig. 6 (Animal),
pi. P, fig. 5, 184 9.

— TENERA. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 295, pi. 14, fig. 2.

— RYCKHOLTIANA ? Nyst. Coq. Foss. de Belg., p. 233, pi. 15, fig. 10, a—b, 1844.

— DECIPIENS. Phil. En. Moll. Sic., vol. ii, p. 48, t. xv, fig. 15, 1844.

— LUCIDA. Blanding. MSS. fide Gould.

Spec. Char. Testa ovatd, trigono-ellipticd, Icevigatd, tenui, latere antico subangulato ;
lunuld parum distinctd, margine ventrali arcuato, integro.

Shell ovate, elliptically triangular, smooth, and thin; anterior side produced,
roundedly angular ; lunule not well defined, ventral margin smooth.

Diameter, \ an inch.

Locality. Cor. Crag? Gedgrave.
Red Crag, Bawdsey.
Mam. Crag, Bridlington, Chillesford.

Recent, Mediterranean, Britain, Scandinavia, and North America.

Two specimens of a species resembling this are in my Cabinet, they were obtained
from the Coralline Crag, but are too imperfect for correct determination. In the
Red Crag Formation it has undoubtedly made its appearance, several individuals were
found by myself, and in the sandy deposit at Chillesford it is an abundant shell
seemingly increasing in numbers towards the present Period. Its greater tenuity and
more ovate form will distinguish this from N. nucleus, as well as the absence from the
margin of all crenulations. It differs from the young of N. Icevigata in being less
transverse, that species having a greater diameter when measured from the anterior
to the posterior margin, the hinge line also forms a greater angle than in tennis, and
the posterior termination is somewhat produced. In this species the anterior dorsal
margin is more rounded than in any of the others, so is the ventral margin,

BIVALVIA. 85

giving a more ovate form to the outline. It has a rather narrow row of denticles on
both sides, those upon the anterior are from ten to twelve in number, with about six
or eight upon the shorter or posterior side. A shell somewhat resembling this is
found in the Upper Marine, in Headon Hill, being free from crenulations at the
margin, and is also a thin shell, with a similar ovate contour, though seemingly
rather more pointed at the posterior extremity, but my specimens of the Eocene
fossil are scarcely in a sufficiently good state of preservation for a fair comparison.

A specimen of this species, found at Bridlington, was obligingly forwarded to me
for examination by Mr. Leckenby.

4. NUCULA NUCLEUS, Linnaeus. Tab. X, fig. 6, a — b.

ARCA NUCLEUS. Linn. Syst. Nat., ed. 12, No. 184, p. 1143, 1767, not Brander.
Chem. Conch. Cab., t. vii, p. 241, t. 58, fig. 574, 1784.
Don. Brit. Shells, vol. ii, pi. 63, 1801.
Broc. Conch. Foss. Subap., vol. ii, p. 480, 1814.
W. Wood. Ind. Test., p. 47, pi. 10, fig. 42, 1825.
NUCULA NUCLEUS. Turt. Brit. Biv., p. 176, t. 13, fig. 4, 1822.

S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 294, pi. 14, fig. 1,

1840.

Thorpe. Brit. Mar. Conch., p. 105, p. 74, 1844.
Loven. Ind. Moll. Scand., p. 34, 1846.
Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 215, pi. 47, figs. 7, 8,

1849.

MARGARITACEA. Lam. Syst. des An. s. Vert., p. 115, 1801 (mostly).
G. B. Sowerby. Genera, No. 17, fig. 7.
De Blainv. Malac., pi. 7-5, fig. 5, 1825.

? Bast. Mem. de la Soc. d'Hist. Nat., t. 2, p. 78, No. 2, 1825.
Payr. Cat. Moll. Cors. p. 64, 1826.
Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 12, 1827.
Dubois. Conch. Foss. Wolhyn. Podol., p. 66, t. 7, figs. 35, 36,

1831.

Goldf. Pet. Germ., vol. ii, p. 158, t. 125, fig; 21, a — d.
Phil. En. Moll. Sic., vol. i, p. 64, t. v, fig. 8, 1836.
Bronn. Leth. Geol., vol. ii, p. 929, t. 39, fig. 5, a— c, 1838.
Swains. Malac., p. 382, fig. 125,/— a, 1840.
G. B. Sow., Jr. Conch. Man., fig. 137, 1842.
Forbes. Report on JSgean Invert., p. 180, 1843.
Sism. Syn. Meth. An. Inv. Piedm. Foss., p. 15, 1847.
ARGENTEA? Brown. Illust. Conch. Gr. Brit., pi. 25, figs. 14, 15, 1827.
GLYCIMERIS ARGENTEA. Da Costa. Brit. Conch., p. 170, pi. 15, fig. 6, 1778.
DONAX ARGENTEA. Gmel. Syst. Nat., p. 3265, 1/88.
Ency. Meth., pi. 311, fig. 3, a~ b.

Spec. Char. Testa obliqud, ovatd, transversd, subtriangulari, Icevi, aut obsolete striatd ;
dentibus cardinalibus acutis ; margine crenulato.

Shell obliquely ovate, transverse, slightly triangular, smooth or obsoletely striated ;
hinge with numerous, sharp, and erect teeth ; margin crenulated.

86 MOLLUSCA FROM THE CRAG.

Diameter, fths of an inch.

Locality. Cor. Crag, Button, Ramsholt, Sudbourn, Gedgrave.
Red Crag, Sutton, Bawdsey.

Recent, Mediterranean, Britain, and Scandinavian Seas.

Specimens of this species may be plentifully obtained in the lower or Coralline
Crag Deposit, especially at Gedgrave, where it appears to have been abundant, and
the numerous prominent and interlocking teeth being favorable for the preservation
of the valves in their natural position, they are frequently found united.

Considerable variation may be observed in comparing numerous individuals, some
of which closely approach what is called a species in the recent state under the name
of nitida, these differences consist principally in the proportionate dimensions, the
posterior side occasionally projecting more in some specimens than in others, and in
a greater solidity of shell. Faint traces of radiating striae ornament the exterior, they
are most visible near the margin, these lines are also visible within ; the number of
crenulations slightly vary, being smaller and closer of course in the younger shell, and
in this state the contour is generally more rounded, the posterior side in particular
being less truncate.

A species somewhat closely allied to this is found in the upper part of the Older
Tertiary Formations at Hordwell, and in the Isle of Wight, but it is probably distinct.
It is thinner, the hinge line narrower and more regular, with fewer teeth, while in
N. nucleus it is much broader as it approaches the anterior side, and the posterior
margin is rather less rounded.

A shell from the Upper Tertiaries of the United States strongly resembles this
species, and may, when better known, prove to be an identity.

5. NUCULA TRIGONULA, S. Wood. Tab. X, fig. 7, a — b.

NTJCULA TRIGONULA. S. Wood. Illust. Mag. Nat. Hist., vol. iv, New Series, p. 295, pi. 14, fig. 3.
S. Wood. Catalogue, 1840.
Morris. Cat. Brit. Foss., p. 95, 1843.

Spec. Char. Testa minutd, trigonuld, Icevigatd, tumidd, margaritaced ; antice sub-
angulatd, postice abbreviatd, margine ventrali crenulato.

Shell small, trigonular, smooth, tumid, nacreous, anterior side roundedly angular,
posterior side very short, ventral margin crenulated.

Longitudinal diameter, fths. Height, J of an inch.

Locality. Cor. Crag, Sutton.

About a dozen specimens with a much more angular or trigonal form than
is presented by the normal character of N. nucleus, are in my cabinet from the Cor.
Crag, which induced me, when publishing the Crag species of this family, to consider
them as belonging to a distinct species, and I am still inclined to retain them as such,
from a very marked difference in the outline ; it is nevertheless possible they may be
nothing more than specific variations, the result of some local condition ; they possess,

BIVALVIA. 87

however, sufficient difference to remain as specimens of a distinct variety, should they
be hereafter degraded from their isolated position. I have seen this species from the
Coralline Crag only, where JV. nucleus is found in abundance, and of all sizes, but
none of which seem to form any very close connection with this shell. British
Conchologists retain as distinct in this genus forms with less variation of character
than what is exhibited in our fossil specimens.

Nucula nitida, Sow., appears to offer less pretensions for specific distinction, than are
presented by the angulated outline of our fossil, but probably the whole three will
merge into one species.

Nucula proximo, of American authors, according to figures and descriptions, much
resembles our fossil, and is probably only another specific variation of a shell with
a very extended range.

Nucula radiata, Hanley, differs nothing in form from some of our Crag specimens,
and if it be a distinct species, may also have been in existence during that early
period.

LED A,* Schumacher. 1817..

NUCULA (sp.). Lam., 1801.

ARCA (sp.). Mont., 1803.

LEMBULUS. Leach, MS. 1819.

LEMBULA (sp.). Risso, 1826.

DACROMYA. Agass., 1839.

YOLDIA. Moller, 1842. Loven, 1846.

LEDA. Lov6n, 1846.

MOLDIA. Gray, 1847 (misprint).

Generic Character. Shell equivalve, inequilateral, elliptical or fig-shaped, posteriorly
more or less angulated or acuminated ; smooth or transversely striated, covered by
an epidermis in the recent state ; umbones small, approximate. Hinge furnished with
numerous teeth arranged in a linear series, curved or slightly angular, interrupted in
the centre, or immediately beneath the beaks by a triangular fossette for the reception
of the ligament ; impressions by the muscles ovate or subangular, that by the mantle
more or less sinuated.

Animal transversely ovate, mantle open in front with simple, sometimes fimbriated,
margins ; foot large and discoidal, with serrated edges ; posterior side of the mantle
prolonged into two, partially united, slender and unequal siphonal tubes.

The genus Nucula, as established by Lamarck, was intended to contain all those
shells which had a hinge furnished with a line of sharp prominent teeth, separated
at the umbo by an angular depression for the reception of the ligament, and placed

* Etym., a proper name.

88 MOLLUSCA FROM THE CRAG.

within the- margin of the shell, many of these have the posterior portion, as it were,
cut off or wanting, in which the animal is entirely without the protruding siphonal
tubes, and the impression of the mantle is therefore entire, this section constitutes our
genus Nucula, the type of which is Area nucleus, Linn. Many species formerly
included have a prolonged posterior side, making the shell sometimes nearly equi-
lateral, and the animal is then furnished with elongated siphonal tubes. This was
originally proposed by Schumacher, under the name of Leda, without his being at all
aware of the essential difference, as the only reason assigned for the division was that
these shells were more nearly related to Pectunculus (Essai d'un Nouv. Syst. des Vers.
Test. p. 173).

Moller divided these latter or bilateral Nuculae into two genera, without, however,
any apparent distinction, either in the shell or animal ; Nucula arctica, the species he
intended as the type of his genus Yoldia, being furnished with a sinuated impression
like that of N. minuta (the typical form of Leda), indicating the possession of
protruding siphons in the animal of that species ? neither does the form of the exterior
present any essential difference.

These resemblances were more especially pointed out by Professor E. Forbes, in
his valuable essay in the first vol. of the ' Memoirs of the Geological Survey,' p. 418,
where the two genera are united.

Shells possessing the form and characters assigned to this genus are found in some
of our oldest formations, and are continued through the more modern Periods.

1. LEDA LANCEOLATA, /. Sowerby. Tab. X, fig. 16, a — b.

NUCULA LANCEOLATA. J. Sow. Min. Conch., t. 180, fig. 1, 1817.
Morris. Cat. of Brit. Foss., p. 94, 1843.

— OBLONGA. G. B. Sowerby, Genera, No. 17, fig. 6.

Woodward. Syn. Tab. Brit. Org. Rem., p. 15, 1830.

S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 296, 1840.

— ARCTICA. Brod. and Sow. Zool. Journ., No. XT, p. 359, t. ix, fig. 1, 1829.

Middendorff. Mem. de 1'Acad. Imp. de St. Petersb. p. 544, 1849.
YOLDIA ARTICA. Moller. Ind. Moll. Groen., p. 18, 1842.

Spec. Ckar. Testa transversd, elongato-ovatd, incequilaterd, crassd ; antice majiore et
latiore elliptico-rotundatd, postice subrostratd ; externe striatd, striis transversis obliquis,
dentibus crassis angulatis.

Shell transverse elongato-ovate, inequilateral, thick and strong, anterior side the
larger and broader, elliptically rounded ; posterior subrostrated ; externally striated,
striae broad and oblique, teeth thick and angulated.

Longitudinal diameter, 2j inches.

Locality. Red Crag, Bawdsey.

Mam. Crag, Chillesford. Recent, Arctic Seas.

BIVALVIA. 89

This species in the recent state appears to be restricted to colder regions of the
northern hemisphere, and is essentially a Boreal species. In the Red Crag it is by no
means abundant, and until the discovery of the native bed at Chillesford, resting upon
the Red Crag, it was considered a shell of great rarity in our cabinets, but at this latter
locality it may now be obtained in considerable numbers, and the specimens have
there seemingly reached their full development in regard to size, some of mine having
a magnitude of two inches and a quarter in the longest diameter. This and Mya
truncata are the most characteristic as well as the most abundant species in that
Deposit. The anterior side of the shell may be described as forming nearly half a
regular ellipsis, and the posterior side is smaller and rostrated ; the pointed termi-
nation curving a little upwards; a large lanceolated corselet or flattened space occupies
nearly the whole length of the posterior slope, and a smaller or more narrow one is
generally to be seen at the dorsal margin on the anterior side ; the number of teeth are-
variable, generally about twenty on the posterior, and thirty on the anterior side, they
are large, prominent, sharp, and angular, with serrated edges, the lateral teeth
are more distant from each other than those nearer the umbo ; this is the
number in the adult shell ; in the younger state they are less numerous, additions
being made to their amount as the animal enlarges ; a sinus with two or three
obsolete rays curves over the anterior side at some little distance from the dorsal
margin, produced probably by the protrusion of a peculiarly formed foot at that part
of the edge of the shell ; coarse lines of growth cover the exterior, and these are
cut at a small angle by ridges which cross the shell in an oblique direction from
the anterior to the posterior ventral margin ; but not extending over the dorsal
portion of the shell on either side : in some aged specimens, the interior is irregu-
larly and ruggedly thickened, leaving deep impressions on those parts to which the
muscles of the animal were attached : that of the adductor on the anterior side is large
and angularly ovate, and not far from the extremity, the posterior one is smaller, and
situated more within the shell ; the curve formed by the retrocession of the siphonal
tubes is rather variable, extending in some specimens as far as the middle of the
ligamental area. The principal variation to which this species appears to be subject is
merely in the proportional dimensions.

The name proposed by Mr. J. Sowerby has priority of date over that employed by
Lamarck for a very different species, which was published in 1819, and as such it
is retained here for the Crag Fossil ; and for the shell, therefore, so called by
Lamarck, I would substitute that of cnltrata.

12

90 MOLLUSCA FROM THE CRAG.

2. LEDA MYALIS, CoutJtouy. Tab. X, fig. 17, a — c.

NUCULA MYALIS. Couth. Bost. Journ. Nat. Hist., vol. ii, p. 62, pi. 3, fig. 7, 1839.
Gould. Invert, of Massach., p. 99, 1841.
Dekay. Hist. New York Zool., p. 180, pi. 13, fig. 219, 1843.

— OBLONGA 1 Woodward. Geol. of Norf., p. 44, 1833.

— allied to OBLONGA. Lyell. Mag. Nat. Hist., New Series, p. 328, 1839.

— OBLONGOIDES. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 297, pi. 14,

fig. 4, 1840.

Morris. Cat. Brit. Foss., p. 95, 1843.
Forbes. Mem. Geol. Surv., vol. i, p. 420, 1846.

— HYPERBOREA. Loven, sec. Gould.

YOLDTA ANGULARIS. Moller. Ind. Moll. Grb'enl., p. 19, 1842.

Spec. Char. Testa transversd, intsquilaterd, elonffato-ovatd, tenui ; antice elliptico-
rotundatd, postice subrostratd ; Icevigatd ; dentibus mediocriter angulatis.

Shell transverse, inequilateral, elongato-ovate, thin, and externally smooth ;
anterior side roundly elliptical, posterior subrostrated ; externally smooth ; teeth
moderately angulated.

Longitudinal diameter, If inch. Height, 1 inch.

Locality. Red Crag, Sutton and Butley.

Mam. Crag, Chillesford and Bramerton. Recent, North America.

This species, like the preceding one, appears in the recent state to be confined
to the colder regions of the globe, and as a fossil has been found only in the
newer Tertiaries in this country. In the Red Crag I have met with but very
few specimens, while at Chillesford it may be obtained in abundance, and is by no
means scarce, I believe, in the Estuary portion of the Mammaliferous Crag at
Bramerton. It is readily distinguished from L. lanceolata, in being more equi-
lateral, the posterior portion is comparatively larger, and it wants the peculiar
diagonal ridges which ornament the surface of that shell ; nor does it appear
even to attain to such dimensions, my largest specimen being under two inches in
its transverse or longest diameter, neither is it ever so thick a shell. A specimen
obtained in the Red Crag at Sutton is more elongated or attenuated than those
usually found at Chillesford, and it approaches in that character L. limatula of the
American Seas (fig. 1 7, c) ; but that species is rather more elegantly formed, and
more rostrated, with a greater curvature at the posterior termination. Our shell is
covered with concentric striae or lines of growth, but not in regular ridges, and there
is not so distinct a sinus on the anterior side, as in L. lanceolata, although in some
specimens a radiating line traverses that side of the shell from the umbo, which line is
produced by a slight interruption to the regular curve of the margin : a large corselet
is well defined on the posterior side, and the ligamental pit is comparatively larger
than in L. limatula. The shell is sometimes thickened in the interior, though never

BIVALVIA. 91

so much so as in L. lanceolata, and the muscular marks are then deeply impressed,
those produced by the adductors are of a subovate form, and are unequal in size, the
anterior one being the larger, and the sinus formed by the mantle extends about as far
inwardly as the posterior part of the ligamental pit, which is broad and contracted in
the centre.

Our shell appears to correspond with the recent American species to which
it is here assigned, in all its characters, excepting size. Dr. Gould gives the dimen-
sions of his shell as 1^ inch in its largest diameter, which is considerably less than
the magnitude to which our fossil has attained. In the recent state it is generally
eroded at the beaks ; our fossil does not appear to have been at all acted upon at
that part, it is there quite perfect.

A shell from the Antarctic Seas, N. Eiglitsii, Coutkouy, strongly resembles our
British fossil.

3. LEDA SEMISTRIATA, S. Wood. Tab. X, fig. 10, a — b.

NUCULA SEMISTRIATA. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 297, pi. 14,

fig. 5, 1840.

NITIDA. Nyst. Rech. Coq. Foss. d'Anv., p. 16, pi. 3, fig. 62, 1835, (not Brocchi.)
— DEPRESSA. Nyst. Coq. Foss. de Belg., p. 220, pi. 15, fig. 7, 1844.

Spec. Char. Testa transversd, ovato-ellipticd, subaquilaterd, compressd, tenuissimi,
fragili ; antice rotundato-ovatd et Icevigatd, postice subrostratd et transversim striatd ;
natibus approximatis, margine integerrimo.

Shell transverse, elliptically ovate, subequilateral, compressed, thin, and fragile ;
anterior side roundly ovate and smooth ; posterior subrostrated and transversely
striated ; beaks approximate, margin quite smooth.

Longest diameter, 1 inch.

Locality. Cor. Crag, Sutton and Ramsholt.

This shell is abundant in the Coralline Crag at Sutton, but from its great fragility
specimens of the above dimensions are very rarely obtained, and if it be the same as
the Belgian fossil, which I presume is the case, M. Nyst speaks of it as being by no
means rare in the Campinian Beds.

The striae or transverse ridges upon our shell are rounded and obtuse, not sharp
or imbricated ; they cover the posterior half of the exterior, extending from a little
beyond the centre or umbo to the extremity, but often become irregular and obsolete
upon the posterior slope, and the shell is there depressed and subsinuated with a very
slightly recurved and somewhat pointed termination at the extremity of the dorsal
edge. From the extreme thinness of the shell the transverse edges are often visible
in the interior ; a long line of sharp angularly formed and prominent teeth occupy
the hinge area, amounting in large specimens to as many as five and twenty on the
anterior, with twenty or more on the opposite side, while in young ones they are not
above half that number : they are separated by a rather large and obtusely angular

92 MOLLUSCA FROM THE CRAG.

ligamental pit, somewhat contracted in the middle ; a large lanceolate-formed and well
defined lunule and corslet may be seen on both sides of the umbo, but the muscle
marks within are very slightly impressed and are indistinct, with doubtful traces of a
deeply sinuated form in the one by the mantle.

I am not at all acquainted with the range of this species ; but it does not appear
to have a specific relationship with Nucula Itevis, Say, with which M. Nyst has con-
sidered his shell identical, and to which he would also unite N. limatula, a very
different species. It resembles in outline N. sapotitta, Gould, but seems to differ speci-
fically from it in the conspicuous transverse ridges, as well as in having a greater
number of teeth, depending upon the figure and description of that very accurate
observer, Dr. Gould, who would undoubtedly have pointed out the exterior ornament
had it possessed any.

4. LED A CAUDATA, Donovan. Tab. X, fig. 12, a — b.

ARCA CAUDATA. Don. Brit. Shells, vol. iii, pi. 78, 1802.
— MINUTA. Mont. Test. Brit., p. 140, 1803, not Broc.
Turt. Conch. Diet., p. 11, fig. 98, 1819.
W. Wood. Ind. Test., p. 47, pi. 10, fig. 44, 1828.
NUCULA MINUTA. Turt. Brit. Biv., p. 178, 1822.

Brown. lUust. Conch. Gr. Brit., pi. 25, fig. 18, 1827.

S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 298, pi. 14, fig. 6,

1840.

Gould. Invert. Massach., p. 101, 1841.
— ROSTRATA. G. Sowerby. Genera No. 17, fig. 5.

Mac Gill. Moll. Aberd., p. 245, 1843.
LEDA MINUTA. Moller. Ind. Moll. Groenl., p. 17, 1842.
King. Ann. Nat. Hist., vol. xviii, p. 240.
Forbes. Mem. Geol. Surv., vol. i, p. 419, 1846.
— CAUDATA. Loven. Ind. Moll. Scand., p. 34, 1846.

Alder. Cat. Moll. North, and Durh., p. 79, 1848.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 226, pi. 47, figs. 12, 13, and
pi. P, fig. 2, 1849.

Spec. Char. Testa transversd, elongato-ovatd, vel faiformi, convexiusculd, tenui ; con-
centrice striatd, antice dreviori, rotundatd ; postice longiori attenuatd, angulatd, et sub-
rostratd, margine integro.

Shell transverse, elongato-ovate or fig-shaped, slightly convex, thin; covered
with transverse or concentric stria?; anterior side the shorter, rounded, posterior
attenuated, angulated, and subrostrated, margin smooth.

Longitudinal diameter, \ an inch nearly.

Locality. Red Crag, Sutton.

Mam. Crag, Bridlington.

Clyde Beds. Recent, Britain, Scandinavian Seas, and North America-

BIVALVIA. 93

I have seen but one specimen of this species from the Red Crag, which was found
by myself nearly twenty years since, and I presume it, therefore, to be rare in that
Deposit ; one specimen also from the Cabinet of Mr. Leckenby, found at Bridlington,
appears to belong to the same species, and they are both assigned to the recent
British one, and to the more ventricose or less transverse variety : specimens of the
recent shell, corresponding in every respect with our Crag fossil, have been obtained
by myself on the shore at low water on the Coast of Suffolk, and I have no hesitation
in pronouncing upon their identity.

5. LEDA PERNULA, Miiller. Tab. X. fig. 13, a — c.

AECA PERNULA. Mull. Besch. Berl. Naturf. Fr., iv, 57, 1779, fide Loven.
MARTINI. Chem. Conch. Cab., t. vii, t. 206, fig. 550, 1784.
ROSTRATA. Gmel., fide Lov6n.

W. Wood. Ind. Test., p. 47, pi. 10, fig. 43, 1825.
— FLUVIATILIS. Schrot. Flusc., p. 187, pi. 9, fig. 2, fide Desk.
NUCULA FLUVIATILIS. G. Sowerby, Genera No. 17, fig. 3.

— OBLONGA. Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 17, 1827.

— ROSTRATA. G. Sowerby. Conch. Illust., fig. 12.

Desk. 2d ed. Lam., t. vi, p. 504, 1835.
JACKSONI? Gould. Inv. Massach., p. 102, fig. 65, 1841.

Defray. Nat. Hist. New York Zool., p. 181, pi. 12, fig. 213, 1843.
TENUISULCATA. Couth. Bost. Journ. Nat. Hist., vol. ii, p. 64, pi. 3, fig. 8, 1839.
LEDA ROSTRATA. Forbes. Mem. Geol. Surv., p. 420, 1846.

Schum. Essai, &c., p. 1/3, pi. 19, fig. 4, a— b, 1817.
PERNULA. Loven. Ind. Moll. Scand., p. 34, 1846.

Spec. Char. Testa transversd elongatd, antice rotundatd, postice duplo longiori, in
rostrum obtusum attenuatd, concentrice striatd.

Shell transverse, elongate, anterior side rounded, posterior twice the length and
attenuated, terminating in an obtuse beak, concentrically striated.

Longest diameter, |ths of an inch.

Locality. Mam. Crag, Bridlington.
Clyde Beds.

One specimen (fig. 13, c) belonging to Mr. Bean, found at Bridlington, and
obligingly lent to me by that gentleman for the purpose of description, appears to
be somewhat different from the preceding, it corresponds with the recent form found
in the Boreal Seas of Europe, and which is most probably also a native of the
Northern Coast of America. Our fossil is not in good condition, being compressed
and slightly broken, and its natural form in consequence somewhat distorted, but it is
sufficiently perfect to permit of a presumed evidence of identity with the recent species.
It is more inequilateral than the preceding species, larger, and with finer concentric
striae, corresponding with the figure and description of N. tenuisulcata, Couthouy, and
of which, probably, N. Jacksoni, Gould, is only a variety. Fig. 13, a, d, is the repre-
sentation of a specimen from the Clyde Beds, given to me by Jas. Smith, Esq., of

94 MOLLUSCA FROM THE CRAG.

Jordan Hall ; all the specimens I have seen from these Deposits are small, scarcely
exceeding half an inch in length, while the one from Bridlington has nearly twice
that diameter.

This appears to differ but very slightly from the more elongated variety of
Z. caudata, considered a different species by our British Conchologists, as well as by
Dr. Loven, the principal difference is in the striae, which in this shell is finer or
more numerous.

6. LEDA TRUNCATA, Brown. Tab. X, fig. 14, a — 6.

NUCULA TRUNCATA. Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 19, 1827.
Smith. Mem. Wern. Soc., vol. viii, p. 42, 1838.

Spec. Char. Testa transversd, ovatd ; concentrice striatd, tumidd, subcequilaterd ;
antice rotundatd, postice truncatd vel subsinuatd ; umbonibus prominulis ; margine
integerrimo.

Shell transverse, ovate, subequilateral, tumid, concentrically striated ; anterior
side rounded, posterior truncate or subsinuated ; umbones slightly prominent ; margin
smooth.

Length, Jths of an inch nearly. Height, \ an inch.

Locality. ?

This shell has been rejected by the authors of the ' Hist, of British Mollusca' as
an existing British species, and although not found in any of our Crag Deposits,
belongs undoubtedly to the Upper Tertiaries of England. It is an animal still living
in the Arctic Seas, but is no longer an inhabitant of our own.

The specimen figured was obtained by Robert M'Andrew, Esq., who has
obligingly permitted me the use of it for the purpose of description : it was, he says,
in company with other, supposed extinct, species as Pecten Islandicus, &c., and
dredged from the depth of 40 to 60 fathoms, off the North Western Coast of the Isle of
Skye. It is ornamented with close-set strise, that appear independent of lines of growth,
as they occasionally bifurcate, and are not, therefore, quite parallel to the margin ; its
most peculiar character is on the posterior side, where there is a somewhat angular
ridge or keel from the umbo to the projecting beak-like termination, forming above
a large and elongate lunule-like space between it and the margin of the shell ; below
is another obtuse ridge extending from the umbo to the posterior part of the ventral
margin, and between this and the pointed termination, the shell is flattened or slightly
contracted at the margin, from which it is presumed it received its name : the shell is
tumid, the umbones somewhat curving over, so that the ligamental area projects
inwards ; there are from 12 to 18 teeth on each side, while the sinus in the mantle is
not very deep : the specimen is a full grown or aged individual, as the interior is
irregularly thickened, and more especially rugose between the margin of the shell
and the line of attachment by the mantle.

BIVALVIA. 95

7. LEDA PYGM^EA, Miimter. Tab. X, fig. 11, a — b.

NUCULA PYGM^A. Munst. Apud. Goldf. Pet. Germ., vol. ii, p. 157, t. 125, fig. 17.

S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 298, pi. 14, fig. 7,

1840.

Phil. En. Moll. Sic., vol. ii, p. 46, 1844.
Middendorff. Mem. de 1'Acad. Imp. de St. Petersb., p. 544, 1849.

— GIBBOSA. Smith. Mem. Wern. Soc., vol. viii, pi. 2, fig. 10, 1838.
CORBULOIDES. Id. in addendum.

— TENUIS. Phil. En. Moll. Sic., vol. i, p. 65, pi. 5, fig. 9, 1836.

Jeffreys. Ann. Nat. Hist., vol. xix, p. 313.
LENTICULA. Moll. Ind. Moll. Groenl., p. 17, 1842.

PHILIPPIANA. Nyst. Coq. Foss. de Belg., p. 224, pi. 17, fig. 5, a— c, 1844.
LEDA PYGM/EA. Forbes. Mem. Geol. Surv., vol. i, p. 419, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 230, pi. 47, fig. 10, and

pi. P, tig. 3, 1849.
YOLDIA PYGM^EA. Loven. Ind. Moll. Scand., p. 35, 1846.

Spec. Char. Testa minutd, ovato-trigonuld, subesquilatera ; tumidd, lavigatd, polifd,
clausd ; antice ovato-rotundatd, postice subrostratd ; lunuld indistinctd ; margine inte-
gerrimo.

Shell small, triangularly ovate, subequilateral, gibbous, smooth, glossy, and closed ;
anterior side roundedly ovate ; posterior subrostrated, without a distinct lunule ;
margin very smooth.

Longitudinal diameter, ith of an inch.

Locality. Cor. Crag, Sutton, Ramsholt, Gedgrave.

Clyde Beds. Recent, Mediterranean ? Britain, Scandinavia.

This species is found in several localities of the Coralline Crag, and very abundantly
at Sutton. It may be further described as having a very broad hinge line furnished
with 8 to 12 teeth on each side of the umbo, they are angular, large, and promi-
nent in the centre of the area and towards the sides, with large interspaces for
the interlocking of the teeth of the opposite valve, by which the two valves are
often found in conjunction. The shell is very tumid, moderately thick and strong,
and perfectly closed all round, it has a somewhat prominent umbo, and is without any
defined lunule or corselet ; the posterior side is generally though not always the
larger, and its termination rather acuminated and a little curved upwards : the
fossette for the ligament is very small, and the muscle marks not in general deeply
impressed or well defined ; that by the mantle has a small sinus. The shell is glossy
both within and without, and slightly nacreous. My Crag specimens are small, not
exceeding the sixth of an inch in the transverse or greatest diameter; but a few
specimens from the Clyde Beds, obligingly given to me by James Smith, Esq., of
Jordan Hall, appear to have attained larger dimensions, and are rather less equilateral.

This shell is given by Philippi, on the authority of Scacchi, as a species living
in the Mediterranean, and it is also found fossil in the Upper Tertiaries of that part
of the world.

96 MOLLUSCA FROM THE CRAG.

The living animal has recently been obtained by Mr. M'Andrew, from the depth
of nearly 50 fathoms, on a muddy bottom, in the Sound of Skye ; and it is quoted by
Loven as an existing species on the Coast of Finmark, while Moller gives it from the
Greenland Seas.

8. LEDA THRACI^FORMIS, Storer. Tab. X, fig. 15.

NUCULA THRACLEFORMIS. Stor. Bost. Journ. Nat. Hist., vol. ii, p. 122, 1838.

Gould. Invert. Massach., p. 97. fig. 66, 1841.
Dekay. Nat. Hist. New York (Zoology), p. 178, pi. 12, fig. 217,
a— b, 1843.

Spec. Char. " Testa ovato-o&longd, transversd, nigrd, crassd ; antice rotundatd, postice
truncata et compressd, umbonibns prominentibus ; cardinefoved magnd" (Storer.)

" Shell ovato-oblong, transverse, black, and thick ; anterior side rounded, posterior
truncated and compressed, beaks prominent, with a large ligamental pit."

The specimen figured, was obtained by R. M'Andrew, Esq., a gentleman to
whom science is so largely indebted for a more correct knowledge of our native
Marine Fauna. This novelty is the result of one of his very recent explorations in
the Sound of Skye, and was dredged, he tells me, at the depth of about 50 fathoms,
and found in association with Leda truncata, Pecten Islandica, &c., species supposed to
have become extinct in our own Seas, though still existing in some other regions of
the Northern Hemisphere : the specimen (although but a fragment, is a considerable
portion of the shell), was consigned to Professor E, Forbes, who is also of opinion
that it is identical with Leda Thraciteformis, and I am much indebted to those two
gentlemen for the privilege of being the first to make it known as having once been an
inhabitant of our own Seas ; and although it be another, to which as a describer of
the Crag species I may not strictly have a claim, it belongs at least to the bygone
times, and comes into the province of the Palaeontologist.

What remains of the specimen seems to justify its being considered as belonging
to the species to which it is here assigned, although the most characteristic portion of
the shell is destroyed ; I have, therefore, copied the specific character from the
original describer : it differs from L. truncata in being somewhat thinner and more
compressed, but there is scarcely enough of the shell remaining to show satisfactorily
the peculiar ridge on the posterior side sloping from the umbo to the extremity of
the ventral margin : it is ornamented with concentric striae, like L. truncata, and they
are slightly wavy in their direction.

The specimens of this species hitherto recorded as having been found in the recent
state were from the stomachs of the Cod and Sand-dab, and these fishes were taken
at the depth of 30 fathoms and upwards.

The outline tracing is copied from the figure of the recent shell in Dr. Gould's
1 Invertebrata of Massachusets.'

BIVALVIA,

97

UNIO, Retzius,

MYA (sp.). Linn., 1747.

TRIQUETRA. Klein, 1753.*

LIMN^A and LIMN^IODERMA (sp.). Poli., 1791.

CRISTARIA. Schum., 1817.

PAXYODON. Id. „

PRISODON. Id. „

MARGARITAKA. Id. „

AMBLEMA. Rafinesque, 1819.

1788.

ELLIPTIO.

Id.

EURYNIA.

Id.

OBOVARIA.

Id.

PLAGIOLA.

Id.

PLEUROBEMA.

Id.

PROPTERA.

Id.

TRUNCILLA.

Id.

AXIMEDIA.

Id.

DlPLASMA.

Id.

ELLIPSARIA.

Id.

LAMPSILIS.

Id.

LEPTODEA.

Id.

METAPTERA.

Id.

OBLIftUARIA.

Id.

QUADRULA.

Id.

ROTUNDARIA.

Id.

SCALENARIA.

Id.

1820.

SYNTOXIA. Rafinesque, 1820.
ALASMODONTA. Say, 1820.
MYSCA. Turton, 1822.
DIPLODON. Spix, 1827.
TETRAPLODON. Id. „
LASMIGONA? Rafin., 1831.
LASMONOS 1 Id. „
MONOCONDYL^A. D'Orb., 1835.
^EGLIA. Swainson, 1840.
CANTHYRIA. Id. „
CALCEOLA. Id. (notion.), 1840.

COMPLANARIA. Id. 1840.

CUNICULA.

HEMIODON.

HYRIDELLA.

IRIDEA.

LIGUMIA.

LYMNADEA.

MEGADOMUS.

NAIA.

NAIDEA.

POTAMIDA.

THELIDERMA.

UNIOPSIS.

Id.
Id.
Id.
Id.
Id.
Id.
Id.
Id.
Id.
Id.
Id.
Id.

LUTICOLA. Goldfuss, 1846.

Generic Character. Shell equivalve, inequilateral, generally thick and externally
smooth, occasionally ornamented with nodules or spines. In the recent state covered
with an epidermis, often wanting at the umbones, where the shell is sometimes much
eroded. Hinge, with two cardinal teeth in the left valve, and one, sometimes two, in
the right, an elongated lateral tooth on the posterior side. Impressions by the
adductor muscles large and deep, that by the mantle without a sinus. Ligament
external. Shell nacreous.

Animal of the form of the shell, its mantle open in front, with simple edges or
slightly fringed ; siphonal tubes short, plain or fringed, sometimes scarcely defined ;
foot large, compressed.

This is pre-eminently a fresh-water genus, and although found living in the rivers
of Europe, Asia, and Africa, appears to be only fully developed in the lakes and
rivers of North America, more than 200 species have been named and described from
that part of the world.

* In compliance with the recommendation of the Committee appointed by the British Association for
the Advancement of Science, 1842, "to consider the rules by which the Nomenclature of Zoology may be
established on a uniform and permanent basis," — the 12th edition of Linnseus's ' Systema Naturae,' 1/67,
is made the starting point from which the dates of priority have been adopted.

13

98 MOLLUSCA FROM THE CRAG.

The difference between this genus and that of Anodonta is in the absence of teeth
in the latter, as the name implies ; but the modification of the hinge as well as the
outward form of the shell in the whole group is so exceedingly variable, some being
perfectly orbicular, while others are elongated and cylindrical, as to have caused it to
be divided into numerous Genera, but these divisions appear to be founded upon
characters alike unstable and insignificant.

As fossil, this genus is said to date its existence from the Coal Measures ; it is
found in the Wealden, and in the Fresh-water Deposits of the Older as well as the
Newer Tertiaries, and wherever met with, the species are seldom numerous, but the
individuals are usually very abundant.

•

1. UNIO LITTORALIS, Lamarck. Tab. XI, fig. 12, a — b.

UNIO LITTORALIS. Lam. Syst. des An. sans Vert., p. 114, 1801.

Id. Hist, des An. Sans. Vert., t. vi, p. 66, 1815.

Drop. Hist. Nat. des Moll. Ter. et Fluv. de France, p. 133, No. 3,

pi. 10, fig. 20, 1805.

Brard. Hist. Coq. des Env. de Par., p. 222, pi. 8, fig. 6, 1815.
Pfeifer. Land and Sussw. Moll., p. 117, pi. 5, fig. 12, 1821.
Phil. En. Moll. Sic., vol. i, p. 66, and vol. ii, p. 48.
Mag. Nat. Hist., New Ser., vol. ii, p. 548, fig. 27, 1838.
Lyell, Elem. of Geol., 2d ed., vol. i, p. 62, fig. 29, 1841.
G. B. Sow., Jr. Conch. Man., fig. 145, 1842.
Rossmas. Icon, der Land and Sussw. Moll., No. xi, p. 14, t. Iv, figs. 473,

744, and No. xii, p. 27, t. Ivi, figs. 752—754, 1844.
Dupuy. Ess. sur les Coq. Viv. et Foss. Dep. du Gers., p. 86.

— PIANENSIS. Farines. ~\ „

, . f fide Rossmasler.

SUBTETRAGONTJS. Mich. J

— NANA. Desk. 2d ed. Lam., t. vi, p. 539, No. 17, 1835.

— ANTIQTJIOR. Strickland. Silur. Syst., p. 555, 1839.

— INCURVUS. Lea. Obs. Gen. UNIO, vol. i, p. 107, pi. 13, fig. 27, 1832.

— GRANOSUS. Schum., fide Lea.

MYA RHOMBOIDEA. Schritter. Ausland. and Flussch., t. 2, figs. 2, 3, 1783.
Ency. Meth., pi. 248, fig. 2.

Spec. Char. Testa ovato-oblongd, crassd, valde inaquUaterd, antice rotundatd, postice
subquadratd, compressiusculd ; umbonibus prominulis, flexuosis, undulatis ; dente antico
cardinis dextri crasso, triangnlan.

Shell ovato-oblong, thick, very inequilateral ; anterior side rounded, posterior
subquadrate, slightly compressed ; umbones with undulating rugosities ; anterior
cardinal tooth in the right valve thick and triangular.

Length, 2| inches. Height, \\ inch.

Locality. Cropthorn (Strickland], Clacton, Grays (Morris], Ilford (Morris).

Recent, France, Sicily.

Exceedingly abundant in the Fluviatile Deposit at Clacton.

BIVALVIA. 99

It may be further described as being furnished with two cardinal teeth in the left
valve, the anterior one is somewhat thin, sharp, and angular, sloping towards the muscle
mark on that side, the other one on the posterior side of the umbo is thick, strong, and
rugose, with a sharp, linear, lateral tooth, nearly parallel to the dorsal margin, or liga-
mental fulcrum : the right valve has one large cardinal tooth divided in the middle, this
fits into a depression in the left valve of a corresponding form, and parallel to the margin
is an elongated, sharp, and elevated, lateral tooth ; the muscle marks are deeply im-
pressed, more especially the anterior one, this is rugose and subquadrangular, and is
bipartite or has a smaller one adjoining, more within the shell; the posterior one,
placed at the extreme edge of the ligament, is slightly ovate, with the mantle mark
parallel to the margin of the shell, connecting the adductors ; the posterior is obtusely
angular, and the shell on that side is somewhat compressed or less tumid than at the
anterior : the surface of the shell is roughened by irregular and prominent lines
of growth ; on many of the individuals there are the remains of the epidermis, and
in most instances the specimens have the ligament entire, with the valves in their
natural position.

Several valves in my Cabinet have specimens of Balanus adhering to them,
showing the proximity of the Sea at one time to this Deposit, or perhaps the re-
occupation by salt-water of the locality once filled with fresh-water and its inhabitants.

This species has now an extensive Geographical range, being found in the North
of France, and in the fresh-waters of the Island of Sicily ; and Lea, in his ' Observations
on the Genus Unio,' vol. i, p. 201, says "the shell found in the Euphrates, near
Bagdad, is only a variety of this species," and he records it also as the opinion of the
Baron de Ferussac. I have never seen this shell.

2. UNIO TUMIDUS, Retzius. Tab. XI, fig. 13.

UNIO TUMIDUS. Rets. Nova. Gen. Test., p. 17, 1788.

Pfeiff. Land und Sussw. Moll., pt. ii, p. 34, pi. 7, figs. 2, 3, and pi. 8,

figs. 1, 2.

Rossm. Icon. Laud und Sussw. Moll., pt. i, p. 117, pi. 8, fig. 70;
pt. iii, p. 27, pi. 14, figs. 262—4; pi. 40, fig. 542; pi. 60,
figs. 772—778.

Gray. Man. Land and F. W. Shells, p. 297, pi. 2, fig. 13, 1844.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 140, pi. 40, fig. 1, 1849.
MYA OVALIS. Mont. Test. Brit., p. 34, 1803.

— DEPRESSA. Don. Brit. Shells, vol. iii, t. 101, 1802.
- OVATA. Don. Brit. Shells, vol. iv, t. 122, 1803.

MYSCA OVATA. Turt. Brit. Biv., p. 246, 1822.

Swains. Malac., p. 277, fig. 56, 1840.
SOLIDA. Turt. Brit. Biv., p. 246, pi. 16, fig. 2, 1822.
UNIO PICTOIIUM. Brown. Illust. Brit. Conch., pi. 26, fig. 2, 1827.

— OVALIS. Sowerby. Genera of Shells, No. 16, UNIO, fig. 1.

Brown. Illust. Brit. Conch., 2d ed., pi. 31, figs. 1—4.

— ROSTRATA? Desk. 2d ed. Lam., p. 540, t. vi, 1835.

100 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa ovatd, transversd, elongatd^ crassd, valde inaquilaterd ; antice
rotundatd, postice productd, cuneatd, subrostratd ; umbonibus rugosis.

Shell ovate, transversely elongate, thick, very inequilateral ; anterior side rounded,
posterior produced, somewhat pointed, and obtusely angulated or wedge-shaped ;
umbones rugose.

Length^ 3^ inches.

Locality. Stutton, Grays. Recent, Britain, France, and Germany.

This species is very abundant at Grays, where specimens have been obtained in
great perfection, and although by no means rare at Stutton, they are in a very
decorticated condition. Both these localities present us with forms deviating con-
siderably from what are generally met with in the living state, more especially those
from the latter locality, where they attain a magnitude of nearly four inches in length,
and appear to have a greater proportion of the shell on the anterior side of the umbo,
while in those from Grays, which are smaller, that side is shorter and proportionally
broader than in the living specimens ; in the Grays fossil the posterior side is obtusely
pointed, and the whole shell is more angular, while the Stutton specimens are rather
less so than the general or common form of the recent shell ; as these extremes of
variation can readily be connected through the living species, it is presumed that the
differences are wholly insufficient for specific separation, and I have no hesitation in
assigning the fossils of both localities as identities of the existing British species ; the
dental characters are also similar, the anterior tooth of the right valve being coarsely
crenated on the upper or dorsal side, and somewhat compressed; the elongated
lamina on the posterior side is linear, sharp, and nearly smooth.

It was at first thought, that as the Land and Fresh-water shells found in the
newer Tertiaries of this country are all assumed to be the Homogenitors of exist-
ing animals, a name alone with' reference to a work in which they have been
described would have been sufficient for Geological purposes ; but upon more minute
examination many of them have been found to present characters deviating in so great
a degree, that their identity has by some Conchologists been called in question ; it is
therefore now considered desirable that a figure and description of a part of them at
least should be given, more especially as they have never yet appeared in any publi-
cation as British Fossils.

3. UNIO PICTORUM. Linn&us.

MYA PICTORUM. Linn. Syst. Nat., ed. 12, No. 28, p. 1112, 1/67.

Poll. Test. Sicil., vol. i, p. 2, t. 9, figs. 6, 7, 1791.
UNIO PICTORUM. Drap. Moll. Tert. et Fluv. de Fr., pi. 11, fig. 4, 1805.

Gray. Man. Land and F.-W. Shells, p. 295, pi. 2, fig. 11, 1844.
Rossm. Icon. Land und Sussw. Moll., figs. 71, 196; pi. 29, fig. 409 ;

pi. 58, figs. 762—766, 1844.

Forb. and. Hani. Hist. Brit. Shells., vol. ii, p. 142, pi. 39, fig. 1, and
pi. Q, fig. 2 (Animal), 1849.

BIVALVIA.

101

MYSCA PICTORUM. Turt. Brit. Biv., p. 245, 1822.

— DESHAYESII. Brown. Illust. Brit. Conch., p, 81, pi. 32, figs. 1 — 4.

Rossm. Icon. Land und Sussw. Moll., p. 23, pi. 13, fig. 197.

— LONGIROSTEIS. Ziegl. in Rossra. Iconog., pt. 3, p. 26, pi. 14, fig. 200, and pt. 12,

pi. 54, fig. 38.
Ency. Meth., t. 248, fig. 4.

Spec. Char. Testa transversd, elongatd, subovatd, inceguilaterd, antice rotundata,
postice, anyulatd, mx rostra ta ; margine dor soli et ventrali subrectd.

Shell transversely ovate, elongate, inequilateral ; anterior side rounded, posterior
angulated, scarcely rostrated ; dorsal and ventral margins nearly straight.

Length, 2 inches.

Locality. Grays, Cropthorn. Recent, Britain, France.

This shell appears very rare as a British fossil ; one specimen in the cabinet of
Mr. Pickering is of a form that may be determined without much hesitation as belong-
ing to this species, and resembles rather the thinner variety of the recent shell. The
principal or perhaps only difference observable between this and the preceding species
in the fossil state, is a more elongated dorsal area, less sloping on the posterior side,
so that the ventral margin is more parallel with the upper edge than in U. tumidus.
A specimen in the British Museum, from the same locality, seems to possess the like
determinable characters, and one in the Museum of the Geological Society, presented
by Mr. Strickland as from Cropthorn appears to be of this species. These specimens
are all that I have seen, they mostly resemble fig. 766, Rossmasler.

ANODONTA, Cuvier, 1798.

MUSCTJLUS (sp.). Lister.

MYTILUS (sp.). Linn.

LIMN^A and LIMN.EODERMA (sp.). Poli,

1791.

ANODONTITES. Brug., 1799.
DIPSAS. Leach, 1814.
APPIUS. Id. MSS., fide Gray,
ANODON. Oken., 1815.

CRISTARIA. Schum., 1817.
STROPHITUS. Rafinesque, 1820.
LASTENA. Id.

SYMPHYNOTA (sp.). Lea., 1832.
ODATELIA. Rafinesque, 1832.
LAMPROSCAPHA. Swains., 1840.
HEMIODON. Id.

PATULARIA. Id.

Generic Character. Shell equivalve, inequilateral, ovate, transverse, usually thin,
more or less eared, and closed ; smooth, and in the recent state covered with an
epidermis generally eroded at the umbones. Hinge linear, edentulous, or with one
elongated lamina on the posterior side. Ligament external. Impression of the mantle
without a sinus.

The animal of this genus closely resembles that of the preceding one, being furnished
with a large fleshy, compressed foot, and the hinder part of the mantle is ornamented
with short and pointed tentacles ; anal opening is large, and the margin plain.

102 MOLLUSCA FROM THE CRAG.

These animals are bisexual, and the young shell is completely formed before
exclusion, although differing then materially in shape from that of its parent. Their
power of multiplication is said to be enormous. Mr. Lea states that he counted not
less than six hundred thousand young in an adult specimen.

The shells of this genus are also exceedingly variable, more especially in the out-
ward form; some species have the hinge area largely elevated into the form of a wing,
and in consequence of these variations, as well as from differences in size of dental
characters, they have also been separated into several genera.

It appears to be a modern genus, and only yet known in the fossil state from the
newer Tertiaries.

1. ANODONTA CYGNEA, Linneeus. Tab. XI, fig. 11.

MYTILUS CYGNEUS. Linn. Syst. Nat., ed. 12, No. 257, 1158, 1767.

Mat. and Rack. Linn. Trans., vol. viii, pi. 3A, fig. 2, 1807.
Poli. Test. Sicil., vol. ii, p. 212, pi. 33, fig. 2, 1795.
Sheppard. Trans. Linn. Soc., vol. xiii, p. 84, pi. 5, fig. 3, 1822.

— ANATINUS. Linn. Syst. Nat., ed. 12, p. 1158.

Poli. Test. Sicil., vol. ii, p. 213, pi. 33, fig. 1, 1795.

— AVONENSIS. Mont. Test. Brit., p. 172, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 250, pi. 3.

— MACULA. Sheppard. Linn. Trans., vol. xiii, p. 88, pi. 5, fig. 6, 1822.
STAGNALIS. Sowerby's Brit. Miscellany, pi. 16.

Brown. Illust. Brit. Conch., pi. 27, fig. 2, 1827.
DENTATUS. Turt. Conch. Diet., p. 115, 1819.

— INCRASSATUS. Sheppard. Linn. Trans., vol. xiii, p. 85. pi. 5, fig. 4.
ANODONTA CYGNEA. Pfeiff. Land und Sussw. Moll., p. Ill, t. vi, fig. 4, 1821.

ANATINA. Id. - p. 112, t. vi, fig. 2, „

INTERMEDIA. Id. - p. 113, t. vi, fig. 3, „

VENTRICOSA. Kickx. Moll. Brab. Aust., p. 80.

PISCINALIS. Nils. Moll. Succ. Ter. et Fluv., p. 116, fide Forb. and Hani.

CYGNEA. Rossm. Icon. Land and Sussw. Moll., pp. 1, 111, t. 3, fig. 67, 1835.
ANODON PALUDOSA. Turt. Brit. Biv., p. 240, pi. 15, fig. 6, 1822.
SYMPHYNOTA CYGNEA. Lea. Obs. on the Gen. UNIO, vol. i, p. 70, 1832.

Spec. Char. Testa oblongo-ovata, scepe compressd, tenui, interdum tumidd et incrassafd ;
antice rotundatd, postice productd, et angulatd ; natibus depressiusculis, rugosis.

Shell oblongo-ovate, generally compressed and thin, sometimes tumid or inflated,
occasionally thick ; anterior side rounded, posterior produced, and angulated ; umbones
rather flat, with undulating rugosities.

Length, 3^ inches. Height, 2 inches.

Locality. Stutton, Clacton. Grays (Pickering] , Cropthorn, and Bacton (Morris}.

Recent, Britain, and North of Europe.

This species is abundant in individuals both at Stutton and Clacton, the two
localities of Fresh-water Deposits that I am best acquainted with, although from
their great fragility specimens are very difficult to obtain in any degree of

BIVALVIA. 103

perfection. In all probability it was equally variable in the earlier periods of its
existence, as it is at the present day. The few specimens that I possess present
considerable differences in outward character, from which, therefore, it is not unfair
to infer, that amongst a greater number, and from different localities, we should, as in
the living shell, which varies under different external conditions, also have a great
variety in the fossil state.

The specimens from Stutton (generally in a decorticated condition) are very in-
equilateral, the anterior side being particularly short in proportion to the other, and
the shell is rather less in length comparatively, but it is almost impossible to obtain a
specimen at that locality without some slight degree of distortion, and its true characters
are therefore difficult to determine ; but there is no doubt it is the homogenitor of our
old acquaintance, which in the living condition puts on such a variety of shapes. The
one from Clacton is more elongate, and corresponds with a variety abundant in the
Thames above Maidenhead, in Berkshire. Mr. J. E. Gray (Manual of Land and
Fresh-water Shells of the British Islands) considers the many different forms found in
this country, and described under distinct specific names, to be only modifications of
the same species, and the authors of the ' History of British Mollusca' are of the same
opinion ; from what I have seen I fully acquiesce in their decision, and the fossil
specimens that have come under my observation may be arranged in the same
category.

As the geographical range of this species extends over the greater part of Europe,
we may naturally expect to find it in the fossil state.

CYRENA, Lamarck. • 1818.

VENUS (sp.). Chem.
TELLINA (sp.). Gmelin.
CYCLAS (sp.). Lam., 1799, 1801.
CORBICULA. Meyerle, 1811.
CYANOCYCLAS. Ferussac, 1818.
GELOINA. Gray, 1844.
VELORITA. Id. „

Generic Character. Shell equivalve, roundly trigonal or subovate, generally
tumid or inflated, more or less inequilateral, thick and strong. Hinge with three
cardinal teeth, and a large extended lateral tooth on each side, serrated or striated in
some species : in the recent state covered with an epidermis : ligament external :
impression of the mantle without a sinus.

The animals constituting this genus are in a recent state inhabitants of pure
fresh-water, and are only known in tropical or sub-tropical rivers, where the climate is
particularly mild. They are described by Malacologists as not differing essentially

104 MOLLUSCA FROM THE CRAG.

from the fresh-water genus Cyclas, excepting in their shelly covering, which in this shell
is thick and opaque, while in Cyclas it is thin and corneous or semitransparent. Lamarck
placed them in his Family Conchse fluviatiles, in consequence of a resemblance to the
animals of the Veneridse, and from possessing the lobes of the mantle prolonged into
siphonal tubes, distinct and separated down to their bases.

Although in the recent state, this is a genus of pure fresh-water origin ; specimens
have been found in the Estuary Deposit of the Norwich or Mammaliferous Crag almost
too numerous to be considered as entirely of accidental introduction.

1. CYRENA CONSOBRINA, Caillaud. Tab. XI, fig. 15, a — c.

CYRENA CONSOBRINA. Gail, Voy. en Egypt, t. 2, pi. 61, figs. 10, 11, 1823.

Desc. de 1'Egypt Hist. Nat., t. 22, p. 193, pi. 7, fig. 7, 1, 2, 3.

— TRIGONULA. S. Wood. Mag. Nat. Hist., vol, vii, p. 275, fig. 45, a, b, c, 1834.

Lyell. Elem. Geol., 2d ed., vol. i, p. 61, fig. 26, 1841.

— GEMMELLARII. Phil. En. Moll. Sic., vol. i, p. 39, t. 4, fig. 3, 1836.

/</.--- vol. ii, p. 31, 1844.

— DUCHASTELLII. Nyst. Bull, de la Soc. de 1'Acad. Roy. de Brux., p. 113, pi. 1,

figs. 1—4, 1838.

Spec. Char. Testa rotundato-trigonuld, subcequilaterd, tumidd, crassd ; lineis elevatis,
concentricis, Icevibus, distantibus ; cardine tridentato, divergens, inter se insertis ; dentibus
lateralibus longissimis, perpendicnlariter striatis.

Shell roundly trigonal, subequilateral, tumid, and thick; externally ornamented
with smooth, concentric, sharp, and distant ridges ; hinge with three cardinal diverging
teeth in each valve, lateral teeth elongated and perpendicularly striated.

Locality. Mam. Crag, Brarnerton, Wangford, and Bulcham (Alexander).

Stutton and Grays. Recent, River Nile.

This species is exceedingly abundant in the purely Fresh-water Deposit at Stutton,
where the valves are commonly united, as they are in general with fresh-water species,
individual specimens may be obtained by hundreds. When the shell was first
described and figured in the ' Mag. Nat. Hist./ as referred to above, it was imagined to
be specifically distinct in consequence of the posterior side being somewhat angulated,
in which character it differs from the general form of the recent species, now con-
sidered as identical ; but among a large series of the British fossils this character
disappears, and as a distinguishing mark cannot be faithfully relied upon, as the
specimens from Grays do not possess it, but have both sides more rounded, and
correspond in form precisely with the Nile shell ; there is every reason, therefore, to
believe its descendant to be now living in the rivers of Egypt, to which part of the
world it appears to have retired through the once existing fresh-waters of Sicily, for
I consider the shell figured by Philippi, as nothing more than a variety of this species,
although he has described it as having only two cardinal teeth in each valve, while
there are three perfectly distinct in our shell ; the anterior one in the right valve and

BIVALVIA. 105

the posterior in the left being the smallest, these in imperfect specimens of the fossil
might have been overlooked.

The outline of our shell is roundly trigonal, the posterior side being rather more
angular and larger than the other, and the diameter is generally greater in a longi-
tudinal direction, but in others it is even higher than long; the right valve has one
central, triangular, sub-bifid, cardinal tooth immediately beneath the umbo, and
another on each side of it diverging at a very considerable angle ; in the left valve, the
three cardinal teeth correspond in form with the interstices of the right valve, two large
elongated and elevated lateral teeth, occupy the whole of the dorsal portion of the shell
in the left valve, and these fit into depressions of the right one so as firmly to fix
the two pieces when they are closed, and on each of these lateral teeth, as also on
each side of the dental furrow in the right valve, are numerous fine striae perpendicular
to these lateral ridges, and on the inside of the callus or fulcrum for the support of
the ligament are the same markings ; the muscular impressions are somewhat unequal
in size, the posterior one being the larger and of a subquadrate form, while the anterior
is more triangular, these are connected by the line of the mantle-mark which has an
incipient sinus or indentation close to the posterior adductor ; these marks are seldom
deeply impressed and not always visible, but when seen, they do not extend beyond
the extreme verge of the lateral teeth. On the ouside, the shell is ornamented with
numerous, sharp, generally equidistant ridges, parallel to the margin, and in the
concave spaces between them may be seen the lines of growth ; a faint line is visible
in perfect specimens curving from the umbo on each side, forming a sort of large
corselet and lunule, of an elongated ovate form, beyond which the ridges do not
extend, precisely similar to what is seen in the ^Egyptian shell : in most of the
specimens of the fossil, the outside is more or less decorticated, but there is very little
of erosion visible in any of my specimens at the umbones, nor is the ligament ever
preserved, but that is not very thick even in the recent state.

It has been thought necessary to be thus tediously particular in giving all the
minutiae of characters belonging to this species, in order to remove any doubt respect-
ing its identity with the well-known shell now inhabiting a part of the world where
climatal conditions are different from what it is supposed were those under which it
existed in this country.

A few specimens of this species have been obtained by Capt. Alexander and
myself from the Coralline Crag at Gedgrave, near the mouth of the Butley River, but
in association with some Helices and other land shells, all identical with existing
animals. At this locality, the Crag appears to have been denuded of its more Coralline
portion, and these shells are intermixed near the present surface with the remains
of the Marine Molluscs of the lower part of that Deposit.

Depending, therefore, upon this evidence alone, we can scarcely consider the
Geological Age of this species to date its existence so far back as the Period of the
Coralline Crag.

14

106 MOLLUSCA FROM THE CRAG.

CYCLAS.* Bruguiere, 1792.

SPHyEBIUM. Scopoli, 1777.

Nux. Humph., 1797.
CORNEA. Megerle, 1811.
COENEOCYCLAS. Ferus., 1818.

Generic Character. Shell equivalve, subequilateral, more or less tumid or inflated,
thin and closed, sometimes semipellucid, smooth or slightly marked by lines of
growth, and in the recent state covered with an epidermis. Hinge furnished with
one or two cardinal teeth, and distant lateral teeth on each side. Impressions of the
adductor muscles indistinct. Palleal impression with a small sinus. Ligament
external, slender.

Animal suborbicular, its mantle open in front, with plain or simple margins ;
siphon produced and divided at the extremity into two distinct tubes, the edges plain
or without fringes : foot large, compressed, extensile, and more or less pointed.

Priority of name most properly belongs to Scopoli, but the small and corneous
shells here included are so universally known by the above designation, that I do
not feel disposed to make the alteration, more particularly as Sphtfrium has been
since adopted in another department of Natural History as a Generic Term. Animals
now determined to belong to three distinct Genera were included by Bruguiere, as
well as by Lamarck, under the name of Cyclas, and the latter author subsequently
proposed to sever from them the thicker and more ponderous species, and unite them
into a genus by themselves, under the name of Cyrena.

The shells constituting this genus are for the most part very thin, and of a
corneous or semitransparent texture in the living state ; their little inhabitants are
possessed of considerable powers of locomotion, and move about in the water with
facility by means of their large and flexible foot ; they frequent pools, ditches, lakes,
and sluggish streams, and when still, are generally found buried in the sand or muddy
bottom of the water. They are viviparous or rather ovoviviparous, and the young are
not only perfectly formed before exclusion, but are sometimes of considerable magni-
tude, occupying a large portion of the parent shell to the manifest inconvenience of
the mother.

They are purely Fresh-water Molluscs, and the Formations in which they are
found fossil, are either of Fresh-water origin or of Estuaries in close proximity into
which they have been washed. Species have been figured and described as belonging
to this genus from the Wealden Formation ; an undoubted Cyclas was found by myself
in the Fresh-water Deposit at Hordwell, belonging to the Older Tertiaries.

* Etym. KVK\ds, circular.

BIVALVIA. 107

1. CYCLAS RIVICOLA, Leach. MSS.

TELLINA CORNEA. Linn. Syst. Nat., ed. 12, No. 72, p. 1120 (part), 1767.

Var. /3. Mat. and Rack. Linn. Trans., vol. viii, p. 59.
CARDIUM CORNETJM. Mont. Test. Brit., p. 86, 1803, Var.

NUX. Da Costa. Brit. Conch., p. 189.
CYCLAS CORNEA. Drop. Moll. Terr, et Fluv. Fr., p. 128, t. 10, figs. 1—3.

Brard. Coq. Ter. et Fluv. des Env. de Par., p. 219, t. 8, figs. 2, 3.
BivicoLA. " Leach" in Lam. Hist, des An. s. Vert., t. v, p. 558, 1815.
Turt. Brit. Biv., p. 248, pi. 11, fig. 13, 1822.
Pfeiff. Land und Sussw. Moll., p. 121, pi. 5, figs. 3—5, 1821.
Sowerby. Genera of Shells, No. 38, CYCLAS.
G. Sow., Jr. Conch. Man., fig. Ill, 1842.

Forl. and Hani. Hist. Brit. Moll., vol. ii, p. Ill, pi. 37, figs. 1, 2.
Ency. Metb., pi. 302, fig. 5'.

Spec. Char. Testa transversd, ovatd, tumiduld, crassiusculd, subaquilaterd, antice et
postice convexd ; concentrice striatd ; ligamento cardinali conspicuo.

Shell transversely ovate, somewhat tumid and strong, slightly inequilateral,
anterior and posterior sides rounded ; finely striated concentrically ; cardinal area
conspicuous.

Length, 1 inch. Height ', fths.

Locality. Southend (Warburtori), Faversham (Trimmer}.

I have not myself met with this species as a fossil, but specimens in that state
have been obtained by Messrs. Warburton and Trimmer, from Faversham and
Southend. The specimens referred to are in the Museum of the Geological Society.

2. CYCLAS CORNEA, Linnaeus. Tab. XI, fig. 2, a — b.

TELLINA CORNEA. Linn. Syst. Nat., ed. 12, No. 72, p. 1120, 1767.

Chem. Conch. Cab., t. vi, p. 136, t. 13, fig. 133, bad.
Penn. Brit. Zool., ed. 4, p. 89, pi. 49, fig. 36.
Donov. Brit. Shells, vol. iii, t. 96, 1802.

— RIVALIS. Mull. Verm. Hist., t. ii, p. 202.

— STAGNICOLA. Sheppard, Linn. Trans., vol. xiv, p. 150, 1825.
CARDIUM CORNEUM. Mont. Test. Brit., p. 86, 1803.

CYCLAS CORNEA. Pfeiff. Deutsch. Land und Sussw. Moll., p. 120, t. v, figs. 1, 2, 1821.
Turt. Brit. Biv., p. 248, pi. 11, fig. 14, 1822.
Gray. Man. Land and F.-W. Shells, p. 280, pi. 1, fig. 2, 1840.
Jenyns. Trans. Camb. Philos. Soc., p. 295, 1831.
Phil. En. Moll. Sic., vol. ii, p. 30, 1844.
Forb. and Hani. Hist. Brit. Moll., vol.ii, p. 113, pi. 37, figs. 3—6, 1849.

— RIVALIS. Drap. Moll. Terr, et Fluv., p. 129, pi. 10, figs. 4, 5, 1805.

Brard. Coq. Terr, et Fluv. Env. de Paris, p. 222, pi. 8, figs. 4, 5, 1815.

— FLAVESCENS. Mac Gilliv. Moll. Aberd., p. 246, 1843, fide Forb. and Hani.

Spec. Char. Testa transversd, ovatd, inflatd, tenui, etfragili, subinaquilaterd ; postice
majiore, subquadratd, antice rotundatd, concentrice striatd, margine ventrali leviter arcuatd,
apicibus obtusis.

108 MOLLUSCA FROM THE CRAG.

Shell transverse, ovate, tumid, very thin and fragile, slightly inequilateral, posterior
side the larger, and sub quadrangular ; anterior rounded, very finely striated con-
centrically ; ventral margin lightly curved.

* Length, \ an inch. Height, fths of an inch.

Locality. Mam. Crag, Bulcham, Southwold.

Cropthorn, Grays, Clacton, Stutton, Faversham.

Recent, Britain, France, Sicily.

This species is abundant in the Fresh-water deposits of Clacton and Stutton. The
principal form is nearly ovate, and some have both sides equally rounded, but occa-
sionally the posterior is obtusely angulated, the line of hinge carrying the lateral tooth
rather further backwards than ordinary, giving it on that side a somewhat square
outline. The animal in the recent state has strong adductor muscles, but they have
made only a very indistinct impression upon the shell ; the hinge is furnished with an
apparatus well adapted to assist the close security of the valves, the right one having
a sharp prominent arched or diverging tooth, immediately beneath the umbo, which
locks into or between two others of similar form in the left valve ; the lateral teeth
are prominent and at unequal distances, that on the posterior side being considerably
the more distant ; in the left valve there is one before and one behind the umbo}
and in the right there are two on each side, between which the single one is inserted
when the valves are closed. Some specimens are quite smooth, while others are
distinctly marked with numerous, obtuse concentric ridges. In the young state the
shell is much flatter than when full grown.

This species is common throughout Europe, extending its range from Sicily on
the south to Sweden in the North.

A few specimens of this fragile shell were found by Capt. Alexander, in the
Estuary portion of the Mammaliferous Crag.

PISIDIUM,* Pfei/er. 1821.

TELLINA (sp.). Linn.

CARDIUM (sp.). Poli.

CYCLAS (sp.). Lam.

PISUM. Megerle, 1811, fide Gray.

PERA. Leach, MSS., 1819.

EUGLESIA. Id. „ 1820.

GALILEJA. Costa, 1839, fide Phil. ,

Generic Character. Shell small, equivalve, inequilateral, subovate, more or less
inflated, somewhat thin ; in the recent state subpellucid, and covered with an
epidermis ; smooth or concentrically striated. Hinge with one or two cardinal, and

* Etytn. Pisum ?

BIVALVIA. 109

two lateral teeth in each valve. Ligament external, situated on the shorter side.
Impressions of the adductors and of the mantle indistinct.

Animal subovate, with its mantle open on the anterior side and the margins
without fringes, united towards the posterior, where it forms a short and single
siphon, the orifice of which is plain ; foot large, tongue-shaped, and extensile.

This genus has been separated from Cyclas in consequence of a difference in their
animal inhabitants, those of Cyclas having the siphon dichotomous, or divided near
the end into distinct tubes, whereas in this it remains single and simple, to the
extremity, and is not so long. The species as yet known are all small, and have
similar habits to the preceding, frequenting ditches or pools of stagnant water, or
where the stream is not very rapid, and like the allied genus they are perfectly
formed in the parent animal before exclusion. They differ also in having the side
on which the ligament is situated, the posterior, shorter than the anterior ; in Cyclas
it is the reverse.

It has not as yet been met with in any Deposit of an anterior date to the Newer
Tertiaries.

1. PISIDIUM AMNICUM, Mutter. Tab. XI, fig. 1, a — b.

TELLINA AMNICA. Mull. Verm. Terr, et Fluv., pt. 2, p. 205, 1774.

Chem. Conch. Cab., t. vi, p. 138, t. 13, fig. 134, 1782.

— EIVALIS. Maton. Trans. Linn. Soc., vol. iii, p. 44, pi. 13, figs. 37, 38.

Donovan. Brit. Shells, vol. ii, pi. 64, fig. 2, 1801.
CAEDIDM AMNICUM. Mont. Test. Brit., p. 86, 1803.
CYCLAS PALUSTRIS. Drop. Moll. Ter. et Fluv., p. 131, pi. 10, figs. 15, 16, 1805.

— OBLIQUA. Lam. Hist, des An. s. Vert, t. v, p. 559, 1815.

Brown. Illust. Brit. Conch., pi. 17, fig. 14, 1827.
AMNICA. Turt. Brit. Biv., p. 250, pi. 11, fig. 15, 1822.

Id. Land and F.-W. Shells, p. 15, pi. 1, fig. 5.
Lyell. Elem. of Geol., 2d ed., vol. i, p. 227, fig. 103, 1841.
PEKA FLUVIATILIS. Leach, MSS., fide Jenyns.
PISIDIUM OBLIQUUM. Pfeiff". Land und Sussw. Moll., pt. 1, p. 124, pi. 5, figs. 19, 20,

and pi. 1, fig. 19, 1821.
Phil. En. Moll. Sic., vol. ii, p. 31, 1844.
AMNICUM. Jenyns. Trans. Camb. Phil. Soc., vol. iv, p. 309, pi. 21, fig. 2.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 133, pi. 37, figs. 8, 9,
and pi. 0, fig. 8, 1849.

Spec. Char. Testa ovatd, oblique trigond, ventricosd, sulcato-striatd umbonibus
obtusiusculis.

Shell ovate, obliquely- trigonal, ventricose, striated or sulcated, umbones rather
obtuse.

Length, | an inch.

Locality. Mam. Crag, Southwold.

Grays, Erith (Morris}, Cropthorn (Strickland}, Clacton, Stutton.
Faversham, and Kennet Valley (Pickering}. Recent, Britain, France, Sicily.

110 MOLLUSCA FROM THE CRAG.

This is a most abundant shell at Clacton and Stutton, and is subject to a
good deal of variation, both in the outline and in its exterior ornament ; in all varieties
the young shell is generally natter or more compressed than when full grown ; there
is also a difference in the substance of the shell, some specimens are thin and tender,
while others are quite thick and strong. Those which are most flat are also in
general thinner, and have a greater length from the anterior to the posterior, and are
longer also on the hinder side. The specimens from Grays are mostly the thicker
variety, in which the posterior side is remarkably short and truncate, and the striae on
the outside are finer and more numerous : this has been called P. sulcatum (fig. 1, 6),
but it is, I believe, no more than a variety, as a recent acquisition of numerous
specimens show every intermediate alteration to those which are much less inequi-
lateral, and have more distant ridges upon the exterior. These fossils seem to present
rather more differences than any specimens that I have seen of the recent shell, and it
is, therefore, thought desirable to have the two extreme forms represented, in order
more effectually to display these variations. The hinge is furnished with two cardinal
teeth in each valve, one small and simple, the other large and bifid, the posterior one
in the right is bifid, while in the left valve it is the anterior ; there is a large promi-
nent lateral tooth before and behind the umbo at nearly equal distances in the left
valve, and two on each side in the right : this hinge line is broad with teeth of cor-
responding magnitude in the thick variety, and in some specimens these form with the
umbo an angle of little more than 90°, whereas in others of the elongated variety that
angular line will be as large as 130°. In the thick variety, the posterior side projects
but very little behind the umbo, nearly the whole of the animal being on the anterior
side of the shell ; in other specimens, this side is two fifths as large as the other, and
the shell much less inequilateral. Similar differences may be also observed in the
sculpture of the exterior, they are always ornamented more or less with concentric
or elevated lines of growth, but in some, these markings are numerous, rounded, and
placed close together, while in others they are sharp and narrow with a considerable
plain concave space between them.

It is a common shell in England, in the living state, and has a wide Geographical
distribution in Europe, extending from Sicily to Sweden.

A few specimens also of this species were obtained by Capt. Alexander from the
Mam. Crag.

2. PISIDIUM HENSLOWIANUM, Sheppard.

TELLINA HENSLOWIANA. Shep. Trans. Linn. Soc., vol. 14, p. 150, 1825.

CYCLAS APPENDICULATA. Turt. Man. Land and F.-W. Shells, pi. 1, fig. 6.

PERA APPENDICULATA. Leach, MSS., fide Jenyns.

PISIDIUM HENSLOWIANUM. Jenyns. Trans. Cam. Phil. Soc., vol. iv, p. 308, t. 21, figs. 6 — 9, 1831.

Cray. Man. Land and F.-W. Shells, p. 285, pi. 1, fig. C.
— Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 131, pi. 37, fig. 1 1, 1849.

BIVALVIA. Ill

Spec. Char. Testa minutd, obliqud, sub-ovatd, valde intequilaterd, tumidd ; antice
productiore attenuatd, vel diminuatd ; umbonibus prominulis et appendiculatis.

Shell minute, oblique, sub-ovate, very inequilateral, and generally ventricose ;
anterior side much the longer ; umbones slightly prominent, furnished with a
projecting appendage.

Length, ^th of an inch.

Locality. Clacton, Stutton, Cropthorn (Strickland), Grays (Pickering).

Recent, Britain, Ireland, Germany.

This is an abundant shell at the localities, Clacton and Stutton, where they are
often found with the valves united.

The form is somewhat variable, but in general it may be described as triangularly
ovate, the posterior side being higher, that is from the umbo to the ventral margin,
diminishing towards the anterior side which is narrower and rounded, it is very
inequilateral and tumid, having at the umbo an appendage or projection, which is
its most distinguishing character.

3. PISIDIUM PULCHELLUM, Jenyjis.

PERA PULCHELLA. Leach, MSS., fide Jenyns.

PISIDIUM PULCHELLUM. Jenyns. Trans. Camb. Phil. Soc., vol. iv, p. 306, t. 21, figs. 1 — 5,

1831.

Gray. Man. Land and F.-W. Shells, p. 284, pi. 12, fig. 151.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 128, t. 37, figs. 12,

13, 1849.
FONTINALE. Brown. Illust. Brit. Conch., 2d ed., pi. 39, fig. 23.

Pfeiffer. Land und Sussw. Moll., pt. 1, p. 125, t. v, figs. 15, 16,

1821.

Phil. En. MoU. Sic., vol. ii, p. 31, 1844.

CYCLAS FONTINALIS. Drap. Moll. Terr, et Fluv., p. 130, t. x, fig. 12?
GALILEJA TENEBROSA. Da Costa. Corresp. Zool., fide Phil.

Spec. Char. Testa minutd, oblique-cordatd, valde inaequilaterd, ventricosd, concenirice
striatd, tenui, fragili ; umbonibus prominulis.

Shell small, obliquely heart-shaped, very inequilateral, ventricose, finely striated
concentrically, thin and fragile ; umbones slightly prominent.

Length, |-th of an inch.

Locality. Stutton, Clacton, Grays (Pickering], Copford (/. JSrowti).

Recent Britain, France, Sicily.

This appears to be by no means a rare shell in any of the above localities, though
it is less abundant than Henslowianum at the two former, and like the recent shell it
is subject to much variation.

112 MOLLUSCA FROM THE CRAG.

4. PISIDIUM PUSILLUM, Turton.

TELLINA POSILLA, Turt. Conch. Diet., p. 167, 1819.

CYCLAS PUSILLA. Turt. Brit. Biv., p. 251, t. 11, figs. 16, 17, 1822.

Id. Land and F. -Water Shells, pi. 1, fig. 7.
GIBBA. Alder. Trans. Nat. Hist. Soc., Newcastle, vol. i, p. 41.
— FONTINALIS. Drop. Moll. Terr, et Fluv. France, p. 130, pi. 10, fig. 8, 1805.
EUGLESIA HENSLOWIANA. Leach, MSS., fide Jenyns.
PISIDIUM PUSILLUM. Jenyns. Trans. Camb. Phil. Soc., vol. iv, p. 302, t. 20, figs. 4 — 6,

1831.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 123, t. 37, fig. 10, and
pi. 0, fig. 9, 1849.

Spec. Char. Testa pusittd, orbiculato-ovatd, compressiusculd, subincequilaterd, subti-
lissime striatd ; umbonibus prominulis.

Shell small and slender, roundedly ovate, somewhat compressed, slightly inequi-
lateral, very finely striated ; umbones but little projecting.

Length, |-th of an inch.

Locality. Clacton, Copford (/. Brown), Grays (Pickering). Recent, Britain, France.

This species is by no means abundant in my Cabinet from the former locality,
while Mr. Brown has found it in large numbers, in what is, perhaps, a more Modern
deposit at Copford. The principal distinction of this shell appears to be its generally
greater gibbosity ; it is less inequilateral than any of the other species.

We have thus, it seems, four well determined species in this genus from the
purely Fresh-water Deposits of this Kingdom, while the living British Pisidia have
been separated by British Conchologists into not less than eight or nine. I confess,
not to be very well acquainted with the recent forms, but judging from a general
knowledge of the variability amongst the fresh-water shells in particular, I think too
much dependence has been placed upon differences, arising from locality and other
external causes, and that slight variations resulting therefrom have been considered of
sufficient importance for the establishment of distinct species ; I am inclined to
believe, all the forms existing in England might be included in four or at most five
species.

In the beautiful and extensive collection of British Land and Fresh-water
Molluscs, in the Cabinet of Mr. John Pickering, are numerous forms of this genus,
and I have applied to that gentleman for his assistance upon the recent as well as
fossil Pisidia, and as he has devoted many years to the examination of these animals,
I conceive his opinion to be of much more value than my own ; he says (in Lit.) " I
am of opinion, we have not more than five species of Pisidia in this country, viz.,
P. amnicum, P. Henslowianum, P. pulchellum, P. obtusale, and P. pusillum. After
selecting the first three species, there are many forms remaining, from which without
much difficulty may be selected pusillum which appears a less variable species than
most of the others ; then follows obtusale the most variable of the whole, differing in
almost every locality, in some comparatively large and free growing, in others small

BIVALYIA. 113

and stunted according to the nature of the habitat, changing its form in each stage of
growth from compressed and decidedly inequilateral, to very tumid and nearly
equilateral, even in the same locality, yet merging so imperceptibly into each other,
that they cannot be separated without dismembering what appears to me a good and
natural species ; and it is yet a doubt in my mind whether on a fuller investigation of
the genus, 'pmiUifni ' can continue to rank as a species."

" These opinions have not been suggested by the sight of a few isolated and typical
forms, but .after a long and patient examination of several hundred specimens, col-
lected in various localities in the counties of Berks, Cumberland, Devon, Dorset,
Essex, Hants, Herts, Kent, Lancashire, Middlesex, Northumberland, Surrey, Sussex,
and Yorkshire."

In the form of my fossil specimens of pusilhini, I can see no material difference
from obtusale, except that in the latter the shell is more tumid ; but the differences
between the two do not appear to me to be more evident than some of the forms are
in the fossil Cyclas cornea, where specimens are occasionally excessively tumid, while
others of the same length and height are much compressed, and the like differences
are observable in specimens of P. amnicum. The few individuals of these last two
species, that I have seen from the Mam. Crag, are of the ordinary form or intermediate
between the extremes we have had figured.

LEPTON,* Turton, 1822.

SOLEX (sp.). Mont., 1803.
LUTRARIA (sp.). Gray, 1825.
PSAMMOBIA (sp.). Brown, 182/.
ERYCIKA (sp.). Nyst, 1844.

Generic Character. Shell equivalve, subequilateral, ovate, or subtrigonal, thin
and compressed ; umbones more or less acute, not prominent ; surface elegantly
ornamented ; margin plain ; hinge composed of two diverging teeth in each valve,
between which is placed the ligament wholly internal. Impression of the mantle
simple or without a sinus.

The animal of this genus is said to have its mantle freely open in front with a fringe
all round the- margin, and capable of extending itself considerably beyond the shell ;
a short siphonal tube with a single aperture, and a thick foot furnished with a byssal
groove ; one of the filaments of its marginal fringe is longer and larger than the others.

In addition to the two recent British species, the Crag contains one quite distinct, with
another doubtful one resembling what appears to be a different species in the Campinian
beds of Belgium. Conrad also describes one living in the Seas of America, as well as
another from the Upper Tertiaries of that country, but few specimens of either of

* Etym. Aerroj, thin.

15

114 MOLLUSCA FROM THE CRAG.

these have been examined carefully, and their correct specific establishment is not at
present upon a firm and stable basis ; and my own species are not given with any
great confidence, but more to call the attention of Collectors to their probable
existence.

Specimens apparently belonging to this genus have also been obtained at Barton
from the London Clay or Older Tertiaries.

1. LEPTON SQUAMOSUM, Montague. Tab. XI, fig. 8.

SOLEN sauAMOsus. Mont. Test. Brit., p. 565, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 48, 1807.
Turt. Conch. Diet., p. 164, 1819.
Dillw. Desc. Cat. Rec. Shells, p. 70, 1817.
W. Wood. Ind. Test. p. 16, 1825.

PSAMMOBIA PUNCTURA. Brown. Illust. Conch. Gr. Brit., pi. 16, fig. 7, 1827.
LEPTON SQUAMOSUM. Turt. Brit. Biv., p. 62, pi. 6, figs. 1 — 3, 1822.
Flem. Brit. An. p. 429, 1828.
S. Wood. Catalogue, 1840.

— _ Thorpe. Brit. Mar. Conch., p. 49, 1844.

— G. Sowerby. Conch. Man., fig. 62, 1843.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 98, pi. 36, figs. 8, 9,

and pi. 0, fig. 6, 1849.
LCTRABIA SQUAMOSA. Gray. Ann. of Philos., 1825.

Hanley. Recent Shells, vol. i, p. 28, Supp., pi. 9, fig. 47.
LEPTON SQUAMEUX. Chenu. Traite Elem., p. 47, fig. 148.

Spec. Char. Testa ovato-trigonuld, tsquilaterali, compressd, tenui ; utroque latere
rotundatd, margine ventrali leviter arcuatd; eleganter ornatd; dente cardinali unico, dentibus
lateralibus magnis.

Shell small, triangularly ovate, equilateral, thin, compressed ; rounded on both
sides, ventral margin slightly arched ; elegantly ornamented externally ; hinge with
one small central tooth and two large lateral teeth.

Length^ \ of an inch.

Locality. Cor. Crag, Sutton. Recent, British Seas.

One specimen only of this species was found by myself in the sandy portion of
the Coralline Crag, at Sutton. The interior is sufficiently perfect for comparison, but
the markings upon the exterior are rubbed and obliterated, and although there is
some slight difference in the outline of our shell, there is every reason to believe it
belongs to the same species as that now living in the British Seas, and to which I have
assigned it. The hinge area is large, furnished with a small central tooth, and a
double set, as it were, of lateral teeth, the innermost of which are large, diverging at
an angle of about 90°, those placed outwardly are small and close to the dorsal
margin, between these are deep depressions for the reception of the lateral teeth of
the opposite valve. The dorsal margin is short, not extending beyond the lateral

BIVALVIA. 115

teeth, it then slopes to the sides which are both rounded, and the ventral margin is
also slightly convex, differing thus a little in not presenting quite such a quadrate
form as the recent shell ; perhaps a larger number of individuals both recent and fossil
would present a greater resemblance. The beautiful sculpture which ornaments the
recent shell, is replaced in the fossil by a granulated surface, the effect of probably
unequal erosion, and the semipellucid appearance is changed into an opaque one from
the loss of its animal matter. Two ovate rather deeply impressed muscle marks are
distinctly visible in my specimen, which measures barely a quarter of an inch in
length, and a little less in height.

2. LEPTON DELTOIDEUM, S. Wood. Tab. XI, fig. 9, a — d.
KELLIA DELTOIDEA. S. Wood. Catalogue, 1840.

Spec. Char. Testa subtriangulatd, vel deltoided, tequilaterali, tumidd, politd, fragili ;
utrinque rotundatd, margine ventrali recta ; dentibus later alibus approximatis.

Shell triangular or deltoidal, equilateral, tumid, glossy, and fragile ; anterior and
posterior sides rounded with the ventral margin straight, lateral teeth approximate.

Length, ^ an inch. Height, T\ths.

Locality. Cor. Crag, Sutton, Ramsholt.
Red Crag, Sutton.

This delicate and very elegant species is not particularly scarce in the Coralline
Crag, where I have procured more than a couple of dozen specimens, 'and notwith-
standing its extreme fragility, its presence in the Red Crag is also undoubted, two
specimens belonging to that Formation are in my Cabinet, where they have been for
many years, but their exact locality is uncertain, as the label has been unfortunately
lost. We may fairly presume it to have prolonged its existence into the Period of the
latter Deposit, as such delicate shells could only under very favorable protection
have survived, being washed from an Older into a Newer Formation, and I give them
without hesitation as natives of the Seas of that part of the world in both Periods.

I am not acquainted with any described species to which this can with certainty be
assigned. Bornia corbuloides, Phil., En. Moll. Sic., vol. i, p. 14, 1. 1, fig. 15, somewhat
resembles it in outline, but the difference as given by the description appears
to present characters sufficient to keep them distinct, being recorded to have
its margin crenulated on both sides, which our shell certainly has not.

Lepton fabagetta, Conrad, a very indifferent figure of which is given by Dekay,
in the ' Nat. Hist, of New York,' a little resembles our shell in outline, and a fossil
species by Conrad, Lepton mactroides, from the Upper Tertiaries of America, present
general or generic resemblance, but the specimens must be examined for correct
determination, and I have not been able to see any of the three species above referred
to : our fossil must, therefore, for the present, remain with the name originally imposed

116 MOLLUSCA FROM THE CRAG.

in my Catalogue. The shell is very thin, and in the living state was no doubt nearly
transparent, it has a prominent umbo, sloping towards each extremity, and is rounded
there, while the ventral margin is quite straight, even inclining a little inwards in
some specimens, and is deep or tumid, particularly at the upper part; the hinge is
furnished with two teeth in each valve, diverging from the ligamental area, but do
not extend far towards the sides, and in the left valve immediately beneath the umbo,
and before the ligament, is a small cardinal tooth, but not one in the right valve ; in
perfect specimens the shell is beautifully glossy, and the exterior possesses a sort of
irregular concentric striae, which I imagine is not its original appearance, and that
probably it was ornamented in its recent state with more elaborate sculpture.

3. LEPTON DEPRESSUM, Nyst. Tab. XI, fig. 6.

CYCLAS? DEPRESSA. Nyst. Rech. Coq. Foss. d'Anv., p. 36, pi. 5, figs. 5, 6, 1836.
ERYCINA DEPRESSA. Nyst. Coq. Foss. de Belg., p. 88, pi. 4, fig. 5, «, a, b, c, e, 1844.

Spec. Char. Testa transversd, ovatd, in&quilaterali, depressd, tenui ; dente cardinali
unico, dentibm lateralibus obtusis.

Shell transversely ovate, slightly inequilateral, depressed and thin ; hinge with one
cardinal, and two obtuse lateral teeth.

Length, \ of an inch.

Locality. Cor. Crag, Button.

A single specimen of this shell in my Cabinet seems to correspond with what M. Nyst
considers, probably with better materials than I possess, to be a distinct species, and
the form certainly is different from that of any other already described ; and as I am
not imposing a new name, it will at least serve to call the attention of Collectors to
its existence for better examination.

My specimen maybe thus more particularly described. One side is rather broader
or deeper than the other, the longer side being the more narrow, and slightly pointed,
the hinge teeth are very obtuse, perhaps not quite perfect, dorsal area truncate, with
a depressed umbo : lateral teeth not very distant, two ovate muscular impressions
rather deep, and a continuous line formed by the mantle. The exterior is somewhat
rough and eroded, but appears as if it once had a more regular ornament. M. Nyst
says of his shell : " Transversim subtilissime irregulariterque striata/' and that it is
in Belgium also a rare species.

4. LEPTON NITIDUM, Turton. Tab. XI, fig. 7.

LEPTON NITIDUM. Turt. Brit. Biv., p. 63, 1822.
Flem. Brit. An., p. 429, 1828.
8. Wood. Catalogue, 1840.
Thorpe. Brit. Mar. Conch., p. 49, 1844.
Macgill. Moll. Aberdeen, p. 278, 1843.
KELLIA NITIDA. Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 92, pi. 36, figs. 3, 4, 1849.

BIVALVIA.

117

Spec. Char. Testa minutd, ovata, subintequilaterali, compressa, tenui, fragili ; dente
cardinali unico ; dentibus later aUkus magnis, distantibus.

Shell small, ovate, nearly equilateral, compressed, very thin, and fragile ; hinge
with one cardinal tooth, and two large and distant lateral teeth.

Length, |-th of an inch.

Locality. Cor. Crag, Button. Recent, British Seas.

When compiling my Catalogue, one specimen of a shell strongly resembling the
description given by Turton as a distinct species of Lepton, was in my Cabinet, and
I am sorry to say it is the only one I have as yet seen. As the authors of the * Hist,
of British Mollusca ' confirm its existence in the recent state, and have given a good
distinguishable figure, I am able with a little more confidence to describe my shell
under the name originally given. My solitary specimen possesses characters more in
accordance with the diagnosis of Lepton than of Kellia, as given by the proposer of
the two Genera, both as regards the hinge as well as the shell. My specimen is, I
suppose, the left valve having the cardinal tooth before the ligament, which is placed
in a triangular fossette immediately within a slightly prominent umbo, two large
lateral teeth extend to the edge of the dorsal area, and the two sides are a little
unequal in size, the anterior being a trifle the larger, and the less rounded ; the shell
appears to have been very thin, and the impression of the muscles indistinct, while
the exterior is somewhat rough and uneven, as if it had been altered by erosion.

KELLIA,* Turton, 1822.

AMPHIDESMA (sp.). Lam., 1818.
LASEA. Leach, MS., 1819. Brown, 1827.
ERYCINA (sp.). Desk., 1824.
PETHICOLA (sp.). Gray, 1835.
TELLIMYA (sp.). Brown, 1827.
CYLADINA. Cantraine, 1830.

BOBNIA. Phil., 1836.
ALIGENA. H. C. Lea, 1843.
, SCACCHIA (sp.). Phil., 1844.
MYALINA? Conrad, 1845.
PORONIA. Recluz., 1846.
CHIKONIA. Desk., sec. Gray.

Generic Character. Shell generally small and thin, equivalved, subequilateral,
orbicular, spheroidal, ovate, or roundedly-oblong ; tumid, or compressed ; surface
smooth, or covered with visible lines of growth. Hinge composed of two, sometimes
only one, tooth in each valve, with a trigonal pit for the reception of the ligament,
which is within the margin of the shell, though visible in some species when the
valves are closed. Impressions by the adductor muscles suborbicular, often indistinct,
that by the mantle without a sinus.

Animal of the form of the shell, with the edges of the mantle disconnected
only in places, extending posteriorly into one short siphonal tube, and at the anterior

* Etym. Name commemorative of J. M. Kelly, Esq.

118 MOLLUSCA FROM THE CRAG.

side there is a prolonged canal with an opening for the protrusion of its foot, at
the base of which is a byssal gland and groove.

This genus was proposed by Dr. Turton for the reception of two small species of
British shells, one of which had been previously placed in the genus Mya, and the
other in that of Cardium.

The species known, belonging to this genus, are somewhat minute but elegant
bivalves, which in the living state are usually found located either in rocks or seaweeds,
though most of them are capable of spinning a byssus ; they possess a considerable
vertical range, some living near low water mark, while others inhabit the sea at the
depth of 60 fathoms. They appear to have been somewhat largely developed in the
Coralline Crag Period, and are invariably found free or loose in the sand, and if ever
imbedded it must have been in the leaves or roots of seaweed, or in some material
which by decomposition or disintegration has liberated them from their confined
position. All my specimens were found in one locality, where there is a large accumu-
lation of numerous small species. This genus has been obtained in considerable abun-
dance from the Older Tertiaries of this country, and several species enrich the Cabinet
of my friend F. E. Edwards, Esq. There has not been anything found in the secondary
Formations that can with certainty be referred to this genus, although a shell in the
Green-sand strongly resembles it.

One or two species from the Crag included under this generic title possess
characters that will perhaps scarcely come within the range of our diagnosis. A
considerable variation may be observed in their dental arrangement, some being
furnished with two or more of these appendages, while others seem to be wholly
deficient, an internal ligament placed in an oblique depression appears an universal
character.

1. KELLIA SUBORBICULARIS, Montague. Tab. XII, fig. 8, a, b.

MYA SUBORBICULARTS. Mont. Test. Brit., pp. 39, 564, t. 26, fig. 6, 1803.
Mat. and Rack. Linn. Trans., vol. viii, p. 41, 1807.
Dillw. Des. Cat. Eec. Shells, p. 55, 1817.
TELLINA SUBORBICULARIS. Turt. Conch. Diet., p. 179, 1819.
AMPHIDESMA PHYSOIDES. Lam. Hist, des An. s. Vert., t. v, p. 493, 1818, fide

G. B. Sow.

KELLIA SUBORBICULARIS. Turt. Brit. Biv., p. 57, t. 11, figs. 5, 6, 1822.

Flem. Brit. An., p. 430, 1828.
Macgill. Moll. Aberd., p. 276, 1843.
Thorpe. Brit. Mar. Conch., p. 51, 1844.
J. Sowerby. Min. Conch., t. 637, fig. 1.
Lovtn. Ind. Moll. Scand., p. 44, 1846.
Alder. Cat. Moll. North, and Durh., p. 93, 1848.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 87, pi. 18, fig. 9,

a, b, and pi. 0, fig. 4, 1849.
KELLIA LACTEA? Lovtn. Ind. Moll. Scand., p. 44, 1846.

BIVALVIA. 119

TELLIMYA SUBORBICULARIS. Brown. Illust. Conch. Gr. Brit., pi. 14, figs. 14, 15, 1827.
TELLIMYA LACTEA? Id. - pi. 14, figs. 10, 11.

TENUIS. Id. - pi. 14, figs. 12, 13.

Smith. Wern. Trans., vol. viii, p. 45, 1838.

BORNIA INFLATA. Phil. En. Moll. Sic., vol. i, p. 14, and vol. ii, p. 11.
ERYCINA PISUM. Scacchi. Catal., p. 6, figs. 1 and 2, 1836.

Spec. Char. Testa tumidd, orbiculato-oUongd vel suborbicidari, subaquilaterali, tenui,
fragili ; striis tenuibus incrementi distinctis ; cardine bidentato, dentibus lateralibus
remotis.

Shell tumid, roundedly-oblong or suborbicular, nearly equilateral, very thin and
fragile ; smooth or covered with very fine lines of growth ; hinge with two cardinal
teeth in one valve and one in the other, lateral teeth remote.

Diameter, % of an inch.

Locality. Coralline Crag, Sutton.
Red Crag, Walton Naze.

Recent, Britain, Scandinavia, and Mediterranean.

The animal of this species, which may be considered the type of the genus, has
been examined by Mr. Alder, and a description published in his valuable Catalogue of
the ' Mollusca of the Coast of Northumberland' (page 94), where he has pointed out a
remarkable deviation from the normal form of the Bivalvia, which in general have the
siphonal tube or tubes, when they exist, placed at the posterior side of the shell, while in
this one, in addition to a short siphon in its natural position, there is a large tube capable
of being projected a considerable distance on the anterior side. The mantle has three
openings, he says, one posteriorly for the usual siphon which scarcely projects beyond
the margin of the shell ; another in front in the form of a tube, which is protruded when
the animal is in a state of activity, to a distance equalling the diameter of the shell; and
the third is for the emission of a long subcylindrically-formed foot, at the base of which
is a small opening and gland for the production of delicate threads or filaments, whereby
the animal is enabled freely to suspend itself in the water to some foreign body
although it is more often found located in the aperture of a rock.

A considerable degree of variation in form may be observed among the shells of
this species in the recent state, but it is more particularly so with those which are
found in the crevices of rocks, which probably in some measure distort or alter the
otherwise natural form of the shell. This species is not by any means common in the
Coralline Crag.

The more general form of my fossils is nearly orbicular, but one specimen (fig. 8, b]
is more transverse, or has a greater diameter from the anterior to the posterior
extremity : the same differences exist in those now found in our own seas. The Red
Crag at Walton Naze has furnished me with one specimen. It is said to range from
low- water mark to a depth of 60 fathoms.

120 MOLLUSCA FROM THE CRAG.

2. KELLIA ORBICULARTS, S. Wood. Tab. XII, fig- 9, a — c.
KELLIA? ORBICULARIS. S. Wood. Catalogue, 1840.

_ /. Sowerby. Min. Conch., t. 637, fig. 2, a. 1844.

Spec Char. Testa rnimttd, orbiculari, tumidd, obliqud, subaquilaterali, clausd;
concentrice et rugose striatd ; latere postico breviore ; dente cardinali unico in utraque
valva ante fov earn ligamenti ; fovea trianyulari, obliqud, profundd.

Shell small, orbicular, or spheroidal, inflated, subequilateral, closed; roughly
striated concentrically ; posterior side the shorter ; one cardinal tooth in each valve
before the ligament ; ligamental pit oblique, deep, and of a triangular form.

Diameter, j of an inch.

Locality. Cor. Crag, Sutton.

This is more abundant than the preceding species, and is limited, as far as I
know, to one locality. I have not been able to trace it higher up in the Series,
or nearer to our own time than the Cor. Crag. A shell called Scacchia inversa,
(Pkilippi, En. Moll. Sic., vol. ii, p. 27, T. 14, f. 10,) resembles this in some respects,
but differs in others, sufficiently, it is presumed, to be considered specifically distinct,
depending upon the figure and description by Philippi.

The ligament is wholly internal, and the pit for its reception is an oblique,
angular depression beneath or within the dorsal margin, extending backwards to
some distance, with a ridge or ledge for its support. The umbo is prominent, and
there is a considerable obliquity in the shell; an obtuse kind of ridge slopes from the
umbo towards the anterior ventral margin, behind this the shell is a little flattened,
giving a squarish outline by a somewhat straightened ventral margin. The left valve
has the larger tooth, this is situated a little in advance, and not immediately beneath
the umbo ; the cardinal tooth of the right valve is placed further backward, and
locks in behind the larger tooth of the opposite valve, making that tooth appear in
some specimens to have a ledge, or another rudimentary one. In the figure of this
species in Min. Conch., the teeth are represented as of equal size, but there is an evident
inequality, neither are they both in the same position, there is no vestige of a tooth
on the posterior margin, in wrhich character it differs from any of the three figures
given by Brown in his ' Illustrations of British Conchology.' Conrad, in his
* American Miocene Fossils,' figures and describes a similar species under the name of
Amplddesma tsquata, p. 65, PL 36, f. 5, but the figure is so inferior, and the descrip-
tion so brief, that it is impossible to institute a fair comparison.

3. KELLIA AMBIGUA, Nyst. Tab. XII, fig. 11, a, b.

CORBULA AMBIGUA. Nyst. and West. Nouv. Rech. Coq. Foss. d'Anv., p. 6, pi. 3, fig. 4, 1839.
ERYCINA AMBIGUA. Nyst. Coq. Foss. de Belg., p. 89, pi. 4, fig. 6, a, b, 1844.

— STRIATULA. Id. - ... p. 90, pi. 4, fig. 7, b, c.
KELLIA DUBIA. S. Wood. Catalogue, 1840.

J. Sow. Min. Conch., t. 637, fig. 4, a, 5, 1846.
— Tennant. Strat. List. Brit. Foss., p. 15, 1847.

BIVALVIA. 121

Spec. Char. Testa transversd, elongato-ovatd, tequilaterali, leviter convexd, Itevigata,
vel tenuissime striatd; utrinque rotundatd, dente cardinali unico, obtuso ; lateralibus nullis,
foved ligamenti elongatd obliqud.

Shell transverse ovate, equilateral, slightly convex rounded at both extremities,
smooth, or with very fine lines of growth ; hinge with one cardinal tooth, no lateral
teeth, ligamental area elongated, and oblique.

Length, fths. Height, T7¥ths. of an inch.

Locality. Coralline Crag, Sutton.

Red Crag, Walton Naze, and Sutton.
Mam. Crag, Chillesford.

This shell is abundant in the Coralline Crag, but the specimens are generally small,
rarely exceeding half an inch. Fig. 11, b, is from the Red Crag, and measures at least
three quarters of an inch. Among a large number of individuals a considerable varia-
tion may be observed, but these differences are principally in the proportional dimen-
sions, although some specimens have occasionally a more triangular form (fig. 1 1, a). It
is furnished with one somewhat prominent but obtuse tooth in the right valve, with a
depression before it, and in the left valve there are two teeth, when perfect, which is
not often the case, one immediately beneath the umbo, erect and compressed, the other
decumbent along the margin and at right angles to the other; the ligamental area slopes
obliquely backwards, forming a thickened ridge, against which it rested. The impressions
by the adductors are large and rather elongated, while that formed by the edge of the
mantle is at some distance within the margin of the shell, and is without any inflection,
and in some thin specimens from the Coralline Crag, fine radiating lines are visible in
the interior.

This is the largest species of Kellia that I am acquainted with, and strongly resembles
in form a shell from the Paris basin, to which it was assigned in my Catalogue ; but
by a comparison with a specimen from the Older Tertiaries of this country, now in the
cabinet of Mr. John D'Urban, and which probably is identical with the Psammotea dubia,
Desh, a material difference is exhibited sufficient to prove them specifically distinct, as
in that shell the ligament is placed on the outside, whereas in ours it is wholly internal.

A recent species from the Coast of Lower California, described and figured by
Conrad in the ' Journal of the Acad. of Nat. Sci.,' Philadelphia, 1850, Art. xxii, p. 279,
pi. 39, fig. 1, under the name of Solecardia eburnea, has a strong generic relationship
with our Crag fossil, although no doubt specifically distinct.

4. KELLIA ELLIPTICA, Scacchi. Tab. XII, fig. 13, a — c.

TELLINA ELLIPTICA. Scacchi. Oss. Zool.. ii, p. 14, 1833,1

( fide Phihppi.
LORIPES ELLIPTICUS. Scacchi. Ejusd. Cat., p. 5, fig. 1, J

LTJCINA OBLONGA. Phil. En. Moll. Sic., vol. i, p. 34, t. 4, fig. 1, 1836.
KELLIA FLEXUOSA. S. Wood. Catalogue, 1840.

J. Sowerby. Min. Conch., t. 637, fig. 5, a, 1844.
SCACCHIA ELLIPTICA. Phil. En. Moll. Sic., vol. ii, p. 27, t. 14, fig. 8, 1844.

16

122 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa transversd, ovatd vel ellipticd ; valde incequildterali, convexd,
lavigatd, politd, tenui ; antice productd, utrinque rotundatd ; margine dorsali Jlexuosd ;
cardine valvuld sinistrd bidentato ; dentibus lateralibus nuttis.

Shell transverse, ovate or elliptical, convex ; very inequilateral, smooth, glossy, and
thin; anterior portion much the larger, and rounded at both extremities; dorsal
margin sinuated ; hinge with two cardinal teeth in left valve ; no lateral teeth.

Length, T\ths. Height, Jth of an inch.

Locality. Coralline Crag, Sutton. Recent, Mediterranean.

A large number of this pretty little shell have been obtained at the rich Depot
of Molluscan remains at Sutton, where the two valves are occasionally, though
rarely, found united.

The most distinguishing mark of this species is the peculiar sinuosity of the upper
margin of the shell on each side of the umbo in both valves, but that in the right one
is the most conspicuous ; a sinus or rather an indentation at a considerable, but about
an equal distance both before and behind the umbo, received the edge of the margin
of the left valve by which it is a little twisted, thus interlocking and serving the office
of lateral teeth. The hinge is furnished with one obtuse tooth in the right valve with
a deep depression immediately before it ; in the left valve are two teeth, one of which
is somewhat prominent and compressed, the other placed at right angles to it and in
a line with the margin ; these two, when the valves are closed, occupy a position on
each side of the single tooth of the right valve. The ligamental area is small and
oblique, sloping towards the posterior side ; the muscular impressions are large and
distinct, and the mantle mark without any inflection.

I have not been able to compare my shell with the recent Mediterranean species,
but from the peculiar character of a flexuous margin there cannot be much doubt of
its identity ; my specimens do not appear quite so large as the one represented by
Philippi.

Scacchi's name is restored upon the authority of M. Philippi.

5. KELLIA CYCLADIA, S. Wood. Tab. XI, fig. 4, a, b.
KELLIA CYCLADIA. S. Wood. Catalogue, 1840.

J. Sowerby. Min. Conch., t. 637, fig. 6, a, 1844.
SCACCHIA OVATA? Phil. En. Moll. Sic., vol. ii, p. 27, t. 14, fig. 9, 1844.

Spec. Char. Testa transversd, obliqud, tumidd, ovato-trapezoided, valde inaquilaterali,
tenui, fragili ; margine dorsali integerrimo ; antice majiore, postice subrecto ; dente cardinali
unico, dentibus lateralibus nullis.

Shell transverse, oblique, tumid, of an ovate trapezoidal outline ; very inequilateral,
thin and fragile ; dorsal margin without any inflection ; anterior side the larger,
posterior nearly straight ; one cardinal tooth and no lateral teeth.

Length, \ of an inch nearly.

Locality. Coralline Crag, Sutton. Recent, Mediterranean.

BIVALVIA. 123

Two or three specimens only of this delicate and fragile shell were all that I
possessed when Mr. Sowerby figured and described it in ' Min. Conch./ and I am sorry
to say I have seen none in addition to that number. A recent shell from the
Mediterranean above referred to, seems to correspond in most characters with our
own, and I should imagine there was no doubt of the identity, but that the Crag shell
is wholly destitute of lateral teeth, which M. Philippi describes as being distinct in
his species. The hinge was probably furnished with one cardinal tooth in the right
valve and two in the left, but in my specimens of both valves they are nearly obsolete.
The recent shell was no doubt in a better state of preservation and more to be de-
pended upon.

Its outward form and absence of all flexuosity in the margin will distinguish this
from the preceding, which probably it resembled in its dentition. In the general
form and fragile texture it much resembles one of the Freshwater Cyclades, whence its
specific name.

Amphidesma equalis, Conrad, ' Amer. Mioc. Foss.,' p. 76, PI. 43, fig. 9, in outward
form is somewhat like our shell, but the figure, as with A. aquata, is not sufficient for
comparison, and the description is too concise to supply the deficiency.

6. KELLIA COARCTATA, 8. Wood. Tab. XII, fig. 10, a, b.

KELLTA COABCTATA. S. Wood. Catalogue, 1840.

GALEOMMA COMPRESSUM? Phil. En. Moll. Sic., vol. ii, p. 19, t. 14, fig. 5, 1844.

Spec. Char. Testa minutd transversd, oUongd, Itevigatd, politd, compressd, subcequi-
laterali ; antice majiore, dente cardinali unico in utraque valvd, lateralibus nullis ; margine
ventrali recto, vel coarctato.

Shell small, transverse, oblong, smooth, and glossy, compressed nearly equilateral,
anterior side the larger ; hinge with one cardinal tooth in each valve, lateral teeth
none, ventral margin straight, or subsinuated.

Length, TTT^S- Height, Jth of an inch.

Locality. Coralline Crag, Sutton.

Two or three dozen specimens of this species are in my Cabinet, all from one
locality. The form of the shell is somewhat oblong, rounded at the corners ;
the posterior side is not onjy the shorter, but is rather narrower ; the dorsal margin of
the anterior side being nearly straight, while the posterior has a gentle slope by which
that side is a little diminished. The exterior in perfect specimens has a beautiful
glossy appearance, and it was probably in the living state a semitransparent shell.
There is one tooth in each valve, that in the right is the larger and more prominent,
behind this is the ligament, placed on an oblong kind of shelf, inclining inwards on the
posterior side, the edge of this shelf is in some individuals slightly elevated above the
margin, and might be mistaken for another tooth ; the lines of growth are occasionally
visible but no regular striae, and the impressions of the muscles are not distinguishable.

124 MOLLUSC A FROM THE CRAG.

In dental characters and position of the ligament it corresponds with some of the
other species included in this genus, and appears to be more closely allied to it, than
to Galeomma in which Philippi has placed his shell, which is considered here with
doubt as an identity.

One specimen of mine has the two valves united, but does not show an opening
at the ventral margin, a character essential to that genus ; there is a twist in the
shell, and the single valve, when laid with its margin downwards, will not touch on all
sides, and this bend in the opposite valve is in the contrary direction, so as to bring
the margins of the two pieces together at all parts when the valves are closed ; never-
theless there is something about it peculiar to itself as possibly not to belong to either
this or to Galeomma.

7. KELLIA PUMILA, S. Wood. Tab. XII, fig. 1 5, a, b.

MONTACUTA PUMILA. <S. Wood. Catalogue, 1840.

KELLIA PUMILA. J. Sowerby. Min. Conch., t. 637, fig. 3, 184G.

Testa minima transversd, ovatd, obliqud, tumidd, valde inaqmlaterali, Itjemgatd, politd;
antice majiore et longiore, utrinque rotundatd; dente cardinali unico, dentibus later alibus
magnis.

Shell small, transverse, ovate, oblique, tumid, very inequilateral, smooth, and
glossy ; anterior side much the larger and longer, both sides rounded ; hinge with
one cardinal tooth, and two lateral teeth.

Diameter, TVt;h of an inch.

Locality. Cor. Crag, Sutton.

This is a very abundant shell at the above locality, where the two valves are
often found united, their large and prominent teeth having kept them in their natural
position.

Without allowing a latitude in variation beyond what we are accustomed to do,
even with such variable species as were the inhabitants of the Crag Seas, this shell
can scarcely be admitted as an identity with the K. rubra, although it bears a close
approximation ; and as the Malacologists have placed the recent shell in Kellia, it is
thought best to follow their example, although it does not strictly accord in its dental
characters with the diagnosis of that Genus.

Our shell is more inequilateral than K. rubra, and the hinge is quite at the side,
the umbo being almost terminal, and the posterior lateral tooth then forms nearly a
right angle with the beak and anterior lateral tooth : in the recent shell the hinge
is much more central, with less of gloss upon the exterior ; ours was perhaps a more
transparent shell, with the teeth rather less distinct: thus differing more from the
Mediterranean shell, according to Messrs. Forbes and Hanley, than from the British ;
there are two prominent lateral teeth, with a central one in the right valve, and
two smaller nearly obsolete lateral teeth in the left valve.

BIVALVIA. 125

Turton, in his 'British Bivalves,' p. 258, states the animal of this species to be
viviparous, and that he found many specimens filled with perfectly formed young ones,
similar in habit to the Genus Cydas.

8. KELLIA RUBRA, Montague. Tab. XI, fig. 10.

CARDIUM RUBRUM. Mont. Test. Brit., p. 83, t. 27, fig. 4, 1803.
Mat. and Rack. Linn. Trans., vol. viii, p. 66.
W. Wood. Ind. Test., p. 24, 1825.
TELLINA RUBRA. Turt. Conch. Diet., p. 168.

KELLIA RUBRA. Turt. Brit. Biv., pp. 57 & 258, pi. 11, figs. 7, 8, 1822.
Flem. Brit. An., p. 430, 1828.
Gould. Inv. Massach., p. 60, 1841.
Thorpe. Brit. Mar. Conch., p. 51, 1844.
Alder. Cat. Moll. North, and Durh., p. 94, 1848.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 94, pi. 36, figs. 5—7, and

pi. O, fig. 3, 1849.

LAS^A RUBRA. Brown. Illust. Conch. Gr. Brit., pi. 20, figs. 18, 19, 1827.
BORNIA SEMINULUM. Phil. En. Moll. Sic., vol. i, p. 14, pi. 1, fig. 16.

Desk. Exped. Scient. Algerie. Moll., pi. 43, figs. 8—11, and pi. 43 A,

figs. 6, 8.
PORONIA RUBRA. Reduz. Rev. Cuv. Zool., p. 175, 1843.

Hanley in Brit. Mar. Conch. Syst. Ind., p. xxv, 1844.

Spec. Char. Testa minutd, ovatd, tumidd, subin&quilaterdli lavigatd, utrinque rotundatd,
umbonibus prominuUs.

Shell small, ovate, tumid, slightly inequilateral, smooth ; both sifles rounded,
umbones rather prominent.

Diameter, TVtn °f an> inch.

Locality. Coralline Crag, Sutton.

Recent, Mediteranean, Britain, North America.

A single slightly injured specimen from the rich Depot of small shells in the
Coralline Crag at Sutton is all that I have been able to obtain ; it seems to have the
essential characters of the recent species, to which it is here referred, and as such
is introduced as an identity, although a few more and better specimens would be
desirable for confirmation : the character in which the preceding species seems most
to differ from the recent shell, and upon which its specific separation was founded, is
its being more inequilateral, and among all my numerous specimens there may be
observed a very general uniformity in that respect. The specimen now under notice has
the hinge more in the centre, placed as in the recent shell, the two lateral teeth forming
a very obtuse angle with the umbo ; they appear rather less in size than those of the
British specimens, and these are said to be less developed than in the Mediterranean shell.
This is said by Mr. Clark (Mag. Nat. Hist., 1849,) to be the most terrestial of
Bivalves, its habitat being generally in Lickina pygmaa, and that often from ten to
twenty feet above the level of the highest spring-tides.

126 MOLLUSCA FROM THE CRAG.

MONTACUTA. Turton, 1822.

LIGULA (sp.). Mont., 1808.

PETRICOLA (sp.). Gray, 1825.

ERYCINA (sp.). ^Desh., 1825 : (sp.) Nyst, 1844.

MESODESMA (sp.). Loven, 1846.

Generic Character. Shell equivalve, inequilateral, transversely oblong, or obliquely
ovate, generally small and thin : surface smooth, or concentrically striated, and
occasionally with a few radiating ridges. Hinge with two diverging elongated teeth,
more conspicuous in one valve than in the other. Ligament internal, placed in a
triangular fossette : impression by the mantle without a sinus.

Animal oblong, having its mantle open in front, margins not fringed ; without
siphonal tubes (?) ; foot large and broad, furnished with a byssal groove.

The name of this Genus was proposed in honour of Montague, the author of
'Testacea Britannica;' it is not, however, well determined, as two or three species,
the animals of which have undergone a careful examination, so far as their diminutive
forms will permit, seem to present considerable differences, and as far as regards the
shells alone, or their dental characters, the species here included would probably justify
their being separated into different Genera. As the authors of the f Hist, of Brit.
Mollusca' have made the same observation, and have not ventured to propose a new
Genus where the animals present characters so materially different, it would ill
become the Palaeontologist with only the shells to guide him, to venture upon such
a step.

Shells apparently of this Genus, at least such as present similar dental characters,
have been obtained from the Older Tertiaries of this country by Mr. Edwards ; but
nothing as yet known have been found in any Deposit of a more ancient date. Its
Geographical range is at present limited to the European Seas and the Western Coast
of America.

1. MONTACUTA BIDENTATA, Montague. Tab. XII, fig. 17, a, b.

MYA BIDENTATA. Mont. Test. Brit., p. 44, t. 26, fig. 5, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 41, 1807.
Turt. Conch. Diet., p. 102, 1819.
MONTACUTA BIDENTATA. Turt. Brit. Biv., p. 60, 1822.

— Gould. Inv. Massach., p. 59, 1841.

Macgill. Moll. Aberd., p. 302, 1843.
Thorpe. Brit. Mar. Conch., p. 52, fig. 58, 1844.
Alder. Cat. Moll. North, and Durh., p. 95, 1846.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 75, pi. 18, figs 6,

6«, 1849.
ANATINA BIDENTATA. Brown. Illust. Brit. Conch., pi. 11, figs. 8, 9, 1827.

BIVALVIA. ; 127

TELLIMYA BIDENTATA. Brown. Ilust. Brit. Conch., 2d ed, p. 107, pi. 44, figs. 8, 9.
PETRICOLA Gray. Ann. of Philos., 1825.

Hanley. Kecent Shells, p. 54.
EBYCINA Recluz. Rev. Zool., p. 331, 1844.

— FAB A. Nyst. Coq. Foss. de Belg., p. 90, pi. 4, fig. 8, a— d, 1844.
MESODESMA EXIGUUM. Loven. Ind. Moll. Scand., p. 42, 1846.

Spec. Char. Testa minutd, oblongo-ovatd, incequilaterali, Itevigata, tenui; postice ab-
breviatd, obtuse angulatd, antice productd, rotundatd, vix attenuatd, margine ventrali
et dor sali leviter arcuatis ; dentibus duobus in utraque valvd ; fovea ligamenti media
subumbone demissa.

Shell small, oblong or ovate, inequilateral, smooth, thin ; posterior side short,
obtusely angulated, anterior produced and rounded, scarcely contracted ; dorsal and
ventral margins slightly curved ; two teeth in each valve ; a moderate sized cavity for
the ligament deeply situated beneath the umbo.

Length, Ts¥ths of an inch. Height, -| ds the length.

Locality. Cor. Crag, Button and Gedgrave.
Red Crag, Walton Naze.

Recent, Britain, Scandinavia, and North America.

Specimens of this species are by no means rare in the Coralline Crag, and I have
found a few in the genuine Deposit of the Red Crag, at Walton Naze. Those from
the latter or newer Formation correspond precisely with the recent shell from our own
seas, and do not exceed it in size. The posterior side is considerably the shorter of the
two, extending about one quarter the distance from the umbo that it does on the other
side : the shell is smooth or very nearly so, and moderately tumid, the anterior or
larger side forms half an ellipse, and the teeth are large and very distinct in the
right valve, the one on the anterior side being the longer ; those in the left valve
are merely an angular elevation of the edge of the margin and inserted, when the
valves are closed, into the depression between the teeth and margin of the right or
opposite valve. The muscles are stated by M. Loven to be large and powerful, but
the impressions left by them in my specimens are very ill-defined, and by no means
deeply seated.

In the recent state as a British species it is not very abundant, and is said by
British Conchologists to be generally found burrowing in very thick valves of dead
Oysters. I have never seen the fossil in such a situation.

2. MONTACUTA TRUNCATA, S. Wood. Tab. XII, fig. 16, a, b.
MONTACUTA TRUNCATA. S. Wood. Catalogue, 1840.

Spec. Char. Testa valde inaequilaterali, cuneiformi vel subrhomboided, compressd, con-
centrice striatd ; postice brevissimd, angulatd, antice productd, rotundatd, attenuatd;
margine ventrali et dorsali rectiusculis ; dentibus duobus divergentibus, in valvd dextrd
majoribus., foved ligamenti parvd.

128 MOLLUSCA FROM THE CRAG.

Shell very inequilateral, subrhomboidal or slightly wedge-shaped, compressed
or flattened, covered with concentric striae; posterior side very short, angulated,
anterior produced, slightly contracted, and rounded ; ventral and dorsal margins nearly
straight ; two diverging teeth in each valve, much the larger in the right ; a small
triangular ligamental cavity placed immediately beneath the umbo.

Length, f ths. Height., J of an inch.

Locality. Cor. Crag, Sutton.

This species is by no means scarce at Sutton, although valves of the above
dimensions are not very often met with.

There are differences in this shell that seem to justify a removal from the pre-
ceding, although it must be confessed it is very nearly related, and in the immature
state it is exceedingly difficult, if not impossible, to separate them, but what are con-
sidered to be the distinctive characters may be pointed out leaving to future obser-
vation to confirm or refute their identity.

In the recent species (fadentata), the shell is not only less in size but more
tumid, and nearly smooth, our fossil is compressed, and the body of the
shell much flattened, the posterior side is particularly short and truncate, sloping
direct from the umbo. On the anterior side, which constitutes nine tenths of the shell,
the dorsal and ventral margins are nearly straight but not quite parallel, the termi-
nation rounded and narrower, giving a somewhat cuneiform shape to the shell; the
exterior is covered with regular and large concentric striae or lines of growth, and the
ventral portion of the shell is slightly compressed, with an imperfect angular ridge on the
shorter side : the right valve has two large diverging teeth, the posterior one being
the smaller ; between these and immediately beneath the umbo is a small triangular
cavity for the ligament. In the left valve, the margin is elevated into angular
denticles which are inserted, when the valves are closed, between the margin and the
teeth of the opposite valve. Muscular impressions not very distinct.

3. MONTACUTA SUBSTRIATA, Montague. Tab. XII, fig. 12, a, b.
LIGULA SUBSTRJATA. Mont. Test. Brit. Sup., p. 25, 1808.
MYA SUBSTRIATA. Dillw. Desc. Cat. Rec. Shells, p. 47, 1817-
Turt. Conch. Diet., p. 103, 1819.
W. Wood. Ind. Test., p. 11, No. 22, 1825.

MONTACUTA SUBSTRIATA. Turt. Brit. Biv., p. 59, t. 11, figs. 9, 10, 1822.

Flem. Brit. An., p. 465, 1828.
S. Wood, Catalogue, 1840.
Macgill. Moll. Aherd., p. 303, 1843.
Loven. Ind. Moll. Scand., p. 43, 1846.
Alder. Cat. Moll. North, and Durh., p. 96, 1848.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 77, pi. 18, figs. 8,

8«, and pi. 0, fig. 2, 1849.

TELLIMYA Brown. Illust. Brit. Conch., pi. 16, fig. 23, 1827.

ERYCINA Recluz. Rev. Zool., p. 330, 1844.

SPHJSNIA COSTULATA. Macgill. Moll. Aberd., p. 301, 1843, fide Forb. and Hani.

BIVALVIA. 129

Spec. Char. Testa minutd, transversd, oUiqud, ovatd, valde ineequilaterali, convexd,
politdy tenuiy fragili ; antice productd, utrinque rotundatd ; costatd, costis acutis panels ;
natibus prominidis ; dente cardinali unico.

Shell small, transverse, oblique, ovate, very inequilateral, convex, glossy, thin and
fragile ; anterior much the larger, both sides rounded ; ornamented with a few small
sharp radiating ribs ; umbones rather prominent ; hinge with one tooth.

Length, -^ths. Height, -|th of an inch.

Locality. Cor. Crag, Sutton. Recent, Scandinavia and Britain.

This shell is by no means rare at the above locality. I have not yet seen it as a
fossil in any Formation of a more recent date. It appears to resemble in every respect
the living species, except perhaps it is a little larger. In order to institute a fair
comparison it may be thus more fully described. The posterior side is very short
and rounded, the anterior dorsal margin nearly straight, with a sharp and somewhat
prominent umbo. The shell is glossy externally, covered with radiating distant striae,
or rather small angular ridges, which extend all over the shell, but are most prominent
and conspicuous about the centre, and are more numerous on the older than on the
younger part of the shell, that is, they do not all terminate, or rather, originate at the
beaks ; an intermediate ray is occasionally introduced on the body of the shell, but
on the anterior slope ten or a dozen of these ridges are interposed between two which
proceed direct from the umbo : hinge with a tooth in the right valve, placed in the
direction of the dorsal margin anteriorly, having a depression on the upper side of it,
and a similarly formed tooth, with a corresponding cavity in the opposite valve;
ligamental pit moderately large, sloping obliquely beneath the posterior dorsal margin.
In most of my specimens a slight depression is visible on the exterior, formed by the
contraction of the ventral margin, probably the result of a protruded byssus.

It is considered in the recent state a deep-water animal, ranging from 10 to 140
Fathoms.

4. MONTACUTA FERRU-GINOSA, Montague. Tab. XII, fig. 14, a, b.

MYA FERRUGINOSA. Mont. Test. Brit., Sup., pp. 22 & 166, t. 26, fig. 2, 1808.
MONTACUTA FERRUGINOSA. Turt. Brit. Biv., p. 60, 1822.

Alder, Cat. Moll. North, and Durh., p. 96, 1848.

Forb, and Hani. Hist. Brit. Moll., vol. ii, p. 72, pi. 18,

figs. 5, 50, 56, 1849.
— Alder. Ann. and Mag. Nat. Hist., 2d Series, vol. v, p. 210,

pi. 6, B, 1850.
OBLONGA. Turt. Brit. Biv., p. 61, t. 11, figs. 11, 12, 1822.

Flem. Brit. An., p. 465, 1828.
— Thorpe. Brit. Mar. Conch., p. 52, 1844.

Macgill. Moll. Aberd., p. 302, 1843.
GLABRA. Macgill. Moll. Aberd., p. 303, 1843.

Thorpe. Brit. Mar. Couch., p. 245, 1814.

17

130 MOLLUSCA FROM THE CRAG.

MONTACUTA FERRUGINEA. Thorpe. Brit. Mar. Conch., p. 52, fig. 16, 1844.

. — OVATA. S. Wood. Catalogue, 1840.

— TENELLA? Loven. Ind. Moll. Scand., p. 43, 1846.

TELLIMYA OVATA. Brown. Illust. Brit. Conch., pi. 14, figs. 20, 21, 1827.

— ELLIPTICA. Id. - - pi. 14, figs. 17, 18, „
GLABRA. Id. - 2d ed., p. 107, pi. 42, figs. 20, 21.

— OVATA. Smith. Mem. Wern. Soc., vol. viii, p. 41, 1838.
ERYCINA FERRUGINOSA. Eecluz. Rev. Zool. Cuv., p. 332, 1844.

Spec. Char. Testa transversd, ettipticd, convexd, tenui, lavigatd vel concentrice striatd ;
antice longiore> postice subattenuatd ; margins dorsali et ventrali leviter arcuatis.

Shell transverse, elliptical, convex, thin, smooth, or striated concentrically,
anterior side the longer, posterior slightly attenuated, dorsal and ventral margins
gently curved.

Length, \ an inch. Height, \ of an inch.

Locality. Cor. Crag, Sutton. Recent, Britain and Scandinavia.

This is not an abundant shell in my Cabinet, a few specimens however are
sufficiently perfect to be fairly compared with the recent British shell, and I believe
the differences are not more than may be considered as local variations.

Our shell is very transverse, having a length about twice that of its height,
the anterior side occupying about three fifths of the entire shell ; the posterior
side is rather more pointed than in the recent specimens I have compared with,
but in Messrs. Forbes and Hanley's description of the living species, it seems
to have a considerable range in variation, occasionally resembling our own shell
in that character, which appears to be its only difference : in perfect specimens
the exterior is covered with regular concentric striae, and the hinge is formed of an
internal ligament of an angular form, deeply inserted, and sloping towards the pos-
terior side ; a portion of the ligament was probably seen externally, as a small sinus
is formed in the umbo, through which it might have extruded, this pit, or support
for the ligament is thickened at the edges, and elevated behind, so as to produce a
sort of denticle in the left valve, and immediately before it is a distinct though not a
prominent tooth, the same appearances are exhibited in the right valve, in which the
tooth is rather more elevated. There are large adductor muscle marks of an ovate
form, and the impression by the mantle is entire.

The animal of this species has been recently examined by Mr. Alder, who has
published his observations in the ' Ann. and Mag. of Nat. Hist.' for the present year,
where he has pointed out a peculiarity in the mantle on the anterior side, by which it
appears, he says, to connect the open-lobed form in Lepton with the anterior tubular
extension of that organ in Kettia.

Very extraordinary forms are assumed by the fleshy covering or mantle in many
of the animals of this group, presenting us with distinctions so apparently anomalous
as to entitle them, if distinguished by that organ alone, to be removed to very distant

BIVALVIA. 131

positions, hut an evident relationship exists between their shelly exteriors, to separate
which would be a violation to any natural arrangement.

5. MONTACUTA ? DONACINA, S. Wood. Tab. XL fiff. 3, a — c.

* " O *

MONTACUTA? DONACINA. S. Wood. Cat. of Crag Shells, Ann. and Mag. Nat. Hist., 1840.
— ? CYLINDRICA, var. Id.

Spec. Char. Testa minutd, transversd, donaciformi, compressd, valde inaquilaterali,
Icevigatd ; postice brevissimd, margine dor soli rectiusculd, margine ventrali conveximculd ;
car dine edentuld ? foved ligamenti profundd, oUiqud.

Shell small, transverse, compressed, wedge-shaped, very inequilateral, smooth ;
posterior side very short, dorsal margin on the anterior side, nearly straight, ventral
margin convex ; hinge without teeth ? ligamental area oblique and deep, inclining
backwards.

Length, \. Height, T\ths of an inch.

Far. cylindrica. Length, -|th. Height, -^th of an inch.

Locality. Cor. Crag, Sutton.

Three or four specimens only of this curious shell have been many years in my
Cabinet, but nothing like it, either recent or fossil, has fallen under my observation,
by which it can be even generically associated, although it appears very closely
allied to this or to the Genus Kellia. My two forms therefore are placed here
provisionally, with the best figures and descriptions their unfavorable condition will
permit, in order to call the attention of future Collectors to their existence.

Figure (b) represents the left valve, which is very flat, and very inequilateral ;
the posterior side being rounded, and scarcely extending beyond the umbo ; nearly
the whole of the shell is on the anterior side, the dorsal margin of which is nearly
straight, but sloping a little from the umbo, the ventral margin convex, becoming
narrower at the anterior side, giving a wedge-shaped form to the outline of the
shell by having a greater height from the ventral margin direct to the umbo ; in
the var. /3. (fig. «) also a left valve, it is not so ; the posterior side being there
rounded, but not higher than any other part of the shell, and having such difference
only in the outline, I imagine it to be merely a variation, as in all its other characters
there is a specific resemblance. In an imperfect specimen of the right valve are two
small prominences of the edge of the shell, one on each side of the ligamental area,
scarcely deserving the designation of teeth, but perhaps a specimen in a better state
of preservation might have them more developed. The ligament is wholly internal,
placed immediately beneath the umbo in an angularly formed pit, inclining on the pos-
terior side. The exterior is smooth and glossy, with the lines of growth scarcely
visible.

132 MOLLUSCA FROM THE CRAG.

CYAMIUM.* Philippi, 1845.

CYAMIUM? Loven, 1846.
TURTONIA? Hanley, 1849.

Generic Character. Shell ovate, equivalve, inequilateral, closed, small, and thin :
externally free from ornament. Hinge with two cardinal teeth. Palleal impression
entire. Ligament internal.

This genus has been proposed for a species found in the Antarctic Seas, with an
internal ligament, and was adopted by Dr. Loven for the little shell called Mya
purpurea by Montague, which has however been erected into a genus by the Authors
of the ' Hist, of Brit. Moll.' under the name of Tartonia, in consequence of its having
an external ligament.

CYAMIUM ? EXIMIUM, 8. Wood. Tab. XI, fig. 5, a, b.

Spec. Char. Testa minima, ovatd, transversd, incequilaterali, l&vigatd, tenui ; postice
longiore, utrinque rotundatd ; cardine bidentato, uno laterali remoto pone lig amentum ;
apicibus prominentibus.

Shell small, ovate, transverse, inequilateral, smooth and thin ; posterior side the
larger, both sides rounded. Hinge with two cardinal teeth, and one remote lateral
tooth behind the ligament ; umbones prominent.

Length, ^th. Height, T^th of an inch.

Locality. Coralline Crag, Sutton.

One specimen of a species that appears to possess characters most in accordance
with the diagnosis of this Genus, is in my Cabinet, and I am induced to place it
here provisionally until some more shall be found, either to establish its right to
the position, or to remove it ; the desire that everything found in the Crag should
be brought under notice must be advanced as an apology for the introduction of some
few imperfect materials here, as well as elsewhere, in this Monograph.

Our shell has an undoubted right to be specifically removed from Mya purpurea,
Mont.., though in some of its characters there is a resemblance. The specimen
figured is the left valve ; it has two distinct, rather prominent, soft teeth close to the
umbo on the anterior side of the ligament, one standing at right angles to the length
of the shell, and the other, a larger one, diverging towards the anterior side, with
a sufficient space between them for the insertion of a tooth which the opposite valve is
supposed to possess : behind these teeth is a depression, where it is presumed the
ligament was placed, and if it were so, it must have been wholly internal, and invisible

* Etym. Kvafiiov, a little bean.

BIVALVIA. 133

when the valves were closed : behind this ligaraental area is a large and somewhat
prominent tooth, which may be called a posterior lateral tooth within the dorsal margin,
and there is a depression outside of it, such as would receive a corresponding elevation
on the edge of the right valve : the posterior side of the shell is the larger, the dorsal
margin of which slopes with a gentle and elegant curve from a rather prominent
umbo, having a rounded extremity, and a gentle convexity in the ventral margin :
the anterior side slopes from the umbo with a straighter line, and is also rounded.
The shell is very thin and fragile, and was probably, when living, a semi-transparent
species. The muscle marks are wholly invisible.

CRYPTODON.* Turtont 1822.

THYASIRA. Leach, MS., 1818, fide Lam. TELLINA (sp.). Mont., 1803.

THYATIRA. Id. MS., 1819, fide Jeffreys.

THIATISA. Id. MS., 1819, fide Gray.

BEQUANIA. Id. MS., fide Brown.

VENUS (sp.). Don., 1801.

AXINUS. J. Sower by, 1821.

Lovtn, 1846.

PTYCHINA. Phil, 1836.
THIATYRA. G. B. Sow., Jr., 1842.

Generic Character. Shell equivalved, subequilateral, tumid, thin, subhyaline, and
closed : hinge with a single obtuse, or somewhat obscure tooth in each valve ;
no lateral teeth. Ligament semi-internal, placed in a linear depression beneath the
dorsal margin : impressions of the adductor muscles indistinct, that by the mantle
without a sinus.

Animal with an open mantle, but no prolonged siphons, foot long, subcylindrical,
and tubular, with a clavate extremity.

The Authors of the ' Hist, of Brit. Moll.' have included this in the Genus Lucina,
but the animal of the one species that has been examined, appears to present
differences sufficient to entitle it to Generic distinction, and the characters of the
shell are so decidedly dissimilar, that a separation seems to be required.

There are several claimants for the honour of distinguishing this as a Genus,
and the strict right of priority is somewhat difficult to determine. Leach, in his
indiscriminate establishment of Genera, proposed several names, some of which were
put in print, and he may perhaps be the one most justly entitled. The name by
Sowerby has scarcely a better claim, as merely the exterior of the shell has been
observed, and the position of the ligament not clearly indicated, as Turton is next in
chronological order, his name is here employed.

Species strictly belonging to this genus have not been described from any
Formation of an older date than the Tertiaries, the shell called Axinus obscurus, from
the Magnesian Limestone, belongs to a different group, and has already been made
a genus of by Professor King, under the name of Schizodus.

* Etym. KpvTT-w, hidden, obovt, a tooth.

134 MOLLUSCA FROM THE CRAG.

1. CRYPTODON SINUOSUM, Donovan. Tab. XII, fig. 20, a, b.
VENUS SINUOSA. Don. Brit. Shells, t. 42, fig. 2, 1801.
TELLINA FLEXUOSA. Mont. Test. Brit., p. 72, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 56, 1807.

Turt. Conch. Diet., p. 177, 1819.

W. Wood. Ind. Test., p. 22, pi. 4, fig. 78, 1825.

AMPHIDESMA FLEXUOSA. Lam. Hist. Nat. des An. s. Vert., t. v, p. 492, 1818.
THYASIRA FLEXUOSA. " Leach, MS.," Lam. Loc. cit. Sup., t. v, p. 492, 1818.
LUCINA SINUATA. Lam. Loc. cit., t. v, p. 543, 1818.

Brown. Illust. Brit. Conch., pi. 17, figs. 4, 6, 1827.

— SINUOSA. Forbes. Keport on JSgean Invert., p. 182, 1843.

Thorpe. Brit. Mar. Conch., p. 74, 1844.

— FLEXUOSA. Flem. Brit. Ann., p. 442, 1828.

Gould. Invert. Massach., p. 71, fig. 52, 1841.

Forb. and Hani. Hist, Brit. Moll., vol. ii, p. 54, pi. 35, fig. 4, 1849.

— Reeve. Conch. Icon. LUCINA, pi. xi, fig. 62.

— SARSII. Id. . . pi. ix, fig. 52.

— GOODHALLI. J. Sow. Geol. Trans., 2d Set., vol. v, pi. 8, fig. 7, 1834.
CRYPTODON FLEXUOSUM. Turt. Brit. Biv., p. 121, pi. 7, figs. 9, 10, 1822.

— Brown. Illust. Brit. Conch., 2d ed., pi. 39, figs. 4, 5.

Moller. Ind. Moll. Groenl., p. 20, 1842.
Alder. Cat. Moll. North, and Durh., p. 91, 1847.
BISINUATUM. S. Wood. Catalogue, 1840.

PTYCHINA BIPLICATA. Phil. En. Moll. Sic., vol. i, p. 15, t. 2, fig. 4, 1836.
AXINUS UNICARINATUS. Nyst. Rech. Coq. Foss. d'Anv., p. 6, pi. 1, fig. 22, 1835.

— BENEDENII. De Koninck. Des. Coq. Foss. Arg. Boom, p. 35, pi. 11, figs. 2, 3,

1837.

— ANGULATUS. Nyst (not Sowerby). Coq. Foss. deBelg., p. 141, pi. 6, fig. 13, 1844.

— Michel. Desc. des Terr. Mioc. de 1'Ital. Septen. (Haarlem Trans.),

p. 118, pi. 4, figs. 23, 23*, 1847.

— FLEXUOSUS. Loven. Ind. Moll. Scand., p. 38, 1846.

— SAKSII. Id. - p. 38, „

Spec. Char. Testa ovato-orbiculari vel suWiexagond, lavigatd, tenui, subpellucidd,
tumidd, subaquilaterd ; later e postico biplicato, margins ventrali producto, lunuld cordato-
ovatd, magnd, impressd.

Shell ovately orbicular, with an irregularly hexagonal outline, smooth, thin and
subpellucid, tumid, and nearly equilateral ; posterior side with two folds or furrows,
ventral margin produced, and a large and deeply impressed heart-shaped lunule.

Diameter, ^ an inch.

Locality. Cor. Crag, Button.

Recent, ^Egean Sea, Britain, Scandinavia, and North America.

This species is not at all abundant. There is no doubt of its identity with the recent
British shell, and I have given it as an inhabitant of the North West Coast of
America, upon the authority of that accurate observer, Dr. Gould. A specimen

BIVALVIA. 135

obligingly presented to me by Professor E. Forbes, obtained by him in the
Sea, does not offer the slightest difference that could be considered as specific.

The recent shell is nearly transparent in its young state, becoming a little
thickened when full grown, and then only the true form of the muscular impressions
can be observed, that upon the anterior side is somewhat elongated, and within the
mantle mark, but has not the band-like form of the true Lucina: the exterior is
smooth, with the exception of rather rough lines of growth, and in the centre of the
shell there is somewhat of a flattened space, which gives one side of a hexagon to
the ventral margin, there are two distinct depressions or sinuses on the posterior
side, and the dorsal margin of the shell is produced so as almost to cover over the
ligament, which might otherwise be called external, as it acts over a small fulcrum,
and opens the valve by its contraction ; there is one obtuse tooth in the right valve
at the anterior termination, or rather commencement of the ligament, with a
corresponding depression in the left valve, and the umbo curves a little towards the
anterior, over its large and deep lunule.

Aaimts angulatus of 'Min. Conch.' T. 315, is decidedly different, but the older
Tertiary shell " Lucina Goodhattii " from Hampstead, appears so strongly to resemble
our species, that I cannot consider their trifling differences to be more than the result
of locality, or of other conditions, and in examining many specimens of this shell
in the rich Cabinets of my friends, Messrs. Edwards and Wetherell, I could come
to no other conclusion, though all the specimens yet obtained have the two valves
so closely united, that their external characters alone are visible. The principal
difference appears to be in a rather more rounded outline to the older shell, which
has also less deeply produced folds or sinuses on the posterior side, but in the
examination of a specimen from Boom, in the Cabinet of Sir Charles Lyell, these
posterior sinuses were more strongly marked than in our Crag shell, with a rather
larger and deeper lunule, while the specimen itself exceeded in magnitude any of
my own, and judging from the figure and description of the Scandinavian shell Axinus
Sarsii, Loven, it does not appear to vary sufficiently to be considered specifically distinct.

It is quoted by Nyst as a fossil from Bordeaux.

2. CRYPTODON FERRUGINOSUM, Forbes. Tab. XII, fig. 19, a, b.
CRYPTODON ROTUND ATUM. S. Wood. Catalogue, 1840.

KELLIA FERRUGINOSA. Forbes. JSgean Invert. Rep. Brit. Assoc., p. 192, 1843.
ARTEMIS? — Jeffreys. Ann. Nat. Hist., vol. xix, p. 313.

CLAUSINA Id. - vol. xx, p. 18.

— ABYSSICOLA. Id. p. 18.

— CROULINENSIS. Id. p. 19.

LUCINA FERRUGINOSA. Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 60, pi. 34, fig. 1, 1849.

Spec. Char. Testa minima, rotundato-ovatd, obliqud, subcequilaterali, tumidd, Icevigatd,
tenui, fragili ; later e postico obsolete uniplicato ; dente cardinali unico, obtmo.

136 MOLLUSCA FROM THE CRAG.

Shell small, roundedly ovate, oblique, sub equilateral, tumid, smooth, thin, and
fragile ; posterior side with one obsolete fold or furrow, one obtuse cardinal tooth.

Diameter, Jth of an inch.

Locality. Coralline Crag, Sutton. Recent, North Britain, and ^Egean Sea.

This is not an abundant fossil, and I have only met with it in the rich Depot
at Sutton.

When my Catalogue was compiled this species had not been recognised in the
recent state, and the name then proposed for it being without description, or anything
by which it could be identified, must give way to the subsequent one of Professor
Forbes. In comparing our fossil with the specimens now obtained in the British Seas,
no essential difference can be detected, and there is little doubt of their identity, and
when it is considered that the recent shell has been separated into three distinct
species, more than ordinary range in variation may be expected ; the fossil is,
however, free from the ferruginous covering which obscures some of the characters of
the living shell ; the Authors of the ' Hist, of Brit. Moll/ after uniting the three
species of Mr. Jeffreys, describe their shell as entirely without a fold, but in the most
perfect specimens of our fossil may be seen an obscure inflection upon the posterior
side, which is here considered to constitute one of its most determinable characters,
and has always been in my Cabinet under the MS. name of Cryptodon, from that
resemblance. In the few specimens that I possess no great variation is observable ;
the general form is obliquely orbicular, the diameter rather greater when measuring
from the umbo to the ventral margin than from the anterior to the posterior side,
and in some specimens the outline shows a decided pentangular form. There is one
obscure tooth in each valve, like that in the preceding species, and the ligament is
placed in a depression beneath the dorsal margin, so that it must have been nearly
hidden when the valves were united; the anterior muscle mark is large, and of
an ovate form, and not band-like as in Lucina. This shell has much the aspect of
Kellia, and might, without much violence to classical arrangement, be placed there,
or at least, judging from the characters of the shell alone, it appears to have a
nearer relationship to that genus than to Lucina. In the living state it has only
been met with as a deep-water shell, both from the ^Egean and the North British
Seas, ranging from 20 to 100 fathoms.

LORIPES,* Poli, 1791.

LiORIPES — LORIPODERMA. Poli.

TELLINA (sp.). Linn.
AMPHIDESMA (sp.). Lam., 1818.
THIATISA (sp.). Leach, 1819,
LIGULA. Menke, 1830,
UNGULINA. Jiosc., 1802.
TAR AS? Risso., 1826.

Ifide Gray.

Etym. Lorum, a strap, and^e*, a foot.

BIVALVIA. 137

Generic Character. — Shell orbicular, sub equilateral, equivalve, lenticular; smooth
or striated externally. Hinge with one or two cardinal and two lateral teeth ; the
latter sometimes obsolete. Muscular impressions unequal, anterior one the longer,
mantle mark without a sinus. Ligament internal.

Animal of the form of the shell, mantle open in front, with the margins crenulated ;
foot sub cylindrical, crooked, club-shaped at the extremity, one siphon.

Although the animal is closely allied to Lucina> it appears to be entitled to
generic distinction, on account of the difference of position in regard to the liga-
ment, being wholly internal, whereas in the other it is placed externally upon a ledge
or fulcrum; the reported difference in the siphonal opening is also an additional
reason for the separation.

This is a recent genus, and its age, as far as it is known to me, does not extend
beyond the Middle Tertiaries.

1. LORIPES DIVARICATA, Linn&us. Tab. XII, fig. 4 a, d.

TELLINA DIVARICATA. Linn. Syst. Nat., ed. 12, p. 1120, No. 70, 1767.
? W. Wood. Ind. Test., p. 23, pi. 4, fig. 87, 1825.
— DIGITARIA. Poll. Test. utri. Sic., vol. i, p. 47, t. 15, fig. 15, 1791.
CARDIUM ARCUATUM. Mont. Test. Brit., p. 85, pi. 3, fig. 2, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 67, 1807.
LUCINA ARCUATA. Flem. Brit. An., p. 442, 1828.

Reeve. Conch. Icon. LUCINA, pi. 11, fig. 61.
DIVARICATA. Woodward. Geol. of Norf., p. 43 (not reference).

Galeotti. Mem. de 1'Acad. Roy. de Brux., t. xii, p. 157, No. 137,

pi. 3, fig. 18, 1835.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 52, pi. 35, fig. 3, 1849.
TRIFARIA. Krynecki. Bull, des Nat. de Mosc., p. 62, No. 11, 1837. Sec. Midd.
COMMUTATA. Phil. En. Moll. Sic., vol. i, p. 32, t. 3, fig. 15, 1836.
Forbes. Rep. ^)gean Invert., p. 182, 1843.
Middendorff. Malacozool. Ross., p. 566, (Me'm. de 1'Acad. des Sci.

de St. Petersb., 1849.)
N. S. allied to DIVARICATA. G. Sow. and S. Wood. Mag. Nat. Hist., vol. iii,

p. 325, 1839.
LORIPES UNDULARIA. S. Wood. Catalogue, 1840.

Spec. Char. Testa orbiculari, subaquilaterali, convexd, bifariam oblique striatd, dwari-
catd, cardine dentibus lateralibus munito ; margine minutissme crenulatd.

Shell orbicular, nearly equilateral, ornamented with oblique divaricating striae ;
hinge furnished with lateral teeth, and the margin very finely crenulated.

Diameter) J an inch nearly.

Locality. Red Crag, Sutton.

Mam. Crag, Bramerton. Recent, Mediterranean, Britain.

This species appears first in the Red Crag, where it is very scarce, but I believe it
is rather more plentiful in the Mam. Crag, though not very abundant there : as a

18

138 MOLLUSCA FROM THE CRAG.

recent British shell it is one of our rarest species. In a comparison with Montague's
specimen, now in the British Museum, I was not able to detect the slightest
difference.

Our shell may be further described as very nearly orbicular, though in some
specimens, from a slight prominence of the umbo, the diameter is rather greater in
height : the hinge is furnished with one rather obtuse and angular tooth in the right
valve, and two lateral teeth, the posterior one is the more distant ; in the left valve are
two diverging cardinal teeth, with two lateral indentations corresponding to the teeth of
the opposite valve, and the ligament is placed behind the cardinal teeth in an oblique
fossette : the adductor muscle marks are slightly unequal : the anterior one is somewhat
elongated, but it has not the band-like form of the true Lucina : that by the mantle
is quite entire : the interior is often furnished with numerous radiating striae, and the
margin in very perfect specimens is finely crenulated. The exterior is ornamented
with diverging or divaricating striae, or rather ledges varying from 25 to 30, they are
slightly undulatory and have the ledge or elevated part on the upper side or towards
the umbo, and are crossed by the lines of growth : the divergence is from an imagi-
nary line a little on the anterior side, at an angle generally of about 100°.

This is the only species with these peculiar markings that I have seen : the shell
from the Old er Tertiaries, which is abundant in the Hordwell Cliff, has the ligament
placed wholly externally upon a projecting fulcrum, and the species from Bordeaux,
with the same specific name, differs in the like character, as also do the West Indian
shells.

There are, probably, several species possessing these diverging and curving
radiations, all of which have been united under the name of divaricata, and a long
extension of Geological Age, as well as a wide Geographical distribution, have been
given in consequence. The common West India shell, and the Older Tertiary fossils,
also belong to the true Lucina.

LUCINA,* Bruguiere, 1792.

VENUS (sp.). Linn.
TELLINA (sp.). Mont., 1803.
CYRACH.EA. Leach, MS., 1819, fide Gray.
MYRTEA. Turt., 1822.
PHACOIDES. Blainv., 1825.
ORTYGIA (sp.). Brown, 1827.

''Generic Character. Shell equivalve, generally equilateral, lenticular, compressed,
occasionally tumid ; surface more or less ornamented with concentric striae or
elevated ridges, sometimes with radiating striae or costae. Hinge usually with two
diverging cardinal teeth in each valve, and two lateral teeth, which in some species

* Etytn. A Proper Name.

BIVALVIA. 139

become obsolete : anterior muscular impression of a ligulate or elongated form.
Palleal impression without a sinus. Ligament external.

The animal of this genus is described as having its mantle open in front, and
fimbriated edges ; very short siphonal tubes, with a long cylindrically-formed foot.

The genus as here restricted is intended to include all those species which have
an external ligament, of which the Venus borealis of Linnaeus may be considered the
type. This appears to form a distinct group, characterised by a differently formed
anterior muscle, which the mantle seems to envelope, and the impression is isolated
within : the edge of the mantle extending up to the anterior part of the adductor,
and not on the posterior edge where the line of the mantle mark, in most of the
Dimyaria, connects the two muscles.

1 . LUCINA BOREALIS, LinncBus. Tab. XII, fig. 1 a, b.

VENUS BOREALIS. Linn. Syst. Nat., ed. 12, p. 1134, No. 143, 1767.

Don. Brit. Shells, vol. iv, t. 130, 1803.

EXOLETA .EQUILATERA. Chem. Conch. Cab., t. vii, p. 22, t. 38, fig. 406, 1784.
SPURIA. Gmel. Syst. Nat., p. 3284, No. 72, 1788.

Dillw. Desc. Cat. Rec. Shells, p. 194, 1817.

— CIRCINATA? Broc. Conch. Foss. Subap., p. 552, t. 14, fig. 6, 1814.
TELLINA RADTJLA. Mont. Test. Brit., p. 68, 1803.

W. Wood. Ind. Test., p. 21, pi. 4, fig. 71, 1825.
LUCINA RADULA. Turt. Brit. Biv., p. 116, 1822.

Phil. En. Moll. Sic., p. 35, t. 3, fig. 17, 1836.
Gould. Invert. Massach., p. 69, 1841.
Mafffill. Moll. Aberd., p. 255, 1843.
Dekay. Nat. Hist. New York Zool., pi. 26, fig. 274, 1843.
ALBA. Turt. Brit. Biv., p. 114, t. 7, figs. 6, 7, 1822.
ANTIO.UATA. J. Sow. Min. Conch., t. 557, fig. 2, 1827.
Woodward. Geol. of Norf., p. 43, 1833.
Nyst. Coq. Foss. de Belg., p. 128, pi. 6, fig. 7, a, b, 1844.
CONTRACTA ? Say. Journ. Acad. Nat. Sc., vol. iv, p. 145, pi. 10, fig. 8.
— ? Conrad. Am. Mioc. Foss., p. 40, pi. 20, fig. 5, 1838.

— FLANDRICA. Nyst. Coq. Foss. de Belg., p. 127, pi. 6, fig. 6, a, b, 1844.

— BOREALIS. Lovtn. Ind. Moll. Scand., p. 38, 1846.

Alder. Cat. Moll. North, and Durh., p. 91, 1848.
Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 46, pi. 35, fig. 5, and
pi. M, fig. 6, 1849.

— MITIS. Woodward (not Sow.). Geol. of Norf., p. 43, 1833.

Spec. Char. Testa orbiculari, lenticulari, compressiusculd ; striis concentricis nume-
rosis, erectis, approasimatis vel distantibus ; antice rotundatd, postice subquadratd, lunuld
lanceolatd, cardine bidentato.

Shell orbicular, lenticular, somewhat compressed, covered with numerous con-
centric, erect striae or ridges, close or distant ; anterior side rounded, posterior of a
squarish outline, lunule small, elongate, hinge with two cardinal teeth.

140 MOLLUSCA FROM THE CRAG.

Diameter. 1-Jths of an inch.

* o

Locality. Cor. Crag, Sutton, Ramsholt, Sudbourn, and Gedgrave.

Red Crag, Passim.

Mam, Crag, Postwick and Thorpe.

Recent, Mediterranean, Britain, Scandinavia, and North America.
This is one of our most abundant shells in the Coralline as well as in the
Red Crag.

In the young state, it is rather less equilateral than in the adult, and has
comparatively a larger and deeper lunule, with the teeth more distinct and prominent.
It is nearly orbicular, though sometimes there is a trifling difference in the dimensions,
the diameter from the anterior to the posterior side exceeding that from the umbo to
the ventral margin, and vice versa. In the right valve are two cardinal teeth, one
large and bifid, the other small and simple, with a prominent lateral tooth on the
anterior side, and in the left are also two cardinal teeth, one simple and the other
bifid, but their positions are reversed, the bifid one in the left being the anterior, with
a corresponding lateral tooth on that side. The interior is often strongly marked with
radiating striae, most distinct beyond the edge of the mantle mark : there are two deep
impressions by the adductor muscles, the posterior of an ovate form, the anterior one is
much elongated, being as it were bipartite, that nearest the anterior lateral tooth of
the usual form, with a ligulate prolongation down to near the middle of the shell ; in
addition to which, in the interior about the centre is a banded impression extending
half way across the shell, in a direction at right angles to the ligamental fulcrum, as
if the mantle had there a division. In some specimens, the exterior is covered with
close-set lamellated striae, and the shell is somewhat tumid, while in others the shell is
flat or much compressed, and the concentric markings distant. A little inflection is
always to be seen on the posterior side, producing a more or less distinctly marked
sinus, and both sides are generally a little elevated, giving the shell the appearance of
being high-shouldered. A small but distinct lunule is visible, curving strongly near
the umbo, which gives to the young shell a comparatively larger mark there than
when it is full grown. This shell is said in the recent state to have a range from
low water-mark to the depth of 90 fathoms.

2. LUCINA CRENULATA, S. Wood. Tab. XII, fig. 7 a, b.
LUCINA CRENULATA. S. Wood. Catalogue, 1840.

— STRIATULA? Nyst. Rech. Coq. Foss. de Hoesselt et Kl. Sp., p. 5, No. 11, pi. 1,

fig. 11, 1836.
— ? Nyst. Coq. Foss. Belg., p. 131, pi. 6, fig. 9, a—c, 1844.

— DENTATA? Goldf. Pet. Germ., vol. ii, p. 230, t. 147, fig. 1.

— CRENULATA. Conrad. Amer. Mioc. Foss., p. 39, pi. 20, fig. 2.

Spec. Char. Testa parvd orbiculari, aequilaterali, convexd, concentrice striatd, striis
numerosis confertis, lunuld impressd, elongato-ovatd ; dentibus later alibus distinctis; margine
crenulatd.

BIVALVIA. 141

Shell small orbicular, equilateral, convex, concentrically striated, striae close-set,
and numerous ; an ovate impressed lunule ; lateral teeth distinct ; margin crenulated.

Diameter, \ of an inch.

Locality. Coralline Crag, Sutton.

This species is exceedingly abundant, but restricted, as far as I have seen, to one
locality, where, from the prominence of the lateral teeth, the valves are sometimes
found united.

Our shell is furnished with one cardinal, obtuse, triangularly formed tooth in the
right valve, and a distinct and distant lateral tooth on each side : in the left valve
are two cardinal diverging teeth, with a triangular space between them, also two
lateral teeth : anterior muscle mark large, but not very narrow. The striae upon
the exterior are rounded, and about as broad as the spaces between them, and
the posterior side is marked with an obscure ridge, produced by a slight inflection of
the margin on that side, and at the ridge the striae often bifurcate, being less
numerous upon the inflected portion.

A shell in my Cabinet from Bordeaux, which I presume to \seLucina dentata, Bast.,
appears to differ from the Crag shell in several characters, it is more tumid, rather
wider in a contrary direction to our shell, and is more finely striated externally,
and has not so distinct a ridge on the posterior side ; the anterior tooth is the
more prominent in our shell, and the inside has fine radiating striae, which I do
not observe in Basterot's species ; in ours the ligament is wholly external, placed
on a prominent fulcrum ; in the Bordeaux shell it is internal, placed obliquely beneath
the umbo, and if I am right in the species, belongs to the genus Loripes.

Lucina striatula, Nyst, may possibly be the same as our shell, though it is distinctly
stated by that author to have the margin free from crenulations, but, judging from the
locality, his shell may perhaps belong to the older or Bordeaux species.

From the description and figure of the American fossil by Conrad, I presume his
shell to be the same species. We have seen the preceding (borealis) to have a range
from the Mediterranean to the Coast of the United States, and there is great proba-
bility that the fossil from the Upper Tertiaries of that side of the Atlantic is identical
with our own ; it is somewhat singular the author should have chosen for his shell
the same name under which the Crag species had passed in my Catalogue, and the
coincidence is perhaps the more remarkable, the American fossil having been obtained
from Suffolk, in Virginia.

3. LUCINA DECORATA, S. Wood. Tab. XII, fig. 6 «, b.

LUCINA SQUAMOSA? Gold/. Pet. Germ., vol. ii, p. 230, t. 147, fig. 3, a, b.

Spec. Char. Testa transversd, ovatd, in&quilaterali, crassd, striis radia?itibm, et
decussantibus ornatd ; lunuld magnd, lanceolatd ; cardine unidentato> dentibus lateralibm
perspicuis : umbonibus prominentibus.

142 MOLLUSCA FROM THE CRAG.

Shell transverse, ovate, inequilateral, thick, and strong ; ornamented with radiating
striae, decussated by concentric ridges ; a large elongated lunule ; hinge with one
cardinal tooth and two lateral teeth in each valve : umbones prominent.

Length, \ of an inch. Height, T\ths of an inch.

Locality. Cor. Crag, Sutton.

This is by no means an abundant shell, and the above dimensions are to the
full amount of my largest specimen.

It is a pretty species, covered externally with large obtuse rays, or depressed ribs,
they are but few in number in the young state, increasing as the shell enlarges by the
introduction of an intermediate ray, sometimes diverging in pairs ; they are crossed
by large obtuse ridges, or thickened lines of growth, placed sometimes in pairs,
generally more irregular ; the shell is nearly oval, but the anterior side is much] the
larger of the two, the umbo is elevated, and immediately beneath it is one triangular,
sub-bifid tooth in the right valve, with two distinct, nearly equidistant lateral teeth,
and in the left valve are two, diverging on each side of the triangular space, for
the reception of the one of the right valve, with two lateral teeth : the rays are
visible within the shell, and the muscle marks are not very deeply seated: the
anterior one is elongated, though not strictly of that ligulate or tongue-shaped
form so characteristic of the true Lucina. Tellina reticulata, Poli. (Lucina pecten,
Phil., 'En Moll. Sic.,' p. 31, T. 3, fig. 14), slightly resembles our shell, but it has finer
and more numerous rays, and is more orbicular.

Some time since I sent over to M. Deshayes a few specimens of three or four
species, thought to bear a very close resemblance to those of the Paris basin,
requesting he would be kind enough to compare them with his own types ; and since
the first part of my MS. had gone to press, I have received a communication from that
gentleman, who has obligingly complied with my request. He says : " J'ai examine
avec la plus grande attention vos trois especes Lucina squamosa, Erycina miliaria, and
Nucula miliaris, avec les types qui me restait dans ma collection et il resulte pour moi
de cet examen repete un grand nombre de fois, qu'aucune de vos especes n'est
parfaitment identique avec celles de notre bassin Parisien. Ces especes et les
notres ont entre elles de grandes resemblances mes elles offrent aussi des differences
constantes."

The means of determination possessed by M. Deshayes are probably sufficient
to enable him justly to separate the Crag shell from the Older Tertiary species, and
I have given a new name to our fossil upon such decision ; and in consequence of the
above opinion so strongly expressed, I have re-examined my own Crag specimens of
Nucinella miliaris with what I have considered as the same species from the Paris
basin in my own Cabinet, but with a high respect for the opinion of that able naturalist,
I cannot reconcile myself to the belief, that the differences observable between the two
are sufficiently prominent to justify a specific removal for the British fossil.

BIVALVIA. H3

DOUBTFUL.

4. LUCINA COLUMBELLA, LamarcJc.

LUCINA COLUMBELLA. Lam. Hist, des An. s. Vert., t. v, p. 543, No. 15, 1818.

Basterot. Mem. Geol. des Env. de Bord., p. 86, pi. 5, fig. 11, 1825.
Bronn. Lethaea Geogn., p. 959, t. 37, fig. 15, a — d, 1837.
Dujard. Mem. de la Soc. Geol. de France, torn, ii, pt. 2, p. 258,

1837.

Dubois de Mont. FOBS de Wolhyn., p. 57, pi. 6, figs. 8—11, 1831.
G. B. Sowerby. Genera of Shells, No. 27, fig. 6.
Phil. En. Moll. Sic., vol. ii, p. 26, 1844.
Reeve. Concb. Icon. LUCINA, pi. 6, fig. 30.
— VULNERATA. De France, sec. Basterot.

Three specimens of this species are among the Red Crag Fossils in the Wood-
wardian Museum at Cambridge ; and as it will be seen by the above references, it
was an inhabitant of the Seas which deposited the Bordeaux Beds, found also in the
Faluns of Touraine, in the Plateau Wolhyni-Podolien, and according to Philippi, has
been obtained at Sortino, in the Val di Noto, it is very possible it may have had
an extension into the Red Crag, more especially as a shell resembling this (probably
only a variety) is still a living species on the N. W. Coast of Africa.

No satisfactory information respecting these so called Red Crag specimens could,
however, be given by any of the gentlemen connected with the Cambridge Museum,
although Professor Sedgwick says he believes them to be true Crag shells, but being
myself unable thoroughly to examine their lithological character, and never having
seen the same species in any other Collection of Crag Fossils, and in the absence of all
knowledge of their correct locality, they must, at least for the present, be considered
as not strictly entitled to a place in the undoubted Fauna of that Period.

DIPLODONTA,* Bronn. 1831.

TELLINA (sp.). Mont., 1803.

MYSIA (sp.). Leach, MS., 1819. Brown, 1827.

VENUS (sp.). Broc. Nyst.

LUCINA (sp.). Def. Desk.

DIPLODONTA. Bronn., 1831.

SPH^KELLA? Conrad, 1838.

Generic Character. Shell somewhat thin, more or less orbicular, equivalve sub-
equilateral, externally smooth, or slightly marked by lines of growth, umbones not
very prominent. Hinge composed of two cardinal teeth in each valve, the anterior
one in the right valve simple, the other bifid, and the reverse in the left, no lateral

* Etym. AiTrXo'os, double, o'Sovj, a tooth.

144 MOLLUSCA FROM THE CRAG.

teeth. Ligament external, no lunule. Impressions by the adductors ovate; mantle
mark without a sinus.

Animal of the form of the shell, with its mantle closed all round, except in front,
through which a lanceolate-shaped foot is protruded : margin of the mantle with
plain edges. Siphons are said to be wholly wanting.

Our recent British species has been examined by Mr. Clark, who has pointed out
an apparent anomaly by which it differs from the generality of Dimyaria, in being
wholly destitute of anything resembling siphonal tubes, and without an orifice, except
the pedal one, he says, for the admission of water to sustain the functions of life.

Its position among the Lucinidce is at present considered doubtful by the
Malacologists, in consequence of this anomalous character in regard to the mantle ;
the shell, however, so strongly resembles many of the species of this group, that
no other position seems so appropriate.

1. DIPLODONTA ROTUNDATA, Montague. Tab. XII, fig. 3 a,b.

TELLINA ROTUNDATA. Mont. Test. Brit., p. 70, t. 2, fig. 3, 1803.

Mat. and Rack. Linn. Trans., vol. viii, p. 56, 1807.
W. Wood. Ind. Test,, p. 22,' pi. 4, fig. 77, 1825.
MYSIA ROTUNDATA. Brown. Illust. Brit. Conch., pi. 16, fig. 11, 1827.

Id. Conch. Text. Book, p. 132, pi. 17, fig. 6, 1837.
— MONTAGUI. Leach, MS., fide Brown.

LUCINA ROTUNDATA. Turt. Brit. Biv., p. 114, pi. 7, fig. 3, 1822.
Thorpe. Brit. Mar. Conch., p. 73, 1844.
Forbes. Report on JSgean Invert., p. 180, 1843.
Brown. Brit. Conch., 2d ed., pi. 40, fig. 11.
— Reeve. Conch. Icon. LUCINA, pi. vii, fig. 36.

PSAMMOBIA ROTUNDATA. Flem. Brit. An., p. 438, 1828.
DIPLODONTA ROTUNDATA. Phil. En. Moll. Sic., vol. ii, p. 24, 1844.

Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 66, pi. 35, fig. 6,
and pi. M, fig. 7, 1849.

Spec. Char. Testa suborbiculari vel trapezoidea, incequilaterali, postice latiore et
longiore, subquadratd, antice rotundatd ; apicibus prominulis ; margine dorsali fere rec-
tilineo: cardine bidentato.

Shell suborbicular, or of a roundedly trapezoidal form, inequilateral, posterior side
the longer, broader, and somewhat square, anterior rounded, with slightly prominent
umbones : dorsal margin nearly straight : hinge with two teeth.

Length, l|-th of an inch.

Locality. Coralline Crag, Sutton, Ramsholt, Sudbourn, Gedgrave.

Red Crag, Sutton. Recent, Mediterranean, and British Seas.

This is a shell exceedingly abundant in the Coralline Crag, where specimens
may be obtained from nearly 1 \ inch in diameter to those which are less than |-th
of an inch. In the Red Crag it is also found, but less abundantly. The hinge in

BIVALVIA. 145

both valves is furnished with two teeth, one simple, the other bifid, the simple one is
placed before the umbo in the right valve, and the bifid one is anterior in the left,
while the ligament occupies a position wholly external, and is deeply inserted :
the muscle marks are large and well impressed, of an oblong form, with the mantle
mark entire : numerous fine radiating striae are often visible in the interior, like some
of the Lucina, the outside is what may be called smooth, having only the irregular
lines of increase. The shell is somewhat flattened, though occasionally tumid, more
especially on the posterior side.

I have followed Philippi in assigning the Mediterranean shell to this species, as
he has done in his second volume, the figure in the first volume more resembles the
next species, for which it was taken when my Catalogue was compiled.

2. DIPLODONTA DILATATA, 8. Wood. Tab. XII, fig. a, b.
DIPLODONTA DILATATA. S. Wood. Catalogue, 1840.

? Nyst. Coq. Foss. de Belg., p. 138, pi. 7, fig. 1, 1844.

J. Sow., in Dixon. Geol. and Foss. of the Tert. and Cret. Form.

of Sussex, p. 167, t. 3, fig. 16, 1850.
VENUS FRAQILIS? Nyst and West. Nouv. Rech. Coq. Foss. d'Anv., p. 9, pi. 3, fig. 11.

Spec. Char. Testa transversd, ovatd, inftatd, incequilaterali, tenui, postice longiore
utrinque convexd ; margine dorsali rotundato ; apicibus obtusis, depressis.

Shell transversely ovate, tumid, inequilateral, thin, posterior side the larger, both
sides convex ; dorsal margin rounded ; umbones obtuse, depressed.

Length, f ths. Height, •£ ths of an inch.

Locality. Coralline Crag, Sutton, and Gedgrave. Red Crag, Sutton.

This species is not at all abundant. There are about a dozen specimens in my
Cabinet presenting characters that appear of sufficient prominence to entitle it to be
considered as different from the preceding one, and a few more particulars may therefore
be pointed out to support the opinion. Our shell is more regularly rounded on both
sides, and has not the squareness of outline so conspicuously shown in that species,
where the dorsal margin forms a straight line, giving a distinct angle on the posterior
side, whereas in this one it is eminently rounded, and the whole shell is more regularly
tumid ; the posterior side is considerably the larger, and the umbones are rather
depressed, turning a little towards the anterior, and the ligamental area is smaller than
in the preceding species ; the shell is thin, and the muscle marks not very well defined,
but where they are seen, they appear to be different in size, the posterior one being the
longer, and of a rounded oblong form, and that by the mantle without the least inflec-
tion ; the teeth are two in each valve, one simple, the other bifid, the posterior one
is simple in the left valve, in the right it is anterior; the bifid one is less, and the single
one is better defined than in the preceding species ; the whole aspect of the shell is also
different, that I have no hesitation in separating the two. This species and rotundata

19

146 MOLLUSCA FROM THE CRAG.

are found in the same locality, and I have one specimen from the Red Crag in good
preservation, exhibiting the same distinction. The figure by Nyst more strongly resem-
bles this species than the last one, so also does that by Philippi. The latter author states
his shell to be living in the Red Sea, thus giving a greater probability to its being
different from the one living in the British Seas ; a few specimens of apparently the same
species from the Older Tertiaries at Bracklesham are in the Cabinet of Mr. Edwards,
one of which has been figured in Mr. Dixon's work above referred to. In comparing
them with the Crag specimens some trifling differences may be observed, but they
do not appear of sufficient importance for specific distinction, and the Crag shell is in
all probability the prolonged existence of the Bracklesham fossil. In dental characters
they are precisely the same, but the Crag shell is rather more tumid, and it is also a little
longer, the dorsal margin being somewhat less rounded than in the older shell, and the
exteriors of the Crag specimens have merely fine and somewhat irregular lines of growth,
while the Bracklesham fossil has rather more regular concentric striae, they however both
present sufficient distinction to justify a separation from the recent British species.

3. DIPLODONTA ? ASTARTEA, Nyst. Tab. XII, fig. 2, a, b.

TELLINA ASTARTEA. Nyst. Rech. Coq. Foss. d'Anv., p. 5, pi. 1, fig. 18, 1835.
LUCINA GYRATA. S. Wood. Catalogue, 1840.

— ASTARTEA. Nyst. Coq. Foss. de Belg., p. 121, pi. 6, fig. 4, 1844.
MYSIA AMERICANA ? Conrad. Foss. Shells of the Med. Tert. United States, p. 30, pi. 16, fig. 2.
DIPIXJDONTA PARVTJLA? Nyst. Coq. Foss. de Belg., p. 139, pi. 7, fig. 2, 1844.

Spec. Char. Testa obliqud, ovato-obiculari, depressiusculd, inGequilaterali ; in senec-
tute intus spissatd ; postice majiore, antice subangulatd ; dente cardinali bifido.

Shell oblique, ovately orbicular, somewhat depressed, inequilateral, inside of
specimens thickened ; posterior side the larger, anterior subangulated : cardinal tooth
bifid : no lunule.

Diameter, f ths of an inch.

Locality. Cor. Crag, Sutton. Red Crag, Sutton.

This shell is very abundant in the Red Crag, but it is rather scarce at one locality,
from the Older Formaiton of the Coralline Crag, and presents some slight differences,
though not sufficient to remove it from the species.

Our shell measures three quarters of an inch from the anterior to the posterior
side, and about the same or a trifle less from the umbo to the ventral margin, these
proportions are occasionally reversed, but there is in general not much variation
in this species : it is somewhat oblique, and measures rather more from the dorsal edge
or position of the ligament to the opposite margin than in a contrary direction, although,
in the young shell, it is the reverse; the umbones are prominent, the hinge has one simple
and one bifid tooth in each valve, the surface is marked with somewhat irregular lines of
growth at considerable distances. The interior in the adult shell is much thickened,

BIVALVIA. 147

as in some of the species of Lucina, showing the muscle marks deeply impressed ;
they are nearly equal in size, though the anterior one is rather narrower, the line
of the mantle is without the least inflection : in the thickening of the interior a
ridge is produced near the upper anterior margin, giving the appearance of an addi-
tional muscle mark ; a similar appearance may be seen in the old specimens from
the Coralline Crag, besides an obscure ridge running down the centre dividing it
into two nearly equal parts. There is no doubt of this species being identical with
the Belgian fossil, and according to M. Nyst, it is said to have been found in the
Older Tertiaries from the environs of Paris. I have not seen it from the Mam. Crao-

o"

D. apicalis, Phil., somewhat resembles the young of our shell, but it appears to
have a greater comparative height from the umbo to the margin ; and I have been
unable to see a specimen of this or of D. trigonula, Bronn, which also does not very
greatly differ.

The dentition of this species precisely resembles that of D. rotundata, as well as
the muscle marks of the interior, from which it is presumed to belong to the same
genus, but the interior of aged specimens is thickened like those of Lucina, to
which it appears to be very closely related. The specimen figured has a somewhat
sinuated form in the margin on the posterior side, which is merely accidental ; it was
selected for the purpose of showing the interior.

LUCINOPSIS, Forbes and Hanky, 1849.

MYSIA. "Leach," Lam., 1818. King, 183- ? S. Wood, 1840.
VENUS (sp). Penn. Mont. Flem. Phil. Lovtn.
LUCINA (sp.). Turt. Lam.
CYTHEREA (sp.) Macgill, 1843.
ARTEMIS (sp.). Alder, 1847. Becluz.
DOSINIA (sp.). Gray, 1847.

Generic Character. " Shell more or less orbicular, rather thin, equi valve, slightly
inequilateral, closed ; surface smooth or concentrically striated, inner margin entire ;
muscular impressions oblong or suborbicular, nearly equal. Palleal sinus wide, deep,
central, obtuse. Hinge composed of two diverging central teeth, one of which is
bifid in the right valve, and three, the central one bifid, in the left. Ligament
external, prominent, rather long. No defined lunule."

" Animal suborbicular, its mantle freely open, the margins entire. Siphonal tubes
short, diverging, separate, the branchial with its orifice fringed, the anal simple.
Foot lanceolate. Labial paps, small, triangular."

This being the first and only diagnosis of the genus I have seen, it is copied from
the authors of the ' Hist, of British Mollusca,' whose name is here adopted.

The long and well-known British species Venus undata, of Pennant, is considered
as the type of the genus.

148 MOLLUSCA FROM THE CRAG.

It has been justly remarked, by Messrs. Forbes and Hanley, that in consequence
of its anomalous character, this shell has been bandied about and placed in many
different genera, but generally with a doubt respecting its true position ; the deep
palleal sinus indicated the possession of somewhat elongated or at least projecting
siphons, thereby differing from the animals of true Lucina, in which genus some
authors had placed it, where from its dental characters and general appearance it
seemed most entitled to be situated. They have, however, removed it from among the
family Lucinidce, and placed it in the Veneridce, in consequence of the deeply sinuated
form of the palleal impression ; and this view of its connection seems to have been
taken by other Malacologists.

The possession of a sinus in the impression of the mantle mark is a distinction,
we have elsewhere seen, in all probability sufficient for the removal of a shell with
such a character out of a genus, where others have the mantle mark perfectly entire,
but there is no sufficient reason in that alone that it should be removed to any very
distant position. Its general affinities appear more in connection with those of Lucina
than with those of Venus, differing from the former only in the aberrant character of a
prolongation in the siphonal tubes, bearing the same relationship to Lucina, or rather
to Diplodonta, that Leda does to Nucula, or as Adacna to Cardium : I have, therefore, again
ventured to remove it from among the Venerida to what appears a more correct position.

The name of Mysia was proposed in MS. for a genus by Dr. Leach, in which the
Venus undata, Penn., was placed; and this name has been published by Lamarck in his
' Hist. Nat. des An. sans Vert.,' t. v, p. 543, 1818, thereby giving it a status in regard
to time ; and considering that sufficient for its right to priority, it was adopted by
myself in ' The Catal. of Crag Shells/ for the Crag species, but another well-identified
shell belonging to the genus Diplodonta had also attached to it the same generic
name, and this was published by Brown, in 1827. It is not now possible to say which
of the two species was intended as the type of his proposed new genus, and therefore,
to unravel the difficulty, or rather to cut the Gordian knot, the authors of Lucinopsis
have, perhaps wisely, rejected in toto the name of Mysia.

This appears a very natural genus, although very few species are yet known
either in a recent or fossil state. Two or three shells from the Greensand Formation,
figured and described under the name of THETIS, somewhat resemble it in the dental
characters, but they have a deeper and more angulated sinus in the mantle mark.

1. LUCINOPSTS LAJONKAIRII, Payraudeau. Tab. XI, fig. 14, a — c.

Ency. Method., p. 272, fig. 2, a— b, 1800.
VENERUPIS LAJONKAIRII. Payr. Cat. Moll.del'Ile de Corse, p. 36, pi. l,figs. 12, 13, 1826.

Desk. 2d ed. Lam., t. \i, p. 164, 1835.

VENUS LUPINOIDES. Nyst. Rech. Coq. Foss. Prov. d'Anv., pi. 11, No. 41, pi. 3, fig. 14.
MYSIA ORNATA. S. Wood. Catalogue, 1840.

TELLINA LUPINOIDES. Nyst. Coq. Foss. de Belg., p. Ill, pi. 5, fig. 4, a — c, 1844.
— ? ARTICULATA. Id. - p. 110, pi. 6, fig. 1, a, b.

BIVALVIA. 149

Spec. Char. Testa tenui, orbiculari vel subpentangulari, vice aquilaterali, tumidd, sub-
obliqud ; striis confertis, articulatis ; timbonibus prominulis, approccimatis ; maryine integro.

Shell thin, orbicular, or somewhat of a pentangular outline, scarcely equilateral,
tumid, and rather oblique ; ornamented with numerous close-set articulated striae ;
beaks slightly prominent and close ; margin smooth.

Diameter, 1^-th of an inch.

Locality. Cor. Crag, Ramsholt, and Sutton.

Red Crag, Sutton. Recent, Corsica and Sicily.

About a dozen specimens of this species in perfect condition have been obtained
by myself from the Coralline Crag at Ramsholt : a few with the valves united, and
one only from the Red Crag.

Not having been able to obtain a specimen of the recent shell for comparison, its
identification is dependent upon the figures and descriptions above referred to, but
its outward form and ornamented exterior are so peculiar, that it is assigned to the
Mediterranean species without much hesitation.

The hinge of the right valve is furnished with two primary diverging teeth, the
posterior one being bifid, while the left valve has three teeth ; the centre one of which
is large and double, or so deeply cleft, as to give that valve the appearance of having
four ; there are no distinct lateral teeth, though on the anterior side the lateral edges
interlock ; it has but an elongated fulcrum for the external ligament ; there are no
lunule : the two large impressions by the adductors, the anterior one being the smaller
and more narrow ; the impression by the mantle is large, deep, and rounded, ascending
beyond the middle of the shell, and extending over to the anterior side. In outline
it much resembles L. undata, and also in its very visible but somewhat irregular lines
of increase, but it differs in the possession of numerous radiating striae. The length
generally exceeds the height by about an eighth, but in some specimens there is no
difference.

HIPPAGUS.* Isaac Lea, 1833.
VEBTICORDIA. S. Wood, MSS., 1842.

Generic Character. " Shell cordate, inflated, without teeth ; beaks large, recurved,
margin slightly overwrapping beneath the beak : anterior cicatrix long, posterior
cicatrix round."

The above is given by Lea in his ' Contributions to Geology/ as the diagnosis of a
genus proposed to be established upon a small fossil shell found in the United States,
in a Formation of the Older Tertiary Period, and it has been adopted by Philippi, who
has included in it a fossil from the Valley of the River Lamati, in Calabria, and as this
appears to be identical with our Crag Species, I have followed the latter Author in the
generic assignment.

* Etyra. Hippagus, a horse-ferry boat.

150 MOLLUSCA FROM THE CRAG.

1. HIPPAGUS VERTICORDIUS, S. Wood, Tab. XII, fig. 18, a, b.
CRYPTODON? VERTICORDIA. 8. Wood. Catalogue, 1840.
VERTICORDIA CARDIIFORMIS. S. Wood. MS., 1844.

J. Sowerby. Min. Conch., t. 639, 1844.
HIPPAGUS ACUTicosTATUs. Phil. En. Moll. Sic., vol. ii, p. 42, t. 14, fig. 19, 1844.

Spec. Char. Testa suborbiculari vel cordiformi, convexd, subtequilaterali, tenui, costatd
costis circa 1 6 incurvatis, compressis, radiantibus, rugosis ; apicibus antrorsum involutis ;
margine denticulate.

Shell suborbicular, or heart-shaped convex, thin, subequilateral, costated, ribs about
1 6, incurved, radiating, compressed, rugose; apices involute; margin denticulated.

Diameter, -fths of an inch.

Locality. Coralline Crag, Sutton.

This elegant shell is by no means abundant as a British fossil, and from the figure
and description above referred to, there is every reason to believe the same species
once inhabited the seas which deposited the Upper Tertiaries of Calabria. A slight
difference exists between our shells, as far as can be determined without an inspection
of the specimens, but such as does not appear to be more than a local variation, and
not sufficient to affect their specific identity.

The Italian fossil has given to it only 13 ribs, while there are 15 to 16 in our shell,
but like some species in the genus Cardium (which it resembles externally,) this may
be a variable character : the ribs are elevated, and laterally compressed, rounded on
the top, but not sharp or angular, as Philippi's name would seem to imply, and as his
figure represents ; they are elegantly curved, and are generally rugose, or coarsely
imbricated, and distributed at about equal distances ; the concave spaces between them
are rather wider than the ribs themselves, and appear to be finely granulated, or studded
over with small papillae. In the interior are the marks of two somewhat large
adductor muscles, the anterior one is the more deeply impressed, that by the mantle
is indistinct : the ligament or cartilage appears to have been placed so far within the
dorsal margin of the shell, that when the valves were closed it was probably not visible,
being placed in a depression beneath the margin, extending into a cylindrically formed
aperture towards the umbo, and the receding of the ligament, or its desertion on the
anterior side, causes a slight involution of the umbones, like that of Isocardia, though
in a very minor degree. A callous, but prominent and obtuse tooth in the right
valve, close to the umbo, fits into a sinus in the left valve : the shell is beautifully
nacreous within, and though not particularly thin, the ribs are visibly marked in the
interior by deep indentations, and they project considerably beyond the margin, inter-
ocking and serving the office of prominent denticles.

BIVALVIA. 151

CARDIUM,* Linnaeus.

PECTUNCULUS. Adanson, 1757.

CERASTES and CERASTODERMA. Poll, 1795.

ISOCARDIA, (sp.) Klein, 1753.

CARDISSA. Megerle, 1811.

APHRODITA. Lea, 1833.

LUNULACARDIUM. Milnst., 1840.

LuEVicARDiUM. Swains, 1840.

HEMICARDIUM. Id.

ACARDO. Id.

PAPYRIDEA. Id.

SERRIPES. Beck, sec. Gould.

MONODACNA (part) and DIDACNA. Eickw., 1841.

Generic Character. Shell equivalve, sub-equilateral, more or less heart-shaped;
generally closed, sometimes gaping posteriorly : usually inflated, orbicular, or ovate,
costated, costse variable, from nearly obsolete to large and prominent, sharp, round and
naked, often ornamented with scales or tubercles ; margin dentated or crenulated ;
hinge composed of two cardinal teeth in each valve, and two remote and prominent
lateral teeth. Ligament external. Impression of the mantle without a sinus.

Animal of the general form of the shell, its mantle open in front, with the margins
generally plain, occasionally fringed, particularly towards the posterior, and around
the syphons ; these are short, and slightly separated, with the margins of one or both
always fringed ; foot large, sub-cylindrical, and bent at nearly a right angle, possessing
the form of an inflected arm or elbow-joint.

Eichwald has described some species from the Caspian sea, which he has separated
into three genera, under the names of Didacna, Monodacna, and Adacna, depending for
his characters upon the numerical presence, or the absence of the hinge-denticles. The
animals of the latter division appear deserving of separation, being furnished with
elongated syphons, and consequent indenture of the mantle mark. Some fossils
also from the Palaeozoic rocks, justly erected into a Genus by Professor Phillips under
the name Pleworhynchus, much resembled the general character of cockles, but were
probably furnished with elongated syphons, as the shell is greatly produced on the
posterior side. Species possessing undoubted characters of this Genus, have been
obtained from the Middle Secondary Formations, and they are largely developed
in the Tertiaries, while from the present seas not less than 200 species have been
obtained. Their range geographically takes in nearly the whole surface of the Globe,
and they are met with in Estuaries as high as low-water mark, while some are
inhabitants of the sea at depths not exceeded by any other Molluscs. They generally
frequent sand or sandy-mud bottom, where they often congregate in prodigious numbers.

* Etym. Kapbia, the heart.

20

152 MOLLUSCA FROM THE CRAG.

1. CARDIUM ECHINATUM, Lmnceus. Tab. XIV, fig. 3 a — b.

Bonanni. Eecr. Ment. et Ocul., fig. 90, 1684.
Lister. Hist. Conch., lib. iii, fig. 161, 1687.
Dale. Hist, and Antiq. of Harwich, p. 292, t. xii, fig. 6, 1730.
CARDIUM ECHINATUM. Linn. Syst. Nat., ed. 12, No. 79, p. 1122, 1767.
Dacostq. Brit. Conch., p. 176, t. xiv, fig. 2, 1778.

— — Miiller. Zool. Danica, t. xiii, figs. 1 and 2, and t. xiv, figs. 1—4.

Donovan. Brit. Shells, t. 107, fig. 1, 1802.
Chemn. Conch. Cab,, vol. vi, p. 165, t. xv, fig. 158.
Brown. Illust. Brit. Conch., pi. xxi, fig. 6, 1827.
IBasterot* Bord. Foss., p. 82, 1825.

— Phil. En. Moll. Sic., vol. i, p. 49, and vol. ii, p. 37.
Forbes. JSgean Invert. Rep., Brit. Assoc., p. 180, 1843.
Loven. Ind. Moll. Scand., p. 35, 1846.

— Alder. Catal. Moll. North, and Durh., p. 83, 1847.

Forbes and Hanley. Hist. Brit. Moll., vol. ii, p. 7, pi. xxxiii, fig. 2,
and pi. N, fig. 3, 1849.

— MUCRONATUM. Poli. Test. Sicil., vol. i, p. 60, pi. xvii, figs. 4, 5, 1792.

— SPINOSUM. Sowerby. Brit. Miscel., t. xxxii.

Encyc. Method., t. 298, fig. 3.

Spec. Char. Testa orbiculato-cordatd, convexd, sub-cequilaterali ; antice rotundatd,
postice sub-quadratd ; costis 19 — 20 convexis.papittiferis, interstitiis concentrice striatis.

Shell orbicularly heart-shaped, convex, slightly inequilateral, anterior side rounded,
piosterior angular, or sub-quadrate; ribs 19 — 20, rounded and papilliform, interstices
marked by concentric striae.

Diameter, 1^ inch.

Localities. Red Crag, Sutton.

Uddevalla.

Recent, ^Egean, Mediterranean, Britain, Scandinavia.

A very few specimens only of this shell have as yet come under my observation,
and those are such as have not the spines or tubercular ornaments of the ribs in a
perfect condition.

The hinge is furnished with strong and prominent teeth, those called lateral are
nearly equidistant from the umbo, and there is a somewhat broad and prominent fulcrum
for the support of the ligament ; the posterior side is truncated or angular ; the bend
which is at the posterior lateral tooth forms an angle of about 100°, and the lines of the
ribs are distinctly visible in the interior. Upon the younger portion of the shell the
tubercles are generally gone, and in the fossil that part has lost the outer portion of
the shell, consequently its ornament. The spaces between the ribs, which are broad
and flat, are nearly as wide as the ribs themselves ; they are covered with ridges or
elevated lines of growth at nearly regular distances.

The figure by Dale is, I presume, of a specimen of this species, more especially as
he refers to Lister's representation of C. echinatum, and although in my researches

BIVALVIA. 153

this species has been very rarely met with, it may possibly have been more abundant in
that part of the Crag whence his shells were taken, but now long since washed
into the sea.

C. echinatum, Dubois, * Wolhyn. Pod./ pi. vi, figs. 13, 14, does not appear from the
figure to correspond with our shell.

2. CARDIUM NODOSUM, Montague. Tab. XIII, fig. 4 a — c.

CARDIUM NODOSUM. Mont. Test. Brit., p. 81, 1803*

Turt. Brit. Biv., p. 186, t. xiii, fig. 8, 1822.
Hartley. Recent Shells. Supp., pi. xvii, fig. 44.
Reeve. Conch. Icon. Cardium, pi. xxii, fig. 128.
Loven. Ind. Moll. Scandia, p. 36.
Alder. Catal. Moll. North, and Durh., p. 83, 1848.
Forbes and Hani. Hist. Brit. Moll., vol. ii, p. 22, pi. xxxii, fig. 7, 1849.
DISCREPANS? Brown. Illust. Brit. Conch., pi. xxii, fig. 9, 1827.
— SCABRUM. Phil. En. Moll. Sic., vol. ii, p. 38, vol. xiv, p. 16, 1844.
Hanley. Rec. Shells. Supp., pi. xvii, fig. 43.

Spec. Char. Testa parvd, ovato-orbiculari, parum convexd, sub-eequilaterali, antice
rotundatd, postice truncatd ; costis circa 26 planulatis, nodulosis ; inter stitlis punctatis.

Shell small, somewhat orbicular, slightly convex, a little inequilateral, anterior side
rounded, posterior truncated ; ribs about 26, flattened, and ornamented with tubercles ;
interstices narrow and punctated.

Length, \ an inch nearly ; height, -f-ths do.

Locality. Cor. Crag, Sutton.

Red Crag, Sutton, Alderton, Bawdsey.

Recent, Mediterranean, Britain, Scandinavia.

This species is particularly abundant, more especially in the Coralline Crag, at Sutton,
where the larger specimens are generally much altered by the loss of all the outer
coating of the shell, and with it, of course, its tubercles ; but in the younger state it
may be obtained plentifully in high perfection, and in some specimens the tubercles are
very deciduous, while in others they cover the entire surface. The diameter is in general
greater from the anterior to the posterior side, than from the umbo to the ventral
margin : it is not so in all. It may be very well distinguished by its contour, which is
slightly angular on the hinder side, but less so than in C. exiguum. The ribs are very
flat and broad, and the interspaces so narrow, that it is only occasionally the ridges or
punctated surface of those furrows can be seen. On the anterior and central portion
of the shell, the nodules, when remaining, are broad and obtuse, reaching across the
ribs, while on the posterior side, the ribs are more convex, and only ornamented in the
centre with sharper or smaller tubercles.

154 MOLLUSCA FROM THE CRAG.

3. CARDIUM NODOSULUM, S. Wood. Tab. XIII, fig. 3 a — c.

CARDIUM NODOSULUM. S. Wood. Catalogue, 1840.

Spec. Char. Testa minutd, subcirculari, parum intequilaterali, compressiusculd, tenui;
costatd et nodosd; costis 30 convexis, papillosis, brevibus, et obtusis.

Shell small, subcircular, slightly inequilateral, rather compressed, thin, costated,
and nodulous ; ribs about 30, convex, and studded with numerous short, obtuse papillae.

Diameter, -|ths of an inch.

Locality. Red Crag, Sutton.

Two or three specimens only of this shell are in my cabinet.

There are several species to which this shell bears considerable resemblance, but to
no one does it appear to accord in all its characters ; it must, therefore, remain for the
present with the provisional name attached to it in my Catalogue. In form and general
outline, it is somewhat like the figure of C. pinnulatum, Conrad ; but from the description
of that shell by Dr. Gould, * Invert. Massach./ p. 91, it has only twenty-six ribs, and
an angular ridge on the posterior side, with other characters assigned to nodosum,
corresponding precisely in description to that species, and in like manner differing from
ours.

Card, minimum, 'Phil. En. Moll. Sic.,' also resembles it in many characters, but from
his description must be distinct, as there appears a great difference in the form of the
ribs, for that author speaks of his shell, p. 38, " costis 30 — 32, planissimis"

Our shell may be more fully described as nearly equilateral, the posterior side a
trifle the larger, very slightly convex, or less tumid than the generality of these small
species, somewhat rounded on both sides, rather the less so posteriorly ; the distin-
guishing character is in the ribs, which are, at least, 30, not flat, but convex, with
a wide space between each, and the centre of these ribs only are covered with short,
narrow, obtuse, nodules ; those upon each side, more especially on the posterior, are
smaller than upon the middle of the shell. The interstices between the ribs are broad,
deep, concave, and smooth. Card. sueCicum has a like number of ribs, but is not
smooth between them, is more inequilateral, and has vaulted scales. Card, papillosum,
Poli, has a less number of ribs, and is otherwise different.

4. CARDIUM STRIGILLIFERUM, 8. Wood. Tab. XIII, fig. 5 a — d.

CAKDIUM ELONGATUM. S. Wood. Catalogue, 1840.

Spec. Char. Testa minutd, ovatd, transversd, valde incequilaterali, tumidd ; costis 24
elevatis, planiusculis, papittiferis, papittis squamaformibus, sulcis magnis punctatis, vel trans-
verse imbricatis.

Shell small, ovate, transverse, very inequilateral, tumid, with about twenty-four
elevated ribs, flattened on the top, and ornamented with vaulted scales or tubercles ;
spaces between the ribs wide, with elevated concentric ridges.

BIVALVIA. 155

Length, f ths of an inch. ; height, -|ths of an inch.

Locality. Cor. Crag, Sutton.

This elegant species is one of the most abundant shells, though very rarely found
with the valves united.

It much resembles the figure of C. elongatum, Turt. Judging from that alone, it
was imagined to have been the same, and inserted under such name in my Catalogue.
The great peculiarity of our shell is the very broad furrow, or intermediate space be-
tween the ribs, and the intersecting of these furrows by regular, sharp, elevated ridges
at right angles to the ribs. It is very inequilateral, and rather tumid, with a somewhat
prominent umbo ; the ribs are thickly studded with elevated and vaulted scales, ex-
tending about three quarters across the depressed but not quite flattened rib ; and
when the specimen is in good condition, the entire surface of the rib is covered with
these prominent half-tubular spines.

On the posterior portion they are more prominent and sharp, the spaces between
the ribs are nearly as broad as the ribs themselves, and filled with the regular ridges,
giving it a somewhat cancellated appearance ; the ribs are seldom less than twenty-two
or more than twenty-four in number, and these are distinctly visible within the shell.

In the very infant state of this species (fig. 5 c\ the ribs are not more than half
in number ; after which, an additional one is interposed between each, so that only
every other rib terminates or converges to the beak. The margin of the shell is deeply
indented by the ribs, more especially on the posterior side, where they project in a
somewhat ragged or jagged manner beyond the margin.

5. CARDIUM EDULE, Linnaeus. Tab. XIV, fig. 2 a — g.

Lister. Hist. Conch, pi. 334, fig. 171.

Vale. Hist, and Antiq. of Harwich, p. 293, pi. xii, fig. 5. 1730.

CARDIUM EDULE. Linn. Syst. Nat., ed. 12, p. 1124, No. 90, 1767.

Don. Brit. Shells, vol. iv, t. 124, fig. 1, 1803.

Phil. En. Moll. Sic., voL i, p. 52, t. iv, fig. 16.

Loven. Ind. Moll. Scand., p. 35, 1846.

Midden. Malac. Rossic., p. 548, t. xv, figs. 10-22.

Basterot. Bord. Foss., p. 81, 1825.

— VULGARE. Dacosta* Brit. Conch., p. 180, pi. xi, fig. 1.

EDULE. Chemn. Conch. Cab., t. vi, p. 198, t. xix, fig. 194, 1/82.

— PECTINATUM. Desk. 2d edit. Lam., t. vi, p. 405.

— ARCUATUM, Reeve. Conch. Icon. Cardium, pi. xxii, fig. 133.

— ZONATUM. Brown. Illust. Brit. Conch., t. xxii, fig. 8, 1827.

— TENUE. Id. „ „ t. xxii, fig. 4.

— CRENULATUM. Reeve. Conch. Icon., pi. xx, fig. 112.

— RUSTICUM. Chemn. Conch. Cab., t. vi, t. xix, fig. 197.

Eichwald. Fauna Caspio-Caucasia Nouv. Mem. dela Soc. Imp. des Nat,

de Mosc., t. vii, t. xxxvii, figs. 24-27.
— Phil. En. Moll. Sic., vol. i, t. iv, figs. 12-14.

— EDULINUM. J. Sowerby. Min. Conch., t. 283, fig. 3, 1821.

156 MOLLUSCA FROM THE CRAG.

CABDIUM EDULINUM. Nyst. Ooq. Foss. de Belg., p. 193, pi. xv, fig. 1, 1843.

— ANGUSTANUM. Id. Eech. Coq. Foss. Prov. d'Anv., p. 13, No. 49, 1835.

— OBLIQ.UUM. Woodward. Geol. of Norf., p. 43, pi. ii, fig. 19, 1833.

— CLODIENSE. Broc. Coq. Foss. Subap., t. xiii, fig. 3, 1814.

— GLAUCUM. Brug. Encyc. Meth., t. i, p. 221, No. 14.

— LAMABCKII. Reeve. Conch. Icon. Cardium, pi. xviii, fig. 93.

— BELTICUM; Id. „ „ pi. xx, fig. 113.

— EICHWALDII. Id. „ „ pi. xix, fig. 94.

Spec. Char. Testa variaMZe, plurimum rotundato-cordatd, obtiqud, interdum ovatd,
transversd, compressiusculd aut tumidd,parum incequilaterali costatd costis 18 — 28 postice
scepe obsoletis ; lineis concentricis elevatis, distantibus, asperis.

Shell variable, for the most part roundedly heart-shaped, oblique, sometimes trans-
versely ovate, often tumid, occasionally compressed; ribs 18 — 28, the posterior obso-
lete ; concentrically rugose, with distant, dwarfish imbrications.

Length, 2 inches ; heit/ht, \\.

Localities. Cor. Crag, Ramsholt (var. rusticum).
Red Crag, passim.

Mam. Crag, Bramerton, Thorpe, Chillesford.
Uddevalla.

Recent, Mediterranean, Finmark, Britain, Caspian.

The first indication of the existence of this species is in the Coralline Crag, from
which Formation I have only one specimen, and this is of the var. called rusticum / its
habits, however, in the living condition, are such as to confine it generally to shallow
water, and to the proximity of rivers, that its presence at Ramsholt in association
with species that are more purely marine, is not, perhaps, to be so much surprised at.
In the Red Crag, though not one of the most abundant, it is of common occurrence,
but the specimens are sometimes rubbed and worn, as if they had been much disturbed,
and probably transported from a distance : this is the state in which that variety
called edulinum by J. Sowerby, in ' Min. Conch.,' is most often found, and it is the one
most common there, and may, perhaps, have been derived from the older Formation,
or Coraline Crag. In the Red Crag the variations are very conspicuous ; in some the
diameter from the anterior to the posterior side greatly exceeds the measurement from
the umbo to the ventral margin ; in others it is slightly the reverse ; and the number
of ribs is alike variable ; the character most distinguishable is the slope on the pos-
terior side where the ribs are less prominent than upon the other parts of the shell,
but this is at times very indistinct, more particularly in that variety called clodiense
(fig. 2 e), which I believe to be only an aberrant form of this species.

BIVALVIA. 157

6. CARDIUM ANGUSTATUM, /. Sowerby. Tab. XIII, fig, 6 a — c.

CARDIUM ANGUSTATUM. J. Sow. Min. Conch, t. 283, fig. 2, 1821.
Woodward. Syn. Tab., p. 13, 1830.
S. Wood. Catalogue, 1840.

$pec. Char. Testa transversd, elongato-ovatd, parum incequilaterali ; depressiusculd,
tenui ; antice rotundatd, inflatd; postice attenuatd, compressiusculd ; costis 27 — 32 depressis,
planulatis, approximatis, aspens ; margine ventrali recto vel coarctato.

Shell transverse, elongato-ovate, slightly inequilateral, somewhat depressed,
thin ; anterior side rounded, and inflated, posterior attenuated, and compressed ;
ribs 27 — 32, depressed, flattened, approximating, roughened ; ventral margin
straight, or rather contracted.

Length, \\ inch; height, 1 inch.

Localities. Red Crag, Sutton, Bawdsey, Ramsholt, Alderton.

This species is very abundant in one or two localities, and it does not appear to
have been as yet met with in any other part of the World than in the Red Crag.

In £Min. Conch.' above referred to, vol. iii, p. 149, it is stated to be abundant in
the Crag of Norfolk, but it is not enumerated amongst the shells from near Norwich by
Woodward, nor have I seen a specimen from that Formation. This species may be well
determined, although occasionally it presents some difference in outward form, but the
posterior side is always more or less attenuated, and the dorsal margin on that side
slopes at a considerable angle from the umbo ; the line of the ventral margin, also, in
that half of the shell, is contracted or drawn inwards, giving it a pointed form,
considerably more so than in any variety of the common cockle, from which it also
differs in having a greater number of ribs, and these are flatter. The umbo is nearly
equidistant from each extremity, but the posterior side is much the smaller ; the marks
of the ribs are very distinct halfway into the interior, and in some very thin specimens
they may be seen up to the umbo. Externally they are flat, broad, and striated, with
a narrow space between them ; they are more distinct on the anterior side and body
of the shell, as in C. edule, becoming obsolete on the posterior slope, and where the
exterior is well preserved, they show a sub -imbricated surface all over. In a part of
the cliff by the river side at Ramsholt, I have found this species in situ with the valves
united, where they show a very slight gape on the posterior side ; the specimens are
particularly thin and tender, with generally a loss of a considerable part of the exterior ;
in these specimens the ligament is well preserved.

158 MOLLUSC A FROM THE CRAG.

7. CARDIUM PARKINSONL, /. Sowerby. Tab. XIII, fig. 7 a — b.

CARDIUM PARKINSONI. J. Sow. Min. Conch., t. xlix, 1814.

Woodward. Syn. Table Brit. Foss., p. 43, 1830.

Id. Geol. of Norf., p. 43, t. ii, fig. 18, 1833.
Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 12, No. 48, 1835.
Potiez and Mich. Cat. des Moll, de Douai, t. xi, p. 183, 1844.
Nyst. Coq. Foss. de Belg., p. 186, pi. xiv, fig. 2 a, b, 1844.

Spec. Char. Testa magnd, rotundato-ovatd, vel oblique-cordatd, convexd, sub-cequi-
laterali ; antice rotundatd, postice sub-angulatd ; costis 28 — 32 planulatis, sub-imbricatis.

Shell large, roundedly ovate, or obliquely heart-shaped, convex, sub-equilateral ;
anterior side rounded, posterior sub-angulated; ribs 28 — 32, rather flattened, and
slightly imbricated.

Lengthy 2| inches ; height, 2J inches.

Localities. Red Crag, Walton-on-the-Naze, Felixstow, Sutton.
Mam. Crag? Thorpe (Woodward}.

This handsome shell appears to be restricted to the Red Crag Period, for the
specimens recorded by Woodward were rare or fragmentary, and may have been
accidental introductions, as my Norwich collecting friends do not appear to have met
with it in their neighbourhood. At Walton-on-the Naze it may be procured in great
abundance, and at that rich deposit the specimens are generally in a fine state of pre-
servation ; my largest does not exceed the above dimensions, but fragments indicate
its having attained a magnitude of at least three inches in diameter. It somewhat
resembles in general appearance C. Islandicum, Linn., but differs from that species in
the form of its ribs ; it also has a resemblance to C. maculatum, Grael., C. ventricosum,
Brug., from the bay of Campeachy, but is never so large, and seldom of such com-
parative dimensions, our shell being generally longer than high; it differs from
C. edule in being less angulated or pointed, but is of a more quadrate form on the
posterior side, although specimens in the young state are exceedingly difficult to be
distinguished. The ribs are sometimes rounded, but more generally flattened, and are,
in the best preserved specimens, distinctly striated, but I have never been able to
count so many as forty, the number given as its specific character in ' Min. Conch.,'
and seldom more than thirty-one ; they are often regularly ornamented with dwarf
ridges, or sub-imbrications, crossing the prominent parts, and they are more distant than
those upon the common cockle, especially on the anterior side of the shell, where, in
some specimens, they are often regular and distinctive ; on the posterior side these
concentric ridges are coarser and closer together ; the dental characters are prominent,
resembling those of edule, though less strongly developed, with a proportionally
smaller ligamental area, and the shell is thinner, in all which characters there is a
sufficient difference to entitle this to be considered as specifically distinct.

BIVALVIA. 159

8. CARDIUM DECORTICATUM, S. Wood. Tab. XIV, fig. 1 a — d.

CARDIUM DECOKTICATUM. S. Wood. Catalogue, 1840.

— OBLONGUM. Nyst. Coq. Foss. de Belg., p. 187, pi. xiv, fig. 3, 1844.

— FRAGILE ? Broc. Conch. Foss. Subap., p. 505, t. xiii, fig. 4 a, b.

Spec. Char. Testa orbiculato-ovatd, obliqud, inaquilaterali, magnd, tumidd, costatd,
costis 34 — 36; latere postico lavigato, ad latere antico costis evanescentibus.

Shell roundedly-ovate, oblique, inequilateral, large, somewhat tumid, costated,
posterior side smooth, ribs becoming obsolete or evanescent on the anterior side.

Longitudinal diameter, 3 inches ; transverse ditto, 2f inches.

Localities. Cor. Crag, Sutton, Ramsholt, Sudbourn, Gedgrave.

This handsome shell is abundant in the Coralline Crag, but it is difficult to obtain in
perfection, from its extreme fragility ; the specimens appear not only to have lost much
of their animal matter, but the exterior of the younger portion of the shell has become
eroded or decorticated down to the base of the ribs, leaving only vestiges of where
they had been, while the outer or older part of the shell exhibits the true characters of
its original ornament.

From the description given by M. Nyst, there is every probability that the Belgian
shell is identical with our English Crag fossil, but I believe it is quite distinct from the
recent C. oUongum, Chemn., and from the Sicilian fossil, as well as from the recent
British shell, C. Norvegicum, and also from C. lavigatum, Linn.; in its much more distinct
and rugose ribs, it approaches closely in that character the Sicilian fossil, differing,
however, from this latter most essentially in its form.

Card, tenellum, of my Catalogue, is probably the young of this species ; it differs
somewhat in outline from the adult shell, having a greater diameter from the anterior
to the posterior side, and it was in consequence considered distinct ; but intermediate
ages have been since obtained, by which it is thought a specific relationship may be
maintained.

9. CARDIUM INTERRUPTUM, S. Wood. Tab. XIV, fig. 4 a — b.

Spec. Char. Testa rotundato-triangulatd sub-obliqud, in&guilaterali ; costis 35 — 40
depressis, interrupts, ad latum posticum nullis ; margine ventrali serrato.

Shell roundedly triangular, slightly oblique, inequilateral ; ribs 35 — 40, depressed
and interrupted ; posterior side smooth ; ventral margin denticulated.

Length, 2j inches ; height, 2 inches.

Locality. Red Crag, Sutton.

I have obtained a few specimens only of this species in perfect condition, and
these are all of the left valve, but fragments are not particularly rare.

The rays upon the shell are about forty in number, strongly marked by periodical
lines of growth, between which the surface is much eroded or decorticated so deep as

21

160 MOLLUSCA FROM THE CRAG.

almost to have obliterated the radiating ridges. There appear to have been periods in
the life of the animal when the margin of the shell was more than ordinarily thickened,
as if the process of increase in the shell was delayed or interrupted, after which it
proceeded with more slender rays until they were again thickened, or rather strength-
ened. This fossil strongly resembles a northern form found in the sea of Ochotsck,
figured by Middendorff in his ' Russian Malacology,' t. xv, figs. 23 — 25, described
under the name of C. Calif orniense, Desh., but it is, I believe, specifically different, as in
that species (according to the figure) the posterior side is much less rounded than in
our Crag fossil ; the hinge also appears thicker, with a wider fulcrum for the ligament.

10. CARDIUM VENUSTUM, 8. Wood. Tab. XIII, fig. 2 a — b.

Dale. Hist, and Antiq. of Harwich, p. 293, pi. xii, fig. 18, 1730.

Spec. Char. Testa cordato-ovatd, odliqua, incsqmlaterali ; obsolete costatd, costis nume-
rosis depresses ; latere postico l&mgato.

Shell ovately heartshaped, oblique, inequilateral ; obsoletely costated, ribs nume-
rous, depressed ; posterior side smooth, naked.

Length, 2 inches; height, 2 inches.

Localities. Red Crag, Walton-on-the-Naze, Sutton.

This is one of the rarer shells of the Red Crag. Being unable satisfactorily to
assign it to any known species, I am reluctantly obliged to give it a new name. The
shell figured by Dale is evidently the same as ours, but I cannot, as he has done, refer
it to Lister's figure, which is C. Norvegicum; there is a strong general resemblance, but
the posterior side is too much rounded to be united with that species, and it was
probably a smoother shell than C. decorticatum of the Coralline Crag.

11. CARDIUM GROENLANDICUM, Chemnitz. Tab. XIII, fig. 1 a — d.

CAKDIUM GB.OENLANDICUM. Chemn. Conch. Cab., t. vi, p. 202, t. xix, fig. 198, 1782.

Gould. Invert. Massach., p. 92, 1841.
Holier. Ind. Moll. Groen., p. 20, 1842.
Dekay. Nat. Hist. New York Zool., p. 206, pi. xxiii, fig. 250.
Reeve. Conch. Icon. Card., pi. x, fig. 53.
Middendorff. Malacozoologia Rossica, (Me'm. de 1'Acad. Imp.

des Sci. St. Petersb.,) p. 557, t. xvi, figs. 6—9, 1849.
EDENTULA. Mont. Test. Brit. Suppl., p. 29, 1808.

— EDENTULUM. G. Sow. Genera No. 34, Cardium, fig. 2.

— ANODONTA. Blainv. Man. Malac., p. 658, 1825.

— BOE.EALE. Reeve. Conch. Icon., pi. xxii, fig. 131.
MACTEA RADIATA. Don. Brit. Shells, vol. v, t. 161, 1803.

APHKODITA COLUMBA. J. Lea. Trans. Amer. Phil. Soc., vol. v, p. 1 10, pi. xviii, fig. 54, 1833.
ACAKDO. Swains. Treat. Malac., p. 374, 1840.
SERRIPES. Seek. Fide Gould.

MONODACNA PROPINQUA? Eichwald. Fauna Caspio-Caucasia, p. 275, t. xl, figs. 3, 4, 1841.
? Encyc. Method., t. 300, fig. 7.

BIVALVIA. 161

Spec. Char. Testa sub-cordatd, transversd, incequilaterali, tenui, sub-l&mgatd ; antice
rotundatd, postice prodmtd et angulatd ; costis radiantibus obsoletis, striis concentricis
distantibus, maryine Integra.

Shell somewhat heartshaped, transverse, inequilateral, thin, and nearly smooth ;
anterior side rounded, posterior produced and angular ; ribs or radiating lines obsolete,
concentric striae distant; ventral margin with a very gentle curve, and free from
crenulations.

Length, 2f inches ; height, 2 \ inches.
Localities. Red Crag, Bawdsey, Button.
Mam. Crag, Chillesford.

Recent, Greenland, North America, Nova Zembla.

This species is abundant in the Red Crag at Bawdsey, but is very scarce in collections,
from the difficulty of obtaining a perfect specimen, the exterior being always more or
less eroded, and the shell becoming very thin and fragile ; the same may also be said
of those found in the sandy deposit of the Mammaliferous Crag Period at Chillesford.
This species is so well marked that there is no danger of its being confounded with
any other, it stands, as it were, upon the very confines of our generic limits, possessing
only the rudiments of those characters by which the majority of the shells in this
genus are so well distinguished, and which, indeed, are in general so prominently
displayed. The costae, if they may be so called, are, in the recent shell, but faintly
visible, and traces of them are left upon the thickened edges or undecomposed portions
of the fossil, most distinctly upon the anterior side ; the shell has much the aspect of a
mactra, and its surface is eroded in the same manner as in the generality of the shells
of that genus from the Crag. The posterior side of our shell has a squarish outline,
being obtusely angular at the extremity of the posterior lateral tooth, while the ventral
margin forms with the posterior side an angle not much less than 90°, though in some
of the specimens from Chillesford that side is much more pointed. The arrangement
of the dental characters are those of a true Cardium, but they are like the costae,
evanescent, as if a corresponding prominence existed between the teeth and ribs : two
large, ovate, and deeply-impressed muscle marks are left in my specimens, seemingly
compensating in its powerful adductors for the deficiency of dental characters.

Cardium Norvegicum and Cardium pygmaum are given in the 'List of Clyde Fossils,'
by Mr. Smith of Jordan Hill.

Genus CHAM A,* Linn., 1758.

GLOBUS (sp.) Klein, 1753.
STOLA. Browne, 1756.
JATRONUS. Adanson, 1757.
MACTIOPHYLLTJM. Gevers, 1766.

* Etym. xhpri, Aristot, a kind of shell fish.

162 MOLLUSCA FROM THE CRAG.

MACROPHYLLA. Chemn., 1784.
PSILOPUS (sp.) Poll, 1791.
GRYPHUS. Humph., 1797.
LACINIA. Id.
LAZARUS. Cuvier, 1800.
ARCINELLA. Schum., 1817.

Gen. Char. Shell thick, strong, and adherent, irregular, rugose or foliated
externally, inequivalve, sub-equilateral, with a distant, unequal, somewhat involute
umbo. Hinge with one thick, oblique, sub-crenulated, obtuse tooth in one valve,
inserted into a corresponding depression in the other. Impressions of the adductor
muscles elongato-oval, that by the mantle entire, or without an inflection. Ligament
external.

The figure of the animal of one species, as given by Poli, has the mantle open in
front, with the edges slightly fringed, long, sub-cylindrical, somewhat bent : foot with
a projecting heel, and two short and ciliated siphonal tubes, not extending beyond the
margin of the shell.

Amongst the recent species of this genus are some whose shells are elegantly orna-
mented with spines or foliations, while others are rough, and possessed of but little
beauty, and the rugose exterior often forms a firm attachment for species of sponge, by
which they are occasionally covered.

The animal generally fixes itself by the left valve, though sometimes by the right,
and specific distinctions have been formed in consequence, upon the belief that the
same species always adheres by the same valve. Recent observations have proved
the fallacy of this dependence.

Animals belonging to this Genus are inhabitants of tropical or sub-tropical regions,
and are not known in a living state further north than the Mediterranean. It is
rather a modern genus, no true species being found in any formation older than the
Tertiaries.

1. CHAMA GRYPHOIDES, Linnaeus. Tab. XV, fig. 8 a — d.

CONCHA RUGATA RONDELETII. Aldrov. De Test., lib. iii, p. 458, 1623.

GLOBUS UNDATUS. Klein. Tent., p. 173, No. 3, t. xii, fig. 81.

CONCHA RUPIUM. Chemn. Conch. Cab., t. vii, p. 145, t. li, figs. 510 — 513.

— GRYPHOIDES. Gault. Ind., part v, t. 101, lit. c — E.

CHAMA Linn. Syst. Nat., ed. 12, No. 165, p. 1139, 1767.

Chemn. Conch. Cab., t. vii, t. li, figs. 510—513, 1787.

_ — Poli, Test. Utr. Sic., vol. ii, p. 122, t. xxiii, figs. 3, 4, and 20, 1795.

_ — Broc. Conch. Foss. Subap., p. 519, No. 2, 1814.

IBasterot. Bord. Foss., p. 81.
Bronn. Lethsea Geogn., vol. ii, p. 927, t. xxxviii, fig. 11, 1838.

— Phil. En. Moll. Sic., vol. i, p. 68, vol ii, p. 49.
Savigny. Egypt., t. xxii, p. 211, pi. xiv, figs. 8, 1 — 3.

_ _ UOrbigny. Moll. de. Canar., p. 104, No. 178.

BIVALVIA. 163

CHAMA GRYPHINA. Lam. Hist, des An. s. Vert., t. vi, p. 97.

Goldf. Pet. Germ., vol. ii, p. 205, t. 138, fig. 9 a— c.
Phil. En. Moll. Sic., vol. i, p. 68, vol. ii, p. 49.
Reeve, Conch. Icon. Chama, pi. viii, fig. 43.

— SINISTRORSA. Chemn. Conch. Cab., vol. ix, p. 145, t. 116, figs. 992-3, 1786.

Broc. Conch. Foss. Subap., p. 519, No. 3, 1814.

— BICORNIS. Linn. Syst. Nat., ed. 12, p. 1139, No. 166, 1767.

— UNICORNIS. Desk. 2d ed. Lamarck., t. vi, p. 582, 1835.

Phil. En. Moll. Sic., vol. i, p. 68, 1836.

— UNICORNARIA. Lam. Hist, des An. s. Vert., t. vi, p. 98, 1815.
CORNUTA. Chemn. Conch. Cab., t. vii, p. 150, tab. lii, figs. 519-20.
LACERNATA. Desk. 2d ed. Lam., t. vi, p. 588, 1835.

Spec. Char. Testa crasssd, irregulariter orbiculari, imbricatd, lamettis drevibus, ap-
pressis ; apice valvula inferioris sinistrorsum incurvo.

Shell thick, strong, irregularly orbicular, covered with short, close imbrications,
or lamellae ; apex of the lower or adherent valve curving to the left.

Diameter. 2 inches.

Localities. Cor. Crag, Sutton.

Red Crag, Sutton and Newbourn.

Recent, Mediterranean.

This shell, in my cabinet, is very rare from the Coralline Crag, at the period of which
deposit it was an undoubted inhabitant of our latitude ; a few specimens have been
found in the disturbed portion of the Red Crag, but the solidity of the shell would
protect it in its possible removal from an older formation. In the few specimens
that I possess from the Red Crag, a somewhat greater difference appears to exist
between the two valves than is generally observable in C. gryphoides^ or recent
variety, but that is so variable a character in the living shell as to give no warrant
for specific difference, depending, as it does, upon its mode of growth, or place of
attachment.

The differences observable in C. grypldna and gryphoides appear to depend entirely
upon the mode by which the animal chooses to attach itself, the one by the right valve,
while the other is fixed by the left. In some species, as shown by Mr. Broderip,
(in the ' Trans, of the Zool. Soc.,') this mode of adherence is wholly eclectic, depending
upon the will of the animal, and that it almost as often employs the one valve as the
other for that purpose.

In the var. grypltina the lower and larger valve, or that which has been the fixed
one, is the right, with the umbo taking a spiral or involute direction towards the left
hand, and the free valve appears more as an operculum to cover the animal, which
principally occupies the lower valve, like the oyster. In C. gryphoides this is reversed,
the left valve being made the adhering one, has consequently become the larger. Such
a character is a less organic change than we find exhibited in the two opposite forms
of Trophon antiquum, the spire of which, in the recent shell, turns commonly to the

164 MOLLUSCA FROM THE CRAG.

right, while that of the fossil from the Crag, now admitted by all conchologists as
only a variety, turns generally to the left. In my first examination of the recent
species, there appeared a difference of form in the impressions by the adductors, which,
however, further observation proved to be no permanent character; the shape of
these muscle marks being considerably modified by the outward form of the shell, and
like the oyster, or any other adherent species of the Bivalvia, is more subject to dis-
tortion by the position it has chosen to fix itself, than is ever partaken of by those
species which are free, and the muscle marks undergo an elongation or contraction,
conforming themselves, in that respect, to the varying properties of the shell, and
showing that these are no more to be relied upon than are the outward forms of
the shells themselves.

CARDITA,* Bruguiere. 1789.

ANOMALOCARDIA (sp.) Klein, 1753.
ACTINOBOLUS. Klein, 1753.

LlMNEA et LlMNODERMA (sp.) Poll, 1795.

TRAPEZIUM (sp.) Humph., 1797.
BEGUINA. Bolten, 1798.
ARCTURUS. Humph., MS.
VENERICARDIA. Lam., 1801.
GLANS. Megerle, 1811.
ARCINELLA. Oken, 1815.
CARDISSA. Olten, 1815.
MYTILICARDIA. Elaine., 1824.
, CARDITAMERA. Conrad, 1838.
AGARIA. Gray, 1840.

Gen. Char. Shell regular, thick, and strong, equivalve, inequilateral, suborbicular
or transverse, closed, generally covered with more or less elevated, thick, and distinct
costae ; hinge furnished with two teeth, one short, placed near the umbo, the other
oblique, sub-marginal, prolonged towards the posterior. Impression of the mantle
without a sinus, those by the adductors deeply seated. Ligament external.

Animal of the form of the shell, with the edges of the mantle disunited, and
without projecting siphons ; foot small and elongated : buccal opening furnished with
three or four pairs of tentacles.

Shells constituting this genus are ornamented upon the exterior with ribs radiating
or diverging from the umbo, and are more or less elevated, becoming in some species
nearly obsolete, and the shells are always thick and strong.

In the recent state, as a Genus, it has an extended geographical range, one species
being found on the Coast of Norway, while others inhabit the seas of New Holland,
the Indian Ocean, China Seas, shores of Western Africa, and the East Coast of

* Etym. Kapbta, the heart.

BIVALVIA. 165

America; though not numerous in species, they are widely distributed. They
are all marine, and probably, from the thickness of their shells, were inhabitants
of not very deep water. The animal is said to be occasionally fixed by a byssus,
though that is seldom the case, as, generally, the valves are capable of being
perfectly closed.

It does not appear to be a very ancient genus, though largely developed in the
Tertiaries.

1. CARDITA SENILIS, Lamarck. Tab. XV, fig. 1 a— -f.

VENERICARDIA SENILIS. Lam. Ann. du Mus., t. vii, p. 57.

Id. Hist, des Env. de Par., p. 222.

Desk. 2d ed. Lam., Hist, des An. a. Vert., t. vi, p. 384, 1835.
Parkinson. Org. Rem., vol. iii, p. 191, pi. xiii, figs. 15, 17, 1811.
J. Sow. Min. Conch., t. 258, figs. 1—3, 1820.
Nyst. Rech. Coq. Foss. d'Anv., p. 11, No. 43, 1835.
Lyell. Trans. Geol. Soc., 2d ser., vol. v, p. 245, fig. 1, 1836.
ANTIQUATA. Leathes' MS., fide J. Sowerby.

INTERMEDIA? Dubois. Wolh. Podol., p. 61, pi. v. figs. 20-1, 1831.
CARDITA SQUAMULOSA. Nyst. Coq. Foss. de Belg., p. 207, pi. xvi, fig. 4 b, and fig. 5 a, b,

1844.
Dale. Hist, and Antiq. of Harw., p. 291, t. xii, fig. 4, 1730.

Spec. Char. Testa oblique-cordatd, incequilaterali, oblongd, sub-quadratd vel orbiculari ;
compressd vel turgidd, crassd, dausd ; costis 17 — 20 magnis, convexis, rugosis, inter dum
squamis, elevatis, fornicatis, asperis; lunuld parvd, impressd, dentibus crassis, perpendicu-
lariter striatis.

Shell obliquely heartshaped, inequilateral, oblong, subquadrate, or orbicular,
tumid or compressed, thick, strong, and closed, furnished with 17 — 20 large, convex,
rugose costse, sometimes ornamented with distant, arched, and elevated squamae ;
lunule small, deeply impressed, teeth thick, and striated in a vertical direction.

Largest Diameter, If inches.

Localities. Cor. Crag, Ramsholt, Button, Sudbourne, and Gedgrave.

Red Crag, Sutton, Newbourn, Alderton, Bawdsey, Felixstow.

At Gedgrave it may be procured by hundreds, and occasionally with the valves
united, when it forms one of our handsomest shells. It appears to have flourished in
great profusion during the period of the Coralline Crag; and from the large number of
specimens met with in the Red Crag, it may probably have extended its existence into
the period of that deposit, although I have not yet found it at Walton-on-the-Naze.*

This is also one of the most variable of the whole class of Bivalves. The shell
with this name, as given from the Environs of Paris by Lamarck, is probably an error,
at least I have not been able to see an Eocene species with which it could be identified ;

* Dale gives it from Harwich, but as a shell of rare occurrence.

166 MOLLUSCA FROM THE CRAG.

the fossil from Angers is, in all probability, the same, as I have no doubt the one figured
and described by M. Nyst (C. squamulosd} is no more than a variety of this Protean
shell. The valves are always very thick and strong, ornamented with rounded
radiating ribs ; these are covered with more or less rugose lines of growth at all
times, and in some well-preserved specimens large and elevated squamae may be
observed at somewhat irregular distances ; the spaces between the ribs, upon the
centre and anterior part of the shell, are rather narrower than the ribs themselves,
more especially on the posterior part, where they are also less elevated. The umbones
are slightly involute, and have a small plain space or lunule immediately beneath them.
The right valve has one large tooth sloping towards the posterior side, with the rudi-
ments of a small one before it, near the umbo ; in the left valve is a large depression
for the tooth of the opposite one, and a thin, linear, compressed tooth, nearly parallel
to the dorsal margin, with a small triangularly-formed cardinal tooth, that becomes
obsolete in some specimens : these elongated teeth are marked with vertical striae like
the lateral teeth in some species of Mactree, Cyrena, &c.

In those species with a very transverse form of valve, the shell is generally more
compressed, and vice versa, in the orbicular varieties it is more tumid ; deep impressions
are left by the adductors, and the margin of the shell is indented by the elevation of
the ribs ; a small additional muscle mark is left upon the shell joining the anterior
adductor, such as is common to most of the species of Astarte and some of the
Venenda, and the ligament was probably strong and powerful, as indicated by the
fulcrum, and deeply impressed furrow on the outside.

In all my specimens, notwithstanding its extreme range in variation in regard to
form, from that which is truly orbicular and nearly equilateral, to those which are more
especially transverse and very inequilateral, they invariably possess the character of
being somewhat rounded at the posterior side, and never angulated, like Ch. antiquata,
Linn. I am not sufficiently acquainted with the Italian fossils to say whether either of
the shells figured by Brocchi could be united with the Crag shell, but those specimens
I have seen appear to differ in being also less rounded on the posterior side, with a
slight difference in the form of the ribs, and covered with more prominent scales.

2 CARDITA SCALARIS, Leathes MSS. Tab. XV, fig. 5.

VENERICARDIA SCALARIS. J. Sowerby. Min. Conch., t. 490, fig. 3, 1825.

Nyst. Rech. Coq. Prov. d'Anv., p. 12, No. 47, 1835.

Potiez et Mich. Catal. des Moll, de Douai, p. 166, No. 19, 1844.
CAEDITA Gold/. Pet. Germ., vol. ii, p. 188, t. 134, fig. 2 a, b.

Nyst. Coq. Foss. de Belg., p. 213, pi. xvi, fig. 9 a, b, d, 1844.

Spec. Char. Testa orbiculato-triangulari, depressd ; costis 20 — 22 convexis, nodosis ;
concentrice sulcatis ; umbonibus medianis.

BIVALVIA. 167

Shell triangularly orbicular, depressed, with 20 to 22 convex, close set nodulous
ribs ; concentrically sulcated ; umbones moderately elevated.

Diameter, \ an inch.

Localities. Cor. Crag, Sutton, Sudbourn, and Gedgrave.
Red Crag, Sutton, Walton-on-the-Naze.

This species is very abundant in the Coralline Crag at Gedgrave and Sudbourn,
and it is by no means scarce in some parts of the Red Crag. The most distinguishing
character in this shell is the nodulous form of the ribs, which are placed near together,
separated only by a narrow line. The outline of this shell is in general pretty regular,
being of a roundly trigonal form, with the umbo turning slightly towards the anterior ;
occasionally the umbo is more elevated, giving it then a thicker hinge; a small smooth
space or lunule is visible, when perfect, on the anterior side, and the elevated ribs
produce a deeply crenulated margin.

3. CARDITA ORBICULARIS. Leathes* MS. Tab. XV, fig. 4.

^^ \

VENERICARDIA OBBICULARIS. J. Sowerby. Min. Conch., t. 490, fig. 3, 1825.

, Potiez et Mich. Cat. des Moll, de Douai, p. 165, No. 17, 1844.

CARDITA Nyst. Coq. FOBS, de Belg., p. 214, pi. xvi, fig. 10 a, b, d, 1844.

TUBERCULATA. Gold/. Pet. Germ., vol. ii, p. 188, t. 134, fig. 3 a, b.

Spec. Char. Testa orbiculari, tumidd, convexd, crassd; costis 16 — 18 distantibus ;
concentrice sulcatis.

Shell orbicular, convex, tumid, and thick; 16 to 18 convex ribs, with a flat space
between them ; concentrically sulcated.

Diameter, \ an inch.

Localities. Cor. Crag, Sutton.

Red Crag, Sutton, Newbourn.

This species is also abundant both in the Coralline and in parts of the Red Crag,
but I have not seen it from Walton-on-the-Naze. The shell is more orbicular than
the preceding, and it is also more tumid ; the costae are different, being narrower and
standing apart, having a flat space between them, equal to the breadth of the ribs ;
the costae are ornamented with nodules like those of scalaris, but are fewer in number;
the interstices show the obtuse lines of increase, but they are not elevated like those
upon the ribs, and the umbo is rather more curved and less prominent.

4. CARDITA CHAM^FORMIS, Leathes MS. Tab. XV, fig. 3 a — b.

VENERICARDIA CHAJLEFORMIS. J. Sow. Min. Conch., t. 490, fig. 1, 1825.

Potiez et Mick. Cat. des Moll, de Douai, p. 162, No. 3, 1844.
CARDITA CHAM^EFORMIS. Gold/. Pet. Germ., vol. ii, p. 189, t. 134. fig. 4 a, b.

— Nyst. Coq. Foss. de Belg., p. 211, pi. xvi, fig. 7 a, 6, dt 1844.

22

168 MOLLUSCA FROM THE CRAG.

Spec. Ckar. Testa suborbiculari, convexiusculd, crassd; costis 14 — 16 converts, rugosis;
natibus prominentibus.

Shell suborbicular, slightly convex, thick; with 14 — 16 rugose and convex ribs,
umbones rather prominent.

Diameter, ^ an inch.

Localities. Cor. Crag, Sutton.

Red Crag, Sutton, Newbourn.

This shell is not very abundant in my cabinet. It has a more elevated umbo and
a less number of ribs than either of the preceding species ; the form of the hinge as
well as the muscle marks being the same in all, only varying a little in conformity
with the varying outline of the shell. The ribs in my specimens are somewhat distant,
more rounded, and less nodulous than in C. scalaris, less distant than in C. orbicularis.

5. CARDITA ANALIS ? Phil. Tab. XV, fig. 6.

CARDITA ANALIS. Phil. Palseont. Beitr., p. 50, t. vii, fig. 6 a — c.
(?) — DUNKERI. Id. „ „ t. vii, fig. 7, a — c.

Spec. Char. Testa suborbiculari, depressiusculd, costis circa 20 convexis, rugosis vel
subtuberculatis ; natibus prominentibus.

Shell suborbicular, slightly depressed, with about 20 convex, rugose, or obsoletely
tuberculated costse ; umbones prominent.

Diameter, f ths of an inch.

Locality. Mam. Crag, Bridlington.

This species appears to be peculiar to the more recent Formation at Bridlington,
differing in some degree from all my Red or Coralline Crag specimens of this genus,
in having the depressed form of rib, and resembling in that character C. chamceformis ;
but they are more numerous, being from 20 to 24 in number, and somewhat nodulous,
more especially in the young state ; they are not so prominent or distinct, the con-
centric striae being more numerous, and not deeply impressed, so as to separate the
shell into nodules, and there appears also to be a larger anterior muscle mark, ex-
tending more into the shell ; my series of this species is not very extensive, and I am
unable to say if these characters be permanent.

6. CARDITA CORBIS, PJiilippi. Tab. XV, fig. 2 a — d.

CARDITA CORBIS. Phil. En. Moll. Sic., vol. i, p. 55, pi. iv, fig. 19, 1836.
Id. „ vol. ii, p. 41, 1844.

If Orb. Moll, de Canar., p. 106, No. 183, 1839.
Nyst. Add. & la Faune Conch, des Terr. Tert. de Belg. ; Bull. Acad. de

Brux., t. ix, p. 444, No. 34, 1842.
Nyst. Coq. Foss. de Belg., p. 216, pi. xi, fig. 9, 1844.
Forbes. Geol. Survey, vol. i, p. 415, 1846.

BIVALVIA. 169

CARDITA NUCULINA. Dujard. Mem. de la Soc. Geol. de France, t. ii, part ii, p. 265, t. xviii,

fig. 13 a— f, 1837.

EXIGUA. Id., p. 265, t. xviii, fig. 17 a — 6.
MINUTA. Sacchi. Catal. Conch. Reg. Neap., p. 4, figs. 5, 6, 1836.
VENERICARDIA COKBIS. S. Wood. Catalogue, 1840.
ANCEPS, var. Id.

Spec. Char. Testa minutd, ovatd vet trigonuld, obliqud, crassd; apicibus acutis ; striis
concentricis, densis, undulatis ; sulcis radiantibus, obsoletis.

Shell small, ovate, or subtriangular, oblique, thick and strong ; concentric strise
or ridges thick and undulating ; radiating sulci obsolete.

Diameter, j of an inch.

Localities. Cor. Crag, Sutton.

Red Crag, Walton-on-the Naze.

This is one of the commonest shells in the Coralline Crag at Sutton, and the two
valves are often found united. Among the numerous specimens that are in my
cabinet, the two forms figured by Dujardin from the Touraine beds may be dis-
tinguished. In that variety which has the greatest diameter from the umbo to the
ventral margin, (which appears to be the one now living in the Mediterranean, as given
by Philippi,) the shell is most ventricose, the umbo most prominent, and the concentric
ridges much more elevated and distinct, than those are which have more distinct
radiations from the umbo ; in the other extreme form of variation which I had called
anceps (exigua, Dujard.), the shell is more compressed, with a greater proportional
diameter from the anterior to the posterior side, and the radiating ridges are more visible
to the naked eye, and this variety appears to have attained rather larger dimensions,
measuring as much as -j^ths of an inch. In what may, perhaps, be called the normal
form (Nnculina, Dujard.), the exterior is covered with concentric ridges at rather
unequal distances, and in the young state, or at the umbo, they are very wide apart; they
appear to undulate, or are made uneven by the rays which cross them, but the rays
fade away so imperceptibly into those in which they are obsolete, that I am unable to
draw a line between the two. Our shell possesses one large tooth in the right valve,
of a somewhat triangular form, stretching out towards the posterior, and in the other
valve there are two teeth, one smaller, immediately beneath the umbo, of a triangular
shape, the other compressed and elongated, sloping posteriorly, and nearly parallel to
the dorsal margin ; the muscle marks are large in comparison with the size of the
shell.

170 MOLLUSCA FROM THE CRAG.

ERYCINELLA, Conrad? 1845.
EEYCINA (sp.) Desk., 1825.

GOODALLIA. S. Wood.

Gen. Char. Shell trigonal, equivalve, inequilateral, thick ? strong ? and closed.
Hinge composed of two teeth in each valve, and a triangular space between them.
Lateral teeth obscure. Ligament internal. Palleal impression without a sinus.

ANIMAL UNKNOWN.

In 1822 Dr. Turton proposed a Genus of Bivalves under the name of Goodattia,
with a diagnosis almost in the above words, having an internal ligament. The shell
constituting the type of his genus, and, indeed, the only one that it contained, is now
well known to be a true Astarte, and has a ligament placed externally upon a fulcrum ;
his name, therefore, has lost its claim to be retained.

The figure of a small shell is given by Conrad in his ' Fossils of the Medial
Tertiaries of the United States,' corresponding apparently with the above characters,
and described under the name of Erycinella ovalis, but without a generic diagnosis,
and I have adopted it here upon the presumption that he has used it as one that had
been fairly established.

The name was no doubt intended as a diminutive of Erycina, a genus in which a
shell resembling E. ovalis has been placed by Deshayes, (' Coq. Foss. des Env. de Par.,'
t. i, pi. vi, figs. 23 — 5.) The genus Erycina, as proposed by Lamarck, had included in
it by himself an assemblage of heterogeneous materials, making it almost impossible
to determine the species intended as the type, in consequence of which it has been
pretty generally rejected, although retained by a few continental Conchologists for a
group of shells closely related to Tellina, possessing elongated siphons, a genus to which
our present species has no relationship, and the name Erycinella is consequently very
inappropriate, our shell being evidently connected with Astarte* Preserving, there-
fore, its close affinity, and retaining it still in the family of the Goddess of Beauty, it
has, since its removal from Goodallia, remained in my Cabinet under the MS. name of
Astartetta, a name it was intended to have proposed, and to which I would now lay
claim, provided no regular diagnosis has previously been given to the one Mr. Conrad
has employed.

* There is also a general resemblance, and probably near relationship, with Cardita, as one small
species of that Genus has the exterior ornamented with concentric instead of radiating ridges, and with a
crenulated margin, but the hinge furniture and position of the ligament are quite different.

BIVALVIA. 171

1. ERYCINELLA OVALIS ? Conrad. Tab. XV, fig. 10 a— -f.

ERYCINELLA OVALIS 1 Conrad. FOBS, of the Miocene Formation of the United States, p. 74,

pi. xlii, fig. 5, 1845.
GOODALLIA? PYGM^EA. S. Wood. Catalogue, 1840.

? CRENATTJLA. Id.

Spec. Char. Testa minutd, obligud, ovato-trigonuld, incequilaterali, tumidd, crassd,
concentrice striatd; postice rotundatd, antice rectiusculd ; cardine bidentato ; margins
ventrali cremilato.

Shell minute, oblique, ovately triangular, inequilateral, tumid, thick and strong,
concentrically striated ; posterior side rounded, anterior nearly straight ; hinge with
two teeth, ventral margin crenulated.

Diameter, -^h of an inch.

Locality. Cor. Crag, Sutton, and Gedgrave.

This little shell is particularly abundant in the Coralline Crag at Sutton ; and from
its prominent dental apparatus and crenulated margin, the two valves may be often
obtained in their natural position, giving thus an opportunity of observing the entire
margins of the shell in juxtaposition, without the slightest appearance of any fulcrum
or depression into which the ligament could have been inserted, so as to have become
visible externally when the valves are closed, the two pieces locking so close together
as to be with difficulty separated. The shell is thick and strong, with a prominent
obtuse umbo, and the whole exterior, when in perfect condition, is covered with
concentric ridges or rounded striae. The hinge of the right valve consists of
two large teeth diverging from the umbo, having a triangular space between them,
and a small obscure lateral tooth on both sides; in the left valve there are two
large cardinal teeth also diverging, which lock into depressions on the outside of
the teeth of the right valve ; besides these two cardinal teeth in each there are two
small denticles in the left, between which and the larger teeth are spaces for the
reception of the two large teeth of the right valve, thus leaving in the centre a vacant
space immediately beneath the umbo, where it is presumed the ligament was inserted ;
and in this valve also are two lateral teeth, the one at the extremity of the slope of the
anterior margin is prominent, fitting into a corresponding depression in the anterior
margin of the right valve, while on the other side it is the reverse, corresponding in
this character with the lateral teeth of the small species of Astarte, to which it is
evidently nearly related. The edge of the margin is deeply denticulated in the adult
shell, but in the immature state it is perfectly smooth ; the adductor muscles are
deeply impressed, large, and of an ovate form, situated near the extremity of the
lateral teeth ; they are connected by a simple mantlemark, without the least inflection :
in the young state the teeth of the hinge are comparatively larger than when full
grown, and the margin is then without crenulations; from these, with some other minor
differences, it was thought to be a distinct species, but a better examination and more
specimens give reason to believe it to be only the immature state.

172 MOLLUSCA FROM THE CRAG.

A small shell from the Paris basin, figured by M. Deshayes, ' Coq. Foss. des Env.
de Paris,' torn, i, pi. vi, figs. 22 — 25, much resembles ours, and I applied to that
gentleman for permission to inspect one of his duplicates, and he most obligingly sent
over to me, for comparison, the only two specimens he possesses, and for which I beg
to express my obligation. I fully concur with him in opinion that his fossil is speci-
fically distinct from the Crag shell: although it would have been desirable to have seen
a larger series of the Eocene shell, there is still so much difference between the two,
that unless a much greater amount of variation exists in the older Tertiary species
than is generally observable, they may very fairly be kept specifically distinct. The
Crag shell is much thicker, with a different arrangement of the dental furniture, and
there are no well-marked lateral teeth in the French shell ; and although the artist of
the figure above referred to has given an angular and pointed outline to the base of
his shell, with a row of crenulations at the margin, I could not observe either of those
characters in the specimens submitted to my examination, nor are they so specially
mentioned in the text ; it is possible, however, they may be immature specimens, and
would consequently have the margins smooth.*

ASTARTE,! /. Sowerby. 1816.

VENUS (spec.) Linn.

PERON^EA and PERONEODERMA (spec.) Poli.

TELLINA (spec.) Poli.

MACTRA (spec.) Mont.

CYPRINA (spec.) Turt.

TRIDONTA. Schum., 1817.

CRASSINA. Lam., 1818.

CYPRICARDIA (sp.) Id.

NICANIA. Leach, 1819.

GOODALLIA. Turt., 1822.

MACTROLDEA.
MACTRINA.
ORE AD A.

PUSCHIA.

I Brown, 1827.
r Roullier, 1846.

* Since the above had gone to press Sir Charles Lyell has returned from America, whence he had
kindly undertaken to procure for me, if possible, a specimen of the Transatlantic species for examination,
and in a letter received by him from Mr. Conrad the following observation occurs, which I have the per-
mission of Sir Charles to publish .

" I have examined the shell sent by Mr. Wood, and have compared it with the only specimen we have
of Erycinella ovalis. It is a smaller shell than the latter, of a more ovate form, and proportionally
narrower, still, I believe, they constitute one species. Our specimen has radiating lines, as seen through a
magnifier, but this may be owing to a weathered surface. I have seen a recent shell from the Gulf of
Mexico, which I think is a congener with these fossils, but I have now none to refer to."

f Etym., the Syrian name of Venus.

B1VALVIA. 173

Gen. Char. Shell thick, strong, and capable of being perfectly closed by the
animal ; generally more or less inequilateral, with a slightly trigonal form, equivalved,
often smooth, sometimes rigid, or deeply furrowed on the exterior ; hinge with two
diverging cardinal teeth in the left valve, and a trigonal space between them for the
reception of a prominent tooth of the same form in the right valve, often striated ;
generally a lateral tooth on the anterior side beneath the lunule, and sometimes an
elevated ridge or tooth inside the dorsal margin on the posterior side; two deep
impressions are left upon the shell by the adductor muscles,* and the impression of
the mantle is without any inflexion ; ligament external.

Animal of the form of the shell ; edges of the mantle plain ? disunited, except
at the posterior, where they form two siphonal openings, with simple orifices, and
not extending beyond the shell ; foot rather small, strong, and somewhat of an
angular shape.

The greater number of the species of this Genus have the inner margin of the shell
covered with crenulations, and their presence or absence was for a long time considered
a character of sufficient importance for specific distinction, it is now well known that
those appearances are not to be depended upon for such a purpose, as in all the species
of this Genus the immature, or, at least, the young, state of the shell has its margin
smooth or free from crenulations, and never, until it has attained to maturity, does it
assume that character ; and whenever a specimen has its margin crenulated, it may
then be considered to have arrived at its full growth.

English authors have generally adopted the above name, while upon the Continent
Crassina appears to have been more frequently employed ; there is no doubt, however,
that priority belongs to Mr. Sowerby, and that Lamarck's name is entitled to rank
only as third in point of date.

This genus has a considerable vertical range in the living state, but it is more often
found in waters of considerable depth, and the greater number of known recent species
are inhabitants of the colder regions of the North.

1. ASTARTE TRIANGULARIS, Montague. Tab. XVII, fig. 10 a — d.

MACTRA TRIANGULARIS. Mont. Test. Brit., p. 99, t. iii, fig. 5, 1803.

MINUTISSIMA. Id. Test. Brit. Suppl., p. 37, 1808.
GOODALLIA TRIANGULARIS. Turt. Brit. Biv., p. 77, t. vi, fig. 14, 1822.

MINUTISSIMA. Id. „ „ t. vi, fig. 15, 1822.

MACTROIDEA TRIANGULARIS. Brown. Illust. Brit. Conch. Syst. Ind., 1827-
MACTRINA TRIANGULARIS. Id., pi. 16, fig. 25.

MINUTISSIMA. Id., 2d edit., p. 108, pi. xlii, figs. 25, 26.
ASTARTE SUBTRIGONA. S. Wood. Catalogue, 1840.

There is also in most of the species a deeply indented mark near the anterior adductor.

174 MOLLUSCA FROM THE CRAG.

ASTARTE TRIANGULARIS. Alder, Catal. North, and Durh., p. 87, 1848.

Jeffreys. Ann. and Mag. Nat. Hist., vol. viii, p. 166.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 467, pi. xxx, figs. 4, 5,
1848.

— L^VIGATA? Phil. En. Moll. Sic., vol. ii, p. 30, 1844.
CRASSINA TRIANGULARIS. Gray. Ann. of Philos., 1825.

— MINUTISSIMA. Id.

— MINIMA ? Smith. Mem. Wern. Nat. Hist. Soc., vol. viii, p. 45, 1838.

Spec. Char. Testa minutd, obliqua, triangulari, sub&quilaterali, favi, crassd: postice
convezciore, margine crenulatd ; umbonibus prominentibus.

Shell minute, obliquely triangular, nearly equilateral, smooth, thick, and strong ;
posterior side the more convex : margin crenulate ; umbones prominent.

Diameter, ith of an inch.

Localities. Cor. Crag, Sutton.

Red Crag, Walton-on-the-Naze.
Clyde Beds.

Recent, Mediterranean ? Britain, Hebrides.

This species is very abundant in that rich Depot of small shells, in the Coralline
Crag at Sutton, and from its denticulated margin and prominent hinge teeth, the
valves are often found united. There are two different forms or varieties of it, one of
which is larger and more compressed, with the posterior side less rounded, correspond-
ing precisely with the recent shell, this is comparatively rare, while the other, (which,
from its greater difference in being smaller, longer, that is with a greater comparative
diameter from the anterior to the posterior margin, more tumid, and more rounded on
the posterior side, was thought to be a different species, and named subtrigona in my
Catalogue,) may be procured in large numbers. Until lately this shell was regarded as
a very rare species in the recent state, and is said now to be more plentiful in the seas
of North Britain than in the South, and the difficulty of obtaining a good series for
comparison in 1840, induced the belief of its distinction for the Crag shell. The variety
subtrigona, the common Crag shell, is roundedly triangular, having a diameter quite
as large, occasionally even more so when measured from one side to the other, than
from the umbo to the ventral margin, but in the other variety it is quite the reverse ;
the exterior is quite smooth, and the margin of the adult shell is crenulated on the
inside, with about two dozen obtuse denticulations. In all cases the young specimens
have the margins smooth, but there are others which have attained their full
magnitude, with the edge quite free from crenulations ; most of my specimens are
colourless, but some few have the reddish brown, with which the recent shell is
tinged only partially removed, leaving, as it were concentric bands of this colouring
matter. The ligament of this species is placed upon a somewhat prominent fulcrum,
readily distinguished externally when the valves are united, and not even partially
covered by an extension of the dorsal edge.

BIVALVIA. 175

2. ASTARTE PARVULA, S. Wood. Tab. XVII, fig. 11 a— b.

ASTARTE PARVULA. 8. Wood. Catalogue, 1840.

Spec. Char. Testa minima, obliqud, ovato-triangulari, in&quilaterali, compressiusculd,
sublavi ; postice latiore : antice longiore, et productiore ; margine integerrimo.

Shell minute, oblique, of a triangularly ovate form, inequilateral, somewhat com-
pressed, nearly smooth ; posterior side very short and broad, anterior produced and
elongated ; margin smooth.

Length, ^th of an inch ; height, TVth ditto.

Locality. Cor. Crag, Sutton.

This is also an abundant shell at Sutton, but rarely obtained with the valves
united. It is a true Astarte, and may be distinguished from the preceding, which
is the species it most resembles, and for the young of which, without care, it might be
mistaken; its differences are principally in outline, this being much more inequilateral,
and in place of having the form of an imperfect equilateral triangle, like that of
A. triangularis, the lines of the margins form with the umbo nearly a right angle ;
the posterior side is particularly short, with a very gentle curve to the ventral margin,
while the anterior is very much produced, sloping in a straight line to within a short
distance of the extremity, considerably reducing the breadth, or rather height, of that
side ; the hinge is furnished with one large triangular tooth in the right valve, as in
all the species of the genus, with two in the left, and the prominent marginal or
lateral tooth of the right valve, which fits into a corresponding depression in the left,
is on the posterior side, while on the anterior side of the umbo, the elevated ridge is in
the left valve, and at a considerable distance ; the exterior is generally smooth, but in
perfect specimens, obsolete, concentric ridges, though not very regular, may be
detected.

The shell in its recent state was probably of a reddish-brown colour, like the
preceding species, traces of which remain in some specimens, and in others it is also
formed into concentric bands. The margin in all my specimens is free from the least
appearance of crenulations, as well in those which are the largest, and presumed to be
full grown, as in the smaller and consequently younger.

3. ASTARTE BOREALIS, Chemnitz. Tab. XVI, fig. 3 a — d.

VENUS BOREALIS. Chem. Conch. Cab. vii, t. xxxix, fig. 412, 1784.

— COMPRESSA. Mont. Test. Brit. Suppl., p. 43, t. xxvi, fig. 1, (large fig.) 1808.

— SULCATA. Mat. and Rack. Linn. Trans., vol. viii, p. 81, t. ii, fig. 2, 1807.
ASTARTE PLANA. /. Sow. Min. Conch., t. 179, fig. 2, 1817, (not Nyst.)

— Id. Geol. Norf., p. 43, t. ii, fig. 14, 1833.

— BOREALIS. S. Wood, Catalogue, 1840.

Phil. Neuer. Conch., vol. ii, p. 58, Astarte, pi. i, fig. 11.

23

176 MOLLUSCA FROM THE CRAG.

ASTARTE BOREALIS. Forbes. Mem. Geol. Surv., vol. i, p. 413, 1846.

— COMPRESSA. Macffill. Moll. Aberd., p. 261, 1843.

— Thorpe. Brit. Mar. Couch., p. 247, 1844.

— CYPRINOIDES. DuvaL Revue Zool. Cuv. Soc., p. 278, 1841.

Hanley. Recent Shells, Suppl., pi. xiv, fig. 40.

— CORRUGATA. Loven. Ind. Moll. Scand., p. 37, 1846.

Middendorff. Mem. de 1'Acad. Imp. St. Petersb., p. 562, t. xvii,
figs. 4—10, 1849.

— ARCTICA. Moller. Ind. Moll. Groenl., p. 19, 1842.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 461, pi. xxx, fig. 7, 1848.

— LACTEA. Brod. and Sow. Zool. Journ., vol. iv, p. 365, 1829.

Gray. App. to Beechey's Voy. Zool., p. 152, t. xliv, fig. 19, 1839.

— SEMISULCATA. Gray. List Brit. Moll., p. 92, 1851.
CRASSINA ARCTICA. Gray. Append, to Parry's Voyage.

Hanley. Recent Shells, vol. i, p. 88.

BOREALIS. Nilson. Nov. Act. Holm., p. 188, pi. ii, figs. 3, 4, 1822.
COMPRESSA. Brown. Illust. Brit. Conch., pi. xviii, figs. 4, 5, 1827.

CORRUGATA. Id. „ „ pi. xvi, fig. 4 „

WITHAMI. Smith and Brown. Mem. Wern. Soc., vol.-viii, p. 57, pi. i, figs. 24, 25,

1838.

SEMISULCATA. Leach, in Ross's Voy., Append., p. 175, 1819, (fide Gray.)
TRIDONTA BOREALIS. Schum. Essai d'un Nouv. Syst. des Hab. des Vers. Test., p. 146,
• pi. xvii, fig. 1 a — b, 1817-

">f ''f in •'{ '"ill 'I'* '*•' ;** TO ; 1;'v i ><h •on'1"1'

Spec Char. Testa crassd, cordato-trigond, inteqnilaterali, postice longiore, subcompressd,
lunuld elongatd, profunde excavatd ; margine integerrimo.

Shell thick, somewhat triangularly heartshaped, slightly compressed, inequilateral,
posterior side the longer ; a deep and elongated lunule ; margin smooth.

Length, \\ inch; height, \\ inch.

Localities. Mam. Crag, Bramerton, Bridlington.

Clyde Beds, Opslo, Udde valla.
Recent Arctic Seas, Britain, Nova Zembla, Behring Straits, (Middendorff

This appears to be comparatively a modern species. In its living state it is deci-
dedly a Boreal shell, although it is occasionally obtained alive in our own seas. As a
fossil it is not at all rare in this country, either from Norwich or from the Clyde beds.
Like most of the species of this genus, it is subject to considerable variation, not only
in its outward form but in the markings of its exterior.

The specimens in my Cabinet from near Norwich, are generally uniform in shape,
and when not decomposed, the outside is nearly smooth, with scarcely the appearance
of ridges, but in the Bridlington shells, a very material difference is exhibited, even in
the few specimens that I possess. The more common form is somewhat rounded,
having a height only a little less than the length, but that which has been called
A. Withami is not only comparatively much longer, but has the posterior side sloped off
to a rounded point (fig. 2 c, d], and this has the umbo covered with distinct ridges
extending over a fourth of the exterior, while the one from Norwich is in that part

BIVALVIA. 177

smooth. In the recent state it is covered with a thick, olivaceous, or dark coloured
epidermis, and at the umbones the shell is often eroded ; marks of erosion are visible
also, more or less, in most of the fossils.* Old specimens are generally thickened
within, showing deeply-indented muscle marks. There is a deeply-excavated lunule
on the anterior side, and a corresponding slope on the posterior dorsal margin, with a
prominent fulcrum for the ligament.

It is said to be obtained in deep water in the British seas, though probably it had
an extensive vertical range, being found as a fossil at Bramerton, in association with
Littorina littorea, Mytilus edulis, and others that now inhabit very shallow water ; and
the fossil specimens are in that good state of preservation to justify the supposition
that they had not been transported from any great distance.

4. ASTARTE BASTE ROTH, Lajonkaire. Tab. XVII, fig. 2 a — d.

ASTARTE BASTEROTII. Lajonk. Not. Geol. env. d'Anv. (Mem. de la Soc. d'Hist. Nat. de Par.),

t. i, p. 129, pi. vi, fig. 3 a— c, 1823.
Nyst. Rech. Coq. Foss. d'Anv., p. 7, No. 26, 1835.

Id. Coq. Foss. de Belg., p. 151, pi. viii, fig. 4 a—c, 1844.
— NITIDA. J. Sow. Min. Conch., t. 521, fig. 2, 1826.

8. Wood. Catalogue, 1840.
CRASSINA NITIDA. Desk. 2d edit. Lam., t. vi, p. 258, 1835.

Dale, Hist, and Antiq. of Harwich, t. xi, figs. 12 and 14, 1730.

Spec. Char. Testa transversd, ovato-trigonula, sublavigatd, antice rotundatd, postice,
subangulatd natibus tenui-sulcatis ; lunuld elongato-ovatd ; margine crenulato.

Shell transverse, ovately triangular, nearly smooth, anterior side rounded, posterior
subangulated ; umbones finely sulcated ; lunule elongate and smooth ; margin cre-
nulated.

Length, If ths of an inch ; height, 1^-th ditto.

Localities. Cor. Crag, Sutton, Ramsholt, Sudbourn, Gedgrave.

Red Crag, Sutton, Bawdsey, Felixstow, Walton-on-the-Naze ?

The most distinguishing character of this species is a set of fine concentric ridges
covering the young shell, and occupying generally less than the fourth part of the
diameter of the surface, or a little beyond the umbones of the adult, while all the other
part is smooth, or at least with only visible lines of growth, f

The general size of the most common form of the Suffolk shell is an inch in length
and |-ths of an inch in height, and it has generally then a crenulated margin, but the
other specimen figured (fig. 2 c, d) measures as much as an inch and f ths in length, with
an edge perfectly smooth; they are all rather compressed, and have a deep, elongated

* A recent specimen in the possession of Mr. Lowry, with the specific name of lactea attached, but
which I believe to be only a var. of this species, is quite free from ridges about the umbo.

f The ridges upon the umbo of the Belgian shell are somewhat larger than those upon the British
specimens, and may be considered a distinct variety.

178 MOLLUSCA FROM THE CRAG.

and smooth lunule, and an elongated corselet on the posterior side ; there is an
elevated ridge of the dorsal margin in the right valve, and a correspondent furrow on
the same side in the left : the anterior lateral tooth or ridge is in the left valve, and
the corresponding furrow on that side in the right ; there are three teeth in the right
valve, one large and two very small, with two large teeth in the left one ; the large
central triangularly-formed tooth is ridged or roughened on its sides, and the same
may be seen in perfect specimens on the inner side of the two diverging teeth of the
left valve.

5. ASTARTE INCRASSATA ? Brocchi. Tab. XVI, fig. 6 a — b.

VENUS INCRASSATA. Broc. Conch. FOBS. Subap., p. 557, t. xiv, fig. 7, 1814.

CRASSINA INCRASSATA. Desk. 2d edit. Lam., t. vi, p. 257, 1835.

ASTARTE Goldf. Pet. Germ., vol. ii, p. 194, t. 135, fig. 2 a, b.

Phil. En. Moll. Sic., vol. i, p. 38, vol. ii, p. 29.
NITIDULA. S. Wood. Catalogue, 1840.

Spec. Char, Testa crassd rotundato-triangulari, tumiduld, subcequilaterali,postice paullo
longiore, Icevi, praterquam ad apices; lunuld ovatd, profundd ; margins crenulato.

Shell thick, roundedly triangular, slightly inflated, subequilateral, posterior side
rather the longer ; smooth, except at the umbones ; lunule ovate, and deep ; margin
crenulated.

Diameter, f ths of an inch.

Localities. Cor. Crag, Sutton, Sudbourn.

Red Crag, Sutton. Recent, Mediterranean ?

This species is abundant in the Coralline, and it is occasionally met with in the
Red Crag. Although somewhat variable as a British fossil, it is less so than many
other species of this genus. It most resembles the shorter varieties of the preceding,
but may be distinguished by several characters that appear to be permanent. Our
Crag species has its identification in a Sicilian fossil, which is presumed to be the
same as Ast. incrassata, Phil., and V. incrassata, Broc., the former of these two authors
speaks of his shell as very variable in its external appearance, some, he says, are almost
smooth, whilst others are sulcated almost to the margin ; our Crag specimens are
generally very regular in that character, and only in the region of the umbones is the
shell at all ridged, and these extend only to a short distance, while all the rest of the
surface is perfectly smooth. The shell as represented by Brocchi, is free from ridges
of any kind, although in the text, p. 557, he says, IC natibus transversim rugosis."

The general form of our shell is somewhat angulated or truncated at the posterior
side, the umbones turning a little towards the anterior one, over a large and deep
lunule, and on the other side is a large lanceolate corselet, within which is a con-
siderable space that was occupied by the ligament ; the umbonal region is occupied
by numerous small and rounded ridges, and the margin of the adult shell is deeply
crenulated.

BIVALVIA. 179

6. ASTARTE MUTABILIS, S. Wood. Tab. XVI, fig. 1 a— h.

ASTARTE MUTABILIS. S. Wood. Catalogue, 1840.

— PLANATA. Nyst, (not Sowerby.) Rech. Coq. Foss. d'Anv., p. 7, No. 23, 1835.
Id, Coq. Foss. de Belg., p. 151, pi. vii, fig. 6 a— b, 1844.

8pec, Char. Testa transversd, oblongd, subcordatd, crassd, incequilaterali, postice
longiore, truncatd ; natibus late sulcatis ; lunnld profunde excavatd ; l&vigatd; marginibus
incrassatis, crenulatis.

Shell transversely oblong, inequilateral, slightly heartshaped, thick and strong;
posterior side the longer, and truncated ; umbones broadly sulcated ; lunule smooth,
and deeply excavated ; margins thickened and crenulated.

Length, 2 inches ; height, Ifths ditto.

Localities. Cor. Crag, Ramsholt, Sudbourn, Gedgrave, Sutton.
Red Crag, Sutton, Alderton, Baldersey.
Mam. Crag, Bridlington, (Leckenby.}

This is one of our most changeable species in this variable genus, and the two
forms that have been figured are the extremes of variation, fig. a, b, being the most
constant, may be described as the type of the species. The adult shell is particularly
thick and strong, with the muscle marks deeply indented ; the posterior one is large
and nearly oval, the anterior one is rather less, and more straightened on the inner
side, and immediately beneath the anterior lateral tooth is the third small muscular
impression ; the line of the mantle indicates posteriorly the short siphons of the living
animal ; externally the shell is nearly smooth, except at the umbones, which are nearly
flat in the adult shell, with about a dozen broad and deep furrows ; the umbones are
generally sharp, curving over a broad and deeply-excavated lunule, with a large and
elongated corselet, both of which are quite naked or smooth ; in the right valve the
cardinal tooth is large and projecting, somewhat rugged at the sides, with the like
striations upon the inner surfaces of the two teeth in the left valve ; lateral teeth
obsolete ; the ventral margin is nearly straight, and the posterior side somewhat
quadrate. The margin of this species is quite smooth and sharp until it has attained
its full size, when it becomes much thickened and deeply crenulated. Numerous
specimens of the young shell may be obtained at Sutton, and I have traced them
down to less than a line in diameter.

Fig. 1 e,f is, I presume, only an aberrant form of this species ; it was obtained at
Bridlington by Mr. Leckenby, to whom I am indebted for permission to have it
figured.

180 MOLLUSCA FROM THE CRAG.

7. ASTARTE OMALII, Delajonkaire. Tab. XVII, fig. 1 a—f.

ASTARTE OMALII. Lajonk. Not. Geol. env. d'Anv. (Mem. de la Soc. d'Hist. Nat. de Par.)

torn, i, p. 129, pi. vi, fig. 1 a— c, 1823.
Desk. Ency. Meth. Vers., t. xi, p. 77, No. 2, 1830.
Nyst. Rech., Coq. Foss. d'Anv., p. 7, No. 24, 1835.
Id. Coq. foss. de Belg., pi. 152, pi. ix, fig. 2 a, b, c, 1844.

— RUGATA. Lajonk (not J. Sowerby). Loc. cit., torn, i, p. 130, pi. 6, fig. 5 a—c, 1823.

Nyst. Rech. Coq. Foss. d'Anv., p. 7, No. 25, 1835.

— BIPARTITA. J. Sow. Min. Conch., t. 521, fig. 3, 1826.

— OBLONGA. J, Sow. Min. Conch., t. 521, fig. 4, 1826.
CRASSINA OMALII. Desk. 2dedit. Lam., t. vi, p. 258, 1835.

BIPARTITA. Id. „ „ t. vi, p. 259, 1835.
ASTARTE. Lyell. Manual of Elem. Geol., 3d edit., p. 165, fig. 149, 1850.

Spec. Char. Testa variabile, interdum oblongo-ovatd scepe trigonali ; subleevigatd
aut sulcatd, tumidd vel compressd, plurimum in&quilaterali, postice longiore, subangulatd ;
lunuld ovatd, prof nude excavatd ; natibus acutis, semper sulcatis : marginibus crenulatis.

Shell variable, sometimes ovately oblong, often trigonal, smooth or sulcated, tumid
or compressed, for the most part inequilateral ; posterior side the longer, subangulated;
lunule ovate, deeply excavated ; umbones sharp, sulcated ; margin crenulated.

Length, l-|ths of an inch; height, l^th ditto.

Localities. Cor. Crag, Button, Ramsholt, Gedgrave.
Red Crag, Button.

This shell is exceedingly abundant in all parts of the Coralline Crag. Of all the
species of this very variable genus found in the Crag, this is, '•'•par excellence" the most
perplexing and difficult to determine. There is a fossil found in the Middle and Upper
Tertiaries of America in which the variations in form appear even greater than in our
Crag shell, as shown by a large suite of specimens in the Cabinet of Sir Charles
Lyell, and that geologist, in his Paper upon the " Miocene Tertiary Strata of Maryland,
Virginia, and N. and S. Carolina," published in the ' Proceedings of the Geological
Society,' 1845, vol. iv, part iii, p. 555, considers A. vicina, A. arata, A. cuneiformis,
A. obruta, A.perplana, of the American authors, to be varieties of A. undulata, Say., in
which opinion I fully concur ; but he further says, " I have some specimens of
A. bipartita from the Suffolk Crag, which agree perfectly with the American fossil,
except that in the latter the sides of the hinge teeth are much more distinctly grooved.
A few only of the English specimens exhibit a faint trace of this grooving." In a
species so exceedingly variable as this appears to have been in the seas of the Coralline
Crag, and in the same, or at least in localities so little removed as those of Suffolk,
where they are now found, it is difficult to say what effect localities so far removed
as those of South Carolina might have produced upon an animal with such a tendency
to variation; there is scarcely a limit to be put to its specific range, and this ex-
cessively variable character is perhaps an argument in favour of specific identification.

BIVALVIA. 181

From the specimens of the American shell, and from the representations that I have
seen, I was inclined to consider them distinct from the peculiarly angular extremity
of the posterior side.

This species in the adult state has the margin thickened within and roughly
crenulated, although in some large specimens this character is not seen. In all
specimens the shell in its young state is covered externally with broad and deep
furrows, and is much compressed, and it is in the older shell that it becomes so variable ;
these ridges or furrows are in some limited to a rather small space upon the surface,
or what may be called the umbonal region, while in others the surface is covered with
them entirely ; these latter continue generally much compressed, while those which
have the surface, or at least the greater part of it, quite smooth, and comparatively
short, are very tumid, the lunule and corselet in that case becoming of course very
large ; the posterior side is always more or less truncated, and the umbo sharp, often
much pointed. The rugae spoken of by Sir Charles Lyell as so conspicuous upon the
teeth, at least on the outside of the large cardinal tooth of the right valve, and the
corresponding inside of the two teeth in the left valve of the American shell, are
visible enough in well-preserved specimens of the English fossil, but these markings
are no good specific character, and may be seen in several other species. I have
traced this species down to the young shell, with a diameter little more than the eighth
of an inch, when the cardinal tooth extends to the umbo, but as the shell enlarges,
these teeth proceed forward, leaving a space between them ; the beaks stand up
prominent and sharp, but do not touch, and the opening of the valves is carried
backwards by a somewhat extended ligament.

8. ASTARTE ELLIPTICA, Brown. Tab. XVI, fig. 7.

CRASSINA ELLIPTICA. Brown. Illust. Brit. Conch., pi. xviii, fig. 3, 1827-

OVATA. Id. Edinb. Journ. Nat. and Geogr. Sci., vol. i, p. 12, pi. i,

figs. 8, 9.
Id. Illust. Brit. Conch., 2d ed., p. 96, pi. xxxviii, figs. 12, 13.

— DEPRESSA. Id. „ „ p. 96, pi. xxxviii, fig. 2.

— STJLCATA. Nikon. Nov. Act. Holm., p. 187, pi. ii, figs. 1, 2, fide Forb. and Hani.

— GAIRENSIS. Smith. Mem. Wern. Soc., vol. viii, p. 42.
ASTARTE ELLIPTICA. Macgill. Moll. Aberd., p. 259, 1843.

Alder. Catal. Moll. North, and Durh., p. 87, 1848.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 459, pi. xxx, fig. 8, 1848.

— GAIRENSIS. W. Nicol. MS.

Morris. Catal. Brit. Foss. p. 79, 1843.

— SEMISULCATA. Moller. Ind. Moll. Groenl., p. 19, 1842.

Phil. Neuer. Conch., vol. ii, p. 57; Astarte, pi. i, fig. 10.

— Lavtn. Ind. Moll. Scand., p. 37, 1846.

Spec. C/tar. Testa transversd, ettipticd, incequilaterali, compressiusculd; postice longiore,
truncatd, semisulcatd; lunuld profundd, lanceolato-cordatd ; margine integerrimo.

182 MOLLUSCA FROM THE CRAG

Shell transverse, elliptical, somewhat compressed, semisulcated, inequilateral .
posterior side the longer, and truncated ; lunule deep, of an elongated heartshape ;
margin without crenulations.

Localities. Mam. Crag, Bridlington, Bramerton ?

Glacial Beds of Scotland, Ireland, Wales, and North of England, (Forbes,}
Uddevalla. Recent, Coast of Scotland, Finmark, and Greenland.

I have seen only one specimen of this species belonging to the Mammaliferous
Crag, and that is from the Cabinet of Mr. Bean, who has obligingly permitted me to
have it figured, and this appears the oldest Deposit in which it is found ; there is no
specimen in my Cabinet from the Red Crag that can be fairly referred to this species ;
it is stated by Messrs. Forbes and Hanley to be particularly abundant in the more recent
beds of the glacial or antihuman period. This shell is said never to have its margins
crenulated, in which it differs essentially from the elliptical variety of A. Omalii.

In the living state it appears confined to the northern portion of our seas, extending
into the colder regions of Finmark and Greenland, and is said to have a vertical range
of from 10 to 40 fathoms, usually on a muddy bottom.

9. ASTARTE SULCATA, Dacosta. Tab. XVI, fig. 5 a — b.

PECTUNCULUS SULCATUS. Dacosta. Brit. Conch., p. 192, 1778.

VENUS BOREALIS (part). Chemn. Conch. Cab., t. vii, p. 26, t. xxxix, fig. 413, 1784.

— SCOTICA. Mat. and Rack. Linn. Trans., vol. viii, p. 81, t. ii, fig. 3, 1807.

Mont. Test. Brit. Suppl., p. 44, 1808.

— DANMONIA. Id. „ „ p. 45, t. xxix, fig. 4, 1808.

— STJLCATA. Id. Test. Brit., p. 131, 1803.

CRASSINA DANMONIENSIS. Brown. Illust. Brit. Conch., pi. xviii, fig. 1, 1827.
SCOTICA. Turt. Brit. Biv., p. 130, pi. xi, figs. 3, 4, 1822.

— SULCATA. Id. „ p. 131, pi. xi, figs. 1, 2, 1822.
CRASSINE CRASS ATELLE"E. Chenu. Traite Elem., figs. 232, 233.
ASTAKTE SCOTICA. Flem. Brit. Animals, p. 440, 1828.

Loven. Ind. Moll. Scand., p. 36, 1846.

Alder. Catal. Moll. North, and Durh., p. 87, 1847.

— DANMONIENSIS. G. Sowerby. Gen. of Shells, figs. 1 — 3.

Loven. Ind. Moll. Scand., p. 36, 1846.

Middendorff. Mem. de 1'Acad. Imp. de St. Petersb., p. 560,
t. xvii, fig. 3, 1849.

— SCOTICA. Id., p. 560, t. xvii, figs. 1 and 2, and t. xvi, figs. 10 — 12.

— PALLIDA. Jeffreys. Conch. Mag., p. 44, 1839.

— SULCATA. Flem. Brit. Anim., p. 439.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 452, pi. xxx, figs. 5, 6,
pi. M, fig. 5.

— DANMONIA. Alder. Catal. Moll. North, and Durh., p. 86, 1847.

— OVALIS. Woodw. Geol. of Norf., p. 43, t. ii, fig. 15, 1833.

— ANTIQUATA? (Leathes' MSS.) Id., p. 43, t. ii, fig. 16, 1833.

— VULGAEIS. Jeffreys. Conch. Magaz., p. 44, 1839.

BIVALVIA. 183

Spec. Char. Testa ovato-cordatd, sulcatd, subcequilaterali, postice parum longiore,
truncatd, antice rotundatd ; margine crenulato, vel l&vigato.

Shell ovately heart-shaped, sulcated, nearly equilateral, posterior side a little the
onger, anterior rounded ; margin crenulated, or smooth.

Length, -f ths of an inch ; height, |-ths ditto.

Localities. Red Crag, Sutton.

Mam. Crag, Bridlington (Forbes), Bramerton.

Clyde Beds. Recent, Britain, Finmark, North America.

As a Crag shell this is very rare ; my cabinet contains a few specimens from
Suffolk, and several of those are quite young, having the margin free from crenulations ;
the one figured is, no doubt, of this species, but differs rather from the generality
of specimens now found living in the British seas, and resembles the one given by
Middendorf, more especially figs. 1 — 3, the latter figure being probably only the
mature state of the former.

10. ASTARTE COMPRESSA, Montague. Tab. XVI, fig. 8 a — c.

VENUS COMPRESSA. Mont. Test. Brit. Suppl., p. 43, t. xxvi, fig. 1, 1808.

— MONTACUTI. Dillw. Desc. Cat. Eec. Shells, p. 167, 1817.

— MONTAGUI. W. Wood. Ind. TestaceoL, p. 34, pi. vii, fig. 19, 1825.
NICANIA BANKSII. Leach. Ann. of Phil., vol. xiv, p. 204, 1819.

— STRIATA. Id. „ vol. xiv, p. 204, 1819.

CYPBINA COMPRESSA. Turt. Brit. Biv., p. 136, pi. xi, figs. 22, 23, 1822.
CRASSINA STRIATA. Brown. Illust. Brit. Conch., pi. xviii, fig. 8, 1827.

oBLiauA. Id. „ „ pi. xviii, fig. 6, 1827.

CONVEXIUSCULA. Id. „ „ pi. xviii, fig. 7, 1827.

MULTICOSTATA. Smith and Brown. Mem. Wern. Nat. Hist. Soc., vol. viii, p. 56,
pi. i, fig. 20, 1838.

COMPRESSA. Thorpe. Brit. Mar. Conch., pp. 80 and 247, 1844.

MONTAGUI. Gray. Ann. of Phil., 1825, p. 136.
ASTARTE ANGULATA. Woodward. Geol. of Norf., p. 43, t. ii, fig. 17, 1832.

— STRIATA. Brown. Illust., 2d ed., p. 96, pi. xxxviii, figs. 6, 7, 8.

Holier. Ind. Moll. Groenl., p. 20, 1842.

Lovtn. Ind. Moll. Scand., p. 37, 1846.

Gray. Append, to Beech Voy. Zool., p. 152, t. xliv, fig. 9.

— BANKSII. Id. „ „ p. 38, t. xliv, fig. 9, 1842.

Moller. Ind. Moll. Groenl., p. 20, 1842.

— COMPRESSA. Forb. and Hanley. Hist. Brit. Moll., vol. i, p. 464, pi. 30, figs. 1 — 3,

1848.

Middendorf. Me'm. de i'Acad. St. Petersb., p. 560, 1849.
MULTICOSTATA. Macffill. Moll. Aberd., p. 260, 1843.

Phil. Neuer Concbyl., vol. ii, p. 59, pi. i, fig. 8.

— PULCHELLA (Jonas) Phil. Id. (fide Middendorf.)

Spec. Char. Testa rotundato-trigond, subtequilaterali, nonnihil obliqud, deformi,
postice latiore, sulcatd, vel dense striatd, margine dorsali convexiusculo, margine ventrali
integer rimo.

24

184 MOLLUSCA FROM THE CRAG.

Shell roundedly trigonal, slightly inequilateral, often somewhat oblique, and
deformed ; posterior side the broader or higher ; dorsal margin rather rounded ;
externally sulcated, or covered with numerous rounded ridges ; margin smooth.

Diameter, fths of an inch.

Localities. Red Crag, Sutton, Alderton, Bawdsey, Walton-on-the-Naze.
Mam. Crag, Bridlington, Bramerton, Thorpe.

Clyde Beds and Uddevalla. Recent, Britain, Scandinavia.

This species is not by any means rare in the Red Crag, but the shell found there
is generally that variety which has the lesser number of ridges, although amongst
my specimens there is a variation from 30 to nearly 50. In the newer deposits of
Bramerton and Bridlington the specimens are often nearly smooth, or have a greater
number, and finer striae, while the shells also are often somewhat deformed, with a
greater comparative length, and a more quadrate kind of outline, and the apices are a
little eroded.

What may be called the normal form (fig. 8 a] is subtrigonal, with a diameter as
great from the umbo to the ventral margin as from the anterior to the posterior side,
the umbo curving a little towards the anterior; the shell is generally somewhat
compressed, and the ridges of the exterior are rounded and smooth, and about as
broad as the spaces between them ; the hinge is not very broad, and there is a
somewhat prominent anterior lateral tooth at the extremity of a large and elongated
lunule, and the dorsal margin is generally more or less rounded. The Red Crag
furnishes specimens very variable in outline and somewhat deformed, but they are
always regularly ridged and sulcated.

The recent specimens do not often exceed half an inch in diameter, and have been
obtained in ten as well as in eighty fathoms.

11. ASTARTE CREBRILIRATA, 8. Wood. Tab. XVI, fig. 2 a — b.

Spec. Char. Testa transversd, ovato-trigond, intequilaterali, tumidiusculd, crassd; postice
longiore, subtruncatd; striatd, striis crebris obtusis confertis, lunuld elongatd, excavatd,
margine crenulato.

Shell transverse, ovately triangular, or wedge shaped, inequilateral, slightly tumid,
thick ; posterior side the longer, and truncated, externally striated or ridged ; strise
numerous, close, rounded, and obtuse ; lunule elongated, deep ; margin crenulated.

Length, ^ths of an inch ; height, -f- ths ditto.

Localities. Red Crag, Sutton, Walton-on-the-Naze.

Recent, Arctic Seas.

A few specimens only of what appears to be a distinct species have been obtained
by myself from the Red Crag. They correspond very closely, and in such a variable
genus as this, may perhaps be considered as identical with a living species in the
Cabinets of Messrs. Morris and Lowry, and said by those gentlemen to have been

BIVALVIA. 185

procured in the Arctic seas. In a comparison with the recent shell, some slight
difference may be observed, the Crag one being somewhat compressed, with a rather
more elevated umbo ; in the two specimens belonging to Mr. Morris, there is a dif-
ference, one being less transverse than the other, and the smaller of the two has the
margin of the valves deeply crenulated, while in the other it is quite smooth, and in
both the umbo is much eroded, thereby considerably reducing its elevation, but in the
Crag shell the umbo has not in the least been acted upon in that manner. There is a
considerable resemblance with A. gracilis which is also found in the Red Crag, but
that species is more equilateral, with the sculpture more distinct and elaborate.

12. ASTARTE GRACILIS, Mtiwter. Tab. XVII, fig. 3 a— e.

ASTARTE GRACILIS. Miiwt. apud Goldf. Pet. Germ., vol. ii, p. 194, t. 135, fig. 4 a— e.
PROPINQUA. Id. „ vol. ii, p. 194, t. 135, fig. 3 a — c.

— GALEOTTI. Nyst. Coq. Foss. de Belg., p. 159, pi. vi, fig. 17 a — c.

— LIEATA. Conrad. Sec. Lyell Proc. Geol. Soc., 1845, p. 555.

Spec. Char. Testa orbiculato-trigonuld, ovatd, transversd, tumidd ant compressiusculd
plurimum subcequilaterali; lineatd vel sulcatd, lineis magnis convexis ; margine crenulato
vel integro.

Shell roundedly trigonal, ovate, transverse, tumid, or compressed, for the most
part nearly equilateral, ridged or sulcated externally, with large rounded lines ; margin
crenulated or smooth.

Diameter, ^ths of an inch.

Localities. Cor. Crag, Sutton, Ramsholt, Sudbourn, and Gedgrave.
Red Crag, Sutton, Bawdsey.

This species is very abundant in the Coralline, while a few specimens only, and
those not in very good condition, have been found by myself in the Red Crag. The
most common variety is that which corresponds with the figure by Goldfuss ; this is
very regular in shape, nearly equilateral, longer than high, and covered upon the ex-
terior with about forty or fifty rounded, regularly-formed ridges, wider than the spaces
between them upon the body or older part of the shell, while in the younger or in the
umbonal region these ridges are somewhat sharp upon the hinder or upper side, or, as
it were, obtusely reflected ; the same character in regard to the ridges pervades all the
varieties, and covers the entire surface, except the lunule and corselet, which are
smooth ; another form is more trigonal, has a thicker hinge, with a more prominent
umbo, and is quite as high as it is long; var. multilineata, (fig. 3 e,} of which I have only
a few specimens, varies in no other character than a greater number of these con-
centric ridges, amounting in these to as many as 90 ; the shell is very thick, tumid,
and elevated, and is as high as it is long. In the full grown state the shell is crenulated
at the margin, and although large specimens are often met with in which this part is
quite smooth, these have not, it is presumed, attained to full maturity. It was probably

186 MOLLUSCA FROM THE CRAG.

deeply coloured in its living condition, as in some specimens a tinge of this remains,
and in others there are vestiges of coloured bands.

Sir Charles Lyell speaks of a fossil in the Miocene Deposits of America as allied to
this species, and a specimen in my Cabinet from Savigny very closely resembles it, and
is probably only a variety with the ridges rather larger, and the intermediate spaces
broader.

13. ASTARTE INCERTA, S. Wood. Tab. XVII, fig. 4.

ASTARTE PLANA. Nyst. Coq. Foss. de Belg., p. 161, pi. xi, fig. 2 a — b, 1844.

Testa orbiculato-ovatd, compressa, subincequilaterali, regulariter siriatd; natibus pro-
minulis; lunuld ovatd, Itsvigatd; margine crenulato.

Shell roundedly ovate, compressed, somewhat inequilateral, regularly striated ;
umbo slightly prominent ; lunule ovate and smooth ; margin crenulated.

Length, ^ths of an inch ; height, £ ths ditto.

Localities. Cor. Crag, Sutton, Gedgrave.

Belgium.

This species is not very abundant in our Crag. As it is perfectly distinct from
A.plana, of 'Min. Conch.,' to which species the Belgian fossil was referred, and which
appears to be the same as the English Crag shell, I have proposed for it a new name; it
approaches very near to one of the varieties of A. gracilis, but the differences are such
as seemingly to justify a removal. It is natter or more compressed than any of the
numerous specimens of that species that I have seen, and is more inequilateral, with a
greater height. In the full grown shell, and in good condition, the margin is regularly
and deeply crenulated, differing thereby most essentially from A. plana, as also in being
covered with small and regular ridges. It is stated to be abundant in Belgium, where
it has attained to rather larger dimensions.

14. ASTARTE CREBRICOSTATA ? Forbes. Tab. XVII, fig. 6.

ASTARTE CREBRICOSTATA. Forbes. Annals Nat. Hist., voL xix, p. 98, pi. ix, fig. 4, 1847.
Jeffreys. Ann. and Mag. of Nat. Hist., vol. xix, p. 314.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 456, pi. xxx, fig. 9,

1848.
Gray. List of British Mollusca, p. 92, 1851.

Spec. Char. Testa ovato-trigond, compressiusculd, crassd, subinaquilaterali, postice
potius longiore; concentrice costatd, costis crebris odtusis, ad postice evanescentioribus,
margine crenulato.

Shell ovately trigonal, slightly compressed, thick, nearly equilateral, posterior side
rather the longer, concentrically costated ; ribs or ridges numerous, thick and obtuse,
obsolete on the posterior part ; margins crenulated.

BIVALVIA. 187

Length, ^ths of an inch : height, £ ths ditto.

Locality. Mam. Crag, Bridlington. Recent, Britain.

One specimen only of this species has come under my observation, it was found by
Mr. Leckenby, who has obligingly permitted me to have it figured.

If it were in almost any other genus than the present, the differences between this
shell and the figure and description given, above referred to, might, perhaps, be
sufficient to justify its being considered a new species ; but with only a single specimen,
I am unwilling to do more than refer it to one already established. Our present shell
may be further particularised as having a prominent and sharp umbo curving a little
over a lunule, large and deep ; the ridges upon the exterior are large, somewhat
prominent and rounded, about as wide as the spaces between them, and on the anterior
side they extend up to the lunule, and there stop rather abruptly ; while on the
posterior side, in the young state, they reach to the edge of the corselet, becoming
obsolete and nearly smooth down the slope in the older part of the shell ; our specimen
is more equilateral, less broad posteriorly, and of a more triangular form than the
figures above referred to, but in other respects there is so great a resemblance that
it may be considered as probably an aberrant form of the above species. The
lunule and corselet are smooth, or, at least, show only lines of growth, and the
numerous and close set ridges seem to remove it from any specific connection with
A. sulcata.

A fossil in the Cabinet of Mr. Morris, brought from the mouth of the Varga, 200
miles up the Dwina, by Sir Roderick Murchison, more resembles the figure and
description of crebricostata in the ' Hist, of Brit. Mollusca/

|

15. ASTARTE PYGM^EA, Munster. Tab. XVII, fig. la— b.

ASTARTE PYGM.EA. (Mtinst.) ex Gold/. Pet. Germ., vol. ii, p. 195, t. 135, figs. 5, 6 a, b;

(excl. syn.)
S. Wood. Catalogue, 1840.

Spec. Char. Testa minutd, orbiculato-trigond, compressiusculd, equilaterali, umbonibus
prominulis ; concentrice costatd, costis crebris, convexis ; margine crenato vel Integra.

Shell small, roundedly trigonal, somewhat compressed, equilateral; umbones
slightly prominent, concentrically costated ; ridges thick, numerous, and convex ;
margin crenulated or smooth.

Diameter, ^th of an inch.

Locality. Cor. Crag, Sutton.

This species is exceedingly abundant at the above locality, but the valves are
rarely found united. It appears to correspond with the figure and description by
Goldfuss.

Our shell has the posterior dorsal edge somewhat rounded, and the longitudinal
diameter generally exceeds the height ; the umbo is neither very sharp, nor very

188 MOLLUSCA FROM THE CRAG.

prominent, and the exterior is covered with ridges parallel to the margin, and varying
in number from 16 to 25 ; these are rounded and obtuse, and rather wider than the
spaces between them, and in many of my specimens there are the remains of coloured
bands. In the adult shell the margin is covered with about 25 — 30 large crenu-
lations.

Amongst some specimens given to me by Sir Charles Lyell from Touraine, is a
single valve of a shell that may probably be referred to this species, but it is not in a
sufficiently perfect condition for a fair identification. Amongst a large number of
specimens of our Cor. Crag shell, some may be found with the crenulated margin
whose diameter does not much exceed half that of others in which such part of the
shell is smooth, but the size is no argument against its having attained to a state of
maturity.

Astarte Bosquetii, Nyst, 'Coq. Foss. de Belg.,' pi. vi, fig. 16, which that author has
doubtingly referred to A. pygmtea of Goldfuss, is probably different, and may be the
same as A. circinnaria, Mich., it is larger and more angular than our species. Some
specimens of A. minuta, Nyst, brought home by Sir Charles Lyell, are also different,
and, I think, cannot be referred to our species ; the shell is smaller, more triangular ;
the exterior is ridged, and it has a smooth margin : neither can it, in my opinion, be
referred to our British species, A. triangularis, nor to A. parvula.

16. ASTARTE BURTINII, Lajonkaire. Tab. XVII, fig. 5 a — d.

ASTARTE BURTINEA. Lqjonk. Mem. de la Soc. d'Hist. Nat. de Par., t. i, p. 129, pi. 6 a — c,

1823. t

Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 8, No. 38, 1835.

— BURTINII. Id. Coq. Foss. de Belg., p. 160, pi. ix, fig. 7 a, b, 1844.

— OBLIQUATA. Id. (not Sowerby.) Id., p. 160, pi. vii, fig. 7.

— PISIFORMIS, var. /3. S. Wood. Catalogue.

Spec. Char. Testa crassd, subtrigonuld, cordiformi, tumidd, aut compressd, snbincequi-
laterali, striatd vel sulcatd, striis obliquis admarginem excurrentibus ; umbonibusprominulis;
lunuld magnd, lavigatd ; margine crenulato.

Shell thick, subtrigonal, heartshaped, tumid or compressed, slightly inequilateral,
striated or sulcated; striae oblique, running out at the margin; umbones a little
prominent ; lunule large, deep, and smooth ; margin crenulated.

Length, -|-ths of an inch ; height, -f-ths, nearly

Length of var. pisiformis, -f ths ditto ; height, ^ths ditto.

Localities. Cor. Crag, Sutton, Ramsholt, Sudbourn, and Gedgrave.
Red Crag, Sutton.

Very abundant in the Cor. Crag, but exceedingly scarce in the Red, so much so,
that judging from my own collection, it is doubtful if true and genuine specimens have
been found in it.

BIVALVIA. 189

This shell is so excessively variable, and presents such extraordinary differences in
character, that when my Catalogue was compiled, the smaller variety was considered
as a distinct species, and passed under the MS. name of pisiformis, given to it by my
friend the late Rev. G. R. Leathes, in consequence of its pea-like form, which this
small variety assumes when the two valves are united ; a large additional number of
specimens since obtained are found to possess intermediate characters, and it is there-
fore thought necessary to unite the two.

The typical form may be considered as fig. 5#, b ; this is a large shell, inequilateral
and somewhat compressed, and slightly angular on the posterior side, and if found
alonej would most deservedly be separated from the smaller and more globose variety,
as two shells cannot well appear more distinct. The smaller variety, or pisiformis, has
a height greater than its length, and the posterior side is nearly convex ; the lunule is
large and smooth, and the shape of it is modified by the form of the shell. The ex-
terior is covered with ridges, broad and smooth, having only a narrow line between
them ; the ridges pass over the shell obliquely, from the edge of the corselet round to the
edge of the lunule, and they take their rise on the posterior side, where they are closer
and more numerous, running out or disappearing at the margin of the shell, the lines
of growth, of course, crossing them at a variable angle ; the number of these ridges
vary according to the age or size of the specimen, the very minute not possessing
more than half a dozen, while seventy may be counted in the larger and full grown
individuals.

A specimen from Thorigny, given to me by Sir Charles Lyell, very much resembles
our shell, and is probably only a variety.

17. ASTARTE OBLIQUATA, /. Sowerby. Tab. XVI, fig. 4 a — d.

ASTARTE OBLIQUATA. J. Sow. Min. Conch., t. 179, fig. 3, 1817.
8. Wood. Catalogue, 1840.

/Spec. Char. Testa ovatd, transversd, subaquilaterali, compressd, striatd, striis obliquis;
umbonibus acutis prominulis ; lunuld lanceolatd; margine crenulato.

Shell ovate, transverse, slightly inequilateral, compressed and striated, striae
oblique ; beaks rather sharp, and somewhat prominent ; an elongated lunule and
margins crenulated in the adult state.

Diameter, \\ inch.

Localities. Red Crag, Walton-on-the-Naze, Sutton.

This shell is very abundant at the former locality ; I have very rarely met with it
at any other.

As far as can be determined by the figures and descriptions of the Belgian authors,
it is very doubtful if this species has been found in that part of the world ; the shell
so called by M. Nyst appears to be only a variety of A. Burtinii, the species so common
and so variable in the Coralline Crag.

190 MOLLUSCA FROM THE CRAG.

It appears quite distinct from the preceding, in being flatter or more compressed,
and the line of hinge much narrower ; it is also a thinner shell. The exterior markings
are much alike in both species, having somewhat flat ridges with narrow spaces between
them ; they pass obliquely over the shell from the posterior to the anterior side, some
of which run out at the ventral margin, and cut the lines of growth at an acute angle ;
the hinge is composed of one large triangularly formed tooth in the right valve, with
one anterior lateral tooth at the extremity of the lunule ; in the left valve are two
diverging cardinal teeth, with the triangular space between them, and the more distinct
lateral tooth, or that which has on the outside of it a depression for the elevated edge
of the opposite valve, is on the posterior side. This has also the small auxiliary
muscular impression on the anterior side, and the mantle mark is without the least
indentation. In the adult shell the margin is crenulated, while the younger specimens
have it quite smooth. The two valves are occasionally found united in the less
unmixed portion of the Red Crag Deposit at Walton-on-the-Naze.

18. ASTARTE DIGITARIA, Linnaeus. Tab. XVII, fig. 8 a — d.

TELLINA DIGITARIA. Linn. Syst. Nat., edit. 12, p. 1120, No. 71, 1767-

Chemn. Conch. Cab. vi, p. 126, t. xii, fig. 121, 1782.
LUCINA DIGITALIS. Lam. Ann. sans Vert., t. v, p. 544, 1818.
? Bast. Bord. Foss., p. 87, 1825.

Phil. En. Moll. Sic., vol. i, p. 33, t. iii, fig. 19, 1836.

Id. „ vol. ii, p. 25, 1844.

Desk. 2d edit. Lam., t. vi, p. 231, 1835.
Reeve. Conch. Icon., pi. ii, fig. 65.

— DIGITARIA. S. Wood. Catalogue, 1840.

— CURVIRADIATA. Nyst. Rech. Coq. Foss. d'Anv., p. 6, pi. i, fig. 20, 1835.

Id. Coq. Foss. de Belg., p. 137, pi. 6, fig. 12, 1844.
Ency. Method., pi. 292, fig. 5.

Spec. Char. Testa minutd; orbiculato-ovatd subceqidlaterali, compressiusculd; striis
obliquis incurvis, umbonibus depressis; dentibus lateralibus distinctis ; margine integer-
rimo.

Shell small, roundedly ovate, nearly equilateral, somewhat compressed, covered
with elegantly curved, oblique, impressed striae; umbones depressed; lateral teeth
distinct ; margin smooth.

Diameter, f ths of an inch

Localities. Cor. Crag, Sutton.

Red Crag, Sutton, Walton-on-the-Naze.

Recent, Mediterranean.

Abundant in the Coralline Crag at Sutton, and by no means rare in the more
genuine portion of the Red Crag at Walton-on-the-Naze, where I have found the two
valves united. The only triflirig difference I can detect between the British fossil and

BIVALVIA. 191

the recent shell is that in the latter the hinge line appears rather thicker ; and the
same may be said of the Sicilian fossil.

In this shell the sulci or ridges take their rise, and are most numerous, like the
two preceding species, on the posterior side, or that on which the ligament is placed,
where they are somewhat rugose, and descend or curve in an oblique direction over
the exterior or centre of the shell, and are lost or run out at different distances on the
ventral margin, most conspicuously so on the anterior portion. These rugosities are
regular on the posterior side, radiating in an opposite direction, like those upon the
posterior side of Venus verrucosa, and are probably produced by the lines of growth
cutting the sculpture at an acute angle ; they are most distinct upon -the Coralline
Crag specimens.

There is a considerable variation in the outline of this species, some individuals
having a height as great, or greater, than the length, but in general the larger diameter
is from the anterior to the posterior margin ; there is also a difference in the sculpture,
the lines being much closer or more numerous in some than in others, and they are
always more distant near the umbo, or on the young shell, and most distinct upon
the Red Crag specimens. There are the remains of colour in some of my fossils,
like concentric bands.

It was at one time thought there was sufficient difference in this species to entitle
it to more than specific distinction, and it remained in my cabinet under the MS. name
of Digitaria vulgaris, and perhaps when the animal becomes known, it may present
characters that are so ; but judging from the shell alone, it so strongly resembles some
of the more aberrant forms of Astarte, that it seems more advisable it should be placed
here, bearing, as it evidently does, a greater relationship to this genus than either
to Tellina or Lucina, to which it has been hitherto referred. Unlike the former, it has
the impression of the mantle entire, or without any inflection, and the impressions of
the adductors are of an ovate form, the anterior one being rather the longer of the
two ; but unlike the latter, it wants the ligulate or band-shaped impression so charac-
teristic of that genus. The same obliquity of ridges may be seen upon a small species
with the hinge of Cardita, a genus probably very closely allied to the present one.

19. ASTARTE EXCURRENS, S. Wood. Tab. XVII, fig. 9ab.

Spec. Char. Testa minima, transversd, ovatd, subaquilaterali, compressiuscutd, striatd,
striis obliquis utrinque excurrentibus ; umbonibus depressis, marginibus denticulatis.

Shell small, transverse, ovate, nearly equilateral, somewhat compressed, covered
with stride that are not parallel to the margin, but run out from each side ; umbones
depressed ; margins denticulated.

Largest diameter, -^th of an inch.

Locality. Cor. Crag, Sutton.

This shell is not by any means rare at the above locality. It differs from the pre-
25

192 MOLLUSCA FROM THE CRAG.

ceding species (a shell to which it seems nearest related) in several characters, being
smaller, and the ridges have an oblique direction, or they are subconcentric, deviating
a little from the lines of growth, so that two or three only are lost in the centre of the
ventral margin, and in some specimens, more especially in those which are longer than
high, this character is less distinct than in those which are more orbicular, or have a
greater comparative height, where this running out of the ridges at the margin is most
conspicuous. The form of the shell resembles that of A. digitaria, but the sculpture is
different, and the margin in this, when it has attained full maturity, is furnished with
rather large crenulations. Tn A. digitaria the ridges are broader and flatter than in this
species, in which they are somewhat rounded. The dental characters are those of a
true Astarte, having one triangularly-formed cardinal tooth in the right valve and
two in the left, while the most conspicuous lateral tooth, or where there is a depres-
sion for the elevated edge of the opposite valve, is on the anterior side in the right
valve, and on the posterior side in the left ; the muscle marks also correspond with the
generic character.

Some specimens of this species have also the remains of coloured bands.

20. ASTARTE PARVA, 8. Wood. Tab. XVIT, fig. 1203.

ASTARTE PAKVA. S. Wood. Catalogue Mag. Nat. Hist., p. 249, 1840.

Spec. Char. Testa parod, ovatd, transversd, valde intequilaterali, postice breviore,
antice productd, rotundatd ; striata, striis obliguis; umbonibus acutis, prominulis; margine
integerrimo.

Shell small, ovate, transverse, very inequilateral; posterior side the shorter,
anterior much produced and rounded, ornamented with oblique transverse ridges not
parallel to the margin ; umbones sharp, somewhat prominent, and margin smooth.

Length, |-th of an inch ; height, a little less.

Localities. Cor. Crag, Sutton.

The sculpture differs materially in the direction the lines take in crossing the
exterior from that of the preceding species, which deviate a little from the lines of
growth, there being more of them upon the anterior or larger side than there are
upon the posterior side, three or four running out at different parts of the margin,
so that, counting, from the umbo, they number more towards the anterior than
on the other side ; the ridges are broad and flat, separated by a depressed furrow,
much narrower than the ridges, about 12 or 15 on the posterior side, with 15 to
18 upon the anterior, while the umbo or very young shell appears to have been quite
smooth. The dental characters are those of true Astarte, with one large triangularly-
shaped tooth in the right valve, and a distinct, elongated, anterior, lateral tooth at some
distance ; and in the left valve are two diverging cardinal teeth, with a duplicature or
lateral tooth on the posterior margin ; there is a somewhat thickened ridge on the
posterior side, as in most of the species of this genus, within or behind which is the

BIVALVIA. 193

impression of the posterior adductor, and the mantle mark is quite entire. In all my
specimens, many of which are presumed to be full grown individuals, the margin is
quite smooth, and many specimens are marked with coloured bands. There is no
distinct lunule, but an elongated space on the anterior side that is quite smooth, while
on the posterior side the lines run up to the margin. It is thin in the young state
when the ridges are visible on the inside.

It is very abundant at the above locality, and the valves are often found united.

ISOCARDIA,* Lamarck. 1799.

BUCARDIA. Lister, 1687.

CHAMA (spec.) Linn.

GLOSSUS and GLOSSODEKMA. Poli, 1795.

TRAPEZIUM: (sp.) Humphr., 1797.

BUCARDIUM. Megerle, 1811.

DICEEATIA? Oken, 1815.

ISOCAKDIUM. Blainv., 1824.

Generic Character. Shell equivalved, inequilateral, heartshaped, tumid, generally
thick and strong, sometimes smooth, often furrowed ; umbones prominent and in-
volute. Hinge with two cardinal and one lateral tooth in each valve. Ligament
external. Impression of the mantle entire, or without a sinus.

The animal of this genus is described by Malacologists as closely resembling that
of Astarte, with a broad, short, triangularly formed foot, and the siphons not extending
beyond the margins of the shell ; their orifices are fringed, and the edges of the mantle
double.

This genus is said to constitute a connecting link between the families of Cyprinida
and the Cockles, and is also closely allied to Chama and Diceras, particularly in the shell,
by the peculiar involution of the umbones and the recession of the ligament, by
which, in its increase, the anterior portion is deserted, and its extension formed on the
posterior side.

But few species are known in the living state, and at present not a large number
of fossils.

1. ISOCARDIA COR, Linnaus. Tab. XV, fig. 9 a — b.

BUCABDIA. Scilla. De Corp. Mar. Lapid., t. xvi, fig. AA, 1670.
Lister. Hist. Conch., lib. iii, part ii, fig. Ill, 1687.
— COMMUNIS. Schum. Essai d'un Nouv. Syst. des Vers. Test., p. 143, pi. xiii,

fig. 2 a, b, 1817.

CAKDIUM HUMANUM. Linn. Syst. Nat., ed. 10, No. 82, p. 682, 1766.
CHAMA con. Id. „ ed. 12, p. 1137, No. 154, 1767.

* Etym. IPOS, like or equal, and «cap5ta.

194 MOLLUSCA FROM THE CRAG.

CHAMA COB. Poli. Test. Sic., vol. ii, p. 113, t. xxiii, fig. 1 — 3, 1795.

_ _ Sroc. Conch. Foss. Subap., p. 519, No. 4, 1814.
CABDITA con. Brug. Encyc. Meth. Vers., torn, i, p. 403, No. 1, 1792,
— Bosc. Hist. Nat. des Vers., t. iii, p. 85, pi. xxi, fig. 4.
ISOCABDIA COB. Lam. Hist, des An. s. Vert., t. vi, p. 31, 1822.

— /. Sow. Min. Conch, t. 516, fig. 2, 1826.

. — Goldf. Pet. Germ., vol. ii, p. 211, pi. 141, fig. 2«— c.

— Bronn. Leth. Geogn., p. 941, pi. xxxviii, fig. 10, 1838.

— Phil. En. Moll. Sic., vol. i, p. 56, and vol. ii, p. 4.1.

— Nyst. Coq. Foss. de Belg., p. 196, pi. xvi, fig. 1 a, b, e, 1844.

— Sysmonda. Syu. Meth. An. Inv. Pied. Foss., p. 18, 1847.

— Loven. Ind. Moll. Scand., p. 36, 1846.

— GLOBULOSA. Defrance. Diet, des Sc. Nat., t. xxiv, p. 180, Atlas, figs. 2, 2 a.

— HIBERNICA. Reeve. Conch. Icon. Isocard., pi. i^fig. 4.

— YENTBICOSA. J. Sowerby. Min. Conch., vol. vi, p. 28.

— LTJNDLATA. Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 13, pi. iii, fig. 53, 1835.

Id. Coq. Foss. de Belg., p. 189, pi. xv, fig. 2 a—e, 1844.

— CBASSA. Id. „ „ p. 198, pi. xv, fig. 3 a — e, 1844.

— KUSTICA. Conrad. Amer. Mioc. Foss., p. 20, pi. xi, fig. 1, 1838.

— FBATEBNA. Say. Journ. Acad. Nat. Sci., vol. iv, p. 143, pi. xi, fig. 1 a, b.

— MABKOEI. Conrad. Proc. Nat. Inst., vol. i, p. 193, pi. ii, fig. 1.

Id. Amer. Mioc. Foss., p. 70, pi. xl, fig. 2, 1845.
GLOSSUS COB. Gray. List. Brit. Moll., p. 95, 1851.

Spec. Char. Testa cordato-globosd, orbiculari, tumidd, l&mgatd, valde incBquilaterali ;
umbonibus crassis, acutis, involutis et infra subexcavatis ; margine ventrali integro, acuto ;
striis incrementi irregularibus, cardine bidentato.

Shell somewhat orbicular, or globosely heartshaped, tumid, smooth, and very
inequilateral ; umbones sharp, thick, and involute, beneath which the shell is depressed
or subexcavated ; ventral margin smooth and sharp, lines of increase irregular ; hinge
with two cardinal teeth in each valve.

Diameter, 2 inches.

Localities. Cor. Crag, Gedgrave, Ramsholt, Sutton.
Red Crag, Sutton.

Recent, Mediterranean, Britain, Sweden.

This species is by no means abundant even in fragments, either in the Coralline or
Red Crag. The specimen figured is from Gedgrave, and seems to resemble the variety
now found in the Mediterranean, being smaller and more globose, with the umbones
obtuse and very prominent, while the fragments from the Red Crag, as far as they can
be determined, seem to approach the form of the variety found in our own seas, in
which the shell is broader, with the umbones much depressed ; this character consti-
tutes the essential difference; the more tumid variety of the Coralline Crag corresponding
with the Mediterranean form, as the conditions under which each existed were probably
similar, while the Red Crag shell seems more to have resembled the one now living in
the British seas. Our Crag specimens may be said to be smooth, with the exception
of the irregular lines of growth ; the numerous fine radiating striae which ornament

BIVALVIA. 195

the recent shell are scarcely more than skin deep, or penetrate beneath the epidermis,
as may be seen at the umbo of the recent shell, which is generally eroded, but by a
close inspection, these granulated striae may be detected even in the fossil state.

In the Campinian beds of Belgium this shell does not appear to have been rare,
but to have presented considerable diversity of form, and M. Nyst himself seems to
admit, at page 199, the probability of his own three species being modifications or
variations of Isocardia cor.

According to Knorr, this is called in France Cceur de Bceuf, or bullock's -heart,
while in Holland it has the name of Zots-Kappen, or foolscap.

Genus CYPRINA,* Lamarcfc. 1812.

VENUS (sp.) Auct.
AECTICA. Schum., 1817.

Gen. Char. Shell equivalved, inequilateral, more or less orbicular, or obliquely
heartshaped ; smooth, or covered with irregular lines of growth, and in the recent
state invested with an epidermis ; umbones sharp, with a slight inclination to curve ;
the ventral margin smooth. Hinge with strong and prominent cardinal teeth in each
valve, and one posterior lateral tooth. Muscle marks large, anterior one deeply
impressed. Mantle mark with a small or incipient sinus. Ligament external.

Animal suborbicular, with mantle freely open, and finely serrated at the edges ;
siphonal tubes very short, and the margins of the openings fringed ; foot large and
linguiform.

The shells of this genus closely resemble in outward appearance some of the
species of Venus, from which they were separated by Lamarck, who thought them of
scarcely sufficient importance for generic distinction ; there is, however, a marked
difference in the impression of the mantle, which in this is without a sinus, denoting
the possession in the animal of very short siphons; a large lateral tooth on the
posterior margin is another character by which the shell may be distinguished. It
appears to be very closely related to Isocardia. The species as yet known are all
inhabitants of salt water, and in the living state are frequenters of gravelly sand or
mud ; they are somewhat of a large size, and of considerable solidity, and, as a genus,
may perhaps date its existence as far back as the period of the Greensand Formation,
continuing, though sparingly, through the Tertiaries to the present day, without
numbering many species either in the existing state or in the ancient seas.

* Etym. Kvvpu, one of the names of Venus.

196 MOLLUSCA FROM THE CRAG.

1. CYPRINA ISLANDICA. Linn. Tab. XVIII, fig. 2 a—d.

PECTUNCULUS MAXIMUS. List. Hist. Conch., fig. 108, 1685.

_ Dacosta. Brit. Conch., p. 183, t. xiv, fig. 5, 1778.

VENUS ISLANDICA. Linn. Syst. Nat., ed. 12, p. 1131, No. 124, 1767.

— Will. Zool. Dan., vol. i, p. 29, pi. xxviii, figs. 1 — 5, 1776.

— ICELANDICA. W. Wood. Ind. Test., pi. vii, fig. 41, 1825.

— MEKCENABIA. Penn. Brit. Zool., ed. iv, vol. iv, p. 94, pi. liii, fig. 47.

— BUCARDIUM. Born. Mus. Caes. Vind., t. iv, fig. 11, 1780.

— EQUALIS. J. Sow. Min. Conch., t. xxi, 1813.
CYPBINA ISLANDICA. Ency. Meth., pi. 301, fig. 1 a, b, 1789.

— Phil. En. MoU. Sic., vol. ii, p. 31, 1844.

— Nyst. Conch. Foss. de Belg., p. 146, pi. ix, fig. 1, and pi. ii, fig. 1,

1844.

— Agass. Icon, des Coq. Tert., p. 49, t. xiii, figs. 6, 7, 1845.

— Defray. Nat. Hist. New York Zool., pi. xxvi, figs. 268-9, 1843.

— Lovtn. Ind. Moll. Scand., p. 38, 1846.

— ISLANDICOIDES. Nyst. Coq. Foss. Prov. d'Anv., p. 9, No. 33, 1835.

— Pusch. Pol. Pal., p. 74, pi. viii, fig. 5 a— c, 1837.

— ANGULATA. Nyst. Rech. Coq. Foss. d'Anv., p. 9, No. 34, 1835.

— MAXIMA. S. Wood. Catalogue, 1840.

— VULGARIS. G. B. Sow. Genera of Shells, No. 32, 1824.

— JEQUALIS. Phil. En. Moll. Sic., vol. i, p. 39, t. iv, fig. 4, 1836.

Gold/. Pet. Germ., p. 236, pi. 148, fig. 5, a, 6.
Agass. Icon, des Coq. Tert., p. 52, t. xiii, fig. 5, 1845.

ARCTICA VULGARIS. Schum. Essai d'un Nouv. Syst. des Habit, des Vers. Test., p. 145,
pi. xiii, fig. 3, 1817.

Spec. Char. Testa magnd, subcordatd, transversd, vel orbiculari, tumidiusculd; striis
aut lineis incrementi tenuibus et irregularibus ; umbonibus acutis mx incurvatis ; latere
postico subangulato.

Shell large, of a subcordate form, sometimes elongate or transverse, at others
nearly orbicular, somewhat tumid, covered with fine and irregular lines of growth ;
beaks sharp, not prominent, scarcely incurved, posterior side slightly angulated.
Diameter, 4J inches.
Localities. Cor. Crag, Gedgrave, Ramsholt.

Red Crag, Button, Bawdsey, Alderton, Felixstow.
Mam. Crag, Bridlington, Southwold, Chillesford.
Uddevalla and Clyde Beds.

Recent, British, Norwegian, and North American Seas.

This is one of the most common and abundant shells of the Coralline Crag, and
although perfect specimens are somewhat difficult to obtain in the disturbed portion
of the Red Crag, fragments or imperfect specimens are there of no uncommon occur-
rence, neither is it very rare in the still more recent deposit of the Mammaliferous
Crag. It is found living upon our own coasts in various depths of water from five to
thirty fathoms, and mostly where the bottom is of sandy mud, but it is considered as

BIVALVIA. 197

more essentially a species of an Arctic character. From the examination of a large
suite of fossil specimens obtained of different ages, I am convinced no specific sepa-
ration can be made between these fossils and the shells now found living in our own,
and in the Arctic seas ; the form is a character upon which no dependence can be
placed, as in some specimens the diameter in a longitudinal direction is considerably
greater than when measured from the umbo to the ventral margin, as may be seen by
the specimens that have been figured ; while in others it is nearly orbicular, with the
height equal or rather exceeding that of its length ; as a general rule it may perhaps
be said that the umbo of the Cor. Crag shell is thicker and more prominent than it is
in the living species, but even in this there is considerable variation amongst my
fossils, and in the shells of the more modern deposits this is less distinguishable.

This shell is said to attain in the living state to the large dimensions of five and a
half inches in length, but I have never seen a Crag specimen of such magnitude ; mine
range from 4^ inches, down to very little more than ^th of an inch.

2. CYPRINA RUSTICA, /. Sowerby. Tab. XVIII, fig. 1 a — e.

VENUS RUSTICA. J. Sow. Min. Conch., t. 196, 1818.
CYPRINA TUMIDA. Nyst. Rech. Coq. Foss. d'Anv., p. 9, pi. ii, fig. 32, 1835.
Potiez and Mich. Cat. de Moll, de Douai, t. ii, p. 221.
Nyst. Coq. Foss. de Belg., p. 148, pi. x, fig. 1 a, a, 5, b, and pi. viii,

figs. 2, 3, and 4, 1844.
RUSTICA. S. Wood. Catalogue, 1840.

LAJONKAIRII. Gold/. Pet. Germ., vol. ii, p. 237, t. 148, fig. 9 a— c, 1841.
. — DEFRANCII. Fan Beneden. Bull. Zool. de Guerin, 1835, p. 149, fide Nyst.

Spec. Char. Testa tumidd, globoso-cordatd, valde in&guilaterali -, latere postico sub-
quadrato ; subtilissime punctato-striatd ; umbonibus approximatis, subincurvis ; lunuld cor-
datd, profundd.

Shell tumid, globosely heartshaped, very inequilateral ; posterior side subquadrate ;
covered externally with fine, radiating, and punctated striae ; umbones approximate,
slightly incurved; lunule heartshaped and deep.

Length, 2f inches ; height, 2 j inches ; depth, 2| inches.

Localities. Cor. Crag, Sudbourn, Gedgrave, Ramsholt.
Red Crag, Sutton, Newbourn.

This species is less abundant than the preceding one, although in the Coralline Crag
at Gedgrave it is not of rare occurrence ; from the Red Crag I have only been able to
obtain a couple of specimens. The Belgian shell, which I believe to be the same
species, is stated by M. Nyst to be very abundant in several localities.

This being undoubtedly the Venus rustica of Sowerby, I have retained his name as
having a priority of date, and this author appears to have been the first to notice the
species. The right valve has two cardinal teeth,the anterior one is of a triangular form, the
posterior one is elongated and sharp, they fit into depressions of the same form between

198 MOLLUSCA FROM THE CRAG.

three principal teeth in the left valve, with one distant, angular, and somewhat pro-
minent lateral tooth in each ; fulcrum for the ligament long and prominent, and in the
old specimens of this species may be seen the oblong cavity before the ligament, while
in the younger shell the fulcrum extends nearly to the umbo. The surface is covered
with rather prominent and distinct lines of growth, and there are fine, radiating, and
punctated striae, but they are not always visible even with a lens, and were probably,
like those upon Isocardia cor, most distinct in the epidermis. It is very variable in
its outward form, some specimens being transverse and very inequilateral, while others
are very orbicular, with a height rather exceeding the length ; outwardly it so much
resembles Isocardia cor as evidently to denote a close relationship.

CIRCE.* Schum., 1817.

VENUS (sp.) Mont.
CYPRINA (sp.) Turt.
CYTHEKEA (sp.) Phil.

Gen. Char. Shell equivalve, subtrigonal, orbicular or ovate, thick, strong, and
closed ; umbones sharp, not much elevated ; lunule distinct, margins smooth. Hinge
with three primary teeth in each valve, and one anterior lateral tooth. Ligament
external ; palleal impression with a very small sinus.

Animal suborbicular, with its mantle open, and the margins denticulated ; two
short siphonal tubes, with fringed orifices ; foot large and tongue-shaped.

The authors of the ' History of British Mollusca' have adopted Schumacher's genus
for the living homologue of our Crag species, although with some doubt respecting the
propriety of the reference. The main features of distinction are the short or sessile
appearance of the syphons, which correspond in that respect with those of Cyprina and
Astarte, and they have placed it between those genera ; the dentition of our only
species resembles that of Cytherea, and if it does not strictly belong to the latter genus,
deserves a situation but little removed from it.

1. CIRCE MINIMA. Montague. Tab. XIX, fig. 2 a — d.

VENUS MINIMA. Mont. Test. Brit, p. 121, t. iii, fig. 3, 1803.

— TRIANGULARIS. Mont. Test. Brit., p. 577, t. xvii, fig. 3, 1803.

— CYBILLI. Scacchi. 1832, fide Philippi.

— PUMILA? Desk. 2d edit. Lam., torn, vi, p. 370, 1835, No. 86.
CYPBINA MINIMA. Turt. Brit. Biv., p. 137, 1822.

Thorpe. Brit. Mar. Conch., p. 82, fig. 102, 1844.

* Etym., proper name.

BIVALVIA. 199

CYPRINA TRIANGULARIS. Turt. Brit. Biv., p. 136, pi. ii, figs. 19, 20, 1822.
CYTHEEEA MINIMA. Brown. Brit. Conch. Illust., pi. xix, fig. 3, 1827.

MINUTA. Id. „ „ pi. xix, fig. 4, 1827.

TRIANGULARIS. Macffil. Moll. Aberd., p. 268, 1843.

TRIGONA. Nyst. Coq. Foss. de Belg., p. 172, pi. xii, fig. 4, 1844.

APICALIS. Phil. En. Moll. Sic., vol. i, p. 40, pi. iv, fig. 5, 1836.
Forbes. JSgean Invert. Rep. Brit. Assoc., p. 182, 1843.

CYRILLI. Phil. En. Moll. Sic., vol. ii, p. 32, 1844.

PUSILLA. Bonelli fide Sismonda.

LENTICULA. S. Wood. Catalogue, 1840.

EXOLETA OEBICTJLATA? juv. Brown. Brit. Conch. Illust., pi. xx, figs. 19, 20, 1827.
CIRCE TRIANGULARIS. King. Ann. Nat. Hist., vol. xv, p. 112.

— MINIMA. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 446, pi. xxvi, figs. 4, 5, 6, 8'

and Animal, PI. M, fig. 3, 1848.
CRASSINA MINIMA. Gray. Ann. of Philos., 1825.

Spec. Char. Testa parvd, ovato-rotundatd vel subtrigond, subaquilaterali, compressd,
transversim striatd, striis lavibus, convexis ; lunuld distinctd ; margine integerrimo.

Shell small, roundedly ovate, or of a subtrigonal form, nearly equilateral, com-
pressed, transversely striated, striae rounded and smooth; lunule distinct; margin
smooth.

Diameter, f ths of an inch.

Localities. Cor. Crag, Sutton.
Red Crag, Sutton.

Recent, ^Egean, Mediterranean, Britain, Zetland.

This species, in the Coralline Crag, is very abundant ; my cabinet contains only two
individuals from the Red Crag. In outward form it presents considerable variation,
some specimens having a longitudinal diameter much greater than its height, while ir
others the height exceeds the length ; the prominence in the umbo of some individuals
gives rather an angularity to the upper part of the shell, but there is no distinc
triangular variety.

CORALLIOPHAGA.* De Blainv., 1824.

CYPRICARDIA (sp.) Lamarck.
VENERUPIS (sp.) Basterot.

Gen. Char. Shell transversely ovate or oblong, equivalved, inequilateral, closed ;
rugged or smooth externally ; hinge furnished with two teeth in each valve, or two
diverging in one valve, with one triangular and interlocking in the other. Two ovate
muscular impressions ; mantle mark with small indented sinus. Ligament external.

* Etym. KopdXXiof, coral, and 0ayw, to eat.

26

200 MOLLUSCA FROM THE CRAG.

ANIMAL.

This appears to be distinguished by its dental formula having no lateral teeth like
those in Cypricardia. What has hitherto constituted the genus Fenerupis, is a greater
number of cardinal hinge teeth, being three in a parallel direction, whereas in this
there are only two diverging widely from the umbo. Tt appears to be closely related
to the Venus family, but at present little is known respecting the few species that have
as yet been noticed.

1. CORALLIOPHAGA CYPRINOIDES. S. Wood. Tab. XV, fig. la — d.

CORALLIOPHAGA CYPKINOIDES. S. Wood, Catal. of Crag Shells, in Ann. and Mag. of Nat.

Hist., 1840, p. 250.

Spec. Char. Testa ovato-oblongd, transversd, valde intequilaterali, nitidd, laevigatd;
antice dreviore, rotundatd ; postice subtruncatd ; car dine bidentato diver gente, sinu pattiari
minime prof undo.

Shell ovately oblong, transverse, very inequilateral, naked, smooth, closed;
anterior side the shorter, and rounded ; posterior somewhat truncate ; hinge with two
diverging teeth, and a small palleal sinus.

Length, f ths of an inch ; height, ^ an inch.

Localities. Cor. Crag, Ramsholt, and Sutton.

This species does not appear to have been at all abundant. Var. a (fig. b, c)t found
within the walls of a Balanus, represents the right valve, which is very elongated, thin,
and fragile ; this is particularly inequilateral, rounded on the anterior side, somewhat
quadrate posteriorly ; the exterior is nearly smooth, or with merely irregular lines of
growth, and it is rather more tumid on the posterior side, with a sort of obtuse diagonal
ridge running from the umbo to the posterior part of the ventral margin ; the hinge
in this valve has a ledge or fulcrum for the ligament, within which is an elongated
tooth nearly parallel, and behind the umbo, with a compressed one diverging under
the anterior margin ; in the left valve are also two teeth, one of which is of an obtusely
triangular form, and seems to have been inserted between the two of the opposite
valve, while the other fitted into the depression outside the anterior tooth of the right
valve. Var. /3 (fig. a] is comparatively much shorter and thicker, and was found loose
in the sand ; the hinge area in this is broader and thicker ; the marks of the adductor
muscles are large and somewhat deeply impressed, and that by the mantle has but a
very small indentation ; the length of the larger specimen is as one and a half to its
height, whereas the smaller variety is scarcely longer than it is high.

Venerupis striatula of Nyst, ' Coq. Foss. de Belg.,' p. 100, pi. iv, fig. 11 a, b, very
much resembles our shell, but it has a large and deeply-indented sinus in the mantle-
mark, and the shell to which he has referred his species has also the same dis-
tinguishing character.

BIVALVIA. 201

Petricola corattiophaga, Desh., ' Coq. Foss. des Env. de Par.,' resembles one form
of our variable shell, but from description the dental apparatus appears different. An
individual, apparently of this genus, is in the cabinet of my friend Mr. F. Edwards,
and found at Barton, but it is in so deplorable a condition that no fair comparison
can be instituted.

TAPES.* Megerle, 1811.

VENUS (sp.) Linn.

CALLISTA, CALLISTODEBMA (sp.) Poli, 1791.

TAPES. Schum., 1817.

PULLASTRA. G. B. Sow., 1827.

VENERUPIS (sp.) Flem., 1828.

SAXIDOMUS? Conrad, 1837.

Gen. Char. Shell equivalve, transversely oblong, ovate, or subtriangular, inequi-
lateral, closed, and generally somewhat thick and strong ; posterior side the larger ;
externally smooth, striated, or decussated; inner margin free from crenulations.
Hinge composed of three sub-parallel cardinal teeth, two of which are bifid. Palleal
sinus large and deep. Ligament external.

Animal of an oblong form, having the mantle freely open in front ; the margins
plain, or sometimes fringed with fine filaments ; siphons sometimes separated to their
bases, at others united for half their length, with their orifices bordered by cirrhi ; foot
lanceolate and thick, furnished with a byssal groove.

This is an extensive genus, and species that may be referred to it have been
obtained from the seas of all climates, some of which are extremely elegant, and in the
recent state are beautifully ornamented. Many fossils from the older rocks, strongly
resembling in form the recent genus, and possessing a mantle mark indicative of the
possession of siphonal tubes, have been considered as entitled to a generic association ;
the distinctive characters, a byssal groove in the foot of the animal, of course is in the
fossil perfectly useless, but the shell also possesses a good distinction in the peculiar
arrangement of the hinge denticles; this, however, is another character seldom of
much service in the older fossils, .and it is only when we come into the Tertiaries that
we are quite sure of its existence, and in the oldest of these it is doubtfully present.

1. TAPES VIRGINEA, ^ Tab. XX, fig. 1 a — e.

VENUS VIRGINEA. Mat. and Rack. Linn. Trans., vol. viii, p. 89 t. ii, fig. 8, 1807.
Turt. Brit. Biv., p. 156, pi. 8, fig. 8, 1822.

— L^TA. Poll. Test. Utrusq. Sic., t. xxi, fig. 1.

— RHOMBOIDE3. Penn. Brit. Zool., vol. iv, p. 9 7, pi. lv, (fig. right hand.)
— - SARNIENSIS. Turt. Brit. Biv., p. 153, pi. x, fig. 6, 1822.

* Etym. Tairys, tapestry, probably so called from the ornamental exterior of most of the species.

202 MOLLUSCA FROM THE CRAG.

VENUS VIRAGO. Loven. Ind. Moll. Scand., p. 40, 1846.
CAPSA VIRGO. "Leach." Ann. Mag. Nat. Hist., vol. xx, p. 272.
CUNEUS FASCIATUS. Dacosta. Brit. Conch., p. 204, 1778.
VENERUPIS VIRGINEA. Fleming. Brit. Animals, p. 452, 1828.

SARNIENSIS. Id. ,, p. 452.

PULLASTRA VIRGINEA. S. Wood. Catalogue, 1840.

Forbes. Rep. JSgean. Invert., p. 180, 1843.
TAPES VIRGINEA. Forbes and Hani. Hist. Brit. Moll., vol. i, p. 388, pi. xxv, figs. 4, 6, 1848.

Spec. Char. Testa ovatd, compressiusculd, inaquilaterali, postice magiore et longiore,
subangulatd ; concentrice incequaliter striatd, striis versus posticum majoribus ; lunuld
lanceolatd.

Shell ovate, somewhat compressed, inequilateral, posterior side the larger and
longer, subangulated, ornamented with concentric striae or ridges, and these are
larger or broader on the posterior side ; lunule elongated.

Length, 1J inch; height, 1 inch.

Localities. Cor. Crag, Sutton.

Red Crag, Sutton, Walton-on-the-Naze.
Mam. Crag, Bramerton.
Uddevalla.

Recent, Norway, Britain, Mediterranean.

From the Coralline Crag my specimens are few and fragmentary; in the Red
Crag it was not abundant ; specimens, however, are in my cabinet sufficiently nume-
rous and perfect to justify its being considered a fair identification, and I feel no
hesitation in placing the Crag shell under the name of virginea ; it appeared also to
have continued through the more recent period of the Mam. Crag, as a specimen of
this species was obligingly sent to me for description by Mr. Wigham, who found it
in the neighbourhood of Norwich, and it is also enumerated among the shells from the
Clyde beds. In the living state it is one of our most abundant as well as one of our
handsomest species ; and although our largest Crag specimen does not measure more
than an inch and a half in length, the recent shell attains a magnitude of two and a
half inches, a size exceeding those found in the Mediterranean.

2. TAPES AUREA, Gmelin. Tab. XX, fig. 2 a — b.

VENUS AUREA. Gmel. Syst. Nat., p. 3288, 1788.

Mat. and Rack. Linn. Trans., vol. viii, p. 90, pi. ii, fig. 9, 1807.
_ _ Turt. Brit. Biv., p. 155, pi. ix, figs. 7, 8, 1822.
Phil. En. Moll. Sic., vol. i, p. 47, vol. ii, p. 35.
LovSn. Ind. Moll. Scand., p. 40, 1846.
Middendorff. Malac. Ross., p. 569, 1849.

— ^NEA. Turt. Brit. Biv., p. 152, pi. x, fig. 7, 1822.

— NITENS. Id. „ p. 152, pi. x, fig. 8, 1822.

— NEBULOSA. Solander. Pult. Dorset., p. 34.

BIVALVIA. 203

VENUS LITERATA. Linn, Faun Suec. non Syst. Nat.

CAPSA CROCEA. "Leach" Mag. Nat. Hist., vol. xx, p. 272.

PULLASTRA AUREA. Alder. Catal. Moll. North, and Durh., p. 86.

TAPES AUREA. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 392, pi. xxv, fig. 5, 1848.

Spec. Char. Testa ovatd, sub-cordatd, tumidiusculd,sub-m&c[uilateraU,posticeangulatd;
margine ventrali arcuato ; concentrice sulcatd; striis radiantibus obsoletis; lunuld cordato-
ovatd.

Shell ovate or heart-shaped, slightly tumid, inequilateral, posterior side angulated ;
ventral margin convex, concentrically sulcated, with obsolete radiating striae ; an
elongated but not well-defined lunule.

Length, l^-th of an inch; height, |ths ditto.

Localities. Mam. Crag, Bramerton.

Udde valla.

Recent, Norway, Britain, Mediterranean.

The Mammaliferous Crag is its earliest appearance ; one specimen only is all that
I have seen, and that was found by Mr. Wigham, near Norwich, who has obligingly
permitted me to have it figured. In the recent state this is a common species in the
British seas upon the Eastern Coast, where it is subject to considerable variation, both
in regard to form as well as in the external ornament, some specimens being, in fact,
smooth, while others are deeply sulcated, or covered with regular ridges over the
entire surface. The striae upon the exterior of our solitary fossil specimen are fine and
numerous ; the anterior and posterior sides are somewhat compressed, while there is a
tumidity about the middle of the shell differing therein from the preceding species,
from which it also differs in being less elongated and rather less inequilateral.

3. TAPES PEROVALIS, S. Wood. Tab. XIX, fig. 7 a— d.

PULLASTRA PEROVALIS. S. Wood. Catalogue, 1840.

Spec. Char. Testa elongato-ovatd, inaquilaterali, tumidd, nitidd, politd, tenui ; antice
rotundato-angulatd ; margine dorsali postico convexiusculo.

Shell elongately ovate, inequilateral, tumid, smooth, glossy, and thin ; anterior side
roundedly pointed ; dorsal margin slightly convex.

Length, 2 inches; height, lj inch.

Locality. Cor. Crag, Ramsholt.

I have obtained at the above locality about a dozen specimens of this species,
which from loss of animal matter had become excessively fragile.

In many of its characters it strongly resembles Venus geographica, but the smooth
surface or total absence of the transverse ridges, as well as the radiating or decus-
sating striae which ornament that species, will readily distinguish it. A shell figured
and described by Phillippi from the Neapolitan seas, V. nitens, En. Moll. Sic., vol. ii,
p 35, t. xiv, fig. 14, seems to approach even nearer, and may probably be identified

204 MOLLUSCA FROM THE CRAG.

when the specimens can be compared ; there are, however, some differences in the
descriptions : it is therefore thought best to retain its present name. As this latter
species appears its nearest relative, it may be only necessary to point out what are the
distinctions, relying upon the description by that author, who, in comparing his shell
with the geographica, seems to think a specific character exists in being less equilateral,
and in the straight dorsal line of nitens, with a more convex ventral margin. Our
shell, on the contrary, appears to have its dorsal margin more rounded than that of
geographica, and much resembles in outline the virginea, but the smooth and glossy
exterior differs from all that I have seen, with the exception of nitens ; the dental
characters appear the same, the central one bifid in the left valve, with two sub-bifid
in the right ; but the palleal scar, according to the figure, goes deeper into his shell
than it does into our Crag fossil.

4. TAPES TEXTURATA? Lamarck. Tab. XX, fig. 3 a — c.

VENUS TEXTURATA. Lam. Hist, des An. sans Vert., 2d ed., p. 355, No. 43.
TAPES TEXTUKATA. G. Sowerby. Thesaur. Conch. Tapes, No. 39.

Spec. Char. Testa tenui, cordato-ovatd, compressiusculd, incequilaterali ; transversim
striatd, striis numerosis, confertis.

Shell thin, ovately heartshaped, somewhat compressed, inequilateral ; transversely
striated, striae numerous, close set.

Length, \\ inch.

Locality. Red Crag, Walton-on-the Naze.

The specimen figured is the right valve with three teeth diverging from imme-
diately beneath the umbo. The lines which cover the exterior are generally parallel
to the margin of the shell, but they occasionally anastomose, or run into each other
like those upon the recent species, T. texturata. There is, however, a slight difference
in form from that shell, and thelunule is not so distinctly marked ; but having only one
specimen, and that imperfect, I am unwilling to do more than assign it provisionally to
what appears at least its nearest relative ; should, however, future examination of
better specimens justify a specific distinction, I would claim for the Crag fossil the
name of habilis.

VENERUPIS.* Lamarck, 1818.

VENUS (sp.) Linn.

DONAX (sp.) Id.

CUNEUS (sp.) Dacosta.

IRUS. Oken, 1815.

PETRICOLA (sp.) Turt., 1822.

PETRIJFORA. Latr., 1827.

VENERIRUPIS. Blainv., 1825, G. Sow., 1839.

VENERUPES. Swains., 1840.

* Etym., Venus, and rupis, a rock.

BIVALVIA. 205

Gen. Char. Shell ovate or oblong, equivalved, inequilateral, somewhat compressed.
Hinge composed of three cardinal teeth in one valve, and two or three in the other.
Muscular impressions ovate, with a deep palleal sinus. Ligament external.

Animal oblong ; the mantle closed all round with the exception of a small opening
in front for the passage of the compressed and lanceolate foot ; siphons unequal, dis-
united at about half their length ; extremities ornamented with a double row of fringes.

The arrangement of dental characters in what constitutes this genus, as well as
the general form of the shell, approach so closely to those of Tapes, that it seems more
entitled to a position amongst the Venus family than to any other, and so far as the
form of the foot of the animal or its siphons may determine its connections, it does
not any further justify a removal ; its habits certainly resemble those of Saxicava, but
the selection as a habitat in holes, formed in rocks, is not peculiar to one family, as
Bivalves of very different forms have been found located in such situations : and habits
alone are not sufficient for the uniting into one family those Bivalves which possess
them ; perhaps, after all, this genus as it now stands will be found to possess no
sufficient claims for a separate position, and may probably be hereafter united with
Tapes.

As a genus it contains but very few species, and little is at present known respecting
its exotic allies in the recent state, and nothing in the fossil of an older date than the
Upper or Middle Tertiaries.

1. VENERUPIS IRUS. Linnaus. Tab. XIX, fig. 6 a, b.

DONAX IEUS. Linn. Syst. Nat., ed. 12, p. 1128, No. Ill, 1767.

Poll. Test. Sicil., vol. i, t. x, figs. 1, 2, and vol. ii, p. 83, t. xix, figs. 25, 26,

1795.

CUNEUS FOLIATUS. Dacosto. Brit. Conch., p. 204, pi. xv, fig. 6, 1778.
TELLINA CORNUBIENSIS. Penn. Brit. Zool., ed. 4, vol. iv, p. 75, No. 35.
VENUS IRUS. Brown. Illust. Brit. Conch., pi. xx, fig. 9, 1827-

— RUPESTRIS? Broc. Conch. Foss. Subap., p. 559, t. xiv, fig. 1, 1814.
VENEBTJPIS IKUS. Lam. An. sans Vert., t. v, p. 507, 1818.

— Payr. Catal. MoU. Cors., p. 35, 1826.

— Phil. En. Moll. Sic., vol. i, p. 21, vol. ii, p. 20.

— Forb. and Hani. Hist. Brit. Moll., vol. i, p. 156, pi. vii, figs. 1 — 3, and

pi. G, fig. 2.

— — Midden. Malac. Rossic., p. 567-
PETRICOLA IRUS. Turt. Brit. Biv., p. 26, t. ii, fig. 14, 1822.

— RUPESTRIS? Dubois. Coq. Foss. Wolh. Pod., pi. vii, figs. 3, 4, 1831.
PULLASTRA IRUS. Brown. Illust. Brit. Conch., 2d ed., pi. 37, fig. 9.

CAPSA IRUS. "Leach, 1818." Ann. and Mag. Nat. Hist., vol. xx, p. 272.
? Encyc. Method., pi. 262, fig. 4.

Spec. Char. Testa cmato-oblongd, vel subtrapezoidea, crassd ; posticelongiore et latiore,
subangulatd; lamellatd, lamellis transversis, interstitiis radianter striatis ; dentibus tribus
in utraque valvd ; sinu pattiari magno, subangulato.

206 MOLLUSCA FROM THE CRAG.

Shell ovately oblong, or rather sub trapezoidal, thick, and strong ; posterior side
the longer and broader, somewhat angulated ; ornamented with transverse lamellae,
radiatingly striated between the interstices ; three teeth in each valve ; palleal sinus
large and subangulated.

Length, fths of an inch ; height, -|ths ditto.

Locality. Red Crag, Walton-on-the-Naze.

Recent, Mediterranean, Britain.

Only two specimens of this species are in my cabinet, and they are all that I
have seen ; these are somewhat rubbed, with the lamellae much worn down, but quite
perfect enough to justify their being considered identical ; my specimens are rather
shorter than the generality of recent shells, although I believe in those there is con-
siderable variation, and I have assigned it to the living species without any hesitation.
In the recent state it is found imbedded in sponges and seaweed, as well as in rocks,
and ranges from low-water mark to ten or a dozen fathoms.

CYTHEREA.* Lamarck, 1805.

ACTINOBULUS. Klein, 1753.

CHAMA. Browne, 1756.

VENUS (sp.) Linn.

CALLISTA CALLISTODERMA (sp.) Poll, 1795.

HYSTEKOCONCHA. Lang., 1722.

MERETRIX. Lam., 1799.

CHIONE. Gray, 1838.

DIONE. Id. 1848.

GKESSLYA (sp.) Agass., 1845.

Gen. Char. Shell equivalve, inequilateral, closed, usually more or less transversely
oblong or ovate, sometimes obtusely triangular, generally thick and strong, with
slightly prominent umbones. Surface sometimes transversely sulcated, usually smooth.
Hinge furnished with three teeth in one valve, and four in the other ; anterior one
diverging under the lunule. Muscular impressions large and ovate, that by the
mantle with a sinus generally large and wide. Ligament external.

Animal of the form of the shell, with the mantle freely open, having the margins
without fringes ; siphons long, united nearly to their extremities ; orifices surrounded
with tentacles. Foot large and tongue-shaped, not furnished with a byssal groove.

This genus may be considered as being distinguished more especially by its
peculiarity of hinge. The anterior tooth, which gives a prominent character to the
genus, is placed at right angles to the more cardinal teeth, and is situated at a little
distance immediately under the lunule, giving great firmness and security to the close
union of the valves ; the composition of the shell is also somewhat different from that

* Etym., one of the names of Venus.

BIVALVIA. 207

of Venus, which has the outer portion of a fibrous character, while in this it is more
compact, and in the recent shell is often enamelled.

This genus is found extensively in the warmer regions of the globe ; as a fossil it
has been obtained very low in the secondary Formations, and was largely developed
during the early Tertiary Periods.

1. CYTHEREA CHIONE, Linnceus. Tab. XX, fig. 4 a, b.

CHAMA. Reyenfuss. Choix Coquil., p. 56, t. viii, fig. 17.
CURVIROSTRUM. Leigh. Nat. Hist. Chesh., p. 179, pi. iii, fig. 5, 1700.
VENUS CHIONE. Linn. Syst. Nat., ed. 12, p. 1131, No. 125, 1767.

Poli. Test. Sicil., vol. ii, p. 85, pi. xx, figs. 1, 2, 1795.
Broc. Conch. Foss. Subap., p. 547, 1814.
Sismonda. Syn. Meth. Invert. Foss. Fed., p. 19, 1847.

— CHIONOIDES? Nyst. Coq. Foss. de Belg., p. 175, pi. xii, fig. 5 a, b, 1844.
PECTUNCULUS GLABER. Dacosta. Brit. Conch., p. 184, pi. xiv, fig. 7, 1778.
DIONE GLABER. Gray. List Brit. Moll., p. 6, 1851.
CYTHEREA CHIONE. Turt. Brit. Biv., p. 160, pi. viii, fig. 11, 1822.
Payr. Catal. Moll. Corse., p. 47, 1826.
Bronn. Leth. Geogn., ii, p. 954, t. xxxyiii, fig. 3a — c, 1838.
Phil. En. Moll. Sic., vol. i, p. 40, vol. ii, p. 31.
Owen. Comp. Anat. Invert. An. p. 282, fig. 118, 1843.
Forbes. JSgean Invert. Rep. Brit. Assoc., p. 180, 1843.
Agass. Icon. des. Coq. Tert., p. 45, t. x, figs. 10 — 13, 1845.

— NITENS. Andr. Bull, de Sc. de Mosc. p. 104, pi. vi, fig. 9, 1830, fide Bronn.

— L^EVIS. Agass. Loc. cit. supra, t. x.
CYTHEREE FAUVE. Chenu. Traite Element., pi. iii, fig. 10.

Encyc. Method., pi. 266, fig. 1 a. b,

Spec. Char. Testa transversd, ovato-cordatd, incequilaterali, glabrd, politd, trans-
versim obsolete sulcatd ; lunuld elongatd ; antice et postice rotundatd.

Shell transverse, ovate, heartshaped, inequilateral, very smooth, and glossy ; with
obsolete transverse ridges ; lunule elongate, and cordiform : anterior and posterior
sides rounded.

Length, 2^ inches ; height, 1 f ditto.

Locality. Cor. Crag, Ramsholt

Recent, Britain, Mediterranean.

This elegant and beautiful shell I have seen only from the oldest of the Crag
Deposits, and in that from the lowest part, where it is not rare, but of extreme
fragility, and specimens are very difficult to be obtained.

The Crag shell agrees precisely with the British form of this species, in the exterior
being smooth and glossy, and marked in a concentric direction, with occasionally
shallow or indistinct furrows, or depressions, and with the aid of a lens may be seen
numerous, fine, radiating striae, most visible upon the posterior side ; these, however,
are quite superficial, and are not seen when the surface is removed, nor is it imparted
in any way to the margin of the shell which is quite smooth.

27

208 MOLLUSCA FROM THE CRAG.

Poll has given a beautiful drawing of the animal of this species, and its anatomy is
described by Professor Owen in his Lectures upon Invertebrate Animals, where he
considers it as one of the most highly organised of the Bivalvia. In the recent
state this does not appear to have been a very deep water species, and seems more
inclined to the southern or Mediterranean regions, where it is very abundant, and as
a fossil I know it only from the Sicilian beds, unless Venus chionoides, Nyst, be one of
its varieties. C. Chione, Dubois, Wolhyn. Podol., pi. v, figs. 13, 14, appears to
have ridges too regular and too numerous, and according to the figure, is rather too
broad on the posterior side, with the sinus in the mantle mark more rounded, and
appears to be intermediate between our shell and Erycinoides.

Cytherea nitidula, Lam., a recent species from the Mediterranean, is considered by
Philippi as the young of this shell, but the fossil from the older Tertiaries described
under the same name, is quite distinct.

2. CYTHEREA RUDIS, Poll. Tab. XX, fig. 5 a — d.

VENUS RUDIS. Poli, (not Dujard.) Test. Sicil., vol. ii, p. 94, t. xx, figs. 15, 16, 1795.
Middendorff. Malacozool. Rossica, p. 571, 1849.

— PECTUNCULUS. Broc. Conch. Foss. Subap., p. 560, pi. xiii, fig. 12, 1814.

— CYCLADIFORMIS. Nyst. Coq. Foss. de Belg., p. 171, pi. xii, fig. 3, 1844.

— VENETIANA. Sismonda. Syn. Meth. Invert. Pedm., p. 20, 1847.

— OCHROPICTA. Krynicki. Bull, des Natur. de Mosc., No. 11, p. 64, fide Middendorff.
CYTHEREA VENETIANA. Lam. Hist, des An. s. Vert., torn, v, p. 569, 1818.

Phil. En. Moll. Sic., vol. i, p. xl, t. iv, fig. 8, 1836.

Dujard. Mem. de la Soc. Geol. de Fr., t. ii, part ii, p. 260, 1837.

Forbes. ^Igean Invert. Rep. Brit. Assoc., p. 182, 1843.
FILOSA. S. Wood. Catalogue, 1840.
CYCLADIFORMIS. Nyst. Rech. Coq. Foss. d'Anv., p. 10, No. 38, pi. ii, fig. 38,

1835.
RUDIS. Phil. En. Moll. Sic., vol. ii, p. 32, 1844.

Spec. Char. Testa oblique-cordatd, tumidd, inaquilateraU, tenui, transversim striatd,
striis tenuibus, rotundatis, confertis ; lunuld elongato-cordatd, margine integro ; umbonibus,
prominulis.

Shell obliquely heartshaped, tumid, inequilateral, thin, transversely or concen-
trically striated ; striae fine, close, and rounded ; lunule of an elongated heartshape ;
margin smooth ; beaks slightly prominent.

Length, ^ths of an inch ; height., fths of an inch.

Localities. Cor. Crag, Button, Ramsholt, Sudbourn.

Red Crag, Button, and Walton-on-the-Naze.

Recent, Mediterranean, and Black Sea.

This delicate and elegant shell is very abundant in the Red Crag at Walton-on-
the-Naze, and not at all rare in the Lower Formation, or Cor. Crag at Sutton.

It is subject to considerable variation in outline, and in proportional dimensions,

B1VALVIA. 209

but in general the form is transverse, with a diameter of seven to five ; while in
others there is no difference, the height being equal to the length. The hinge is
furnished with three teeth in the right valve, and four in the left, the posterior one
small, parallel to, and a little within the fulcrum for the ligament: in the right
valve the posterior tooth is bifid or cleft ; the surface is ornamented with numerous
close set striae, broader than the spaces between them, and sometimes rather irregular,
bifurcating or inosculating, more especially on the posterior part ; the impression of
the mantle is at some distance within the margin, and the sinus large, rounded, and
reaching about one third across the shell.

A species from the older Tertiaries at Barton, figured and described by J. Sowerby
in 'Min. Conch.,' t. 422, fig. 2, (V. rotundata, Brander, figs. 91, 93,) very much
resembles our Crag fossil, but is, I believe, distinct.

VENUS. Linnteus.

CALLISTA AND CALLISTODEEMA (sp.) Poll, 1795
ANTIGONE. Schum., 1817-
VENULITES. Schlott., 1820.
CLAUSINA. Brown, 1827.
ORTYGIA. "Leach, MS.," id.
TIMOCLEA. Id. id.

CHIONE. Megerle. 1811; Gray, 1851.
DOSINA. Gray, 1838 ; Wood, 1840.
EGESTA? Conrad, 1845.

Gen. Char. Shell equivalve, more or less inequilateral, closed ; orbicular or trans- ,
versely ovate, generally ornamented upon the exterior, imbricated, radiated, or
decussated. Margin crenulated. Hinge composed of three diverging cardinal teeth
in each valve. Ligament external. Muscular impressions roundedly ovate. Mantle
mark sinuated.

Animal ovate or suborbicular, with the edges of the mantle disconnected ; margins
fringed. Siphons united at the base, separated and diverging at their extremities ;
orifices fimbriated ; foot linguiform.

This genus, as the name would imply, is composed of beautiful, and in the living
state, of many highly ornamented shells, and found in the seas of all regions.
Notwithstanding its great curtailment since the time it was established by Linnaeus, it
now contains at least a hundred well determined species, restricting them to such as
possess a dental armature of three diverging cardinal teeth, while the animal possesses
two rather short siphons, giving a somewhat small and angular sinus to the impression of
the mantle mark ; the texture of the shell, at least the outer portion of it, appears to
be of a fibrous character, and it is generally covered with fine and numerous striae in
a radiating direction, and is more or less ornamented with reflexed portions of the
margin or imbrications, and some few are armed with long and formidable looking
spines.

210 MOLLUSCA FROM THE CRAG.

Fossils in the Carboniferous Deposits have been assigned to this genus, but
perhaps their just claim will not go further than a resemblance, or what is called a
family relationship, their true characters not having been well determined.

1. VENUS CASINA, Linncsus. Tab. XIX, fig. 1 a—f.

VENUS CASINA. Linn. Syst. Nat., 12 ed., p. 1130, No. 117, 1767.

_ — Dujard. Mem. de la Soc. Geol. de Fr., t. ii, part 2, p. 261, 1837.
Phil. En. Moll. Sic., vol. ii, p. 33, 1844.
Loven. Ind. Moll. Scand., p. 39, 1846.

— DISCINA. Lam. An. sans Vert., t. v, p. 586, 1818.

— REFLEXA. Mont. Test. Brit. Suppl., pp. 41, 168, 1808.

— RUSTERUCII. Payr. Cat. Moll. Cors., p. 52, pi. i, figs. 26—28, 1826.

— GIBBOSA. J. Sow. Min. Conch., t. 155, fig. 3, 1817.

— TURGTDA. J. Sowerby. Min. Conch., t. 256, 1820.

Nyst. Conch. Foss. de Belg., p. 178, pi. xiii, fig. 4«, b, 1844.

— SENILIS? Dubois. Wolhyn. Podol., p. 60, pi. v, figs. 22, 23.

— SULCATA. Nyst. Loc. cit. sup., p. 177,' pi. xii, fig. 6 a, b, 1844.

— MULTILAMELLOSA ? Nyst. Id., p. 179, pi. xii, fig. 7 a, b.

— SIMILIS? Id. Id., p. 180, pi. xiii, fig. 5 a, b.

— GALLINA? Bronn. Leth. Geog., vol. ii, p. 948, t. xxxviii, fig. 6.

— CASINULA? Desk. Exped. Moree, p. 101, t. xviii, figs. 18, 19.

— CINCTA. Agass. Icon, des Coq. Tert., p. 36, t. iv, figs. 7 — 10, 1845.
PECTUNCULUS MEMBBANACETJS. Dacosta. Brit. Conch., pi. xiii, fig. 4.

CYTHEREA SULCATA. Nyst et West. Nouv. Rech. des Foss. d'Anv., pi. i, fig. 9, 1839.

LAMELLATA. • Id. „ „ „ p. 9, pi. i, fig. 10.

CLAUSINA REFLEXA. Brown. Illust. Brit. Conch., pi. xix, fig. 13, 1827.

— CASINA „ „ „ pi. xx, fig. 15.

DOSINA CASINA. Gray, Analyst, 1838.
— TURGIDA. S. Wood. Catalogue.

Spec. Char. Testa cordato-rotundatd, gibbosd, interdum compressd, crassd ; imbricatd
vel lamettatd ; lamellibus confertis, acutis ; margine crenulato ; lunuld distinctd, impressd.

Shell roundedly heartshaped, gibbous, sometimes compressed, thick, and covered
with concentric imbrications, close, sharp, and reflexed ; margin crenulated ; lunule
distinct, impressed.

Diameter. 2 inches, nearly.

Localities. Cor. Crag, Ramsholt, Sutton, Gedgrave, Sudbourn.
Red Crag, Sutton, Bawdsey, Felixstow, Alderton.
Mam. Crag, ? Clyde beds.

Recent, Mediterranean, Britain, Bergen.

This shell as a Crag fossil is everywhere abundant, and exceedingly variable in
outward form, being sometimes longer than it is high, while in other specimens the
diameter is greater in the opposite direction ; in some individuals there is considerable
tumidity, while others are much compressed.

It is assigned to the living species from the belief that some of its varieties

BIVALVIA. 211

are so intimately connected that no specific character can be pointed out, whereby it
can possibly be distinguished or separated from it.

In the recent shell the umbo appears, in the few specimens I have been able to
examine, to be a little more lateral than in the generality of the Crag fossils, although
this lateral incurvature of the umbo is quite as distinct in the extreme of its variation
as in the living shell. Although considered as extinct by all previous authorities, and
to which I submitted when compiling my own Catalogue, the possession of many
more varieties, and further examination, have given me reason to dissent from that
opinion. The lamellae of the fossil are not often preserved in Cabinet specimens ;
when visible they are sharp and erect, and about equidistant, rather less prominent
upon the posterior margin, but that is a character upon which two species in the living
state have been formed, and is not much to be depended on ; between the lamellae fine
radiating striae are visible, corresponding to the crenulated margin of the interior.

2. VENUS FASCIATA, Dacosta. Tab. XIX, fig. 5 a — c.

PECTUNCULTJS FASCIATUS. Dacosta. Brit. Conch., p. 188, t. xiii, fig. 3, 1778.
VENUS PAPHIA. Pulteney. Hutchins' Hist. Dorset., p. 33.
Mont. Test. Brit., p. 110, 1803.

— PASCIATA. Don. Brit. Shells, vol. v, pi. 170, 1803.

PhilL. En. Moll. Sic., vol. ii, p. 34, 1844.
Lov6n. Ind. Moll. Scand., p. 39, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 415, pi. 23, fig. 3, pi. xxvi,
fig. 7, and pi. L, fig. 7, 1848.

— BROGNIARTI. Payr. Cat. Moll. Cors., p. 51, pi. i, figs. 23—25, 1826.

Phil. En. Moll. Sic., vol. i, p. 43, 1836.
CHIONE FASCIATA. Gray. List Brit. Moll., 1851.
CLAUSINA FASCIATA. Brown. Illust. Brit. Conch., pi. xx, fig. 10, 1827.
DOSINA S Wood. Catalogue, 1840.

PECTUNCULUS FASCIATIS. List. Hist. Conch., lib. iii, sect. 4, fig. 114, 1688.
Encyc. Method., pi. 276, fig. 2.

Spec. Char. Testa crassd, compressiusculd, ovato-trigond vel sub-cordatd, incequi-
laterali, latere postico longiore ; lamellatd, lamellis crassis, recurvis, distanti&us ; lunuld
elongato-cordatd ; umbonibus prominulis.

Shell thick, somewhat compressed, triangularly ovate, inequilateral, posterior side
the longer, and very little pointed ; covered with thick, distant, and slightly recurved
lamellae, or concentric ridges ; lunule elongated, heart shape.

Length, f-ths of an inch ; height, |-ths ditto.

Localities. Red Crag, Sutton, Walton-on-the-Naze.
Mam. Crag, Bramerton.

Recent, Mediterranean, Britain, Scandinavia.

I have only met with true and genuine specimens of this species as far back as the
Red Crag, where it was not very abundant. The young state of Venus imdricata, in
some of its forms, strongly resembles this shell, except where the lamellae are well pre-

212 MOLLUSCA FROM THE CRAG.

served: in this species the ridges are more numerous about the umbo or in the young
shell, whereas in the other they are more prominent and distant, and in the mature
state this species never attains to so great a size : the posterior side is sometimes
slightly pointed, and the length is generally greater than the height, but occasionally
the greater dimensions are the reverse. In the living state it is said to have a vertical
range from four to sixty fathoms.

3. VENUS IMBRICATA, /. Sowerby. Tab. XIX, fig. 30— /.

ASTARTE IMBRICATA. J. Sow. Min. Conch., t. 521, fig. 1, 1826.

Nyst. Coq. Foss, de Belg., p. 153, pi. ix, fig. 3 a, b, 1844.
DOSINA IMBRICATA. S. Wood. Catalogue, 1840.

Spec. Char. Testa suborbiculari, subcordatd, compressinsculd aut tumidd, crassd,
imbricatd, imbricibus crassis 12 — 16, reflexis, striatis ; natibus recurvis ; lunuld ovato-
cordatd ; marginibus crenulatis ; sinu palliari parvo, angulato.

Shell suborbicular, slightly heartshaped, somewhat compressed, occasionally
tumid, thick and imbricated, with 12 — 16 broad, thick, reflexed ridges or imbrications;
umbones recurved ; lunule impressed, elongate ; margins crenulated ; palleal sinus
small and angular.

Diameter, \\ inch.

Localities. Cor. Crag, Ramsholt, and Gedgrave.

Red Crag, Sutton, Walton-on-the-Naze.

This species is not particularly abundant either in the Coralline or in the Red Crag,
and appears in both to be subject to considerable variation.

There are two very distinct forms in this species : what may be called var. <z,
(fig. c, d,} which, in its extreme form, is an elegant shell, curving considerably towards
the anterior, and ornamented with about sixteen thick, obtuse, but reflected ridges, at
nearly regular distances, the fine lamellated ornament of the young shell is worn down
in those from the Red Crag, from which Formation only I have seen this variety. In
this state it approaches very near to V. casina, differing only in the exterior ornament.
Var. /3, or gibberosa, (fig. e,f,) on the contrary, is very inelegant, being a thick, tumid, and
clumsy looking shell, with a hunchedback and, in most instances, bipartite, the older
portion having a very different appearance from that of the young shell, in which the
surface is furnished with a few sharp, erect, and distant lamellae, about eight or ten,
and these, at the extreme edge or posterior margin, terminate abruptly, and are sharp
and almost pointed, after which the shell is nearly smooth, the lamellae being so close
as to represent little more than lines of growth with an irregular surface. In this
variety the shell is nearly orbicular, very tumid, and is rather higher than it is long,
the other variety is more compressed, and the diameter is greater in a longitudinal
direction ; between these extremes there is every imaginable variation, and the specimen
represented in ' Min. Conch.,' appears somewhat of an intermediate character, having
the surface flattened by the abrasion of the lamellae.

BIVALVIA. 213

i
2. VENUS OVATA, Pennant. Tab. XIX, fig. 4 a — d.

VENUS OVATA. Penn. Brit. Zool., vol. iv, p. 206, t. 59, fig. 3, 1777.

Forbes. JSgean Invert. Rep. Brit. Assoc., p. 182, 1843.
Loven. Ind. Moll. Scand., p. 40, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 419, pi. xxxiv, fig. 2, and
pi. xxvi, fig. 1, and pi. L, fig. 6, 1848.

— RADIATA. Broc. Conch. Foss. Subap., p. 543, t. xiv, fig. 3 a, b, 1814.

Bast. Mem. Soc. d'Hist. Nat. de Par., t. ii, pt. i, p. 89.
Marcel de Serres. Geog. des Terr. Tert., p. 150, 1829.
Phil. En. Moll. Sic., vol. i, p. 44, vol. ii, p. 34.

— SPADICEA. Renieri. Fide Brocchi.

Nyst. Coq. Foss. de Belg., p. 165, pi. ii, fig. 3, 1844.
PECTINULA. Desk. 2d. edit. Lam., t. vi, p. 348, 1 35.

CARDIUM STRIATUM EADIATUM. Walk, and Boys, Test. Min. Ror., p. 23, fig. 82, 1787.
TIMOCLEA OVATA. Brown. Illust. Brit. Conch., pi. xix, fig. 11, 1827.

— PENNANTII. Leach, MS. Fide Brown.
CYTHEREA OVATA. Fleming. Brit. An., p. 445, 1828.
CHIONE OVATA. Gray. List of Brit. Moll., p. 11, 1851.

Spec. Char. Testa ovato-trigonuld, incequilaterali, crassd, antice rotundatd, postice
angulatd; radiatim sulcatd, sulcis granulatis ; lunuld distinctd elongato-cordatd ; margine
tenuissime crenulaio.

Shell triangularly ovate, inequilateral, thick ; anterior side rounded, posterior very
slightly elongated ; covered with radiating, bifurcating, and granulated striae ; lunule
elongated, heartshaped ; margin very finely crenulated.

Length, |ths of an inch ; height, \ an inch.

Localities. Cor. Crag, Sutton, Gedgrave.
Red Crag, Sutton.

Recent, Mediterranean, Britain, Scandinavia.

This shell is exceedingly scarce in the Red Crag, but in the older or subjacent
deposit it is particularly abundant, more especially at Sutton, where the specimens are
almost entirely of one variety, in which the rays are finer and flatter, bifurcating about
the middle of the shell, giving, on the outer portion, as many as forty or fifty ridges ;
those which are found at Gedgrave have the rays larger, more elevated, and rounded,
with a more roughened surface, and are seldom divided, having also a wider space
between them : in the other variety they are but little imbricated, and have the
intermediate spaces or sulci very narrow; the form is somewhat variable, but in
general the older shell has comparatively a greater length than in the young state, and
is always a little longer than it is high ; upon the Gedgrave shell, or var. /3, there is an
obtuse ridge upon the posterior side, behind which the rays are closer and more
numerous ; this corresponds with the Italian fossil, V. radiata, Broc., while the Sutton
specimens more resemble the common form of the recent British shell.

This species is said to be abundant in the British seas, with a vertical range from
three to one hundred fathoms ; it is found fossil at Stromstadt.

214 MOLLUSCA FROM THE CRAG.

ARTEMIS,* Poll 1791.

CHAMA (DosiN.) Adans., 1757.

DOSINIA. Scopoli, 1777; Gray, 1851.

CIECOMPHALUS (sp.) Klein, 1753.

AETEMIS ET AETEMIDEEMA. Poli, 1/91. ;

ORBICULUS. M egerle, 1811.

ASA. Leach, MSS., 1819, fide Defrance.

EXOLETA. Brown, 1827.

AECTOC. Risso, 1826.

TAEAS. Id.

AETHEMIS. Desk., Phil., Blainv., Agass.

Gen. Char. Shell suborbicular or lenticular, equivalved, more or less compressed,
generally strong and closed, surface covered with concentric striae ; margins entire.
Hinge composed of three cardinal teeth in one valve, and four in the other ; no
lateral teeth. Ligament external, with a strongly defined, and generally deep lunule.
Impressions of the adductor muscles ovate, nearly equal, that by the mantle deeply
sinuated.

Animal suborbicular, with the edges of the mantle mostly disconnected ; margins
entire, or partially serrated. Siphonal tubes long, united to their extremities. Foot
large, semilunar, or crescent-shaped, exsertible at the middle or basal margin of the
valves.

This is a well-marked genus, said to be characterised especially by its animal
inhabitant, but if our reliance were solely upon the softer parts, to the entire exclusion
of the shell, it might be difficult to know where it should be placed. There is, however,
not much doubt respecting its relationship to the Venus group, but this affinity is better
displayed in the hard or shelly covering of the animal, than by any general resemblance
of either the foot, or the siphons of the mantle. The long siphonal tubes of this genus
are indicated in the shell by the impression of the retractor muscles being placed far in the
interior, so as to give what is called a very deep palleal scar or sinus, denoting, by its
depth, a corresponding proportion in the length of the tubes, this however, is not an
infallible criterion as to their length, nor does it appear to be a character of any great
family dependence, for in Lucinopsis the interior of the shell is marked by the impression
of the mantle with quite as deep a sinus, while the animal has the tubes short and slightly
exsertile, with a slender and delicate foot, and has little or no resemblance, any further
than in the form of the mantle mark, to animals of this genus, where the siphons are
long and united, and the foot is broad and splayed.

In the recent state it has a wide geographical range ; as a fossil I am not aware of
its having been found in any older Formation than the Middle Tertiaries.

* Etym., a proper name.

BIVALVIA. 215

1. ARTEMIS LENTIFORMIS, /. Sowerby. Tab. XX, fig. 7 a — c.

VENUS EXOLETA. Parkinson. Org. Rem., vol. iii, p. 189, 1811.

— LENTIFOEMIS. J. Sow. Min. Conch., t. 203, 1818.
ARTEMIS EXOLETA. Nyst. Coq. Foss. Belg., p. 184, pi. xiv, fig. 1, 1844.
— LENTIFORMIS. <S. Wood. Catalogue, 1840.

Potiez et Mich. Catal. des Moll, de Douai, torn, xi, p. 227, No. 13,
1844.

Spec. Char. Testa orbiculari, lentiformi, compressiusculd inaequilaterali, crassd ; striis
concentricis, magnis, confertis ; lunuld cordatd, impressd; maroine dorsali convexiusculo
postice subangulato.

Shell orbicular, lentiform, somewhat compressed, slightly inequilateral, thick ;
covered with numerous large, close set, concentric striae ; a deeply-seated heartshaped
lunule ; dorsal margin slightly convex ; posterior side subangulated.

Diameter, 2 inches.

Localities. Cor. Crag? Gedgrave.

Red Crag, Sutton, Walton-on-the-Naze.

In the Coralline Crag it is very rare ; indeed I have obtained only one specimen,
which is represented at fig. 7 c, and this is partly imbedded in the matrix with its best
characters obscured ; but in the Red Crag it is one of the most abundant shells at
Walton-on-the-Naze.

In the ' Mineral Concology' the Crag shell was considered to differ from Venus
exoleta (with which it had been placed by Parkinson) sufficiently to justify a specific
distinction, and as this is a genus in which the species do not appear to possess a great
range in variation, I have retained for it Mr. Sowerby's name, although these dif-
ferences are probably the effect of locality, or the result of external conditions.

Our shell is certainly flatter than V. exoleta, but not thinner ; the striae or ridges are
as large and broad as those which ornament the recent species; there is a slight
angularity in the outline on the posterior side, a little beyond the termination of the
large ligament, and a slight slope upon the dorsal edge, differing therein from V. exoleta ;
this slope is not naked, but covered with numerous stria? or fine lines of growth. The
sinus in the mantlemark is large, deep, and linguiform in a direction across the shell ;
I have never seen a specimen with this sinus so vertical as it is represented in ' Min.
Conch.' above referred to.

2. ARTEMIS LINCTA, Pulteney. Tab. XX, fig. 6 a — d.

VENUS LINCTA. Pult. Hutchins, Dorset, p. 34, fide Forb. and Hani.

— EXOLETA. Penn. Brit. Zool., vol. iv, p. 94, pi. Ivi, fig. 49.

— var. /3. Mat. and Rack. Linn. Trans., vol. viii, p. 87, pi. iii, fig. 2, 1807.

— SINUATA. Turt. Ed. Linn., vol. iv, p. 233, 1806.

— LUPINA. Poli. Test. Sicil., t. xxi, fig. 8.

— LACTEA. Mont. Test. Brit. Sup., p. 46, 1808.

28

216 MOLLUSCA FROM THE CRAG.

CYTHEREA LINCTA. Lam. An. sans Vert., t. v, p. 573, 1818.

— — 1 Basterot. Bord. Foss., p. 90, pi. vi, fig. 10, 1825.

— — Phil. En. Moll. Sic., vol. i, p. 41, voh ii, p. 32.

— — Dujard. Mem. Soc. Geol. de France, t. ii, part ii, p. 260, 1837.

— Bronn. Leth. Geogn., p. 955, t. xxxviii, fig. 4 a — c, 1838.

— SINUATA. Turt. Brit. Biv., p. 163, 1822.
ASA LINEATA. Leach, MSS. Defrance, Coll. ex Basterot.
EXOLETA LINCTA. Brown. Illust. Brit. Conch., pi. xx, fig. 4, 1827.
ARTEMIS — Forbes. ^Egean. Invert. Rep. Brit. Assoc., p. 180, 1843.

Loven. Ind. Moll. Scand., p. 39, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 431, pi. xxviii, figs. 5, 6, 1848.

— SINUATA. S. Wood. Catalogue, 1840.

— COMPTA. Loven. Ind. Moll. Scand., p. 39, fide Alder.

ARTHEMIS LINCTA. Agassiz. Icon, des Coq. Tertiares (Extr. des Nonv. Mem. de la Soc.

Helv. des Sc. Nat., tome vii, 1845,) p. 22, t. iii, figs. 11—14.
DOSINIA LINCTA. Gray. List. Brit. Moll., p. 4, 1851.
Lister. Hist. Conch., lib. iii, fig. 126.

Spec. Char. Testa suborbiculari, lentiformi, svMncequilaterali, concentrice stria id
striis numerosis, confertis Icevibus ; lunuld cordatd impressd.

Shell suborbicular, lentiform, subinequilateral, fragile, covered with numerous
close set striae : lunule heartshaped ; impression of the mantle with a deep tongue-
shaped sinus.

Diameter, \\ inch.

Localities. Cor. Crag, Sutton, Ramsholt.

Red Crag, Walton-on-the-Naze.

Recent, Mediterranean, British and Norwegian Seas.

Not very rare either in the Coralline or in the Red Crag, but the specimens are in
general extremely fragile and very difficult to procure ; they are much thinner than
those of the preceding species, and appear to have less of animal matter remaining ;
although this is much less abundant than A. lentiformis, it appears to present a greater
diversity of character in the outline, and I have thought it necessary that two forms
should be represented : where individuals have become more elongated than what
'might be considered as the normal form of the species the shell is invariably more
convex or tumid, so that an equal quantity of space is occupied by the animal.

It is said in the recent state in the British seas to have a range in depth varying
from low water mark to the depth of sixty fathoms.

Mr. Smith, of Jordan Hill, enumerates Cytherea exoleta in his Catalogue of Shells
from the Clyde Beds. Mem. Wern. Nat. Hist. Soc., v 1. viii, p. 45, 1838.

BIVALVIA. 217

GASTRANA,* Schum. 1817.

TELLINA (sp.) Linn. Chemn.

VENUS (sp.) Retz. 1/88.

PSAMMOBIA (sp.) Lam. 1818. Turt. 1822. Flem. 1828.

PETEICOLA (sp.) J. Sow. Lam.

DIODONTA. Desk. 1845. Forb. and Hani. 1848. Gray, 1851. Woodward, 1854.

Generic Character. Shell equivalved, inequilateral,' transverse, ovate or subtrigonal,
covered with concentric striae or lamellae. Hinge with two teeth in one valve, and
one large subbifid tooth in the other. Impressions by the adductors ovate, nearly
equal, that by the mantle with a sinus wide and deep. Ligament external.

Animal with the mantle open, and fimbriated margins ; siphons long, unequal, and
separated to their bases, with slightly fringed orifices ; foot linguiform.

This appears to be a very well marked genus, and strongly characterised by its
dentition. A few species only are as yet known either in a recent or fossil state.
I have not seen it from any older formation than the Faluns of Touraine. One
fossil species has been brought from South Africa, belonging to a tertiary deposit.

1. GASTRANA LAMINOSA, /. Sowerby. Tab. XXV, fig. 1, a — e.

PETRICOLA LAMINOSA. J. Sow. Min. Conch., t. 573, 1827.

Nyst. Coq. Foss. de Belg., p. 99, pi. 3, fig. 16, 1844.

Spec. Char. Testa subirregulari, ovatd vel trigonuld, convexiusculd, clausd, inaqui-
laterali ; antice rotundatd, postice anyulatd ; lamellatd, lamellis erectis acutis, striis
interstitiis exilioribus ; car dine bidentato ; sinu palliari macjno.

Shell somewhat irregular, slightly convex, ovate or trigonular, closed, inequilateral ;
anterior side rounded, posterior angulated ; covered with sharp and erect concentric
ridges or lamellae, and very fine radiating striae between them ; hinge with two teeth,
palleal sinus large.

Length, 2J inches. Height, If inch.

Locality. Cor. Crag, Ramsholt, Gedgrave, Sutton.

Red Crag, Sutton, Alderton, Bawdsey, Walton Naze.

This species is not particularly rare either in the Coralline or in the Red Crag.
It has considerable resemblance to Tellinafragilis, Linn. (Petricola oc/iroleuca, Lam.),
but appears to differ sufficiently to be removed from that species. Like it, however, it
was subject to much distortion ; and though the valves are found free, its habits were
probably such as to lead it into confined situations, so as oftentimes to impede the

* Etym.? ya<m/p, ventral.

29

218 MOLLUSCA FROM THE CRAG.

regularity of growth. The principal difference between this and G.fragilis is a larger
posterior side, which is biangulated, the posterior dorsal portion not sloping off to a
point as in the recent shell : the laminse in our fossil are also larger, more remote, and
the palleal sinus extends only to a line drawn perpendicularly from the umbo ; in
G.fragilis it projects beyond. The right valve of our shell has two large diverging teeth,
while the left one possesses one large central, triangular, bifid tooth, with a cavity on
each side, and two small rudimentary teeth ; a large fulcrum for the ligament ; the
laminse are prominent, and erect, not reflexed.

Tellina fragilis, Linn., is found fossil in the Sicilian Beds, as, also, quoted in the
Faluns of Touraine ; but I have not seen it from the Crag.

DONAX,* Linnaus. 1758.

TELLINA. Adans, 1757-

CHION. Scopoli, 1777.

CUNEUS. Da Costa, 1778.

SERRULA. Chemn. 1782.

CAPISTERIA. Gevers, 1787. Sec. Gray.

PERON^EA, PERON^ODERMA (sp.) Poli, 1791.

LATOXA. — Schum. 1817.
HECUBA. Id.
IPHIGENIA? Id.
CAPSA. Lam. 1818.
DONACINA. Ferus. 1821.
EGERIA? (sp.) Lea. 1833.

Generic Character. Shell transverse, inequilateral, equivalved, more or less wedge-
shaped ; posterior side the shorter ; surface generally smooth and glossy, sometimes
finely striated or decussated ; covered by an epidermis in the recent state. Margin
plain or crenulated. Hinge composed of two cardinal teeth in one valve, and one in
the other, with more or less developed lateral teeth. Muscular impressions ovate with
a large and deeply indented mantle-mark. Ligament external.

Animal somewhat oblong, the mantle open in front, with fringed or partially fringed
margins. Siphons not very long, separated their entire length; foot large, sharp
edged, and pointed.

The principal distinction between this genus and that of Tellina is the truncation
of the posterior side, and the general wedge-shaped form of the shell, as also the
absence of the flexous fold in the margin, and it is in general more inequilateral, but
the two genera are very closely allied. Tellina is made the type of a family by the
malacologists, and the present genus is alike honoured with a similar distinction, upon
what grounds they are so widely separated I am unable to discover.

A fossil from the Carboniferous Period is described under this name, but its true
generic position is doubtful, and there is no certainty of its existence in the fossil state
anterior to the older Tertiaries.

* Etym. Sora£, a sea-fish. Pliny.

BIVALVIA. 219

The habits of the living species are generally littoral ; and they bury themselves
in the sand, leaving their siphons on a level with the surface.

1. DONAX VITTATUS, Da Costa. Tab. XXII, fig. 7, a, b.

DONAX TRUNCULUS. Linn. Syst. Nat., ed. 12, p. 1127, fide Forb. and Hani.
Penn. Brit. Zool., ed. 4, vol. iv, p. 93, pi. 55, fig. 45.
Lovtn. Ind. Moll. Scand., p. 42, 1846.

— VTTTATUS. Gray. List Brit. MolL, p. 46, 1851.

— ANATINUS. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 332, pi. 21, figs. 4 — 6,

and pi. K, fig. 7, 1848.

RUBER. Turt. Brit. Biv., p. 127, pi. 10, fig. 14, 1822.

CUNEUS VITTATUS. Da Costa. Brit. Conch., p, 207, t. 14, fig. 3, 1778.

Spec. Char. Testa transversd, oUongd vel cuneiformi, incequilaterali ; postice breviore,
Iruncatd, antice rotundatd; tenuissime striatd, obsolete decussatd ; margine ventrali
convexiusculo, crenulato.

Shell transversely oblong or wedge-shaped, inequilateral; posterior side the
shorter, truncated, and obtusely pointed ; anterior rounded ; striated externally and
somewhat obscurely decussated ; ventral margin slightly convex and crenulated.

Length, 1 \ inch. Height, f ths of an inch.

Locality. Mam. Crag, Bramerton. Recent, British Seas.

This common living species I have seen only from the above locality, where I am
informed it is by no means rare.

2. DONAX TRUNCULUS, Linnaus. Tab. XXII, fig. 8, a, b.

DONAX TRUNCULUS. Linn. Syst. Nat., ed. 12, p. 1127, 1767.

Born. Test. Mus. Cses., p. 54, t. 4, figs. 3, 4, 1780.

Poli. Test. Sicil., vol. ii, p. 76, t. 19, figs. 12—20, 1795.

Savigny. Descr. de 1'Egypt, torn, xxii, p. 198, pi. 8, fig. 14.

Phil. En. Moll. Sic., vol. i, p. 36 ; vol. ii, p. 28.

Broc. Conch. FOBS. Subappen., p. 535, 1814.

Desk. Exped. Scient. Alger. Moll., pi. 74, figs. 1 — 5 ; and pi. 75.
— TRUNCATA. S. Wood. Catalogue, 1840.
CAPSA TRUNCULUS. Hanley. Recent Shells, p. 87, pi. 11, fig. 38.
SERRULA L^EVIGATA. Chemn. Conch. Cab., vol. vi, p. 259, pi. 26, figs. 253, 254, 1782.
LE GAFET? Adans. Nat. Hist. Senegal, t. 18, fig. 2.

Spec. Char. Testa transversd, cuneatd, Icevigatd, valde inaquilaterali ; latere postico
brevissimo, truncato ; margine ventrali crenulato.

220 MOLLUSCA FROM THE CRAG.

Shell transverse, wedge-shaped, and smooth, inequilateral ; posterior side very short
and truncated ; ventral margin nearly straight and crenulated.

Length, 1 inch. Height, \ an inch.

Locality. Red Crag, Sutton. Recent, Mediterranean.

This shell is rare in my cabinet, and I have met with it from one locality only. It
appears to differ from the preceding, and to correspond with the Mediterranean form in
having a much shorter posterior side, it is also smoother externally, with less distinct
radiating striae, and the ventral margin not so much curved ; the dentition is much the
same in both species, though somewhat more strongly marked in D. anatinus* The
sinus in the mantle mark extends nearly to the middle, rather further beyond the
hinge than in the British shell, with a few other minor differences ; and as the British
Conchologists have separated the recent shells into two species, the fossil forms seem
to warrant a similar proceeding. Philippi mentions this among the Red Sea Shells
collected by Von Hemprich and Ehrenberg.

3. DONAX POLITUS, Poli. Tab. XXII, fig. 9, a, b.

TELLINA POLITA. Poli. Test. Sicil., vol. i, p. 44, pi. 21, fig. 14, 1791.

— VINACEA. Gmel. Syst. Nat., p. 3238.

DONAX COMPLANATA. Mont. Test. Brit., p. 106, pi. 5, fig. 4, 1803.
Phil. En. Moll. Sic., vol. ii, p. 28, 1844.

— LONGA. " Bronn." Phil. En. Moll. Sic., vol. i, p. 37, pi. 3, fig. 13, 1836.

— GLABRA. S. Wood. Catalogue, 1840.

— POLITUS. Forb. and Hani. Hist. Brit. Moll,, vol. i, p. 336, pi. 21, fig. 7, 1848.
CAPSA COMPLANATA. G. B. Sow. Gen. of Shells, No. 10, fig. 2.

PSAMMOBIA POLITA. Costa. Catal. Test. Sicil., p. 20, No. 14.

Spec. Char. Testa elongato-cuneiformi, complanatd, l&vigatd, politd, tenui, inaqui-
laterali ; later e antico longiore ; latere postico angulato ; margine mtegro.

Shell elongately wedge-shaped, flattened or compressed, smooth and glossy, thin,
inequilateral ; anterior side the longer, produced ; posterior angulated ; margin
smooth.

Length, 1 inch. Height, \ an inch.

Locality. Cor. Crag, Sutton and Gedgrave.

Recent, Britain and Mediterranean.

Small specimens not exceeding half an inch in length are abundant at Sutton, but
fragments indicate a magnitude of at least an inch and a quarter. This elegant shell
is beautifully glossy in those specimens that are well preserved, but the generality are

* In the ' Hist. Brit. Moll.,' vol. i, p. 340, the hinge of D. trunculusis said to be destitute of lateral teeth,
while they are described (p. 332) as being present in D. anatinus. I have not been able to make that distinc-
tion. There is a prominent lateral tooth in my fossil on the posterior side, beyond the ligamental support.

BIVALVIA. 221

more or less uncoated. Unlike the preceding species, this is free from radiating striae,
and the margin is in consequence quite smooth. The form of this is also different,
and may be readily distinguished. The palleal sinus is large and deep, extending
beyond the hinge area, and in some old shells the interior is considerably thickened.

Poli has given a good representation of the shell of this species ; but in depicting
the animal he has made the siphons to protrude on the longer, and the foot at the
shorter or posterior side.

PSAMMOBIA,* Lam. 1818.

Lux. Chemn. 1782.
GARI. Schum. 1817.
PSAMMOT.EA. Lumk. 1818.
PSAMMOTEA. Schweig.

PERON^A et PERON^EODERMA (sp.) Poli.

AZOR. Leach, MS., 1819
_

GOBR^EUS. Id.

PSAMMOCOLA. Blainv. 1824.

. 1
^

. Gray.

Generic Character. Shell equivalve, subequilateral, transversely oblong, more or
less compressed, slightly gaping at each extremity; exterior generally covered with
transverse or concentric striae, and occasionally ornamented with radiating lines or
ridges. Hinge composed of two teeth in one valve, and one in the other, and without
lateral teeth. Sinus in the impression of the mantle large and deep. Ligament
external, fulcrum prominent.

The animal has the mantle open the entire length, and bordered by a fringe of
fine simple filaments ; siphons long and slender, marked with longitudinal lines, and
ornamented with minute cirri ; a large and tongue-shaped foot, somewhat pointed.

There is no very essential distinction between this genus and Tellina, the
greatest difference appearing to be a somewhat more oblong form of outline, and
a less distinct inflexion on the posterior side of the shell, with a rather more
prominent fulcrum for the ligament in Psammobia. In the recent state the
species are, like the Tellens, inhabitants of various climes, and generally live buried in
sand or gravelly mud, and they have a vertical range from low- water mark to 100
fathoms.

The name of this genus, being in fact only third in point of date, will have to be
changed.

1. PSAMMOBIA FERROENSIS, Chemn. Tab. XXII. fig. 3, a, b.

Petwer. Gazophyl., t. 94, fig. 9, 1764.

TELLTNA FERROENSIS. Chemn. Conch. Cab., vi, p. 99, t. 10, fig. 91, 1782.
— FEROENSIS. Broc. Conch. Subap., p. 512, No. 6, 1814.

* Etym. ^>afjtfjtos} sand, and ftivu, to live.

222 MOLLUSCA FROM THE CRAG.

TELLINA FERVENSIS. Gmel. Syst. Nat., p. 3235, 1788.

W. Wood. Linn. Trans., vol. vi, p. 174, t. 15, figs. 20, 21, 1802.

— RADIATA. Da Costa. Brit. Conch., p. 209, t. 14, fig. 1, 1778.

— INCARNATA. Penn. Brit. Zool., vol. iv, p. 74, pi. 47, fig. 31, 1776.

— MURICATA. Broc. Conch. Suhap., p. 511, t. 12, fig. 2.

— TRUNCATA. Spengler. Fide Lov6n.

— TRIFASCIATA. Don. Brit. Shells, vol. ii, pi. 60, 1800.
PSAMMOBIA FERROENSIS. Lamk. Hist. Nat. des An. s. Vert., v, p. 512.

Phil. En. Moll. Sic., vol. i, p. 23, pi. 3, fig. 7, 1836.

Lov6n. Ind. Moll. Scand., p. 42, 1846.

Sismonda. Syn. An. Invert. Pedm. Foss., p. 21, 1847.
DDMONTII. Nyst. Coq. Foss. de Belg., p. 103, pi. 4, fig. 12, 1844.
L.EVIS. Id. Coq. Foss. de Belg., p. 104, pi. 4, fig. 13.

MTJRICATA. Id. Coq. Foss. de Belg., p. 105.
— ? Grateloup.- Cat. Zool. des An. Vert, et Invert., p. 67, 1838.

AFFINIS? Dugard. Mem. de la Soc. Geol. de France, torn, ii, part 2,

p. 257, pi. 18, fig. 4, 1837.

Spec. Char. Testa transvervd, ovato-oUongd, subtequilaterali, tenui ; concentrice
striatd ; antice rotundatd ; postice truncatd, angulatd, striatd et decussatd ; margine
ventrali conveuoiuscido ; sinu palliari magno.

Shell transverse, ovately oblong, nearly equilateral, thin ; concentrically striated ;
anterior side rounded ; posterior truncated, and decussated upon the posterior slope ;
ventral margin slightly curved ; palleal sinus large.

Length, 1-| inch. Height, -|ths of an inch.

Locality. Cor. Crag, Gedgrave, Button, and Ramsholt.

Recent, Britain, Mediterranean, Finraark.

This elegant shell, in its full-grown state, is rare ; but small specimens and frag-
ments are by no means scarce. I have assigned it, without a doubt, to the existing
species, although some of my fossils appear rather more transverse, or have a some-
what greater length comparatively than the recent shell. My Crag specimens are
particularly thin and fragile, with scarcely a trace of any muscular impression. In
some of the young specimens the radiating striae upon the angular slope of the pos-
terior side are strongly marked with decussating lines.

This is said to have been found fossil in the Drift beds of Lancashire and Ireland.

2. PSAMMOBIA VESPERTINA, Chemnitz. Tab. XXII, fig. 2, a — d.

Lux VESPERTINA. Chemn. Conch. Cah., vol. vi, p. 72, t. 7, figs. 59, 60, 1782.

SOLEN VESPERTINUS. Gmel. Syst. Nat., p. 3228, 1788.

TELLINA VARIABILIS. Don. Brit. Shells, vol. ii, t. 41, fig. 2, 1800.

GARI. Poll. Test. Sicil., pi. 15, figs. 19, 21, 23, vol. i, p. 41, 1791.

Born. Test. Mus. Cses. Viad., p. 31, t. 2, figs. 6, 7, 1780.
— ALBIDA. Dillw. Desc. Cat. Brit. Shells, vol. 1, p. 78, 1817.

BIVALVIA. 223

TELLINA DEPRESSA. Penn. Brit. Zool., ed. 4, vol. iv, p. 87, pi. 47, fig. 27.
PSAMMOBIA VESPERTINA. Lam. An. s. Vert., t. 5, p. 511, 1818.

Phil. En. Moll. Sic., vol. i, p. 22 ; vol. ii, p. 21.

Lovtn. Ind. Moll. Scand., p. 42, 1846.

Sism. Syn. An. Inv. Pedm, Foss., p. 21, 1847.
PSAMMOCOLA VESPERTINA. Blainv. Malac., p. 77, fig. 4, 1825.
SANGUINOLARIA — Flem. Brit. Anim., p. 460, 1828.

CHAMA LUTESCENS. List. Hist. Conch., t. 417, fig. 261.
Azoa VARIABILIS. " Leach." Ann. Mag. Nat. Hist., vol. xx, p. 272.

Spec. Char. Testa oblongo-ovatd, subintequilaterali, concentrice striatd., striis obtusis
deprcssis; antice rotundatd, postice subtruncatd ; margine subtilissime crenulato.

Shell ovately oblong, slightly inequilateral, concentrically striated, striae obtuse,
depressed ; anterior side rounded, posterior somewhat truncated ; margin very finely
crenulated.

Length, 2 inches. Height, 1 inch.

Locality. Cor. Crag, Ramsholt and Sudbourn.

Recent, Mediterranean, British, and Norwegian Seas.

A very few specimens only of this elegant species have fallen under my observa-
tion. I have no hesitation in assigning the smaller shell (fig. 2, c, d), found at Rams-
holt, as an identity with the recent British species. Fig. 2, a, 6, is the representation
of a specimen found by myself at Sudbourne, and the only difference appears to be in
its having somewhat larger proportions, this one measuring as much as 2f inches
in length, and 1 J inch high ; and our fossil is in all probability only a monstrous form
of the existing shell. It strongly resembles Psam. Stangeri, Gray, ' Faun, of New
Zealand,' p. 273, No. 179.

3. PSAMMOBIA TELLINELLA, Lamarck. Tab. XXII, fig. 4, «, b.

PSAMMOBIA TELLINELLA. Lamk. Hist. des. An. s. Vert., v, p. 515, 1818.

Forb. and Hani. Hist, of Brit. Moll., vol. i, p. 277, pi. 19, fig. 4,

and Animal, pi. K, fig. 1, 1848.
Loven. Ind. Moll. Scand., p. 42, No. 303, 1846.
Alder. Cat. Moll. North, and Durh., p. 89, 1848.
FLORIDA. Turt. Brit. Biv., p. 86, pi. 6, fig. 9, 1822.

Spec. Char. Testa transversd, ovato-oblongd, tenui ; transversim striatd ; antice ovato-
rotundatd ; postice subangulatd ; margine ventrali leviter arcuato ; cardine bidentato, altera
unidentato, sinu pattiari prof undo.

Shell transverse, ovately oblong, thin, very finely striated transversely; anterior
side slightly rounded, posterior somewhat angulated ; ventral margin slightly curved ;
hinge with one tooth in one valve, inserted between two in the other ; palleal sinus
deep.

224

MOLLUSCA FROM THE CRAG.

Length, 1 inch.

Locality. Cor. Crag, Sutton. Recent, Channel Islands, Hebrides, and Bergen.

This delicate and elegant shell is rare in my cabinet ; about half a dozen small
specimens and a few fragments are all that I have seen. It much resembles the
young of Ps. vespertina, but is rather more rounded on the posterior side, and it is a
deeper or more tumid shell. The hinge teeth are small, though apparently a trifle
larger than those of the recent shell. The palleal sinus is large and deep, extending
inwards to a little beyond the hinge denticles. It is said to extend in the living state
from the Channel Islands to the coast of Bergen, and ranges vertically from five to fifty
fathoms.

TELLINA,* Linnaeus, 1767.

PETASUNCULUS. Rumph. 1705. Petiver, 1713.

CHAMELEA (sp.) Klein. 1753.

PERONCEA ET PERONEODERMA (sp.) Poll. 1791.

TELLINARIUS (sp.) Dum. 1806.

AN GULTJS. Mefferle, 1811.

OMALA. Schum. 1817.

ARCOPAGIA. Leach MS. 1816. Brown, 1827.
PHYLLODA. Schum. 1817.
TELLINIDES. Lamk. 1818.
MACOMA. Leach, 1819.
LIMICOLA. Id. 1819. Fide Gray.
HOMALA. (sp.) Agassiz.

Generic Character. Shell transversely ovate, or suborbicular, generally inequilateral,
plain or smooth, but more frequently sculptured or ornamented ; posterior side more
or less angulated, with an irregular flexuosity produced by a slightly sinuated form in
the posterior part of the ventral margin. Hinge with generally two cardinal and two
lateral teeth in each valve, the latter, in some species, are obsolete. Palleal impression
deeply sinuated. Ligament external.

Animal of the form of the shell, having the mantle open in front, with the margins
fringed ; siphons long, sometimes four or five times the length of the shell, separate
throughout, the orifices plain or indistinctly toothed ; foot large, triangular, and
compressed.

The character by which this genus is said to be most distinguished is the flexuous
fold, or slightly twisted form of the posterior side of the shell ; this, however, is not
always discernible, thereby merging into Sanguinolaria and Psammobia which are
characterised by the absence of the fold, and the want of lateral teeth, though in some
species of this genus the latter character is by no means permanent. The outward
form of Tellina is exceedingly variable, some species being nearly orbicular, while
others are much elongated ; in general the shells are slightly compressed, somewhat
unequal in size, one valve being more tumid than the other, especially on the posterior
side, where the ligament is placed ; and this side is generally, though not always, the
shorter of the two.

* Etvm. TeXXtV?;, the name of a mussel.

BIVALVIA. 225

A peculiarity exists in many of the species, as well as in some of the species of its
generic allies, by which a considerable variation is produced in the degree of tumidity
at the posterior part of the opposite valves, causing the impression of the mantle upon
the interior to display a difference in form as well as in extent ; the compressed or
right valve having its sinus shorter and somewhat broader or higher, while in the
more tumid one it extends forward so as almost to touch the anterior adductor. This
does not appear to depend upon a difference in length of the two siphons, as in some of
the members of this, so called, family, which are furnished with tubes of an unequal
length, this difference in the sides of the animal does not exist, and the mantle-
mark is the same in both valves ; but in others, in which the tubes are precisely alike,
this inequality in the valves is very conspicuous ; the difference in the mantle-mark
appearing to be coexistent with the difference in the tumidity of the valves.

If the drawings by malacologists be correct, the inhalent siphon is the longer
one in some species, while in others, this lower or indrawing tube is the shorter of the
two, and apparently without producing any difference of tumidity at the posterior part
of the valves. It is, however, doubtful whether a safe reliance can be placed upon the
published figures of the Bivalve Molluscs, as some of the animals are represented
with the upper siphon most extended, while in other very proximate species the
lower projects beyond the upper one. Mr. Alder informs me these siphons are so
elastic that either may be made to appear the longer at the will of the animal, which
perhaps is the cause of this apparent diversity.

The inequality of proportions in the two valves gives to them a degree of obliquity,
and, when viewed in a position with the animal upon its ventral margin or standing
upon its foot, indicates an inflexion or incipient spirality in a dextral direction.
The want of symmetry in the two valves does not pervade the whole group ; for
species evidently otherwise very closely allied are not possessed of this deformity.

Amongst other peculiarities of this genus may be mentioned T. Burneti, rather an
aberrant species, brought from the Coast of California, it has its right valve quite flat,
while the left is convex or lenticular ; and in the newer Tertiaries of South Carolina
there is a fossil species strongly resembling it in general form, but which differs from
it in having the left valve the flat one. In both of these species the sinus in the
mantle-mark is large and deep, but is unlike that of our other unsymmetrical shells in
being of the same form and magnitude in both valves.

Notwithstanding the great curtailment of this genus since its original establishment
by Linnseus, it still contains a very large number of species, particularly in the recent
state ; and these have a wide geographical distribution, extending from the Equator to
the Polar Regions, and they range vertically from low-water mark to nearly 100 fathoms.
The genus appears as early as the Coral Rag, with some doubtful forms in the Palaeozoic
Formations. In the older Tertiaries, twenty-three species have been figured and
described by Mr. Edwards from the deposits of that period in this country alone, and
ten were inhabitants of the seas by which the Crag was deposited.

30

2.26 MOLLUSCA FROM THE CRAG.

1. TELLINA CRASSA, Pennant. Tab. XXI, fig. 1, a — e.

TELLINA CRASSA. Penn. Brit. Zool., ed. 4, p. 73.

— 1 Dujard. Mem. de la Soc. Geol. de France, t. 11, pi. 11, p. 258, 1837.

— Smith. Mem. Wern. Soc., vol. viii, p. 93.
Phil. En. Moll. Sic., vol. ii, p. 23, 1844.

— — Lovtn. Ind. Moll. Scand., p. 41, No. 296, 1846.

Sismonda. Syn. Meth. An. Inv. Fed. Foss., p. 21, 1847.

— RIGIDA. Pulteney. In Hutcben's Hist, of Dorset, p. 30.
SCABRA. Chemn. Conch. Cab., vol. vi, t. 10, fig. 94.
MACTJLATA. Adams. Linn. Trans., vol. iii, p. 252.

Turt. Brit. Biv., p. 108, pi. 6, fig. 7, 1822.

— OBTUSA. J. Sow. Min. Conch., t. 179, fig. 4.

Nyst. Coq. Foss. de Belg., p. 106, pi. 5, fig. 1, 1844.
SUBROTUNDA. Phil. En. Moll. Sic., vol. i, pp. 29 and 255, 1839.
VENUS CRASSA. Gmel. Syst. Nat., p. 3288.
PECTUNCULUS PLANTJS CKASSTJS. List. Hist. Conch., fig. 136, 1687.

DEPRESSION. Da Costa. Brit. Conch., p. 194, t. 13, fig. 4, right-hand figure.
ARCOFAGIA CR.ASSA. Brown. Illust. Brit. Couch., pi. 16, fig. 8, 1827.
OVATA. Id. Illust. Brit. Conch., pi. 16, figs. 9, 10.

Dale. Hist, and Antiq. of Harwich, t. 11, fig. 13, 1730.

Spec. Char. Testa crassd, ovato-ellipticd, transversd, depressd, utrinque cequaliter
rotundatd ; latere postico breviore ; lineis creberrimis, elevatis, lamelliformibus ornata.

Shell thick, ovate or elliptical, transverse, depressed both sides, equally rounded ;
posterior one the shorter, ornamented with elevated close set ridges or lamellae.

Length, 2 inches. Height, \\ inch.

Locality. Cor. Crag, Button.

Red Crag, Sutton, Walton Naze.

Mam. Crag, Chillesford.

Clyde Beds. (Smith.) Recent, Britain, Coast of Scandinavia.

This shell is rare in the Coralline, but it becomes abundant in the Red Crag, at
Sutton, though very scarce at Walton Naze. There is a slight flexuous fold on the
posterior margin, produced by the small sinus in the margin ; and the exterior is
covered with numerous raised ridges forming obtuse lamellae, scarcely reflexed ; be-
tween these are fine, distinct, radiating or interstitial striae ; the right valve is the more
tumid of the two. The palleal sinus is large and deep, with an upward direction ex-
tending more than half way across the shell ; the adductor muscle marks are deeply
impressed, particularly the anterior one, within which is a thickened obtuse ridge from
beneath the umbo to the lower part of the adductor. Old shells are often thickened
on the inside, thereby deepening the muscular impressions.

The figure of T. subrotunda, Des. 'Coq. Foss. des Env. de Paris/ torn, i, p. 81, pi. 12,
figs. 16, 17, strongly resembles this species, and is considered as identical by Philippi;

BIVALVIA. 227

but in the description by M. Deshayes, that author says it differs from T. crassa, Penn.,
in having only one lateral tooth, and the concentric striae are finer ; there is no mention
of any insterstitial striae, nor of the thickened internal ridge on the anterior side.
T. obovata, F. Edwards, ' Geol, Journ.,' No. 11, p. 49, pi. 2, fig. 2, resembles our shell
in outline, and may probably, when more specimens have been obtained, and it
becomes better known, be the same as T. subrotunda of Deshayes; but until a fair
comparison be instituted, T. crassa can scarcely be considered as dating its specific
existence from the Older Tertiaries.

This species has a range in depth extending from low-water mark to below 50
fathoms, and its favorite habitat is in gravelly sand. It is found fossil in the
Belgian Crag, and in the newer Tertiaries of Calabria, but it is not known as a living-
species in the Mediterranean.

Tab. Ill, fig. 18, 'Phil. En. Moll. Sic.,' called T. radula, is probably this species.

2. TELLINA BALAUSTINA, Linnteiis. Tab. XXI, fig. 4, a — d.

TBLLINA BALAUSTINA. Linn. Syst. Nat., ed. 12, p. 1119, No. 61, 1767.
Poll. Test. Sicil., vol. i, p 49, 1791.
Phil. Enum. Moll. Sic., vol. i, p. 25 ; vol. ii, p. 21.
Forbes. Report ^Egean. Invert., p. 180, 1843.

— TENUILAMELLOSA. Nyst. et West. Nouv. Rech. Coq. Fosa. d'Anv., p. 7, pi. 3,

fig. 6, 1839.
Nyst. Coq. Foss. de Belg., p. 109, pi. 4, fig. 14 a, b> 1844.

— OVALOIDES. <S. Wood. Catalogue, 1840.

LUCINA BALAUSTINA. Payr. Cat. Moll. Cors., p. 43, pi. 1, figs. 21, 22, 1826.

Spec. Char. Testa transversd, ovatd, convexd, subintequilaterali, tenui ; antice
rotundatd, postice subangulatd ; lamellatd lamellis erectis tenuibus, distantibus ; car dine
bidenlato, dentibns lateralibus magma.

Shell transverse, ovate, convex, slightly inequilateral, thin ; anteriorly rounded,
posteriorly subangulated ; covered with distant, thin, erect lamellae ; hinge with two
cardinal teeth and large lateral teeth.

Length, -|ths. Height, ^ an inch.

Locality. Cor. Crag, Sutton. Recent, ^Egean, Mediterranean, and British.

Very few specimens of this delicate and pretty species have fallen to my researches,
and those are all from one locality. The exterior is ornamented with very fine and
numerous concentric striae, and distant, sharp, elevated ridges or lamellae ; the last
are so thin that many of them are rarely left upon the surface ; the posterior side is
the smaller, slightly truncated, or rather biangulated, with an incipient fold very far
back ; the right valve has two cardinal teeth, posterior one the larger and subbifid ;
two lateral teeth nearly equidistant, anterior one large, the other nearly obsolete ;

228 MOLLUSC! FROM THE CRAG.

left valve with one cardidal subbifid tooth, and elevated dorsal margins to interlock
with the lateral teeth of the opposite valve. One side of the right valve is somewhat
compressed, causing thereby a difference of form in the siphonal scar.

The nearest approach to this species that I am acquainted with is T. lamellulata,
F. Edwards, ' Lond. Geol. Journ./ vol. i, p. 14, pi. 23, fig. 2, but that shell seems rather
more equilateral, flatter, and less truncated, with more numerous elevated lamellae.
M. Edwards' specimens are not in very good preservation.

3. TELLINA OBLIQUA, /. Sowerby. Tab. XXI, fig. 7, a — d.

TELLINA OBLIQUA. J. Sow. (not Lamb.) Min. Conch., t. 161, fig. 1, 1817.
Nyst. Coq. Foss. de Belg., p. 107, pi. 5, fig. 2, 1844.
LyelL Elem. of Geol., 2d ed., p. 299, fig. 14, 1841.

Spec. Char. Testa subrotundatd, obliqud iyuequilaterali, crassd, lavigatd vel irregu-
lariter striatd; antice rotundatd ; postice truncatd, subangulatd ; cardine bidentato, denti-
bus lateralibus obsoletis.

Shell rather rounded, oblique, inequilateral, thick, and strong; anterior side
rounded ; posterior truncated or subangulated, smooth, or covered with irregular lines
of growth ; hinge with two cardinal teeth, lateral teeth obsolete.

Length, If inch. Height •, If inch.

Locality. Cor. Crag, Sudbourn, Ramsholt.

Red Crag, Sutton, Bawdsey, Felixstow, Ipswich.
Mam. Crag, Chillesford.

This shell first appears in the lower or Coralline Crag, where it is not very
abundant; in the succeeding period, or Red Crag, it may be found in most locali-
ties. The species may be called obliquely circular, or rather lenticular, the height
being very nearly if not quite equal to the length; the valves are somewhat tumid, and
covered with irregular lines of growth, and the posterior side is rather the shorter of
the two, with the fold very far back ; this side is compressed in the right valve, but
tumid in the left ; the inequality of the two valves at that part having relation to the
unequal magnitude of the siphonal scar in the different valves ; the lateral teeth may
be said to be wholly wanting, as in the proximate genus Psammobia.

4. TELLINA LATA, Gmelin. Tab. XXI, fig. 6, a— d.

TELLINA LATA ALBA. List. Hist. Conch., fig. 253, 1686.

— LATA. Gmel. 1788. (Not Quay and Gaim.) Fide Lovtn.

Midden. Sibiria Reise, vol. ii, part 1, pi. 23, figs. 4, 5.
Loven. Ind. Moll. Scand., p. 41, 1846.

BIVALVIA. 229

TELLINA OVATA. J. Sow. Min. Conch., t. 161, fig. 2, 1817.

Phil. En. Moll. Sic., vol. i, p. 30 : vol. ii, p. 23.
Nyst. Coq. Foss. de Belg., p. 108, pi. 5, fig. 3, a, b, 1844.

— OVALIS. Woodw. Geol. of Norf., p. 43, pi. 2, fig. 11, 1832.

— SABTJLOSA. Spengler. Sec. LovSn.

CALCAREA. Wcthlenb. Sec.Lyell. Geol. Trans., vol. vi, 2d series, p. 137, pi. 16,

figs. 9—11, 1839.

Holler. Ind. Moll. Groenl., p. 20, 1842.

PROXIMA. Smith, Mem. Wern. Soc., vol. viii, p. 105, pi. 1, fig. 21, 1838.
Sow. Append. Beechey's Voy., p. 154, t. 44, fig. 4, 1839.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 307, pi. 21, fig. 1, 1848.
EDENTTJLA. ? Brod. and Sow. Zool. Journ., vol. iv, p. 363, 1829.

? Gray. App. Beech. Voy. Zool., p. 154, t. 41, fig. 5 ; and t. 44, fig. 7,
1839.

— SORDIDA. Couthony. Bost. Journ. Nat. Hist., vol. ii, p. 59, pi. iii, fig. 11, 1839.

— TRIANGULARIS. Lyell. Phil. Trans., 1835, p. 36, fide Lovtn.

— TENERA. Gray. List Brit. Moll., p. 42, 1851.
SANGUINOLARIA SORDIDA. Gould. Invert. Massach., p. 67, 1841.
MACOMA TENERA. Leach. Ann. of Phil., vol. xiv, p. 204, 1819.

Spec. Char. Testa ovatd, transversd, intsquilaterali ; anticelongiore rotundatd ; postice
sub-angulatd ; dentibus utrinqne binis, lateralibus nullis.

Shell ovate, transverse, inequilateral ; anterior side the longer and rounded ;
posterior obtusely angulate, with two teeth in each valve; lateral teeth none.

Length, If inch. Height, \\ inch.

Locality. Red Crag, Sutton.

Mam. Crag, Bramerton, Chillesford.
Clyde Beds, Uddevalla, Russia, Canada.

Recent, Finmark, N. E. Coast of America, Britain,
Behring's Straits (G. B. Sowerby).

I have never seen the present species from the Older or Coralline, and only rarely
from the Red Crag, and never at Walton-on-the-Naze. In the Mammaliferous Crag
Period the two species appear to be more equally distributed, although the oblique
form is there giving way to its more transverse successor, while this latter species
only, remains at the present day, and seems to be restricted to the colder regions of
the Northern Hemisphere. In this, as in the preceding species, there is a considerable
difference in the form and depth of the siphonal scar in the two valves, and the
posterior side of this one is much more pointed than that of obliqua, and the line of the
ventral margin is not only less curved but is somewhat constricted on the posterior
side. T. lata, Middendorff, 'Malac. Ross.,' found in the Arctic Seas and Behring's Straits,
may probably be a dwarf variety of our shell, connecting it with T. Balthica, which it
resembles in many of its characters.

230 MOLLUSCA FROM THE CRAG.

5. TELLINA BENEDENII, Nyst and Westendorp. Tab. XXI, fig. 2, a — d.

TELLINA ZONARIA. Nyst, (not Lamk.) Rech. Coq. Foss. Prov. d'Anv., p. 14, 1836.

— BENEDENII. Nyst et West. Nouv. Rech. Coq. Foss. d'Anv., p. 7, No. 13, pi. 2,

fig. 5 bis; pi. 3, fig. 5, 1839.

— 8. Wood. Catalogue, 1840.

Spec. Char. Testa ovatd, subaquilaterali, cequivalvi, complanatd, Icevigatd, crassd ;
antice rotundatd ; postice angulatd, subacuminatd, valvd alterd dente cardinali duo ;
impressione palliari magno.

Shell ovate, slightly inequilateral, equivalved, compressed, smooth, and thick ;
anterior side rounded ; posterior angulated, and somewhat pointed, two cardinal teeth
in each valve ; palleal sinus large.

Length, 2 inches. Height, 1-| inch.

Locality. Red Crag, Sutton.

My cabinet contains a single specimen of each valve, which are all that I have
seen. This species somewhat resembles T. prcetenuis, from which, however, it may
be readily distinguished. The umbo is somewhat prominent, it has a thickened
hinge furnished with two cardinal teeth in each valve, one small and simple, the
other bifid ; the simple one is posterior in the left valve, anterior in the right ;
besides which there is an obtuse lateral tooth on the anterior side of the left
valve, and a corresponding depression on the anterior dorsal slope in the right, for
its reception ; the adductor muscles are large and deep, and the sinus in the mantle
is of an elliptical form, extending about two thirds across the shell.

The valves have a small and general convexity, and there is no tumid swelling
on the one side, or compression on the other, hence the similarity in the siphonal
scar ; the surface is smooth (?), but may have been worn so; arid there are traces of
the brownish coloured zones, which M. Nyst speaks of as ornamenting the Belgian
fossil.

6. TELLINA PR^ETENUIS, Leathes' MSS. Tab. XXI, fig. 5, a — c.

TELLINA PR^TENUIS (Leathei MS.) Woodw. Synop. Tab. Brit. Organ. Rem., p. 11, 1830.
Woodw. Geol. of Norf., t. 2, fig. 12, 1832.

Spec. Char. Testa ovato-trigond, incequilaterali, tenui, Icsvi ; antice majiore, rotundatd^
et convexiusculd ; postice biangulatd, subrostratd, etcompressd ; car dine bidentato ; dentibus
lateralibus nullis.

Shell ovato-trigonal, inequilateral, thin, and smooth ; anterior side the larger,
rounded, and somewhat convex; posterior biangulated, rather pointed, and com-
pressed ; hinge with two cardinal but no lateral teeth.

Length, 1J inch. Height, \\ inch.

BIVALVIA. 231

Locality. Red Crag, Sutton, Walton Naze.

Mara. Crag, Bramerton, Postwick, and Chillesford.

This shell in some parts of the Red Crag is exceedingly abundant, though rare at
Walton on the Naze. At Sutton I have frequently found specimens with the valves
united and the ligament preserved, strong presumptive evidence of their having lived
and died in the locality wherein they were found.

This species was named by the late Rev. G. R. Leathes, in consequence of its con-
nexion or resemblance to T. tennis, perhaps its nearest relative. It is somewhat in form
like T. Balthica, but is not so tumid or thick : it differs from T. tennis in having more
height, with a greater convexity in the ventral margin ; the two teeth in each valve are
alternately simple and bifid, the bifid one is anterior in the left valve, and vice versa ;
and there are no lateral teeth, but there is a very distinct one on the anterior side in
T. tennis, and in that species the mantle mark is comparatively larger.

In well-preserved specimens, the surface is covered with fine concentric striae, or
lines of growth, more especially upon the posterior slope, and the right valve is the
more tumid of the two ; there is also a slight difference in the magnitude of the
palleal sinus in the opposite valves.

The shell which really makes the nearest approach to this species is one that was
brought from the S. E. Coast of Australia.

'j\ ^IflO L"Jii :£KK) Hoif/ill OYfcll 1

.erun Am £j Ji termini
7. TELLINA BALTHICA, Linn&us. Tab. XXII, fig. 1, a — c.

TELLINA BALTHICA. Linn. Syst. Nat., ed. 12, p. 1120, No. 68.

Born. Test. Mus. Cses. Vind., p. 38, t. 11, fig. 14, 1780.
Phil. En. Moll. Sic., vol. i, p. 28 ; and vol. 2, p» 22.

— BALTICA. Lyell. Phil. Trans., 1835, p. 34, var. a, pi. 11, figs. 1,2; var. b,

figs. 3, 4.
SOLIDULA. Pulteney. In Hutchin's Hist. Dorset, p. 25.

Woodw. Geol. of Norf., pi. 2, fig. 13, 1832.

Lovtn. Ind. Moll. Scand., p. 41, 1846.

Middend. Mai. Ross., loc. cit., p. 577, 1849.
RUBRA. Da Costa. Brit. Conch., p. 211, t. 12, figs. 4, 4, 4.
CARNARIA. Penn. Brit. Zool., vol. iv, p. 88, pi. 49, fig. 32.

— J. E. Gray. List of Brit. Moll., p. 41, 1851.

— ZONATA. Gmel. Syst. Nat., p. 3238, No. 52.

INCONSPICUA. ? Brod. and Sow. Zool. Journ., vol. iv, p. 363, 1829.

— 1 Gray. Zool. Beechey's Voy., p. 153, t. 41, fig. 6, 1839.

— GROENLANDICA. (Beck.) Lyell. Trans. Geol. Soc., vol. vi, 2d series, pi. 16, fig. 8,

1839.
PSAMMOBIA FUSCA. Say. Journ. Acad. Nat. Sc., v, p. 220.

SOLIDULA. Turt. Brit. Biv., p. 95, t. 8, fig. 2, 1822.
SANGUINOLARIA FUSCA. Conrad. Am. Mar. Conch., 34, pi. 7, fig. 1.

Dekay. Nat. Hist. New York (Zoology), pi. 32, fig. 304.
LIMICOLA CARNARIA. " Leach" Sec. Gray.

232 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa orbiculalo-ovatd, tumidd soliduld ; antice rotundatd, postice subangu-
latd ; car dine bidentato, dentibus later alibus nuttis.

Shell roundly ovate, tumid, thick, and strong ; anterior side rounded, posterior
somewhat angulated ; cardinal teeth two, lateral teeth none.

Length, -f inch. Height, f inch.

Locality. Mam. Crag, Bramerton, Weybourne, Bridlington, Dalmuir, Russia,
Canada.

Recent, Britain, Baltic, N. E. Coast of America, Black Sea.

I have not seen this shell from the Red Crag ; as it is, however, an estuary species,
it is less likely to be there. In the recent state, it is often found high up in our rivers,
where the water is nearly fresh when the tide is out. The shells grow large and
thick in muddy localities, and thinner and more delicate in sandy places.

Tellina, is probably its most appropriate place, although the entire absence of lateral
teeth does not strictly accord with the diagnosis of this genus, but it corresponds with
it in all other respects.

Fig. 1 a, b, is the representation of a shell from Clacton, where I obtained it from the
Clay in which Unio littoralis is found in abundance; and upon some of my specimens of
Unio are several barnacles, evidently showing the close proximity of the sea to this
fresh-water deposit when it was formed.*

I have myself obtained only few specimens of the fossil from Norfolk, but I am
informed it is not rare.

8. TELLINA FABULA, Gronovius. Tab. XXI, fig. 3.

TELLINA FABULA. Gron. Zoophyl. Gronov., p. 263, No. 4, pi. 18, fig. 9, 1781.
— Phil. Enum. Moll. Sic., vol. i, p. 26, t. 3, fig. 10, 1836.

— Lyell. Mag. Nat. Hist., vol. iii, new series, p. 327, 1839.
G. B. Sow. Thesau. Conch., vol. i, p. 287, pi. 57, fig. 62.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 302, t. 19, fig. 9.

— DISCORS. Pulteney. Hutchin's Dorset, p. 54.

— SEMISTEIATA. Solander, ex Montague.

Spec. Char. "Testa elongato-ovatd, compressd, transversd subinaquilaterali, tenui ; pos-
tice attenuatd, subrostratd, antice majiore rotundatd; valvula sinistra Itevi, dextrd oblique
striatd; cardine bidentato, dentibus later atibus parvis."

Shell transversely elongato-ovate, compressed, sub-inequilateral, thin ; posterior
side narrow, and somewhat pointed ; anterior broader, larger, and rounded ; left valve

* At Clacton I have also obtained Mytilus edulis, Cardium edule, and Trigonella plana, and also a
rolled specimen of Melania inquinata (Cerithium melanioides, Sow.).

BIVALVIA. ft™ Wrl 233

smooth ; right valve covered with oblique striae ; hinge with two cardinal teeth, and
small lateral tooth.

Length, f inch. Height, \ inch.

Locality. Mam. Crag, Southwold. Recent, British Seas, Mediterranean.

One specimen was found by Captain Alexander some years since, but it is now
unfortunately lost. I am, however, certain of its existence as a Crag shell, and have
in consequence given the representation of a recent individual.

Philippi gives it as a living species in the Mediterranean, but not as a fossil from
that part of the world. He places it in his section of the genus " dentibus lateralibus
carentes." It is not, however, strictly speaking, destitute of lateral teeth ; there is a
distinct and proximate one on the anterior side of the right valve, and another smaller,
but more remote, on the posterior margin, immediately beyond the ligamental fulcrum.
The right valve is prettily ornamented with numerous oblique striae, placed close and
straight on the siphonal side, and are rather more distant and wavy on the anterior
half.

This I have found in the recent state on the sandy shores of the Eastern Coast of
England, and almost within the reach of fresh water. It is usually a littoral species, and
is said to range to the depth of ten or twelve fathoms.

9. TELLTNA DONACINA, Linnaeus. Tab. XXII, fig. 5, a, b.

TELLINA DONACINA. Linn. Syst. Nat., ed. 12, p. 1118, No. 59, 1767.
Phil. En. Moll. Sic., vol. i, p. 24 ; vol. ii, p. 21.
? Dujard. Mem. Geol. Soc. Fr., torn, ii, part 2, p. 258, 1837.
Desk. Exped. Scient. Alg. Moll., pi. 69, figs. 1—3.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 292, pi. 20, figs. 3, 4 ;

and pi. K, fig. 4, 1848.
Middend. Malac. Rossica, p. 576, 1849.

— TRIFASCIATA. Penn. Brit. ZooL, ed. 4, vol. iv, p. 75, No. 33.

— VAKIEGATA. Poli. Test. Sicil., vol. ii, p. 45, t. 15, fig. 10.

— SUBCARINATA. Broc. Conch. Foss. Subap., p. 512, t. 14, fig. 5, 1814, fide Phil.

— LLANTTVYI. Payr. Cat. Moll. Cors., p. 40, pi. 1, figs. 13, 14, 1826.

— LUSORIA. (Say.) fide Lyell. Proc. Geol. Soc., vol. iv, part 3, p. 555, 1845.
DONAX STRIATELLA. Nyst. Coq. Foss. Belg., p. 116, pi. 4, fig. 15 a, b, 1844.

Spec. Char. Testa fransversd, elongatd, vel ovato-oUongd, compressiusculd, tenuissime
striatd, incequilaterali, latere postico breviore, obtuse angulato ; impressione palliari magno
prof undo.

Shell transverse, elongate, subtrapezoidal, somewhat compressed, inequilateral,
and finely striated ; posterior side the shorter, obtusely angulated ; impression of the
mantle large and deep.

Length, § inch. Height^ \ inch.

Locality. Cor. Crag, Button.

Clyde Beds. Recent, Britain, Mediterranean, and North Seas. (Midd.}

31

234 MOLLUSCA FROM THE CRAG.

This species is exceedingly abundant in the Coralline Crag, but I have seen it only
in one locality. The palleal impression is very large and deep, extending inwards
until it almost touches a sort of ridge or thickening of the shell between it and the
impression of the anterior adductor ; the lateral teeth are at unequal distances : two
obtuse ridges diverge from the umbo to the ventral margin on the siphonal side, most
distinct in the right valve, upon the interior of full-grown specimens ; in the left, these
markings, instead of being in relief, are impressed. Upon some of my fossils there are
the remains of continuous coloured bands, not intercepted by white radiations. None
of my Crag specimens have attained to so great a magnitude as is given to the recent
British shell, my largest scarcely reaching three fourths of an inch in length. This has
been well named : it strongly resembles a Donax in all its characters.

A specimen, in the cabinet of Sir Charles Lyell, has the locality of Bramerton
attached to it.

10. TELLINA DONACILLA, S. Wood. Tab. XXII, fig. 6, a, b.

TELLINA DONACILLA. S. Wood. Catalogue, 1840.

Spec. Char. Testa transversd, ovato-oblongd, subintequilaterali, compressiuscitld, politd ;
postice breviore, truncatd, biangulatd; antice rotundatd ; cardine bidentato ; dentibus late-
ralibus duobus.

Shell transverse, ovately oblong, somewhat inequilateral, compressed, glossy ;
posterior side the shorter, truncated, and biangulated; anterior side rounded ; two
cardinal, and two lateral teeth.

Length, ^ inch. Height, § inch.

Locality. Cor. Crag, Sutton.

This shell appears to be rare, one specimen of each valve, in my own cabinet, are
all that I have as yet seen. It very much resembles in outline T. Oudardii, Payr., ' Moll.
Cors./ p. 40, pi. I, fig. 16 — 18, and I had considered it different, in consequence of
the want of the peculiarly characteristic marks of that species, which has the exterior,
as stated by the author/ beautifully ornamented with lozenge-shaped cancellse, formed
by radiating striae intersecting the lines of growth. If these lines be upon the
recent shell and not alone in the epidermis, our fossil does not possess them. The
surface is covered with some broad and flat obsolete ridges on the body of the shell,
which are sharp and elevated upon the posterior slope. It is flatter than T. donacina,
less inequilateral, and has not the fine and regular striae of that species. It also
somewhat resembles the figure of T. compressa, Broc., pi. 12, fig. 9; and may possibly
belong to one of the Mediterranean or Subappennine species, but I have not been able
to obtain specimens for comparison.

Our shell has two diverging cardinal teeth in the right valve, with one large,

BIVALVIA.

235

elongated, lateral tooth on the anterior side, and one lateral tooth on the posterior
slope, beyond the large and prominent fulcrum for the ligament ; this fulcrum is so
conspicuous, as almost to justify the species being placed in the genus Psammobia, and
forms one of the links that so closely unite that genus with Tettina. The left valve has
one large triangular cardinal tooth, and a rudimentary one behind it, with correspond-
ing elevations or teeth, which fit into the lateral depressions of the right valve ; and
there is an obscure diagonal ridge on the inside, from beneath the umbo towards the
anterior side of the ventral margin. The palleal scar is not well defined in our shell,
but is probably very large and deep.

Tettina tennis is enumerated in Mr. Smith's ' List of the Clyde Fossils/

TRIGONELLA. Da Costa. 1778.

SPOONMUSSEL. Petiver.
MACTRA (sp.) Gmelin.
MYA (sp.) Chemn.
TELLINA (sp.) Donov,
LIGULA (sp.) Mont. 1808.
SOLEN (sp.) Olivi.
ARENARIA. Megerle. 1811.
SCROBICULARIA. Schumacher. 1817.

LAVIGNON. Cuv. 1817.

LUTRARIA (sp.) Lam. 1818. Swains. 1840.

LISTERA. Turt. 1822.

LUTRICOLA. Blainv. 1824.

AMPHIDESMA (sp.) Flem. 1828.

CALCINELLA. Agass. 1842.

SEMELE (sp.) Woodw. 1854.

Generic Character. Shell equivalved, subequilateral, somewhat compressed, nearly
smooth. Hinge furnished with two small cardinal teeth in the right valve, and one
in the left ; no lateral teeth. Muscular impression ovate. Palleal sinus large and
deep. Ligament small, external. Cartilage large, internal.

Animal with its mantle open, having the margins denticulated. Siphonal tubes
iong, slender, and disconnected, with simple orifices. Foot large, tongue-shaped, and
compressed.

This genus is closely allied to Tellina, differing only in the arrangement of the hinge
furniture. In Trigonella the ligament is small and external, separated from the carti-
lage, which is large, and placed in an expanded, spoon-shaped process. In Tettina
the cartilage is invisible, or nearly so.

1. TRIGONELLA PLAN A, Da Costa. Tab. XXII, fig. 14, a — c.

SPOONMUSCLE. Petiver. Gazophylacium, t. 94, fig. 3, cap. 54, 1764.
CHAMA PIPERATA BELLONII. Aldrov. Exsang., p. 471, 1623.
TRIGONELLA PLANA. Da Costa. Brit. Conch., p. 200, t. 13, fig. 11, 1778.

Desk. Expe'd. Sci. Alg^rie Moll., pi. 44 to 64.

Loven. Ind. Moll. Scand., p. 45, 1846.

Gray. List of Brit. Moll., p. 45, 1851.
VENUS BOREALIS. Penn. Brit. Zool., vol. iv, p. 96, pi. 48, fig. 28.

236 MOLLUSCA FROM THE CRAG.

MYA HISPANICA. Chemn. Conch. Cab., torn, vi, p. 31, t. 3, fig. 21, 1782.

— ORBICULATA. Speng. N. H. S. Sk. H., i, p. 38, No. 13, sec. Schum.

— GADITANA. Gmel. Syst. Nat., p. 3221, 1788.

SOLEN CALLOSUS. Olivi. Zool. Adriat., p. 98, t. 4, figs. 1, A — c, 1792.
MACTRA LISTERI. Gmel. Syst. Nat., p. 3261, 1788.

Woodw. Geol. of Norf., p. 43, t. 2, fig. 7, 1833.

— PIPERATA. Gmel. Syst. Nat., p. 3261, 1788.

— COMPRESSA. Mont. Test. Brit., pp. 96 and 570, 1803.
LIGULA COMPRESSA. Mont. Test. Brit. Supp., p. 23, 1808.
TELLINA PLANA. Don. Brit. Shells, pi. 64, fig. 1, 1801.
LTJTRARIA COMPRESSA. Lamk. An. s. Vert., torn, v, p. 469, 1815.
LISTERA COMPRESSA. Turt. Brit. Biv., p. 51, pi. 5, figs. 1, 2, 1822.
LTJTRICOLA COMPRESSA. Blainv. Malac., pi. 77, fig. 2, 1825.
AMPHIDESMA COMPRESSUM. Flem. Brit. An., p. 432, 1828.

TRANSVERSUM? Say. Amer. Conch., pi. 28, mid. fig.
LAVIGNON CALCINELLA. Recluz. Illust. Conch, p. 8, pi. 1, fig. 1.
SCROBICULARIA ARENARiA. Schum. Essai d'un Nouv. Syst. des Vers., p. 127, pi. 8,

fig. 3, a, b, 1817.
PIPERATA. Phil. En. Moll. Sic., vol. ii, p. 8, 1844.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 326, pi. 15, fig. 5 ;

and pi. K, fig. 6, 1848.

PLANA. Alder. Cat. Moll. North, and Durh., p. 90, 1848.

ABRA LISTERI. "Leach" 1819. Ann. and Mag. Nat. Hist., 1847, vol. xx, p. 272.
LA CALCINELLE. Adans. Senegal, p. 232, t. 17, fig. 18, 1757.

Spec. Char. Testa ovatd, transversd, compressd, subceqnilaterali, concentrice striatd ;
cardine bidentato ; sinu palliari magno, prof undo.

Shell ovate, transverse, compressed, nearly equilateral, concentrically striated;
hinge with two teeth ; palleal sinus large and deep.

Length, l^ inch. Height, \\ inch.

Locality. (?) Red Crag, Sutton.

Mam. Crag, Bramerton, Chillesford.

Clyde Beds. Recent, Mediterranean, Britain, and Scandinavia.

One specimen only of this long-known and common recent species was found by
myself, many years ago, and, I think, in the Red Crag at Sutton. I believe it is not
rare in the neighbourhood of Norwich. As the living species is subject to consider-
able variation in its outward form, there is no difficulty whatever in finding the exact
resemblance of our fossil among recent specimens. The habits of the living animal
lead it almost exclusively to the estuary portion of the sea, which may perhaps be a
reason why it has not been more frequently met with. I have obtained one specimen
from Clacton, in association with Unio, Cardium, fyc. There is a slight difference
in the tumidity of the two valves, causing thereby a difference in the palleal impression,
like that in some of the Tellens.

BIVALVIA.

237

ABRA,* Leach. 1819.

TELLINA (sp.) Poll. 1791. J. Sow.
LIGULA (sp.) Mont. 1803.
AMPHIDESMA (sp.) LamJc. 1818.
ABRA. Risso, 1826. Gray, 1851.
MACTRA (sp.) W. Wood, 1825.

ERYCINA (sp.) Phil. 1836.
SYNDOSMYA. Recluz, 1843. Lovtn, 1846.
Forbes and Hanley, 1848.

CUMMINGIA (sp.) Cr. B. Sow.

Generic Character. Shell thin, transversely elongate, more or less inequilateral ;
surface smooth, and in the recent state covered by an epidermis. Hinge furnished
with one or two small cardinal, and two distinct lateral teeth ; cartilage placed in an
oblique, spoon-shaped process, projecting inward ; ligament small, external.

Animal of the form of the shell, with the edges of its mantle disconnected through-
out, and finely fringed ; siphons sometimes very long, slender, and separated the
entire length, with simple orifices ; foot large, and somewhat geniculated or bent.

This genus is closely allied to the preceding one, the ligament and cartilage being
distinctly separated ; but it differs otherwise in the arrangement of the hinge, the
shells of this group being furnished with distinct lateral teeth.

The shells are generally small, thin, and colourless, with an unequal degree of
tumidity in the two valves on the posterior portion, and a difference in form, conse-
quently, in the sinus of the mantle mark.

In the recent state, the species live in sand and mud, have a vertical range of
1 50 fathoms, and extend from the coast of Norway to the Mediterranean.

1. ABRA ALBA, W. Wood. Tab. XXII, fig. 10, a, b.

MACTRA ALBA. W. Wood. Linn. Trans., vol. vi, pi. 16, figs. 9—12, 1802.

BOYSII. Mont. Test. Brit., p. 98, pi. 3, fig. 7, 1803.

TELLINA PELLUCID A? Broc. Conch. Foss. Subap., p. 514, t. 12, fig. 8, mala.
AMPIDESMA BOYSII. Turt. Brit. Biv., p. 53, pi. 5, figs. 4, 5, 1822.

Smith. Mem. Wern. Soc., vol. viii, p. 93.
ALBUM. Flem. Brit. An., p. 432, 1828.
SEMIDENTATA? Scacchi. Catalogue, p. 5.

ERYCINA RENIERI? Phil. En. Moll. Sic., vol. i, p. 12, t. 1, fig. 6.
SYNDOSMYA ALBA. Reclus. Rev. Cuv. Zool., p. 362, 1843.
Loven. Ind. Moll. Scand., p. 44, 1846.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 316, pi. 17, figs. 12—14,

1848.
LIGULA BOYSII? Forbes. JSgean. Invert., p. 180, 1843.

— ALBA. Nyst. Coq. Foss. de Belg., p. 93, pi. 3, fig. 14, 1844.
ABRA — Gray. List. Brit. Moll., p. 43, 1851.

* Etym. ctfip6s, thin, delicate.

238 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa ovatd vel ellipticd, tenui, l&vi, incequilaterali ; latere antico majiore,
rotundato ; latere postico angulato, subcarinato ; dentibus lateralibus parvis, tenuibus ;
sinu palliari magno, prof undo.

Shell ovate or elliptical, thin, smooth, inequilateral ; anterior side the larger, and
rounded ; posterior angulated, and obscurely carinated ; lateral teeth small, thin ;
palleal sinus large and deep.

Length, \ inch. Height, J- inch.

Locality. Cor. Crag, Sutton.

Red Crag, Sutton, Bawdsey, Walton Naze.
Clyde Beds (Smith}, Bracklesham (Dixori).

Recent, British and Scandinavian Seas.

This is abundant in the Coralline Crag, and, although a thin shell, I have found
many specimens in the Red Crag at Bawdsey, some of which had the valves united.
It differs from A. tennis in being less equilateral, though it is more so than the
succeeding species, A. fabalis, and on the siphonal side it preserves a sort of
ntermediate character between the two, being less pointed than the one but more so
than the other. There is an unequal tumidity in the two valves, causing thereby an
inequality in the palleal sinus. The striae or lines of growth are somewhat more
strongly marked in this than in the succeeding species.

2. ABRA FABALIS, S. Wood. Tab. XXII, fig. 12, a, b.

Spec. Char. Testa ovatd, vel elongato-trapezoidali, in&quilaterali, tenui,fragili, Itsvi ;
latere antico longiore, rotundato ; latere postico angulato ; margine ventrali arcuato ;
dentibus lateralibus elongatis ; foved ligatnenti mediocre.

Shell ovate, or elongately trapezoidal, inequilateral, thin, fragile, and smooth ;
anterior side the longer, and rounded ; posterior angulated ; ventral margin curved ;
lateral teeth thin and elongated ; ligamental area moderate.

Length, f inch. Height, J inch.

Locality. Red Crag, Walton Naze.

This shell presents so great a difference to the preceding (alba) as to entitle it, in my
opinion, to an isolated position ; being more elongated and slender, with the posterior
side more pointed, and it also is a thinner shell, with a more delicate and less
pronounced dental apparatus ; less elongated than A. prismaticaf but intermediate
between the two, differing, however, from A. intermedia in being much more inequi-
lateral, that shell having the umbo nearly central, while in this one the anterior side is
at least two thirds larger than the posterior one. Our shell somewhat resembles Tellina
longicottis, Scacchi, Erycina longicollis, Philippi ; but the hinge of that species is even
more slender, with more elongated lateral teeth, and the support for the cartilage is
smaller.

BIVALVIA. 239

3. ABRA PRISMATICA, Montague. Tab. XXII, fig. 13, a, b.

LIGULA PRISMATICA. Mont. Test. Brit. Supp., p. 23, pi. 26, fig. 3, 1808.
Brown. Illust. Conch., Gt. Brit., pi. 14, fig. 5, 1827.
Forb. Rep. ./Egean. Invert., p. 181, 1843.

ABRA "Leach." Lamk. Hist, des An. s. Vert., torn, v, p. 492, 1818.

MYA Turt. Conch. Diet., p. 103, 1819.

SYNDOSMYA — Recluz. Rev. Cuv. Zool., p. 367, 1843.

— • Lov6n. Ind. Moll. Scand., p. 45.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 321, pi. 17, fig. 15.
TELLINA STRICTA. Broc. Conch. Foss. Subap., p. 515, t. 12, fig. 3, 1817.

— DONACIFORMIS. Nyst. Rech. Coq. Foss. d'Anv., p. 5, pi. 1, fig. 17, 1836.
LIGULA Id. Coq. Foss. de Belg., p. 92, pi. 4, fig. 9, 1843.

AMPHIDESMA PRISMATICUM. Turt. Brit. Biv., pi. 5, fig. 3, 1822.
EHYCINA ANGULOSA. "Bronn" Phil. En. Moll. Sic.,- vol. ii, p. 9, 1844.

Spec. Char. Testa elongato-ovatd, inaquilaterali, Icevigatd, tenui ; later e postico duplo
breviore,- subrostrato ; dentibus lateralibus elongatis.

Shell elongately ovate, inequilateral, smooth, and very thin ; posterior side half the
length of the anterior, and pointed ; lateral teeth elongated.

Length^ \ inch. Height, |- inch.

Locality. Cor. Crag, Sutton.

Clyde Beds. Recent, ^Egean, British, and Norwegian Seas.

I have met with this shell only in the Cor. Crag, and there not very abundantly.
If there be any difference between this and the existing form, it is that the
fossil appears rather the more tumid of the two. The ligamental area is small, and
there are two small lateral denticles or dorsal elevations in the left valve, rather
remote from the umbo, with one cardinal tooth ; and two lateral denticles, and
two cardinal teeth in the right valve ; palleal impression not visible. The siphonal
side is somewhat pointed and slightly compressed, forming an obscure angle or
ridge on that side from the umbo to the posterior extremity. This species in the
living state is said to have a vertical range of 100 fathoms, with a wide geographical
extension from Norway to the ^Egean, and there appears very little doubt that the
fossil called Erycina angulosa, from the Upper Tertaries of Calabria, belongs to the same
species. It is found also in the Belgian Crag of Anvers. Ligula fragilis, Bosquet,
'Bull, de 1'Acad. Roy.,' torn, xviii, pi. 11, p. 305, fig. 1, a — d, a shell from Klein
Spauwen, strongly resembles our species, but it is, I believe with that author who has
pointed out the differences between the Belgian shells, quite distinct. Amphidesma
subreflexa, Conrad, p. 37, pi. 19, fig. 6, if one might judge from the figure alone, may
perhaps be united with A. prismatica.

240 MOLLUSCA FROM THE CRAG.

4. ABRA OBOVALIS, 8. Wood. Tab. XXII, fig. 11.

AMPHIDESMA OBOVALE. S. Wood. Catalogue, 1840.

ERYCINA OVATA? Phil. En. Moll. Sic., vol. i, p. 13, t. 1, fig. 13, 1836.

TELLINA KUBIGINOSA? Poli. Vol. i, p. 48, t. 15, fig. 31, 1791, sec. Phil.

Spec. Char. Testa ovatd, crassiusculd, subcequilaterali ; antice rotundatd, convened;
postice angulatd, compressiusculd ; dentibus lateralibus magnis, elevatis, approximatis ;
apicibus prominulis ; impressione palliari mayno pro/undo.

Shell ovate, rather thick, nearly equilateral, smooth ; anterior side rounded, some-
what tumid ; posterior angulated, and slightly compressed ; lateral hinge teeth large,
elevated, and proximate ; apices rather prominent ; palleal impression large and deep.

Length, % inch nearly. Height, f inch.

Locality. Red Crag, Sutton.

Mam. Crag, near Norwich.

Only two specimens of this species have come under my observation ; one was from
the Mam. Crag, given to me by Mr. Charlesworth, the other I found in the Red Crag at
Sutton : they are both unfortunately the right valve. Perhaps the shell described by
Philippi above referred to is the same species, but the figure is by no means good, and
the description does not altogether accord with the Crag shell, which is thick, and not
thin, as therein described ; our shell has a remarkably thick hinge and a large, angular,
or spoon-shaped area for the cartilage, behind which are two small cardinal teeth, and
at a little distance are two prominent angular denticles ; the posterior one close to the
extremity of the hinge pit ; the palleal sinus is very large, extending into the shell more
than two thirds of its entire length. It differs from A. tennis in being more pointed,
and it has a more strongly marked hinge.

A shell much resembling this species has been obtained on the N. E. Coast of
America, called Cummingia tellinoides, Conrad, 1830, Gould, ' Invert. Massach./ p. 56,
fig. 36, and Stimpson ' Catal./ p. 20, but it is specifically distinct. The Crag shell is
not so much compressed ; the ventral margin is more convex, and the lateral teeth of
the hinge larger and more prominent; while the American shell is also different
externally, being covered with larger and more regular ridges.

Erycina ovata, Midden, 1. 19, figs. 5 — 8, as well as Amplddesma ovata, Desh. 'Exped.
Moree/ pi. 6, fig. 8, appear, from the figures and descriptions, to be different from our
shell.

MACTRA,* Linnceus, 1767.

CALLISTA CALLISTODERMA (sp.) Poli, 1791.
TRIGONELLA (sp.) Da Costa, 1778.
MULINIA. Gray, 1836.

SPISULA. Gray, 1837; 1851.
MESODESMA (sp.) Desk. 1835.
HEMIMACTRA. Swains. 1840.

* Etym. /ucurpci, a kneading trough.

BIVALVIA. 241

Generic Character. Shell transverse, subequilateral, equivalve ; ovate, elliptical, or
subtriangular, sometimes thin, occasionally thick and ponderous, slightly gaping
laterally ; surface smooth, or finely striated concentrically. Hinge with a double
cardinal tooth in the left valve, and a triangular space for its reception in the right,
with large and elongated lateral teeth on each side : a large triangular pit for the
cartilage. Ligament small, external. Impression by the mantle sinuated.

Animal with its mantle freely open almost as far backward as the siphons ; margins
fringed ; siphons large and extensile, united to their extremities, and the orifices
ornamented with cirri ; foot long and strong, tongue-shaped, geniculated.

This genus, constituting a well marked group, has not been much dismembered
since the time of its original establishment by Linnaeus : a division under the name of
Spisula, has, however, been proposed by Dr. Gray for those species which have the
ligament entirely hidden by the dorsal margin, and the more complete union of the
cartilage with the ligament, and he has reserved the name of Mactra for the species
which have a small shelly plate interposed between the two portions of the ligament,
and where it is partially visible when the valves are closed ; this distinction is so
very ill defined that it is not thought necessary the separation should be here adopted.
The most distinguishing character is the possession of a sharp diverging or chevron-
formed tooth, somewhat resembling the letter A reversed, and this is placed imme-
diately beneath the umbo before the cartilage. Some of the species have the lateral
teeth and the sides of the sockets, into which they are inserted, covered with rugosities
or ridges in a direction at right angles to these teeth ; others have these parts
quite smooth ; the thicker species are generally furnished with those ridges, but the
thinner ones are not always free or naked : these might almost constitute a sectional
distinction, but the same differences are observable in the genera Astarte and Cyrena.

The species of this genus have been found in most parts of the world, living
principally in shallow water; they are generally buried in the sand, within a short
distance from the surface.

In the fossil state they have been obtained in the Lias and Greensand formations,
and one is recorded as from the Carboniferous series ; but this latter is of doubtful
character. The species, as well as individuals, are largely developed in the newer
Tertiaries, and are abundant also at the present day.

1. MACTRA GLAUCA, Born. Tab. XXIII, fig. 2, a, 6.

MACTRA OLAUCA. Born, Test. Mus. Gees. Vind., p. 51, t. 3, figs. 11, 12, 1780.

— HELVA SEU HELVACEA. Chemn. Conch., Cab., vol. vi, p. 234, t. 23, figs. 232, 233.

— HELVACEA. Payr. Cat. Moll. Cors., p. 29, 1826.

— Phil. En. Moll. Sic., vol. i, p. 10 ; vol. ii, p. 9.

— Forb. and Hani. Hist. Brit. Moll., vol. i, p. 366, pi. 23, fig. 2, 1848.

— NEAPOLITANA. Poll. Test. Sicil., vol. i, t. 18, figs. 1—3, 1791.

32

242 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa ovatd subtrigonuld, subincequilaterali, tenui, Itevi, comprcssiusculd ;
margin e dorsali convexiusculo ; dentibus lateralibus remotis, Itevigatis, acutis, tenuibus ;
foved cardinali magnet ; sinu pattiari semicirculari.

Shell ovate, slightly trigonular, nearly equilateral, thin and smooth, somewhat
compressed ; dorsal margin slightly curved ; lateral teeth remote, smooth, sharp, and
thin ; cartilage pit large ; palleal sinus semicircular.

Length, 3|- inches. Height, 2J inches.

Locality. Red Crag, Newbourn. Recent, Mediterranean, British Channel.

This species, in the recent state, seems restricted to the warmer parts of the British
Seas, and to the Mediterranean, and as such we might have expected to have found it
in the lower Crag deposit. Two specimens were found by myself in the genuine, though
rather disturbed portion of the, Red Crag : there is, I think, little doubt of its having
been an inhabitant of the sea of this latter Period, as so large and thin a species
would hardly have escaped destruction in a removal from one formation to another.
M. stultoTum is the shell with which it is most likely to be confounded; that
species, however, never attains to so great a magnitude. The dental characters in
this are strongly marked ; the right valve has two unequal sized cardinal teeth, the
anterior one short, inside of which the A-formed tooth of the left valve interlocks ;
the lateral teeth are long, thin and sharp, rather less elevated towards the sides than
are those of M. stulforum, and in this species the umbo is rather more prominent : the pit
for the cartilage is of a triangular form, and the mantle sinus is comparatively less.

Born seems intitled to priority, as there is very little doubt his figure, though
not a good one, was intended for this species, and to which Chemnitz (who has given
a much better representation) has referred.

Menke has introduced this species into his ' List of New Holland Mollusca.' This
Australia shell may be what is called by some authors its representative.

2. MACTRA STULTORUM, Linnceus. Tab. XXIII, fig. 3, a — d.

MACTRA STULTORUM. Gualteri. Ind. Test. Conch., t. 71, fig. c, 1742.
PECTUNCULUS. Leigh. Nat. Hist. Chesh., pi. 3, fig. 6, 1700.
CARDIUM STULTORUM. Linn. Syst. Nat., ed. 10, p. 681, No. 8.
MACTRA STULTORUM. Linn. Syst. Nat., ed. 12, p. 1126, No. 99, 1767.

Broc. Conch. Foss. Subap., p. 535, No. 2, 1814.

Phil. En. Moll. Sic., vol. i, p. 10, t. 3, fig. 2, 1836.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 362, pi. 22, tigs. 4—6.

— CINEREA. Mont. Test. Brit. Supp., p. 35, 1808.
MAGNA. Woodw. Geol. of Norf., p. 43, t. 2, fig. 10, 1833.

— STRAMINEA? Desk. 2d ed. Lamk. torn, vi, p. 100, 1835.
TRIGONELLA RADIATA. Da Costa. Brit. Conch., p. 196, pi. 12, fig. 3, 1778.
TELLINA RADIATA. Penn. Brit. Zool.3 ed. 4, vol. iv, p. 87, pi. 49, fig. 30.

131VALVIA. 243

Spec. Char. Testa ovatd, transversd, subtrigond, sub<zquilaterali, l&vi, tenui ; cardine
bidentatd, dentibus lateralibus acutis, elongatis ; sinu palliari semicirculari.

Shell ovate, transverse, subtrigonal, slightly inequilateral, smooth, and thin ;
hinge with two cardinal teeth in each valve, with sharp and compressed lateral teeth ;
impression of the mantle with a semicircular sinus.

Length, 2^ inches. Height, 1 J inch.

Locality. Cor. Crag, Sutton.
Red Crag, Sutton.
Mam. Crag, Bramerton.
Clyde Beds, Smith; Bracklesham (Dixori}.

Recent, Mediterranean and British Seas.

A fragment only of this species is in my cabinet from the lower or Coralline Crag,
and it is not by any means abundant in the succeeding or Red Crag period, but it has
been found plentifully in the Mammaliferous Crag, near Norwich, and in the Clyde
beds, and it has become a very common shell in our own seas.

There is considerable variation among my specimens not only in proportionate
dimensions but also in the outward form. In fig. a the shell is almost as high as it is
long, with the dorsal edge rounded ; fig. b, is comparatively much longer, with the
hinder side angulated and somewhat pointed. The impressions of the adductors are
rather large, and the sinus of the mantle-mark extends inwards about f ths of the length
of the shell. The lateral teeth are thin, double in the right valve, and the cardinal
A -formed tooth diverges nearly at a right angle.

In the recent state it is littoral in its habits, and has a wide geographical range,
extending from the south coast of Norway (Forbes and Hanley) into the Mediterranean,
and it is mentioned by Philippi as having been met with by Ehrenberg in the Red Sea.

3. MACTRA ARCUATA, /. Sowerby. Tab. XXIII, fig. a — c.

MACTKA AKCUATA. J. Sow. Min. Conch., t. 160, fig. 1, 1817.
Woodw. Geol. of Norf., p. 43, 1833.
Nyst. Coq. Foss. de Bdg., p. 78, pi. 11, fig. 7, 1844.

Spec. Char. Testa ovato-trigonula, incequilateraU, Itevigatd, subcompressd, tenui ; antice
latiore et breviore, rotundatd ; margine dorsali arcuato ; cardine bidentato, dentibus
lateralibus perpendicular iter striatis ; sinu palliari linguiformi.

Shell ovate, or rather ovato-trigonal, inequilateral, smooth, slightly compressed,
thin ; anterior side the broader, short, and rounded, dorsal margin curved ; hinge with
two cardinal teeth, and striated lateral teeth ; pallial sinus tongue-shaped.

Length, 3^ inches. Height, 2f inches.

Locality. Coralline Crag, Sutton, Gedgrave.

Red Crag, Walton Naze, Sutton, Bawdsey.

244 MOLLUSCA FROM THE CRAG.

This species is not very abundant in the Coralline Crag ; but in the native
bed at Walton Naze in the Red Crag, specimens are met with in large numbers,
although somewhat difficult to obtain perfect, owing to their extreme fragility. The
exterior is always more or less ridged, from the unequal degree of decomposition, and
the surface is never in its original condition ; but, judging from those in which it is
partially preserved, it was probably nearly smooth in the living state.

The ligamental area is large and simple, running close up to the umbo ; and the
cardinal A-formed tooth very small in the left valve, with a corresponding cavity in the
right ; the lateral teeth are double in the right valve, deeply ridged on both sides of
the interior ; the lateral teeth of the left valve are single, and ridged on the outside ;
the muscular impressions are large, not very deep seated, and the sinus in the mantle-
mark is somewhat narrow, extending into the interior at least one third of its entire
length, but variable, being modified by the comparative length of the shell.

4. MACTRA ARTOPTA, S. Wood. Tab. XXIII, fig. 4, a, b.

Spec. Char. Testa trigonuld vel obtuse cuneatd ; tumidiusculd, inaquilaterali, antice
rotundatd, margine dorsali postico rectiusculo ; umbonibus subprominulis : dentibus lateralibus
perpendiculariter striatis.

Shell trigonal or obtusely wedge-shaped, slightly tumid, inequilateral, anterior side
rounded, dorsal margin of posterior side somewhat straight, umbones rather promi-
nent, lateral teeth striated perpendicularly.

Length, 2^ inches. Height, 2 inches.

Locality. Cor. Crag, Sudbourne.

Several specimens of a Macfra, contained in the collections of Mrs. Corder, Mr.
Perry, and my own, appear to possess a uniformity of character, such as I think
entitle them to be considered as belonging to a distinct species, differing from M.
arcuata, which is perhaps its nearest relative, in having the dorsal margin
less curved than in any specimens of that species which have come under
my inspection. This shell is also rather more tumid, and it has a more elevated
umbo, and its whole aspect appears different. I have seen it only from the Coralline
Crag, in the neighbourhood of Orford. My specimens of M. arcuata, from the same
Formation, were found at Ramsholt.

5. MACTRA PROCRASSA, S. Wood. Tab. XXIV, fig. 8, a, b.

Spec. Char. Testa magnd, crassd ; irregulariter striatd, ovato-trigonuld, incequi-
laterali ; antice snb-angulatd, postice rotundatd ; fovcd ligamenti magnd ; dentibus laterali-
bus perpendiculariter striatis.

BIVALVIA. 245

Shell large, thick and strong ; irregularly striated externally, ovately triangular ;
inequilateral ; anterior side obtusely angulated, posterior rounded ; ligamental area
large ; lateral teeth perpendicularly striated.

Length, 2| inches. Height, 2 inches.

Locality. Red Crag, Felixstow.

One specimen only of this species is all that I have seen. It is from the cabinet of
Mr. Perry, and was obligingly forwarded to me for publication by Mrs. Corder.

It somewhat resembles M. solidissima, Chemn. (M. gigantea, Lamk.), but differs from
that shell in being much more rounded on the posterior side. The lateral teeth in our
shell are also considerably larger, and the sinus in the mantle-mark is also different ;
but that perhaps may depend upon, or would be modified by, the length and form of
the posterior side. A shell in the British Museum, from South America, M. exalbida,
much resembles it in form, but in this latter species the lateral teeth are smooth.

6. MACTRA TRUNCATA, Montague. Tab. XXIV, fig. 2, a, b.

PECTUNCULUS CRASSITJSCULUS. List. Hist. Conch., lib. 11, fig. 87.
MACTRA TRUNCATA. Mont. Test. Brit. Supp., p. 34, 1808,

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 354, pi. 23, fig. 1.

— SUBTRUNCATA. Donov. Brit. Sheila, vol. iv, pi. 126, 1803.

— CRASSATELLA. Desk. 2d ed. Lamk. torn, vi, p. 107, No. 33, 1835.

— CRASSA. Turt. Brit. Biv., pp. 69, 258, t. 5, fig. 7, 1822.
SPISULA — Gray. Mag. Nat. Hist., new series, vol. i, p. 373, 1837.

Spec. Char. Testa rotundato-triangulatd, subcequilaterali crassd ; sinu palliari brevi,
lingmformi ; umbonibus prominentibus, dentibus lateralibus perpendiculariter striatis.

Shell roundedly triangular, subequilateral, thick; palleal sinus short, tongue"
shaped ; umbones prominent, lateral teeth with perpendicular striae or ridges.

Diameter, \\ inch.

Locality. Red Crag, Button, Walton Naze.

Clyde Beds. Recent, Britain, and Scottish Seas.

This is at present a rare Crag species. A worn and somewhat injured specimen
has long been in my possession ; two others, in better condition, have since been
obtained by Mrs, Corder, and these are all that I have seen.

7. MACTRA SOLIDA, Linnaeus. Tab. XXIV, fig. 4, a — c.

MACTRA SOLIDA. Linn. Syst. Nat., ed. 12, p. 1126, 1766.

Goldf. Petr. Germ., vol. ii, p. 253, No. 1, t. 152, fig. 5.
— Phil. En. Moll. Sic., vol. i, p. 11 ; vol. ii, p. 10.

Nyst. Conch. Foss. de Beige., p. 77, pi. 3, fig. 10, 1844.
_ _ Forb. and Hani. Hist. Brit. Moll., vol. i, p. 315, pi. 22, figs. 1—5, 1848.

246 MOLLUSCA FROM THE CRAG.

MACTRA VULGARIS. Chemn. Conch. Cab., vol. vi, p. 230, pi. 23, fig. 229.
TRIGONELLA ZONABIA. Da Costa. Brit. Zool., p. 197, pi. 15, fig. 1, 1778.

GALLINA. Id. Brit. Zool., p. 199, pi. 14, fig. 6.

SPISULA SOLIDA. Gray. Mag. Nat. Hist., 1837, p. 374.

Spec. Char. Testa ovato-trigonali, subcequilaterali, crassd, laemusculd ; dentibus
lateralibus perpendiculariter striatis.

Shell triangularly ovate, slightly inequilateral, thick, nearly smooth ; lateral teeth
perpendicularly striated.

Length, 1 inch. Height, -| inch.

Locality. Red Crag, Button.

Mam. Crag, Bramerton.

Clyde Beds. Recent, Mediterranean and British Seas.

As far as I can ascertain the history of this species, it is of comparatively modern
origin, although by some mistake it was quoted in my ' Catalogue ' as from the Older
or Coralline Crag, from which deposit I certainly have not a well- determined specimen,
and those from the succeeding or Red Crag Period are somewhat doubtful.

I have one characteristic specimen from Bramerton, corresponding precisely with
the common living shell, but it does not appear to have been abundant even there, as
it is not enumerated among the Norfolk Shells by Woodward.

In the recent state, it is generally a littoral species, living buried in the sand, but
has been found in water as deep as thirty-five fathoms (M' Andrew). It is an estuary
species at the present day.

8. MACTRA OVALIS, /. Sowerby. Tab. XXIII, fig. 1, a — d.

MACTRA OVALIS. J. Sow. (not Gould.) Min. Conch., t. 160, fig. 5, 1817.

— DUBIA. Id. Min. Conch., t. 160, figs. 2, 3, 4.

— ELLIPTICA. Brown. Illust. Conch. Gt. Brit., pi. 15, fig. 6, 1827.

Lov6n. Ind. Moll. Scand., p. 45, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 356, pi. 22, fig. 3.

— SOLIDA. Don. Brit. Shells, t. 61, small figure.

— CONGESTA? Conrad. Foss. of the Med. Tert., p. 27, pi. 15, fig. 2, 1838.

— STRIATA. Nyst. Coq. Foss. de Belg., p. 80, pi. 4, fig. 1 a, 1844.
SPISULA ELLIPTICA. Gray. List Brit. Moll., p. 32, 1851.

Spec. Char. Testa ellipticd vel ovato-angulatd, sub&quilaterali, Itevigatd, vel tenuis-
sime striatd, tumidiusculd ; dentibus lateralibus rugosis ; margine ventrali arcuato.

Shell elliptical or angularly ovate, nearly equilateral ; smooth or very finely striated
transversely ; slightly tumid ; lateral teeth rough or striated ; ventral margin curved.

Length, 2 inches. Height, 1^ inch.

BIVALVIA. 247

Locality. ? Cor. Crag, Sutton.

Red Crag, Bawdsey, Sutton, Woodbridge.

Mam. Crag, Bramerton, Chillesford.

Clyde Beds. Recent, Finmark, Britain.

The name of ovalis is selected in preference to that of dubia, as being best suited
to the character of the species, both having been proposed at the same time.

A considerable range in variation is observable in the numerous specimens found
in the Red Crag, some of which very closely approach M. solida, so much so that I
was induced to consider it in my ' Catalogue ' only as a variety, more especially as in
this, when perfect, the dorsal portion is marked with ridges such as are supposed to be
a good distinguishing character for that species. The principal difference appears to
be a greater solidity of substance in the one so named, and the other is of course
thinner. Our Red Crag fossil has the exterior covered with very fine, close-set, and
rather irregular striae, while upon the upper or dorsal portion it is more strongly ridged
than is usual in the recent shell. The variety M. dubia is less elliptical, with the dorsal
portion ridged, connecting it in that character with M. solida, from which it differs only
in being rather more oval and thinner.

In the Red Crag this is one of the most abundant shells, and may be obtained
in most localities ; but I have never found it at Walton-on-the-Naze.

9. MACTRA SUBTRUNCATA, Da Costa. Tab. XXIV, fig. 3, a, b.

TRIGONELLA SUBTRUNCATA. Da Costa. Brit. Conch., p. 198, 1778.
MACTRA SUBTRUNCATA. Mont. Test. Brit., p. 93, and Sup., p. 37, pi. 27, fig. 1.
Loven. Ind. Moll. Scand., p. 45, 1846.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 358, pi. 21, fig. 8 ;

pi. 22, fig. 2 ; and pi. L, fig. 3, 1848.
— 1 Midd. Malac. Rossic., p. 581, t. 18, figs. 11—13.

— Sismonda. Syn. Meth. Anim. Invert. Fed. Foss., p. 22, 1847.

— CUNEATA. J. Sow. Min. Conch., t. 160, fig. 7, 1817.

Woodw. Geol. of Norf., p. 43, t. 2, fig. 10, 1833.
EUXINICA? Krymchi. Bull, des Not. de Moscou, No. 11, p. 63, 1837.

— LIMBATA. Menke. Fide Lov6n.

SPISULA SUBTRUNCATA. Gray. Mag. Nat. Hist., new series, p. 374, 1837-

Spec. Char. Testa ovato-triangulari, vel cuneiformi, inaquilaterali, crassa ; antice
breviorc subtruncatd ; postice producta, angulatd ; dentibus later alibus perpendiculariter
striatis ; margine ventrali convexiusculo.

Shell ovately triangular or obtusely wedge-shaped, inequilateral, thick; anterior
side the shorter, and roundedly truncate ; posterior side produced, and angulated ;
beaks slightly prominent; lateral teeth perpendicularly striated; ventral margin
slightly convex.

248 MOLLUSCA FROM THE CRAG.

Lenfftk, 1 inch. Height, f inch.
Locality. Red Crag, Sutton ?

Mam. Crag, Bramerton.

Clyde Beds, Bracklesham, Uddevalla.

Recent, West Gothland, Britain, Mediterranean.

This is a common shell in the Mammaliferous Crag in the neighbourhood of
Norwich. The cuneiform variety (cuneatd) differs only in so far as to have one
side a little more produced than is usual in the recent shell. The specimens are
always more or less deprived of their outer coating ; but in those best preserved, the
ridges upon the dorsal area may be distinctly seen.

10. MACTRA OBTRUNCATA, S. Wood. Tab. XXIV, fig. 5, a, b.

Spec. Char. Testa subaquilaterali, obtuse triangulari, obtruncatd ; antice angulatd ;
postice truncatd aut rotundatd; umbonibus subprominentibus ; area dorsali striatd ; dentibus
lateralibus rugosis.

Shell slightly inequilateral, obtusely triangular, roundedly truncate ; anterior side
angular, posterior irregularly rounded ; umbones slightly prominent ; dorsal area
striated ; lateral teeth denticulated.

Length, -| inch, nearly. Height, £ inch.

Locality. Cor. Crag, Sutton.
Red Crag, Sutton.

This shell is not rare either in the Red or Coralline Crag. It much resembles in
form the preceding species (M. subiruncata), but differs essentially in being reversed.
In the living species the angular or produced portion is on the side on which
the ligament is placed, and where the sinuated mark of the mantle is seen ;
while in this, the anterior side is angulated, though not much produced. It is a
thick and strong shell, somewhat tumid, with an obtuse ridge on each side, more
distinctly marked on the anterior, running from the umbo to the ventral margin,
within which it is slightly flattened. It has long remained in my cabinet, under the
name of M. subtruncata, imagining it to have been only a reversed variety, like Trophon
antiquum, var. contrarium, so common in the Red Crag. There appears, however, a
difference also in the form and direction of the sinus in the mantle-mark, more than
might be the result of a difference in the length of the siphonal sides of the two
shells.

Mactra striata, Smith, 'Wern. Trans./ vol. viii, pi. 1, fig. 22, much resembles, and
may probably prove to be, this species, but I have not been able to obtain a specimen
for comparison ; and judging from the representation, it does not appear to have the
angular form on the anterior side as in our shell. Messrs. Forbes and Hanley referred

BIVALVIA. 249

the Stevenston shell to M. subtruncata, but Mr. Smith tells me it does not belong to
that existing British species.

I have, therefore, proposed the above name for the Crag fossil, not only from the
state of uncertainty respecting M. striata, but also from the consideration of the name
being employed for another species.

11. MACTRA CONSTRICTA, S. Wood. Tab. XXIV, fig. 6, a — c.

Spec. Char. Testa oblongo-ovatd, inaquilaterali, erased, Icemgatd vel tenuissime striata ;
antice longiore, rotundatd, postice angulatd ; margine ventrali constricto ; dentibus later ali-
bus perpendiculariter striatis.

Shell ovately oblong, inequilateral, thick, smooth or finely striatedcon centrically ;
anterior side the longer, and rounded ; posterior angulated ; ventral margin contracted ;
lateral teeth rough or perpendicularly striated.

Length, \\ inch. Height, finch.

Locality. Red Crag, Sutton.

This is a common shell, and very abundant in some localities. In its adult state
it assumes a form somewhat approaching M. deaurata, the ventral margin on the
siphonal side, after a certain period of growth, becomes contracted or constricted, and
the dorsal margin then slopes suddenly, giving it an angular form. In the young
shell, as indicated by the lines of growth, it has the oval shape of ovalis, and I con-
sidered it as a variety only of that species ; but in many of the species of this genus it
is very difficult to determine to which the immature shell belongs, and I have now
reason to believe this to be entitled to specific distinction. Mactra Caspia, Eichwald
(a Tertiary fossil), ' Fauna Caspio-Caucasia, p. 261, t. 38, figs. 21, 22, has some resem-
blance to our shell ; but it appears to be more equilateral, and too regular in form,
without the contraction or distortion of the Crag specimens.

I have been unable to obtain any information respecting the specimen figured by
Woodward, called M. triangularis, ' Geol. of Norf.,' t. 2, fig. 9, though most obligingly
aided in the search by my collecting friends in Norwich.

12. MACTRA DEAURATA, Turton. Tab. XXIV, fig. 7, a, b.

MACTRA DEAURATA. Turt. Brit. Biv., p. 71, t. 5, fig. 8, 1822.

— DENTICULATA. W. Wood. Ind. Test. Supp. Mactra, pi. 1, fig. 9.

— MODICELLA? Conrad. Sillim. Journ., vol. xxiii, p. 340.

Id. Foss. Med. Tert., p. 25, pi. 13, fig. 3, 1838.

— INEQUILATERA. Nyst. Conch. Foss. Belg., p. 79, pi. 11, fig. 8, 1844.

33

250 MOLLUSCA FROM THE CRAG.

MESODESMA JAURESII. De Joannis. Mag. de Zool. Moll., pi. 54, 1834.

_ __ Gould. Invert. Massach., pi. 58, fig. 38, 1841.

— DEAURATA. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 346, 1848.

ERYCINA DENTICULATA. Cuvier. (Griffiths.) An. Kingd., t. 22, fig. 2.
PAPHIA DEAURATA. Gray. List Brit. Moll., p. 157, 1851.

Spec. Char. Testa transversd, oblongo-ovatd, intequilaterali, crassa ; transverse striatd
vel snbimbricatd ; antice longiore et rotundatd ; postice truncatd ; cardine bidentato ; denti-
bus lateralibus magnis, striatis.

Shell transverse, ovately oblong, inequilateral, thick and strong, transversely or
concentrically striated ; anterior side the longer, and rounded ; posterior truncated ;
lateral teeth large, and perpendicularly striated.

Length, lj inch. Height, f inch.

Locality. Red Crag, Button, Walton Naze.

Recent, North-east Coast of America, Newfoundland.

The specimen figured was found at Walton-on-the-Naze by John Brown, Esq., of
Stanway. There is another in my own cabinet, from the Red Crag at Sutton, but not
in quite so good a state of preservation. It may be thus more fully described : The
anterior side is much produced, the base line of the shell ascending towards the
extremity, where it is roundedly pointed, while the siphonal side is very short, and
obtusely biangulated ; the surface is covered with irregularly elevated lines of growth
or ridges ; corresponding with the figure and description given by Turton, who says
it somewhat resembles in outline M. dealbata, but differs in being thicker, and
also in the teeth, though he does not tell us what these latter are like in either
species.

The recent shell is placed by some authors in the genus Mesodesma. A small
A -formed tooth is present in this left-hand specimen, placed immediately before a
large ligamental area, as in Mactra, with elongated lateral teeth, which are striated.

LUTRARIA,* Lamk. 1799,

MACTRA (sp.) Linn.

PSAMMOPHILA. Leach, MS. 1819. Fide Brown.

LUTRICOLA (sp.) De Blainv. 1824.

Generic Character. Shell transversely ovate or oblong, inequilateral, and gaping
at the lateral extremities ; externally smooth, or slightly striated transversely. Hinge
with a prominent triangular or diverging tooth in the right valve, with a corresponding
pit for its reception in the left. Ligament internal, placed in a large spoon-shaped
depression in each valve. Impression by the mantle deeply sinuated.

* Etym. Lutra? a luto, to daub, probably from its mud-like exterior.

BIVALVIA. 251

Animal oblong, with very elongated siphonal tubes united almost to their extre-
mities ; orifices fimbriated. Mantle .open in front for the emission of a foot of consider-
able size.

The true position of this genus (or what is called its family connexions) is still a
subject of much diversity of opinion, some placing it near to My a, while others claim
for it a close affinity to Mactra.

Few species of this genus are at present known in the recent state, and as fossils
they have been recorded in the Older Secondary Formations. The true generic
position of the latter is doubtful. In the Older Tertiaries it does not appear to have
been found, but the middle and newer Formations contain about nine or ten species.

LUTRARIA ELLIPTIC A, LamarcJc. Tab. XXIV, fig. I, a, 6.

MACTRA LUTRARIA. Linn. Syst. Nat., ed. 12, p. 1126, No. 101, 1767.

Brocchi. Conch. Foss. Subap., p. 536, 1814.
LUTRARIA ELLIPTICA. Lamk. Hist, des An. s. Vert., torn, v, p. 468, No. 2, 18.18.

— ? Basterot. Foss. de Bord., p. 94, 1825.

Phil. Euuni. Moll. Sic., vol. i, p. 9 ; vol. ii, p. 7.
Desk. Exp. Sci. Alger. Moll., pis. 33, 35, 36.
Sismonda. Syn. Method. An. Inv. Fed. Foss., p. 23, 1847.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 270, pi. 12.
Nyst. Conch. Foss. de Belg., p. 75, 1844.

— ? Gratel. Cat. Zool. de Terr. Tert. de la Gironde, p. 76, 1838.
VULGABIS. Flem. Brit. An., p. 464, 1828.

Lister. Hist- Conch. Lib., Ill, fig. 259.

Spec. Char. Testa ovato-oUongd vel ellipticd, incequilaterali, Itsviusculd, antice subangu-
latd, utringue hiante ; sinu pattiari prof undo.

Shell ovately oblong or elliptical, inequilateral, somewhat smooth ; anterior side the
shorter, and slightly angulated ; gaping at both extremities ; pallial sinus deep.

Length, 5£ inches. Height, 3 inches, nearly.

Locality. Cor. Crag, Sudbourn and Ramskolt.
Red Crag, Sutton.
Clyde Beds, and Irish and Lancashire Drift Beds. (Forbes.}

Recent, Mediterranean, Britain.

This fine, handsome shell is, I believe, not very rare at Sudbourn, though specimens
of it are difficult to obtain. My cabinet contains one individual, with the two valves
united, which I found at Ramsholt. There is a slight difference in our fossil, varying
somewhat in its outline, more especially on the anterior or shorter side. In the recent
shell, the dorsal portion is there more convex or rounded ; but in the Crag specimen,
this part is nearly straight, giving an angular form to that side ; this difference, how-
ever, does not appear sufficient to affect the specific assignment. Each valve has a

252

MOLLUSCA FROM THE CRAG.

large angular-formed or spoon-shaped depression for the ligament, before which, and
immediately beneath the umbo, is a prominent A-formed tooth in the right valve,
which fits into an angular depression in the left. The comparative dimensions are
somewhat variable, like what is observable in the living shell.

The habitat of the living animal is said to be in oozy sand, or muddy bottoms,
varying in depth from six to twelve fathoms.

MACHA, Oken. 1815.

CHAMA (golar). Adanson.
HYPOG^EA HYPOG^EODERMA (sp.) Poll, 1791.
SILIQUARIA (part). Schum. 1817.
ADASIUS. Leach, MS. Fide Gray.

PSAMMOSOLEN. Bronn. 1831.

PSAMMOBIA (sp.) Turt. 1822.
SOLECURTUS (sp.) Blainv. 1824.
NOVACULINA? Benson, 1830.
CYRTOSOLEN. Herrm. 1847.
MACHA. Agass. 1839. Gray, 1851,

Generic Character. Shell transverse, of a somewhat oblong form, compressed in
the middle, equivalved, equilateral ; rounded and gaping at both extremities ; surface
generally ornamented more or less with oblique grooves or striae. Hinge composed of
two diverging teeth in one valve, and one in the other, with a large fulcrum for an
external ligament. Impression of the mantle deeply sinuated.

Animal oblong, large and thick, mantle widely open in front for the passage of a
large tongue-shaped foot. Siphons long, deeply separated, but united at their bases.

This has been justly separated from the Solens, on account of the different position
of the hinge, though in its habits there is great similarity, and it is capable of burying
itself rapidly in the sand.

Fossils, probably belonging to this genus, have been obtained from the middle
Secondary Period.

MACHA STRIGILLATA, Linnceus. Tab. XXV, fig. 3, a, b.

SOLEN STRIGILLATUS. Linn. Syst. Nat., ed. 12, p. 1115, No. 30, 1767.

Chemn. Conch. Cab,, vol. vi, t. 6, figs. 41, 42.
? Poll. Test, utriusq. Sic., vol. i, p. 21, t. 12, fig. 1.

Phil. Enum. Moll. Sic., vol. i, p. 5.
— CANDIDUS? Broc. Conch. Foss. Subap., p. 497.
PSAMMOBIA STRIGILLATA. Turt. Brit. Biv., p. 97, t. 6, fig. 13, 1822.
SOLECURTUS STRIGILLATUS. Phil. Enum. Moll. Sic., vol. ii, p. 5, 1841.
MACHA STRIGILLATA. Gray. List Brit. Moll., p. 61, No. 1, 1851.
HYPOG^EA VARIEGATA. Poli. Test. Sicil. utrius., vol. ii, p. 257.

Spec. Char. Testa ovato-oblongd, subcequilaterali, utrinque rotundatd, in media com-
pressd, coarctatd ; dimidiam striatam, striis subobliquis insculptis.

BIVALVIA. 253

Shell ovately oblong, rounded at both extremities, slightly inequilateral, compressed
in the middle, with a small contraction in the ventral margin ; one half covered with
oblique striae.

Length, 2 inches.

Locality. Cor. Crag, Sutton. Recent, Britain? Mediterranean.

My specimens are few and fragmentary. They appear to possess about twenty-two
divergingly imbricated ridges, or lines, covering about two thirds of the shell. These
lines are vertical in the centre, one or two sloping a little towards the anterior.

There are the remains of colour in my specimens, and they correspond in that respect
with what the British conchologists consider to be distinct, and different from the white
variety, which is ornamented with the same kind of sculpture. The lines on my
fossil do not appear to extend quite so far upon the anterior side as in the recent shells,
but there is little doubt of its identity with either this or M. Candida. Philippi gives
both as inhabitants of the Mediterranean, as well as fossil in that part of the world,
distinguishing the two species in the fossil state by the number of rays. This, I am
afraid, is a questionable distinction ; specimens of the red variety may be observed, on
which may be counted the same number he has given to each species.

In that extraordinary book, Pontoppidon's 'Nat. Hist, of Norway,' p. 165, there is
the figure of a shell called the smaller mussel, which is one of the varieties of this
species, but it is not enumerated by Loven in his ' Ind. Moll. Scand.' The shell from
the Older Tertiaries, Solen strigillatus, Lamarck, 'Ann. du Mus/ t. 12, pi. 43, fig. 5, is
distinct ; the one referred to by Basterot (p. 96), from the neighbourhood of Bordeaux,
I have not seen.

SOLEN,* Arist., Linn., fyc.

*

SOLENA. Browne, 1756.

HYPOG^EA and HYPOGEODERMA (sp.) Poll, 1791.

SOLENARIUS? Dumeril, 1806.

VAGINA. Megerle, 1811.

ENSIS. Schum, 1817. J. Sow. 1846. Gray, 1851.

ENSATELLA. Swains. 1840.

Generic Character. Shell equivalved, transverse, linear, subcylindrical, straight or
very slightly curved, gaping widely at both extremities, dorsal and ventral margins
nearly parallel, umbones near the extremity. Hinge with two teeth in one valve, and
one in the other, with sometimes a linear lateral tooth. Muscular impressions dis-
similar. Palleal sinus short and wide. Ligament external, attached to an elongated
fulcrum. In the recent state, covered with a thick epidermis.

* Etym. ffw\?jv, a tube.

254 MOLLUSCA FROM THE CRAG.

Animal narrow, and more or less cylindrical, with the mantle united at the borders,
except in front, where it is open for the passage of a large and truncated foot. Siphons
short and united, their margins fimbriated.

The generic character is here intended for the reception of those species known
under the familiar appellation of Razor Shells, of a form resembling the handle of our
common razors. A few modern authors still consider that the differences possessed
by some of the shells of this peculiar form entitle them to a further division, and have
united, under the name of Ensis, proposed by Schumacher, the species which possess
a lateral tooth or lamina, and reserving to Solen those only in which this linear or
transverse appendage is wanting.

The hinge of this genus is more anterior than that of any of the Bivalves, being
situated at the extremity of the shell. Probably a more than usual strength of union
for the two valves was required at this part to resist the action of its large and
powerful foot, in consequence of the burrowing habits of the animal.*

This appears a modern genus, no true species having as yet been described as
belonging to any Formation more ancient than the Lower Tertiaries, where some of
the species deviate slightly from the type, the hinge not being quite at the extremity.
The few shells somewhat of this form, found in the Palaeozoic Rocks, are very
doubtful Solens.

1. SOLEN GLADIOLUS, Gray. Tab, XXV, fig. 8, a — c.

SOLEN GLADIOLUS. Gray. Zool. of Beechey's Voy., p. 153, t. 43, figs. 4, 4, 1839.

— ENSIS var. MAJOR. Nyst. Coq. Foss. de Belg., p. 44, pi. 1, fig. 3, a, b, 1844.
ENSIS COMPLANATUS. J. Sowerby. Min. Conch., t. 642, figs. 2, 4.

Spec. Char. Testa elongatd, recta, Icevigatd ; extremitate anticd obtuse truncatd j in
valvd sinistrd unidenlalo, in alterd bidentato ; dentibus lateralibus elongatis, marginalia.

Shell lineal or subcylindrical, straight and smooth, anterior extremity obtusely
truncated ; one cardinal tooth in the left valve, and two in the other ; lateral teeth
marginal.

Length, 5 inches. Height, \ inch.

Locality. Red Crag, Walton Naze and Suffolk.

Recent, Arctic Seas.

* Some confusion has existed respecting the anterior and posterior sides of these shells. Poli has
given a good and correct representation of one of the species of this genus, with its foot protruded at the
anterior, and the siphons at the opposite extremity. In the 'Ency. Method.,' vol. iii, pi. 312, fig. 4, the
Solen is depicted with the siphons at the anterior side ; and in pi. I of the ' Hist, of Brit. Moll.,' all the
animals are there represented as having the foot on the posterior or ligamental side of the shell. This is
evidently the result of haste, or of the too numerous avocations of the late much lamented and talented
author of the Malacological portion of that beautiful work, preventing the bestowal of a necessary attention
for the avoidance of these trifling errors.

BIVALVIA. 255

Fragments of this species are by no means rare, and pervade the whole of the Red
Crag Deposit. The specimen figured is one of a pair of valves found in situ at Walton
Naze, but in a very fragile condition, and much reduced in substance. The fragments
from Suffolk display, generally, a greater solidity in the anterior portion, which is
that most commonly obtained.

Much importance has been placed upon differences in proportional dimensions.
In this, the length is about five times that of its height, while in S. siliqua some speci-
mens are as one to eight. The greatest difference appears to be in the impression of
the margins of the mantle ; in this it is more inward, or further from the anterior edge,
and, on the contrary, the more linear shell (8. siliqua} has the impression nearer the
extremity, with a slight difference also in the form of the anterior adductor. The
truncation of this extremity generally forms an angle of about 95°, but this is not
constant ; and I am inclined to believe (although they are here separated in deference
to the recent conchologists, who have better materials to work upon) that the two
forms are merely varieties of one and the same species, the differences of locality and
other conditions producing all the variations shown by the two shells.*

2. SOLEN SILIQUA, Linncem. Tab. XXV, fig. 7, a — e.

SOLEN SILIQUA. Linn. Syst. Nat., ed. 12, 1113, No. 34, 1767.
Poll. Test. Sicil., vol. i, pi. 10, figs. 7—11.
Turt. Brit. Biv., p. 80, pi. 6, fig. 5, 1822.
Phil. En. Moll. Sic., vol. i, p. 4 ; vol. ii, p. 5.
Forb. and Hani. Hist. Brit. Moll., vol. i, p. 246, pi. 14, fig. 3.

— NOVACULA. Mont. Test. Brit., p. 47, 1803.

— LIGULA. Turt. Brit. Biv., p. 82, pi. 6, fig. 6.

— MAJOR. List. Hist. Conch., lib. iii, fig. 255.

Spec. Char. Testa lineari, recta, Icevigatd ; extremitate subtruncatd non marginatd ;
in valvd sinistrd unidentato, in alterd bidentato ; dentibus lateralibus elongatis.

Shell linear or cylindrical, straight and smooth; extremity truncated, not mar-
ginated ; one cardinal tooth in the left valve, and two in the other ; lateral teeth
elongate.

Length, 5 inches. Height, f inch.

* It is possible that a portion of the Red Crag of Suffolk may have been derived from the destruction
of the Older or Coralline Crag Formation, intermixed with the exuviae of animals belonging to the seas of the
former period, as well as with other extraneous fossils. The cliff at Walton Naze, however, affords strong
presumptive evidence that the whole of the Red Crag is not derivative, and that the animals whose remains
are there deposited, lived and died in the spot where they are now found. Bivalves are frequently obtained
in this locality with the two portions united, and it seems scarcely possible that such a specimen as the
above could have been removed out of one Formation to have been deposited, with its two fragile valves
in their natural position, in the mud or sand of a succeeding period.

256 MOLLUSCA FROM THE CRAG.

Locality. Red Crag, Sutton.

Clyde Beds, and Irish Drift.

Recent, Mediterranean, Britain.

This shell, I believe, has not been met with in the Coralline Crag : in the Red
Crag it is not by any means abundant, and always in a fragmentary state. In my best-
preserved specimen, the anterior termination is rather more rounded than that of
the recent species to which it is assigned, but I have not enough to say if such be a
constant character.*

3. SOLEN ENSIS, Linnaeus. Tab. XXV, fig. 6, a—f.

SOLEN ENSIS. Linn. Syst. Nat., ed. 12, p. 1114, No. 35, 1767.

— — Poli. Test. Sicil., vol. i, p. 18, t. 11, fig. 14, 1791.

— — Broc. Conch. Foss. Subap., p. 479, 1814.

— — Gould. Invert. Massach., p. 29, 1841.

— — Desk. Exp. Sclent. Alger., p. 184, pi. 11, figs. 1 — 4.
_ _ Nyst. Coq. Foss. Belg., p. 44, pi. 1, fig. 4, a, b, 1844.

— — Lovtn. Ind. Moll. Scand., p. 49, 1846.

_ _ ? Grateloup. Cat. Zool. Invert. Gironde, p. 68, No. 819, 1838.

— — Sismonda. Syn. Fed. Foss. Invert., p. 23, 1847.

_ _ Forb. and Hani. Hist. Brit. Moll., vol. i, p. 250, pi. 14, fig. 2, 1848.

— CUBVUS. List. Hist. Conch., t. 311, fig. 257.

— ENSIFOEMTS. S. Wood. Catalogue, 1840.

— J. Sowerby. Min. Conch., t. 642, fig. 1.

— ? Conrad. Foss. Med. Tert., p. 76, pi. 43, fig. 8, 1845.

— HAUSMANNI ? Gold/. Pet. Germ., vol. ii, p. 277, pi. 159, fig. 6, a— c, 1842.

Spec. Char. Testa lineari, arcuatd, extremitate anticd curvatd, non marginatd; in
valvd sinistrd unidentato , in alter d bidentato.

Shell linear, curved, anterior extremity rounded, hot marginated ; one cardinal
tooth in the left valve, and two in the right.

Length, 3 inches. Height, \ inch.

Locality. Cor. Crag, Sutton, Ramsholt, Sudbourn.
Red Crag, Sutton, Walton Naze.
Irish Drift (Forbes}.
Recent, N. E. Coast of America, Brit. Seas, Mediterranean, Sea of Okhotsk (Middendorf}.

This species first appears in the Coralline Crag, where it is not very abundant ;

* Since the above was written, I have obtained an imperfect specimen (fig. 7, a, b) of what appears to
belong to this species, judging from its linear character, in which the muscular impressions are, like those
of S. gladiolus, at a greater distance from the anterior margin, and which I first imagined to be a tangible
distinction. I now believe the two may be specifically united.

BIVALVIA. 257

but at Walton Naze, in the Red Crag, small specimens and fragments may be plenti-
fully obtained.

The same proportional and other differences exist between this and the recent
British shell as between 8. siligua and $. gladiolus, and on that account I imagined it
to be specifically distinct when my ' Catalogue' was drawn up, and proposed for it the
name of S. ensiformis, from its near relationship ; but I now believe the Crag shell to
be entitled to no more, if scarcely so much, as a distinct variety, the form and position
of the muscular impression varying according to the greater elongation of the shell
being nearer the extremity in the more lengthened or attenuated varieties, this elonga-
tion probably being dependent upon some peculiarity of habit or locality.

In some specimens given to me as Solen Americanus, the proportional length is even
greater than in the recent British shell, and with a rounded termination ; and none
of the specimens that I have seen from America appear entitled to a specific appellation
different from that of ensis.

S. marginatm has, in the living state, a wide geographical range, being found on
the coast of Finmark (Loveri), and according to Von Hemprich is an inhabitant of the
Red Sea ; but I have never met with a fragment in any of the Crag Formations that
could be justly assigned to that species.

8. (Ceratisoleri) legumen is given by Mr. Smith in his 'List of Shells from the Clyde
Beds.'

CULTELLUS,* Schumacher, 1817.

CULTELLUS. Desmoul. 1832.

SOLEN (sp.) Spengler, Linn., Chemn.

Generic Character. " Testa aquivalvis, transversim oblongd, subcomplanatd utrinque
hians. Car do in valvd dextrd ; denies duo cardinales subcompressi alter erectus, alter
decumbens. In valvd sinistrd cardinales ires medius sub-bifidus, apicibus divaricatis
anterior decumbens. In utraque valvd callus marginalis" — Schum.

Type. Solen cultellm. Animal ?

There is, I think, full justification for considering this as entitled to generic isola-
tion ; the very peculiar form of the hinge furniture, as well as the position of the
ligament (being removed to some distance from the extremity), are characters very
different from those of Solen.

There are at present but few species known, either in a recent or fossil state,
possessing the above characters. Two or three shells, with this peculiar form of hinge,
have been obtained from the Older Tertiaries, but I am not acquainted with any of an

anterior date.

* Etym. Cultellus, a little knife.

34

258

MOLLUSCA FROM THE CRAG.

CULTELLUS TENUIS, Philippi. Tab. XXV, fig. 2, a — d.

SOLEN TENUIS. Phil. En. Moll. Sic., vol. i, p. 6, pi. l,fig. 2, 1836.
Id. En. Moll. Sic., vol. ii, p. 5, 1844.

— GENUIS. Nyst et West. Nov. Rech. Coq. Foss. d'Anv., p. 3, No. 4, 1839. Mis-

print. ?

— TENUIS. Nyst. Coq. Foss. de Belg., p. 46, pi. 1, fig. 5, 1844.
CULTELLUS CULTELLATUS. S. Wood. Catalogue, 1840.

J. Sowerby. Min. Conch., t. 642, figs. 5 — 8.

Spec. Char. " Testa oUongo-tineari, recta, utrinque rotundatd, tenuissimd ; cardinibus
lateri antico approximates, in valvuld dextrd bidentatis, in sinistrd tridentatis." — Philippi.

Shell linearly oblong, straight, rounded at both extremities, very thin ; very inequi-
lateral ; two cardinal teeth in the right valve, and three in the left.

Length, lj inch.

Locality. Cor. Crag, Button.

Red Crag, Walton Naze.

This shell is rare in my cabinet. Two specimens of the right valve, and one of the
left, from Walton-on-the-Naze, are all that I have seen.

The Coralline Crag at Sutton has furnished numerous fragments sufficient to justify
the belief in their identity with the Belgian fossil and the Mediterranean species,
but it is not S. pellucidus, Penn. M. Philippi's figure shows a much greater
inequilaterality than our fossil, one side being four times the length of the other
(probably an error of the artist). In the Crag shell the proportions are as two and
a half to one.

It is somewhat broader or higher on the siphonal side, and equally rounded
at both extremities. The right valve is furnished with two cardinal teeth, the
anterior one is vertical and compressed, the other larger and diverging. In the left
valve are three teeth, the centre one is large, and deeply cleft or bifid, one por-
tion decumbent, almost parallel with the ligamental fulcrum. The muscular marks
in my specimens are indistinct.

The shell to which this appears to bear the nearest relationship (judging alone
from the drawing of the exterior), is one obtained in the Corea, figured by Messrs.
Reeves and Adams (Solen albida), e Voy. of the Samarang, 1850/ p. 84, pi. 23, fig. 15.

THRACIA, Leach, MS. 1819.

MYA (sp.) Montague, 1803.
LIGULA (sp.) Id. 1808.
AMPHIDESMA (sp.) Lamk. 1818.
AKATINA (sp.) Id. 1818.

IXARTIA. Leach, MS. 1819.
THRACIA. Blainv. 1825. Rang. 1829.

OSTEODESMA (sp.) Blainv. 1825.
ODONCINETUS. Da Costa, 1829.
CORIMYA (sp.) Agass. 1842.
ODONTOCINETA. Id.
CINETODONTA. Herrm. 1847.

BIVALVIA. 259

Generic Character. Shell transversely ovate, inequivalve, often nearly equilateral ;
tumid or compressed, generally thin, slightly gaping; surface smooth or minutely
granulated. Hinge with an internal cartilage attached to a projecting callosity. Often
a small cleft in the umbo, formed by the ligament. Impressions by the adductors
unequal ; mantle-mark deeply sinuated.

" Animal ovate ; mantle closed, except for the passage of a compressed linguiform
foot ; siphons rather long, separated to their bases, and furnished with fimbriated
orifices, which are often inflated into a globular form." — Clark.

M. Deshayes having discovered a detached ossiculum in the hinge of one or more
species possessing somewhat similar external characters, presumed it to exist in all,
and proposed, in consequence, a family (Osteodesmida) founded upon this character,
distinguishing the genera by the peculiar form of this " little bone," and its position
in the hinge, it being held between the cardinal callosities by a portion of the internal
ligament, sometimes close to the anterior, at others on the opposite part of the
cartilaginous area.

The distinctions founded upon such characters are but doubtfully sufficient for
generic separation, even where its position could be correctly determined. There is,
however, a peculiarity in the calcareous callus of the hinge, or support for the
ligament, in this genus, sufficient to prevent its being confounded with any other.

The shells are generally thin, with a rugose or scabrous exterior. They are
probably of great antiquity, as fossils of this form are found in the lower Oolites, and
doubtfully so in the Carboniferous series.

In the living state, the species frequent sandy or sandy-mud shores, and have a
range from low-water mark to very considerable depth. Dead shells have been found
as deep as 110 fathoms.

1. THRACIA PUBESCENS, Pulleney. Tab. XXVI, fig. 1, a — d.

MYA PUBESCENS. Pult. In Hutchins' Dorset., p. 27.

Turt. Conch. Diet., p. 99, fig. 35, 1816.
— DECLIVIS. Donov. Brit. Shells, vol. iii, pi. 82, 1801.
ANATINA MYALTS. Desk. 2d ed. Lamk., vi, p. 80, 1835.

— Crouch. Int. to Lamk. Conch., p. 7, pi. 4, fig. 1, a, b, 1827.

PUBESCENS. Turt. Brit. Biv., p. 45, 1822.
AMPHIDESMA PUBESCENS. Flem. Brit. An., p. 431, 1828.
THRACIA PUBESCENS. Kiener. Coq. viv. Thracia, p. 5, pi. 2, fig. 2.
Desk. Exp. Moree. Zool., p. 87, pi. 18, fig. 1.
Couth. Bost. Journ. Nat. Hist., vol. ii, p. 135, 1839.
J. Sow. Min. Conch., t. 631, fig. 1, 1844.
Forbes. JEgean Invert., p. 182.

Forb. and Hani. Hist. Brit. Moll., p. 226, pi. 16, figs. 2, 3.
MONTAGUI. Leach, MSS., 1818. Ann. and Mag. Nat. Hist., vol. xx, p. 272, 1847.
LLGULA PUBESCENS. Mont. Test. Brit. Supp., p. 23, 1808.

260 MOLLUSCA FROM THE CRAG.

Spec. Char. Testa ovato-oUongd, transversd, convexiusculd, tenui, subcequilaterali,
antice rotundatd, postice truncatd, et angulatd ; punctis minutissimis asperatd ; callo
ligamentifero magno.

Shell ovately oblong, transverse, slightly convex, thin, subequllateral, anterior side
rounded, posterior truncated and angulated, exterior minutely granulated ; hinge with
large projecting callus, divided by a ridge.

Length, 2J inches. Height, 2^ inches.

Locality. Cor. Crag, Sutton and Gedgrave.

Clyde Beds. Smith. Recent, Britain and ^gean.

A thin and fragile shell, not very rare, but difficult to obtain. Like most of the
specimens of this genus found in the Crag, they are somewhat distorted from com-
pression, and one or other of the valves in consequence cracked, thereby altering a
little the natural appearance of the shell. On closely comparing it with the existing
species, it may be remarked that the left valve is rather less contracted, — that is, the
ventral margin is more convex, or not so straight, as in the living shell, and the umbo
apparently less prominent ; but the few specimens that I have seen are all pushed a
little out of their natural position, and these trifling differences would probably
disappear in a larger and better series.

2. THRACIA PHASEOLINA, Lamarck. Tab. XXVI, fig. 2, a — c.

MYA DECLIVIS. Turt. Conch. Diet., p. 98, 1816.
ANATINA DECLIVIS. Id. Brit. Biv., p. 47, 1822.

PUBESCENS. Id. Brit. Biv., p. 45, t. 4, fig. 3 (young).

AMPHIDESMA PHASEOLINA. Lamk. Hist. Nat., torn, v, p. 492, No. 11, 1818.
THKACIA PHASEOLINA. Keiner. Coq. viv. Thracia, pi. 2, fig. 4.

Phil. En. Moll. Sic., vol. i, p. 19, t. 1, fig. 7, 1837.

ODONCINETA PAPYRACEA. Da Costa. Test. Sicil., p. 23, pi. 2, figs. 1 — 4, 1829.
THRACIA PHASEOLINA. Forb. and Hani. Hist, of Brit. Moll., p. 221, pi. 17, figs. 5, 6 ;

and pi. H (animal), fig. 4, 1848.

Couth. Bost. Journ. Nat. Hist., p. 147, 1839.

Loven. Ind. Moll. Scand., p. 46, No. 321, 1846.
TELLINA PAPYKACEA. Poli. Test. Sicil., t. 15, fig. 18.

Spec. Char. Testa elongato-ovatd, transversd, subcequilaterali, tumidiusculd, tenui;
antice rotundatd, postice truncatd ; margine ventrali convexiusculo.

Shell elongato-ovate, transverse, nearly equilateral, thin, and fragile ; anterior side
rounded, posterior truncated ; ventral margin slightly rounded.

Length, 1 inch. Height, -f inch.

Locality. Cor. Crag, Sutton.

Recent, Britain, Mediterranean, Scandinavia.

Small specimens are by no means rare at Sutton ; and as the recent conchologists
profess to have sufficient evidence for the separation of this from the young of T.

BIVALVIA. 261

pubescens, I have followed their example, although the characters for specific separation
are not clearly defined, — the distinction appearing to rest solely upon one being more
transverse than the other. There is, I think, little doubt but the so-called two species
lived in the sea that deposited the Coralline Crag.

Two or three fragments of what may be this species, or the young of the preceding,
are in my cabinet, from the Red Crag of Sutton ; and a specimen belonging to this
transverse form is in the cabinet of Mr. Morris, from Uddevalla.

Thracia detruncata, of my ' Catalogue' (fig. 1, e), is probably only a distorted
specimen of a young individual of either this or of the preceding species.

The umbo is cleft by the ligament, which must have been visible when the valves
were closed.

3. THRACIA INFLATA, /. Sowerby. Tab. XXVI, fig. 6, a — e.

THRACIA CONVEXA. 1 S. Wood. Catalogue, 1840.

— INFLATA. J. Sow. Min. Conch., t. 631, figs. 2 — 4, 1845.

CONRADI. 1 Couth. Bost. Journ. Nat. Hist., vol. ii, p. 153, pi. 4, fig. 2, 1839.

Spec. Char. Testa obovatd, convexa, injiatd, subl&vigatd, tcnui, fragili ; antice
rotundatd, postice subtruncatd et angulatd ; margine ventrali arcuato.

Shell obovate, convex, tumid, nearly smooth, thin and fragile ; anterior side
rounded, posterior angulated and pointed ; ventral margin curved.

Length, 3>\ inches. Height, 2| inches.

Locality. Cor. Crag, Sudbourn.

This species appears to be restricted to the neighbourhood of Orford, where it is not
at all scarce, though the specimens are rarely in perfect condition : they are generally
more or less compressed, and the inflated character destroyed. Amongst my specimens
a considerable variation may be observed, some being much more elongated than
others.

The right is the thinner and more inflated valve, and the one that is generally
fractured and compressed. Impressions by the adductors are unequal in size, and the
sinus in the mantle-mark is rounded and rather deep. A small sinus is visible at the
umbones, through which the ligament must have protruded ; but that part of the shell
being particularly thin, it is there generally destroyed or injured. The hinge is an
elongated callosity, on which was placed the cartilage, with a linear depression or
furrow on the outside of it for the ligamental portion, differing from that of T.pubescens,
in which this callus is of a triangular form and projects inwardly. The exterior is
smooth, with the exception of lines of growth and some rugosities, particularly upon
the siphonal side ; but it has not the shagreen-like sculpture which ornaments the
entire surface of T. pubescens.

262 MOLLUSCA FROM THE CRAG.

From the want of a good series of very perfect specimens, it is difficult to say
whether this be really distinct. T. corbuloides appears to have the anterior side the
smaller ; and although T. Conradi comes very near to our Crag fossil, it differs also in
the same character, and has a rather more prominent umbo. A difference also is shown
in the sinus, which is not only deeper, as it would naturally be from the difference in
the proportion of the sides, but it appears somewhat more angular in the recent
American shell. I am, however, inclined to believe, that when a better comparison
can be instituted, it may be found not to differ specifically from T. Conradi.

4. THRACIA VENTRICOSA, Philippi. Tab. XXVI, fig. 5, a — c.

THKACIA PUBESCENS. Phil. En. Moll. Sic., vol. i, p. 19, t. 1, fig. 10, 1836.
VENTRICOSA. Id. Eii. Moll. Sic., vol. ii, p. 17, 1844.

Spec. Char. Testa ovato-oblonffd, tumidd, subcequilaterali, inaquivalvi, tenui ; antice
angustatd, postice truncatd, et angulatd ; valvd dextrd tumidiore ; umbonibus magnis
recurvatis ; margine ventrali conveusiusculo.

Shell ovately oblong, inequilateral, tumid, inequivalved, thin ; anterior side slightly
produced, posterior truncate and angulated ; right valve the more tumid ; beaks large ;
ventral margin slightly curved.

Length, If inch. Height, \\ inch.

Locality. Cor. Crag, Ramsholt, Gedgrave.
Fossil, Sicily.

Two or three specimens only have come into my possession. They are assigned to
the Sicilian species with a slight degree of doubt, differing somewhat from a
Sicilian fossil in my cabinet, which I presume to be the T. ventricosa. It is rare to find
the fossils belonging to this genus in a perfect condition, their extreme thinness being
insufficient to preserve them in their natural form, and their characters in consequence
are difficult to determine.

Our fossil is finely granulated all over, more particularly so on the siphonal side,
differing from the preceding (T. injlatd), the shells of which are nearly smooth. Philippi
represents his shell as equivalved; but in my Sicilian fossil there is an evident
inequality in the valves, and the proportions of the two sides do not exactly cor-
respond.

There is a linear depression for the ligamental portion of the hinge, and the support
for the cartilage is very narrow, giving it almost the appearance of having an entirely
external ligament.

T. convexa is said by Messrs. Forbes and Hanley to be found fossil in the Newer
Tertiaries or Pleistocene Clays of Belfast, as also in the Clyde Beds.

BIVALVIA. 263

COCHLODESMA,* Couthouy, 1839-

SPOONHINGE. Petiver, 1764.
LATERNULA. Bolten, 1798.

BONT.EA. Leach, MS. 1819. Gray, 1851,
GALAXURA. Id. 1819.

MYA (sp.) Mont. 1803. PERIPLOMA. ? Se/iH»z. 1817.

LIGULA (sp.) Id. 1808. AMPHIDESMA (sp.) J?7ewz. 1828.

AURISCALPIUM. Muhlf. 1811. THRACIA (sp.) Loven. 1846.

ANATINA (sp.) iam>t. 1809. Woodw. 1854.

Generic Character. Shell thin, transversely ovate, slightly inequivalved, inequi-
lateral, gaping, rather compressed, right valve the more convex. Hinge with a
spoon-shaped process in each valve, for the reception of the cartilage, with a
minute fissure in the umbo, through which the ligament slightly projects.
Surface smooth, or finely granulated, especially on the siphonal side ; covered in the
recent state with a fine epidermis. Adductor muscles slightly impressed, with a sinus
in theimpression of the mantle.

Animal with its mantle closed, except in front, for the emission of a broad com-
pressed foot ; siphons long and slender, divided in their whole extent.

This genus closely resembles that of Thracia, in the animal as well as in the
shell, differing in the latter, however, by having the support for the cartilage of a more
spatulate or spoon-shaped form, which is less intimately united along the dorsal edge,
and in the absence from the hinge of the ossiculum.

The name Anatina was proposed as a genus by Lamarck in 1809, taking for his
type Solen anatinus, Linn., a shell in some respects similar to those here included, by
having a spoon-shaped process projecting inwardly, upon which was placed its internal
ligament. It has, however, a very wide gape, and the animal has long and united
siphons, clothed with a wrinkled epidermis; while the animal of Cochlodesma has
its siphons long, slender, and divided throughout. The animals, therefore, being
so dissimilar, they are scarcely entitled to the same name, nor could they be
included in the above generic diagnosis.

I have never seen a shell with this form of hinge from any Formation of an age
anterior to that of the Coralline Crag.

1. COCHLODESMA COMPLANATUM, S. Wood. Tab. XXVI, fig. 3, a, b.

Spec. Char. Testa compressd, elongato-subovatd, Z&vi, inceguilaterali, tenui ; antice
majiore, rotundatd ; postice subtruncatd ; valvd sinistrd depressd ; sinu pattiari mediocre.
Shell compressed, elongately ovate, smooth and very thin, inequilateral ; anterior

* Etytn. icoxXos, shell, and $es^a, ligament.

•'<;i MOLLUSCA FROM TIM-; Cll.Ui.

side the larger, and rounded ; left valve much depressed ; palleal sinus of moderate size,
rather broad.

Length, \ inch. Height, -fa inch.

Locality. Red Crag, Walton Naze.

About half a dozen perfect specimens are in my cabinet : unfortunately they are all
the left valve.

In comparing my fossils with a specimen of Cochlodcsma Leanum, Couthouy, ' }\
Journ. Nat. Hist,' vol. ii, p. 170, (a recent species from America, and its nearest
relative,) the Crag shell appears to be less equilateral, the siphonal side being much
the shorter of the two, and I have in consequence considered it distinct. Our shell
maybe further described as rather flatter compressed, the left valve being the more so
of the two, judging from a fragment of the right one in my cabinet; the umbones are
slightly prominent, and cleft by the ligament; the spoon-shaped process is broad and
strong, projecting towards the anterior ; the exterior shows merely lines of growth,
with a slight rugosity on one side, but it is not covered with the granulated or
vshagreen surface of C. pratenue ; the palleal sinus extends inwardly, a little beyond a
line drawn perpendicularly from the umbo.

2. COCHLODESMA PIUETENERUM, 8. Wood. Tab. XXVI, fig. 4, a, b.
ANATINA PR^TENERA. S. Wood. Catalogue, 1840.

Spec. Char. Testa trawversd, ovatd, incequilaterali, intcquivalvi, tenui, frayili ;
rotundatd conveximculd ; postice breviore, truncatd, subrottratd ; tenuissime yranulatd.

Shell transversely ovate, inequilateral, inequivalved, thin and fragile, with a finely
granulated exterior ; anterior side the larger, rounded, and slightly tumid ; ventral
margin curved.

Length, f inch. Height, \ inch.

Locality. Cor. Crag, Button.

I have about half a dozen specimens of this shell. It differs from C. pratenue in
having the siphonal side shorter, narrower/ and truncated, with a more distinct
angular slope from the umbo to the ventral margin ; the anterior dorsal edge is very
thin, and slightly folded over, with a small sinus at the extreme point of the umbo,
through which the ligament was visible, and probably projected somewhat; the
exterior is smooth to the naked eye, but under a magnifier appears finely granulated.
The impressions by the adductor muscles indistinct ; the palleal sinus extends a little
beyond the cartilage support.

A small specimen in my cabinet, from the same locality, strongly resembles, and
is probably the young state of C. pratenue, but the hinge is injured. I have some
fragments also of what may perhaps be another species, with a very scabrous

BIVALViA. 265

surface, which passed in my ' Catalogue' under the name of A. asperima ; they are too
imperfect for further notice. The siphonal side appears too short to belong to
C. prtetenue, and too rugose for the present species.

PHOLADOMYA, G. Sowerby, 1823.

CARDIUM (sp.) Mantel I. J. Sowerby.
LUTRARIA (sp ) J. Sowerby.
CARDITA (sp.) J. Sowerby.

Generic Character. Shell very thin, transparent or hyaline, of a nacreous texture,
transverse, ovate or cordiform, ventricose, equivalved, inequilateral; anterior side
short, posterior produced and gaping. Hinge with a small obtuse tooth. Ligament
external. Mantle-mark deeply sinuated.

Animal of the form of the shell, with the edges of the mantle united, except where
open for the emission of the foot, which is bifurcated. Siphonal tubes large.

Only one species of this genus is known in the living state, and that is an inhabi-
tant of the tropics and was found at St. Lucia.* The animal of this has been examined
by Professor Owen, whose observations thereon were made known at the Zoological
Society in 1842.

Its position, as indicated by the animal, is considered by that anatomist to be near
to Panop&a. Dr. Gray, in his arrangement, has placed it between Cardita and Astarte.

It is, no doubt, very nearly related to a group of shells largely developed in the
Secondary Formations, for wrhich M. Agassiz proposed to establish a family under the
name Myada, ' Etudes Critiques sur les Mollusques fossiles.' These he separated into
several genera, the divisions depending sometimes upon the hinge furniture, but in
most instances upon the outward form of the shell, a dependence by no means safe.f
These fossils are generally found in a state of casts only, though some few of them
have been obtained exhibiting portions of the shell attached, showing them to have
possessed a thin, oftentimes a papyraceous and transparent shell, of a nacreous texture,
and they were in most instances covered with a papillaceous or scabrous exterior. Thev
bear a considerable inter-resemblance in their general character, and are no doubt
intimately connected zoologically ; but they are of very doubtful relationship to Mya,
the reputed father of the family, whose age we are unable to date beyond the
Tertiaries.

* Ph. crispa and Ph. caspica, given by Agassiz in his 'Monog. of the Myadse' as existing species,
belong to, or at least are nearly related to, the genus Cardium, and differ only in having elongated siphons,
and a sinuated mantle-mark (Adacna, Eichwald). Lyonsia navicula, Reeves, 'Voy. of the Samarang,'
p. 38, pi. 23, fig. 1 1, may perhaps be an aberrant form of this genus.

f This family has been ably analysed by Professor Morris in his recent ' Descriptions of the Fossils of
the Great Oolite.'

35

266 MOLLUSCA FROM THE CRAG.

Pholadomya is a genus of great geological antiquity, being known as early as the
Coal Measures, and continued to the present time through the Secondary Periods,
where it was largely developed, presenting only a few species in the Tertiaries.

PHOLADOMYA HESTERNA, /. Sov&rbf. Tab. XXX, fig. 1, a — d.

PHOLADOMYA CANDIDOIDES. S. Wood. Catalogue, 1840.

— HESTERNA. J. Sow. Min. Conch., t. 629, 1844.

Spec. Char. Testa transversd, ovato-oblonyd, aut irregulariterpyriformi, valde incequi-
laterali ; antice ventricosd, rotundatd vel subtruncatd ; postice productd • mediand parte
costatd, costis 10 — 12.

Shell transverse, ovately oblong or of an irregular pear-shape, very inequilateral »
anterior side ventricose, rounded, or slightly truncated ; posterior much produced ;
centre covered with about 10 or 12 ribs.

Length, 4 inches. Height, 2^ inches.

Locality. Cor. Crag, Ramsholt and Sudbourn.

This species, as might be expected, is found only in beds which have undergone no
disturbance ; and at Ramsholt, where these shells are quietly deposited in the sand, I
have seen many specimens, but they are exceedingly difficult to obtain, and then with
only a small portion of its thin shell remaining. Like those from some parts of the
London Clay, the specimens are in general much distorted. Our figure is from one
that has preserved its natural form ; and although there is a considerable resemblance
to the only living species that has as yet been discovered, it seems to be specifically
distinct. The recent shell, Ph. Candida, is more tumid centrally, and less rounded on
the anterior side, while on the other it is not so broad, and there is a greater curve in
the ventral margin. Our shell appears to have been closed on the anterior side, but
had a gape or opening for its probably lengthened siphonal tubes. The hinge is
furnished with a small obtuse tooth in each valve, and a marginal lamina or fulcrum
for the ligament, this is bipartite, separating slightly the cartilage from the ligament ;
the umbones, like those of the recent shell, approximate so closely as to have been
fractured by the opening of the valves. The ribs of our shell extend over rather more
than half the surface, from the obtuse ridge on the anterior side to within about the
same distance from the other extremity, and they are covered with small obtuse tuber-
cles ; while the small portions of the shell that are remaining present a finely granulated
surface, or shagreen, like those of Anatina. This is especially visible near the siphonal
extremity, but was probably more or less granular all over. Ph. arcuata, Agass., ' Etud.
crit.,' p. 63, t. 2, b, figs. 1 — 8, resembles our shell, judging from the figure, but appears to
have had too many ribs. Ph. Esmarkei (Pusch), Goldf., ' Petr. Germ./ vol. ii, p. 272,
t. 157, fig. 10, a — d, may probably be the same. I have been unable to examine
specimens of either, and have therefore retained Mr. Sowerby's name.

BIVALVIA. 267

POROMYA, Forbes, 1843.

CORBULA (sp.) Nyst aud West., 1839.
EMBLA. Lovtn, 1846.

Generic Character. " Shell ovate or suborbicular, equivalve, inequilateral, slightly
produced posteriorly ; surface invested with a scabrous epidermis, beneath which it is
pearly and minutely punctated ; hinge of a minute cardinal ossicle or erect tooth in
one valve, lodged in a pit, or rather depression in the other ; no lateral teeth ; ligament
external ; palleal impression very slightly sinuated.

" Animal with its mantle open in front ; foot long, narrow, and slender ; siphons
short, unequal, with 18 or 20 tentacles surrounding their bases." — Forb. and Hani.

" Testa tequivaluis, postice hians, truncatd ; ligamentum internum/by&® utriusque valvce
insertum, ante quam in v. d. dens cardinalis, in v. s. fossa cardinalis ; in v. s. dens lateralis
anticus et posticus ; in v. d. fossa lateralis, denies laterales nulli. Impressio pattiaris lata,
duplicate) postice leviter sinuosa.

" Animal pallio venire aperto, postice longe cirrigero, siphonibus instructum." — Loven.
Genus, Embla.

Mr. Woodward, in his ' Rudimentary Treatise of Recent and Fossil Shells,' has
concluded the Poromya of Forbes to be a species only of the genus Thetis.

The establishment of a genus by the above-named eminent and able modern authors
upon an existing shell, the one describing it as possessing an external ligament, while
the other considers it to have an internal one, leaves it, as it were, a sort of open
question, or placing it rather in a doubtful position. The type of the genus Thetis has
an external ligament, whereas in the recent British shell and Crag fossil the hinge
furniture is more complex ; and although a portion of the ligament might have been
seen externally when the valves were closed, the larger or cartilaginous part was
situated within the edge of the shell, and its action like that of an internal ligament,
opening the valves by expansion on the removal of pressure ; no portion of which
internal ligament appears to be present in those fossils constituting the genus Thetis ;
and as I am imposing no new name for the Crag shell, the correct position must be
determined by better materials than I possess ; though, judging from my own speci-
mens, I am inclined to believe with Professor Loven, that the action of its ligament
was that of an internal one ; and although the greensand fossils are no doubt closely
related, the difference in position or action of the ligament is sufficient to justify the
separation.*

* The boundary line of generic isolation is indeed exceedingly difficult to define. We all of us give
what we conceive to be a limit, but the want of accordance in this respect shows at least that we are as yet
very far from having discovered it. The different positions of the ligament in Bivalves, whether acting
internally by compression and dilatation, or externally by contraction and elongation over a fulcrum, are
distinctions as good as nine out of ten of the characters that are generally employed for these conventional
divisions.

268 MOLLUSCA FROM THE CRAG.

The recent species Neara kyalina, Hinds, appears to be more nearly connected with
Thetis, having an external ligament on a thin and semi-transparent shell, differing
thereby from our fossil, which is a thick one. The two shells figured by Messrs.
Reeves and Adams in the 'Zoology of the Voyage of the Samarang/ may perhaps
belong to Thetis, but the position of the ligament is not stated, and the shells are
described as being quite smooth and thin.

The Cretaceous fossils of India and Westphalia, assigned to this genus, have not
as yet had their characters sufficiently well determined.

1. POROMYA GRANULATA, Nyst and Westendorp. Tab. XXX, fig. 5, a— -f. .

CORBULA GRANULATA. Nyst and West. Nouv. Rech. Coq. Foss. d'Anv., p. 6, No. 10,

pi. 3, fig. 3, 1839.

— ? — Nyst. Coq. Foss. de Belg., p. 71, pi. 2, fig. 6, 1844.

— ? — Jeffreys. An. and Mag. Nat. Hist., vol. xix, p. 314 ; and vol. xx,

p. 19.
POROMYA ANATINOIDES. Forbes. JEgean. Invert. Brit. Assoc. Report, p. 191, 1843.

— GRANULATA. Forb. and Hani. Hist, of Brit. Moll., p. 204, pi. 9, figs. 4 — 6,

1848; and Animal, pi. w, fig. 2, 1853.
EMBLA KORENII. Lov6n. Ind. Moll. Scand., p. 46, 1846.

Spec. Char. Testa ovatd, ventricosd, subtequilaterali ; antice rotundatd, postice trun-
catd, et obtuse angulatd; aculeis minutissimiss criberrimis aspera; umbonibus prominenti-
bus ; dente unico obtuso.

Shell ovate, ventricose, slightly inequilateral ; anterior side rounded, posterior
truncated, with an obtuse keel or ridge retreally from the umbo to the ventral
margin ; beaks prominent ; one obtuse tooth.

Length, J inch. Height, f inch.

Locality. Cor. Crag, Ramsholt, Sutton, and Gedgrave.

Recent, ^Egean, British, and Scandinavian Seas.

About a dozen disconnected valves have been obtained by myself, several of them
sufficiently perfect for fair comparison, and I have considered them as identical with
the Belgian fossil and the ^Egean and Scandinavian shell.

The hinge of the right valve is furnished with one large obtuse tooth, situated
immediately beneath the umbo, and in the left there is a corresponding cavity between
two small prominences for its reception ; behind these, and within the dorsal margin,
is a depression wherein, I presume, the ligament was placed : this cavity is divided by
a small ridge, which appears to have separated the cartilage from the ligament, and
the latter probably was visible externally when the valves were closed : there is a
small depression on the siphonal side at the dorsal edge, what may perhaps be
called the corslet, produced probably by the opening of the valves ; but there is no
ridge or fulcrum for the support of an external ligament. The impressions by the

BIVALVIA. 269

adductors are rather small and deep, and the mantle-mark has an irregular sinus, by
no means large. The shell is beautifully nacreous within, and the exterior is
ornamented with papillae oivgranulations, studded somewhat like the barrel of a
musical box.

In the living state this species has been met with in deep water, while some of its
associates in the Coralline Crag are very shallow-water forms. Mr. Jeffreys has
dredged it off the Isle of Skye in 50, and Professor E. Forbes obtained it in the ^Egean
at the depth of 150 fathoms.

At page 148 (ante), I had supposed the genus Thetis to have been nearly related
to Lucinopsis, but this allocation is probably incorrect. In Mr. Woodward's ' Rudi-
mentary Treatise of Recent and Fossil Shells/ it is arranged in his family Myacida.
I think, however, the present species, Poromya granulata, cannot be correctly placed,
as it is there, between the genera Mya and Panopea.

Corbula gigantea, J. Sowerby, Thetis gig antea, Woodward, has a granulated exterior,
with an external ligament, and faint or obsolete costse ; and if it be not a true Phola-
domya, it forms a connecting link between that genus and Thetis.

PANDORA,* Brug. 1792.

HYPOG^EA and HYPOGEODERMA (sp.) Poli.
TELLINA (sp.) Linn.
SOLEN (sp.) Mont.

CALOPODIUM. Bolten, 1798.
TRUTINA. Brown, 1827.

Generic Character. Shell transverse, inequivalve, inequilateral, ovate or subrhom-
boidal, externally smooth and of a nacreous texture, gaping at the anterior extremity,
one valve flat, the other more or less convex. Hinge with a prominent obtuse tooth
upon the right or flatter valve, and a corresponding depression for its reception in the
opposite one. Impressions of the adductor muscles subcircular, with a small or scarcely
perceptible sinus in that by the mantle. Ligament internal.

The mantle is described as nearly closed, with a small passage for a narrow tongue-
shaped foot ; and the siphons are represented as very short, united nearly to their
orifices, which are fringed, and diverging.

The inequality of the valves and internal ligament have been considered as charac-
ters sufficient to approximate this genus to that of Corbula, from which, however, it is
sufficiently removed, as essential differences exist in the animal inhabitant, but more
especially in the composition of its shell. In the examination and report by Dr.

* Etyrru Pandora, a proper name. This was given also to the inequivalved Pectens, probably from
their box-like character.

270 MOLLUSCA FROM THE CRAG.

Carpenter, that gentleman seems to think it so peculiar, as almost to constitute a
family by itself. He describes the exterior as composed of regular prismatic cells,
the axes of the prisms being perpendicular to the surface, while the interior is
nacreous.

No well-determined species have been met with in the fossil state in any Formation
older than the Paris Basin. A shell from the Carboniferous Series is described by
Professor M'Coy under this name ; but its claim to a place in this genus is very
doubtful.

1. PANDORA IN^EQUIVALVIS, Linn. Tab. XXV, fig. 5.

TELLINA IN^EQUIVALVIS. Linn. Syst. Nat., ed. 12, p. 1118, No. 56, 1767.

Poli. Test. utri. Sicil., vol. i, p 39, pi. 15, figs. 5, 6, 9, and 7
with the animal.

— Don. Brit. Shells, vol. ii, pi. 41, fig. 1, 1800.
PANDORA ROSTRATA. Desk. 2d ed. Lamarck, torn, vi, p. 145.

— G. B. Sowerby. Spec. Conch. Pandora, p. 2, No. 2, figs. 7—9.

— Phil. En. Moll. Sic., vol. i, pi. 1, fig. 12, 1836.

— Desk. Exp. Scient. Alger. Moll., pi. 24, animal.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 207, pi. 8, figs. 1—4.

— MARGARITACEA. Lamk. Hist, des An. s. Vert., torn, v, p. 137.

— Schum. Essai des Vers. Test., p. 114, pi. 4, fig. 2.
_ _ Turt. Brit. Biv., p. 40, pi. 3, figs. 11—14, 1822.

— IN^EQUIVALVIS. Flem. Brit. Anim., p. 466, 1828.

Spec. Char. Testa elongato-ovatd, l&vigatd, tenui fragili, incequilaterali ; later e postico
longiore, attenuate subrostrato, hinc in utrague valvd anyulato.

Shell elongately ovate, smooth, thin and fragile, inequilateral ; posterior side the
longer, attenuated, and somewhat beaked, slightly angulated in each valve.

Length, f inch. Height, f inch.

Locality. Cor. Crag, Sutton. Recent, Britain and Mediterranean.

My specimens of this species are but few, and those not in good condition. The
one figured has the siphonal area elongated into the form of a rostrum or beak, and
corresponds with what the British conchologists have considered a distinct species.
In the young state, as indicated by the lines of growth, the dorsal margin is more
convex than concave, and the shell comparatively broader, like P. Pinna, and there is
no appearance then of a rostrum.

2. PANDORA PINNA, Montague. Tab. XXV, fig. 4, a—c.

SOLEN PINNA. Mont. Test. Brit., p. 566, t. 15, fig. 3, 1803.
PANDORA OBTUSA. Leach. Ross's Voy. Baffin's Bay, p. 174, 1819.

BIVALVIA. 271

PANDORA OBTUSA. Desk. 2d ed. Lamarck, torn, vi, p. 145, No. 2.

G. B. Sowerly. Spec. Conch. (Pand.), p. 2, figs. 1—3.

Phil. En. MoU. Sic., vol. ii, p. 14, t. 13, fig. 13.

Forb. SLuAHanl. Hist. Brit. Moll,, vol. i, p. 210, pi. 8, fig. 5; and

pi. G, fig. 10, animal.
TRUTINA SOLENOIDEA. Brown. Illust. Brit. Couch., pi. 13, fig. 5, 1827.

Spec. Char. Testa obtme-elongatd; later e postico versus extremitatem dilatato; margine
dor soli planiusculo.

Shell obtusely elongate ; posterior side dilated towards the extremity; dorsal margin
nearly straight.

Length, -f inch. Height, f inch.

Locality. Red Crag, Walton Naze.

Only two or three specimens of this species have fallen under my observation, and
I have, in deference to the malacologists, separated this from what is called rostrata.
Colonel Montague, who, notwithstanding his having described the two shells under
different generic names, was afterwards of opinion that the one was only the younger
state of the other. Messrs. Forbes and Hanley consider the characters of the animal,
as well as those of the shell, to be quite distinct, and have kept the two forms
separate. My own specimens are not sufficiently numerous or perfect to assist in
the determination. The two shells are so much alike in the young state as to be with
difficulty determinable ; and I am inclined to believe with Montague, so far at least in
their specific identity, that if the one be not exactly the young state of the other, there
is not more than a local variation between the two. Both appear to have existed
during the Crag Periods, the rostrata in the Cor. Crag corresponding with the more
Southern form, while that from the Red Crag resembles the Northern one (probably
P.glacialis, Leach, 'An. Phil.,' vol. xiv, p. 203, 1819).

,* J. E. Gray, 1830.

ANATINA (sp.) Lamk.
CORBULA (sp.) Desk. 1835.
THRACIA (sp.) Brown, 1827.

ERYCINA (sp.) Risso, 1826.
CUSPIDARIA. Nardo, 1840.

Generic Character. " Shell transversely ovato-pyriform, inequivalve, inequilateral,
more or less beaked, and gaping posteriorly ; surface smooth or striated, or ribbed
longitudinally, never punctated, with or without an epidermis ; valves strengthened
internally with a longitudinal rib ; hinge composed of a cartilage fulcrum, usually
oblique, and spatulate in each valve, sometimes with a minute tooth beside it, and a
more or less developed lateral tooth on the rostral side of one or both valves ; ligament
external (?), small ; muscular impressions large, pallial with a very shallow sinus.

* Etym. (?) Necupa, proper name. This is also employed for a genus of insects.

272 MOLLUSCA FROM THE CRAG.

"Animal oblong, mantle closed in front, except a plain-edged orifice for the
passage of a lanceolate foot; siphons short, united, unequal, the branchial largest,
both bearing a few long filiform cirrhi at their sides, extending beyond the orifices ;
anal siphon with a very extensile membranous valve." — Forbes and Hanley.

1. NE^RA JUGOSA, S. Wood. Tab. XXX, fig. 7, a, 6.

CORBULA ? SULCATA. S. Wood. Catalogue, 1840.

Spec. Char. Testa parvd, transversd, incequilaterali, aquivalvi ? compressd, juyosd ;
antice rotundatd; postice subrostratd, et angulatd ; cardine unidentato.

Shell small, transverse, inequilateral, equivalved ? compressed, ridged ; anterior side
rounded \ posterior somewhat beaked, and angulated ; hinge with one tooth.

Length, ^ inch. Height, TJT inch.

Locality. Cor. Crag, Sutton.

This shell is not rare in the Coralline Crag, but as yet I have met with it only in
one locality, and never with the valves united.

It much resembles the figure of one of the species from the Paris Basin, Corbula
striaretta, Desh., Coq. Foss. des Env. de Par., torn, i, p. 54, pi. 8, figs. 12 — 15, but
differs in being less than half the size, as well as in other characters ; and I believe it
to be distinct, depending as I am obliged to do upon the figure and description above
referred to.

In our species the hinge of the right valve has one obtuse and somewhat oblique
tooth on the anterior side of the *umbo, with a depression between it and the dorsal
edge, into which fits an elevated portion of the margin of the left valve, while on the
siphonal side of this (left valve) is an elongated and elevated projection that interlocks
within the dorsal edge of the right valve ; between these, and immediately beneath
the umbo, is an oblique pit, where the ligament was situated, and entirely
within the shell ; so much so that I doubt whether any part of it could have been
seen in the living animal when the valves were closed. The dorsal margin
slopes at an angle of about 45°, and a truncated beak is formed by the siphons ;
the upper part being somewhat elevated producing an obtuse keel from the umbo upon
the slope on that side. The exterior has from eight to ten rounded ridges, with
depressions or sulci between them of about the same breadth ; but upon the younger
part of the shells these markings are obsolete, being smooth, or nearly so, about the
umbo. The shell is by no means thin, though the ridges are generally visible upon
the interior. The adductor-mark on the siphonal side is of a triangular form, and
deeply impressed, placed rather backward ; and the sinus- in the mantle-mark mode-
rately deep.

The provisional name given to it in my ' Catalogue' is obliged to be changed, in
consequence of its having been used by Dr. Lov£n for a very different species.

BIVALVIA.

273

2. NE^RA CUSPIDATA, Olivi. Tab. XXX, fi£. 6.

o

TELLINA CUSPIBATA. Oliv. Zool. Adriat., p. 101, pi. 4, fig. 3, A — c, 1792.

Sroc. Conch. Foss. Subap., p. 515.
ANATINA BREVIROSTBIS. Brown. Ed. Journ. Nat. and Geo. Sci., vol. i, p. 11, pi. 1,

figs. 1—4, 1829.

THRACIA BREVIROSTRA. Brown. 111. Conch. Gr. Br., pi. 44, figs. 11 — 14, 1845.
NE^RA BREVIROSTRIS. Loven. Ind. Moll. Scand., p. 48, 1846.

CUSPIDATA. Forb. and Hani. Hist, of Brit. Moll., p. 195, pi. 7, figs. 4 — 6; and

pi. G (animal), figs. 4—7, 1848.
Forbes. JSgean Inv., p. 185.

CORBULA CUSPIDATA. Phil. En. Moll. Sic., vol. i, p. 17, t. 1, fig. 19 ; and vol. ii, p. 12.
— SUBROSTRATA. S. Wood. Catalogue, 1840.

A fragment only of a shell, which I consider to belong to this species, was found
by myself in the Coralline Crag at Sutton, but it is insufficient for correct descrip-
tion : the peculiar form of the siphonal side (the portion I possess) is so characteristic
that it is introduced here without much hesitation. It appears to have belonged to
the British or short beaked variety.

CORBULA.* Bruyviere, 1792.

MYA (sp.) Linn. Mont.
CARDIUM (sp.) Walker and Boys.
TELLINA (sp.) Olivi.
AI.OIDES, Megerle, 1811.

LENTIDIUM, Cristof. and Jans. 1832.
POTOMOMYA, J. Sowerby, 1835.
AZARA, D'Orb. 1839.
CORBULOMYA, Nyst, 1843.

Generic Character. Shell suborbicular or ovate, inequivalve, inequilateral, tumid,
closed ; beaks prominent, recurved surface smooth or striated ; in the recent state
covered with an epidermis. Hinge composed of one thick, conical tooth in each valve.
Ligament internal. Impression by the mantle with a small sinus.

Animal short ; mantle open in front for the emission of a thick foot, of
considerable magnitude; siphonal tubes short and united to their orifices, which
are fimbriated : anal opening with a conspicuous tubular membrane.

Animals constituting this genus are for the most part inhabitants of salt water, but
some are estuary species, and extend their range in the river to where the water is
quite fresh. A separation has been proposed, under the name Potomomya, for those
species which permanently inhabit fresh water, but the characters of shell and animal
differ in no other respect from those which are truly marine. In this genus, as well as
in that of Pandora, the two valves are very unequal in size, but this inequality is not
confined to the siphonal side of the shell, and the sinus of the mantle-mark does not

*Etym. ? Corbula, a little basket.

36

274 MOLLUSCA FROM THE CRAG.

vary in form or magnitude like those so conspicuously shown in some of the

Tettens.

The species are not very numerous, even when admitting those which constantly
inhabit fresh water. They are found sometimes in mud, but more frequently on sandy
bottoms, and have a considerable vertical range. Fossil species have been found as
early as the Lower Oolite.

1. CORBULA STRIATA, Walker and Soys. Tab. XXX, fig. 3, a — d.

CARDIUM STRIATUM APICIBUS REFLEXIS. Walk, and Boys. Test. Min. Rar., p. 24, t. 3,

fig. 85, 1787.
TELLINA GIBBA. Olivi. Zool. Adriat., p. 101, 1792.

Broc. Conch. Foss. Subap., p. 517, No. 15, 1814.
MYA IN/EQUIVALVIS. Mont. Test. Brit., p. 38, t. 26, fig. 7, 1803,
CORBULA GTBBA. Nyst. Coq. Foss. de Belg., p. 65, pi. 3, fig. 3, 1844.

Loven. Ind. Moll. Scand., p, 49, 1846.

— NUCLEUS. Lamk. Hist, des An. s. Vert., v, p. 496, 1818.

Forbes. Report on jEgean Invert., p. 180, 1843.

— Phil. En. Moll. Sic., vol. ii, p. 12, 1844.

Bronn. Leth. Geogn., p. 967, t. 37, fig. 7, a— c. 1838.

— STRIATA. Flem. Brit. An., p. 425, 1828.

Desk. Exped. Scient. Alger., p. 231.
ROTUNDATA. J. Sow. Min. Conch., t. 572, fig. 4, 1827.

— Goldf. Petr. Germ., vol. ii, p. 252, pi. 152, fig. 3, a— e, 1842.

— OLIMPLTCA. Costa. Cat. Syst. e. reg. Test delle 2 Sicil., p. 27, 1829.

— IN^QUIVALVIS. Macgill. Moll. Aberd., p. 303, 1843.

— ELEGANS. Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 3, 1835.

— BICOSTATA. Id. Rech. Coq. Foss. Prov. d'Anv., No. 10, pi. 1, fig. 10.

— PLANULATA. Id. Coq. Foss. de Belg., p. 68, pi. 2, fig. 4, 1844.
Not CORBULA STRIATA. Lamk.

Spec. Char. Testa subtriangulari, gibbosd, subin&quilaterali, valde inceguivalvi, valvd
dextrd tumidiori, concentrice striatd; valvd sinistrd complanatd, sublcevigatd ; antice
rotundatd, postice truncatd.

Shell sub triangular, gibbous, slightly insequilateral, greatly inequivalve, right valve
the more inflated, and roughly striated ; left valve nearly flat and smooth ; anterior
side rounded, posterior truncated.

Diameter, ^ inch.

Locality. Coralline Crag, Button, Gedgrave, Ramsholt.
Red Crag, Sutton, Bawdsey, Walton Naze.

Recent, Scandinavia, Britain, and Mediterranean.

In the Coralline Crag at Sutton this is one of the most common shells, and
although furnished with an apparatus for the firm interlocking of the valves, the two

BIVALVTA. 275

pieces are not often found in their natural position. In the Red Crag even the
separated valves are by no means abundant.

Cardium striatum, of Walker and Boys, is evidently the same as our shell, and Dr.
Fleming adopted that name as most entitled to priority : 1 followed his example in my
Catalogue, and see no reason why it should now be changed. In the fossil state, this
species is liable to great alteration : the outer coating which forms a perfect shell of
itself, with its thick transverse ridges, comes off, leaving the inner portion perfectly
smooth. Corbula planulata, in Sir Charles Lyell's Cabinet, received from Belgium, with
that name, is, I believe, only this species in its exfoliated or decorticated condition.

Sir Charles Lyell, in his paper upon the ' Miocene Deposits of America/ has
considered Corbula elevata, of Conrad, the same as this species, and judging from the
figure by that author, he is probably correct in that assignment.

A single valve, of which I have given a representation (fig. 4), may probably be
C. rosea, but in such a genus as this, in which the species are by no means easily
defined, I prefer leaving it without description for the present.

2. CORBULA COMPLANATA, /. Sowerby. Tab. XXX, fig. 2, a — d.

CORBULA COMPLANATA. J. Sow, Min. Conch., t. 362, figs. 7, 8, 1822.

Desk. Coq. Foss. des Env. de Par., pi. 7, figs. 8, 9, 1824.
Dujard. Mem. de la Soc. de France, torn, ii, pt. 2, p. 256, 1837.
Desk. 2d ed. Lamk. torn, vi, p. 142, 1835.
Graf. Cat. Zool. des An. du Basin Tert. de la Oironde, p. 67,

No. 794, fig. 3, 1838.

Bronn. Leth. Geogr., p. 969, t. 37, fig. 8, a, b, 1838.
DONACIFORMIS. Nyst. Rech. Coq. Foss. de Hoesselt et Kl. Spawen, p. 3, No. 6,

pi. 1, fig. 6, 1836.

CORBULOMYA COMPLANATA. Nyst. Coq. Foss. de Belg., p. 59, pi. 2, fig. 2, 1844.
ERYCINA TRIGONA. Lamk. Ann. du Mus., torn, vi, p. 413, No. 3.

Spec. Char. Testa transversd, ovatd, vel donaciformi intequilaterali, compressd ant
complanatd, Icevigatd, crassd ; antice majiore rotundatd ; postice angulatd, truncatd, et sub-
carinatd ; dente cardinali unico in valvd decctrd.

Shell transverse, ovate, or wedge-shaped, inequilateral, compressed or flattened,
smooth, and thick ; anterior side the larger and rounded ; posterior angulated,
truncated, and slightly keeled ; one cardinal tooth in the right valve.

Length, \\ inch. Height, f inch.

Locality. Red Crag, Sutton and Walton Naze.

Fossil in the Paris basin, and at Kleyn Spauwen, the Basin of the
Gironde, and in the Faluns of Touraine.

This is a rare shell, though solid and strong, and does not appear to have been an
inhabitant of the Coralline Crag sea, though a species supposed to have been trans-

276 MOLLUSCA FROM THE CRAG.

mitted from the Older Tertiaries. M. Deshayes says the Paris Basin shell is un-
doubtedly identical with the Touraine species ; the latter corresponds more closely
with the Crag fossil ; the Kleyn Spauwen shell resembles more (as might be supposed)
the Paris Basin variety. The Touraine specimens differ slightly from the Crag fossil,
but not, I think, sufficiently to invalidate their identity. In our shell the siphonal
side is not so pointed or keeled, and there is a little difference in the dental furniture,
and the palleal sinus is a trifle larger.

The ligament is placed in a fossette in the right valve, visible externally, when the
valves are closed, through a sinus in the umbo ; the left valve has a projection on
which are placed both ligament and cartilage, separated by a ridge : before this
ligament is a tooth in each valve. This was probably an estuary shell. The locality
(Roydon), given for it in ' Min. Conch./ is an error.

SPHENIA BINGHAMI ? Turton. Tab. XXIX, fig. 7.

SPHENIA BINGHAMI. Turt. Brit. Biv., p. 36, t. 3, figs. 4, 5 ; and t. 19, fig. 3, 1822.
SPILENIA BINGHAMI. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 190, pi. 9, figs. 1—3,

1848.

CORBULA BINGHAMI. Hanley. Recent Shells, p. 47; Supp., pi. 12, fig. 4.
Woodw. Man. of Moll., vol. ii, p. 318.

Spec. Char. Testa minutd, transversd, cuneiformi tenui fragili, Icevigatd, valde
in&quilaterali ; antice rotundatd, postice angustd, subrostratd.

Shell small, transverse, wedge-shaped, thin and fragile, smooth, and very inequi-
lateral ; anterior side rounded ; posterior produced and somewhat pointed.

Length, j inch.

Locality. Cor. Crag, Sutton. Recent, Britain ?

The genus Sphenia has been founded upon a single species of Mollusc inhabiting
our own shores, and is at present not well established : the animal has been examined
by Mr. Clark who says it is quite distinct from Mya or Saxicava, though not far removed
from either ; perhaps still nearer to Corbula.

Only two or three specimens, and those not in very good condition, are in my
Cabinet ; they will not throw any light upon the obscurity which hangs over the
recent shell.

My best specimen has a spatulate tooth in the left valve, like that in the young of
Mya, which it resembles in some characters, but it is much thinner, with something of
a nacreous appearance ; and the outline also is different from that of the young of Mya
of the same size : mine is, however, a very doubtful identity of the existing species.

BIVALVIA. 277

MYA.* Limaus, 1747.

MYA, Lamk. 1801.
SPHENIA (sp.) Turt. 1822.

Generic Character. Shell transverse, equivalve, subequilateral, more or less of an
ovate or oblong form, gaping at the siphonal extremity; externally striated or
furrowed by rough or irregular lines of growth ; in the recent state covered by an
epidermis. Hinge composed of a large, projecting, spoon-shaped tooth or process in
the left valve, on which is placed the ligament, with a corresponding depression or
socket beneath the umbo in the right valve. Impressions of the adductor muscles
near the extremities, with a deeply sinuated line in the mantle-mark.

Animal of the form of the shell, with the mantle closed except in front for the
emission of a small tongue-shaped foot. Tubes long, covered with a strong case-like
coriaceous epidermis, separated at their extremities, with fimbriated orifices.

This genus is more especially characterised by the peculiar form of the hinge,
which distinguishes it from all other Bivalves, and as now restricted contains but very
few species in the recent state. They are confined to the colder regions of the globe,
where they live buried in mud or sand, sometimes to the depth of a foot, in an erect
position, with the siphonal extremity upwards, their tubes extending into the
water; they have a vertical range from low- water-mark to upwards of 150 fathoms.
Dead shells have been obtained from even greater depths, but it is no proof in such
case of animals having a very extensive vertical range : Dr. Sutherland has shown, in
regard to Arctic species, they are often transported by icebergs into very deep water.

The secondary fossils figured under this generic name have no relationship
whatever ; but a small species has been obtained from the upper marine of the Older
Tertiary Periods that may be referred to this genus, showing then, as now, its some-
what estuary character, or its tendency to approach the regions of fresh-water.

1. MYA TRUNCATA, Linnaeus. Tab. XXIII, fig. 1, a— -f.

MYA TRUNCATA. Linn. Syst. Nat., ed. 12, p. 1112, No. 26, 1767.
Gould. Invert. Massach., p. 42, 1841.
Mailer. Ind. Moll. Groenl., p. 21, 1842.

Dekay. Nat. Hist. New York Moll., p. 240, pi. 29, fig. 289, 1843.
Phil. En. Moll. Sic., vol. ii, p. 6, 1844 (fossil).
Lovcn. Ind. MoU. Scand., p. 49, 1846.

Forb. &ndHanl. Hist. Brit. Moll., vol. i, p. 163, pi. 10, figs. 1, 2; and
Animal, pi. H, fig. 1, 1848.

* Etym. nva£, a kind of shell-fish.

278 MOLLUSCA FROM THE CRAG.

MYA TRUNCATA. Middendorff. Malacozool. Rossica, p. 585, t. 19, figs. 13 — 15, 1849.

_ _ Lyell. Trans. Geol. Soc., vol. vi, 2d series, p. 137, pi. 17, figs. 5, 6, 1839.

_ — Forbes. Mem. Geol. Surv., vol. i, p. 408, 1846.

— Hancock. An. and Mag. Nat. Hist., vol. 18, p. 337, 1846.

— — var. PELAGICA. King. An. and Mag. Nat. Hist., vol. 18, p. 242.

— OVALIS. Turt. Brit. Biv., p. 33, pi. 3, figs. 1, 2, 1822.

— PULLUS. J. Sow. Min. Conch., t. 531.

— SWAINSONI. Lovcn. Iiid. Moll. Scand., p. 49, 1846.
SPHENIA SWAINSONI. Turt. Brit. Biv., p. 37, pi. 19, fig. 2, 1822.
CHAMA TRUNCATA. Da Costa. Brit. Conch., p. 233, pi. 16, figs. 1,1.

— PHOLAS LATUS. List. Hist. Conch., pi. 482, fig. 269.

Spec. Char. Testa transversd, subovatd, in&qnilaterali ; antice rotundatd, tumidd,
clausd; postice truncatd, hiante ; cardinis dente porrecto, rotundato.

Shell transverse, subovate, inequilateral ; anterior side rounded, inflated, and closed ;
posterior truncated, and gaping; hinge with one large, rounded tooth.

Length, 3^ inches. Height, 2^ inches.

Locality. Cor. Crag, Ramsholt, and Gedgrave.
Red Crag, Button.

Mam. Crag. Chillesford, Bridlington.
Clyde Beds, Bracklesham, (Dixon).

Recent, British and Scandinavian Seas, Behring Straits.

This shell does not appear to have been rare in the Coralline Crag, the oldest
Formation from which I have seen it ; nor is it scarce in the Red Crag ; and in the
more recent Deposit at Chillesford it may be abundantly obtained in great perfection
with the valves in their natural position. Mya pullus is the young of this species, and
not of arenaria, as supposed by the authors of the ' Hist, of Brit. Moll./ vol. i., p. 172.
In my ' Catalogue/ I had assigned this as an identity with M. ovalis, Turt., and having
found this shell in great profusion at Butley, not exceeding it in size, I considered it
then as distinct.

This species is subject to considerable variation, more especially in regard to its
length : those I have met with from the Coralline Crag are all of the longer variety ;
in the Red Crag the long and short are both obtained, but I have seen none there so
short and obliquely truncated as the variety found fossil at Uddevalla ; and in the
Clyde Beds.* At Chillesford, all the specimens I have seen are of the longer variety ;
that is, with the siphonal side somewhat elongated, while, perhaps, it is somewhat

* The difference in the form of the mantle-mark in this variety was considered by the late Mr. G. B.
Sowerby as a character of sufficient importance for a distinct position, and Mr. Smith, in consequence,
proposed for it the name of Uddevallensis ; but this mark is merely the result of the shortened side of
the shell.

It is now well known that many of the species inhabiting the Arctic seas exhibit great variation, and
still more abnormal forms, than are presented by the varieties of this species, have been recently obtained
from that part of the world.

BIVALVIA. 279

remarkable that the specimens of Panopea Norvegica found at this locality, where
the general remains are decidedly of an Arctic character, have this side much
abbreviated.

In the recent state it is found, sparingly, on the coast of the United States ; and
M. Middendorff* describes it as an inhabitant of the Sea of Okhotsk and the Behring
Straits, appearing principally confined to the colder regions of the Northern
Hemisphere.

This is the elder of the two species, and has in the living state a great
geographical range, extending from the Behring Straits, through the Scandinavian
and British Seas, to the coast of the New World westward, through Davis's Straits,
and as far as Baring Island, where the short variety has been found in abundance.
It is thus spread over an area of 280 degrees of longitude, and its range in depth is
upwards of 100 fathoms. It was formerly an inhabitant of the seas which deposited
the Sicilian Beds, where it is now found fossil, extending into this region probably
during the Glacial Period, as it is no longer an inhabitant of the Mediterranean Sea.

2. MYA ARENARIA, Linnceus. Tab. XXVIII, fig. 2, a—f.

MYA ARENARIA. Linn. Syst. Nat., ed. 12, p. 1112, No. 27, 1767.
J. Sow. Min. Conch., t. 364, 1822.
Gould. Inv. Massach., pp. 40 and 359, 1840.
Nyst. Coq. Foss. de Belg., p. 57, pi. 3, fig. 1, 1844.
Lovtn. Ind. Moll. Scand., p. 49, 1846.
Dekay. Hist. New York Moll., p. 240, pi. 30, fig. 290.
Midd. Malac. Rossica, p. 586, t. 20, figs. 1—3, 1849.

— LATA. J. Sow. Min. Conch., t. 81, 1815.

W. Smith. Strata Identif. Crag, fig. 9, 1816.

- SUBOVATA. Woodw. Geol. of Norf., p. 43, t. 2, fig. 5, 1833.

- SUBTRTJNCATA. Id. Geol. of Norf., p. 43, t. 2, fig. 6.

- MERCENARIA. Say. Journ. Acad. Nat. Sc., vol. ii, p. 313, fide Gould.

— ACUTA. Say. Fide Gould, p. 40.

CHAMA ARENARIA. Da Costa. Brit. Conch., p. 232.

Dale. Hist, and Antiq. of Harwich, p. 293, t. 11, fig. 8, 1730.

Spec. Char. Testa transversd, ovatd, elongatd, subcequilaterali> crassd, rugosd ; antice
rotundatd; postice subacuminatd ; cardinis dente denticulo later all acuto.

Shell transverse, ovate, elongate, nearly equilateral, thick, and rough ; anterior side
rounded ; posterior somewhat pointed ; hinge tooth with a sharp lateral denticle.
Length, 3J inches. Height, 2% inches.
Locality. Red Crag, Sutton, Bawdsey, Felixstow.
Mam. Crag, Bramerton, Bridlington.
Bracklesham (Dixon).

Recent, Britain, Scandinavia, and N. E. Coast of America.

t

* The figure by Middendorff is not the short variety.

280 MOLLUSCA FROM THE CRAG.

This species I have not as yet seen from the Lower or Coralline Crag ; and although
abundant in the Red Crag, I have never found anything but detached valves, and
those in the more disturbed portion of that Formation.

It is subject to great variation ; and I think, with the authors of the ' Hist, of Brit.
Mollusca,' that the shell called lata by Mr. Sowerby, above referred to, is onlv a
modified form of this species, although presenting an intermediate character between
the truncated posterior of truncata and pointed termination of the ordinary form of the
living shell, depending probably upon some peculiarly local conditions, as I have never
met with it but in one locality. The form of the spatulate tooth in the hinge of this
variety is precisely like that of the recent arenaria. It was furnished with a large and
strong ligament, or rather cartilage, the greater part of which is preserved in most of
the fossil specimens.

The cause assigned for this variation (lata), by the authors of the * Hist, of Brit.
Mollusca/ appears to me to be somewhat doubtful, this not being, I believe, one of
the forms found in the estuary portion of the Mammaliferous Crag, where distortions
are by no means rare, and where, in all probability, the influx of ice or the efflux of
more than ordinary quantities of fresh water, produced deformities like some of the
specimens of Purpura lapillus and Littorina littorea, found in that Deposit. The
variation in lata does not appear to be a distortion, as understood in this case, but a
character that pervaded a whole race, making it what is called a permanent variety.

The depth, of the palleal sinus is a character here not to be much depended upon,
as, in my large series, considerable differences in regard to depth may be observed ;
for in soms specimens this mark extends considerably beyond the hinge ligament,
while in others it falls short of it, being modified by the length of the tubes, which
would probably vary under the influence of external conditions.

This, in the living state, is generally a very shallow-water species, burying itself in
sand, near low- water mark ; extending, at times, into rivers as far as where the water,
when the tide is out, is nearly fresh. Its geographical distribution takes in the whole
circuit of the Northern Hemisphere, being found, according to Middendorff,* at Sitka,
in the Sea of Okhotsk, on the coast of Russian Lapland, and Nova Zembla, and, by
the American authors, on the soast of the United States, as far to the southward as
nearly to 40°, exhibiting thus an equal, or perhaps a greater, extent of range than its
elder confrere, truncata. It has not had, however, on our side of the Atlantic, quite
so great a range to the southward, not having been found, either recent or fossil, in or
near the Mediterranean.

The animal of this species is, according to Dr. Gould, extensively employed as bait
in the cod fisheries of Newfoundland, and is called 'the long clam, to distinguish it
from the giant clam, Mactra gigantea, or the round clam or Quahog, Venus mercenaria.

The specimen figured by Middendorff appears rather distorted, with a short siphonal «ide.

BIVALVIA. 281

PANOPEA.* Menard de la Groye, 1807.

MYA (sp.) Linn. Broc.
CHAM^EPHOLAS (sp.) Petiver.
GLYCIMERIS. Lamk. 1812.

Goldf. Phil. Bronn. Valenciennes.

PANOPIA. Swains. 1840.
PANOPOEA. Nyst, 1844.
HOMOMYA (sp.) Agass. 1845.

Generic Character. Shell transversely oblong, equivalved, inequilateral, more or
less gaping at both extremities ; surface smooth or marked by rough and somewhat ir-
regular lines of growth ; elongated impressions by the adductors ; mantle-mark with a
large, deep sinus ; hinge furnished with one conical tooth in each valve ; ligament
external, placed on a prominent fulcrum.

Animal with very long and extensible siphonal tubes united to their extremities ;
mantle closed throughout its length, except a small opening in front for the passage
of a short, stout, muscular foot ; large and strong adductor muscles.

This genus is closely related to Mi/a, in the animal as well as in the shell, differing
principally by the position of the hinge-ligament, which in this is placed upon a
prominent ridge, and its action consequently different. The animal has very long
siphonal tubes, which are incapable of being withdrawn into the shell, and are con-
sequently thickened, and covered with a strong coriaceous epidermis.

In 1839, M. Valenciennes published a valuable monograph of this genus, and
described the animal of one species found on the shore of Port Natal, which
seems to have been an inhabitant of shallow water, and left dry at the retreat
of the tide. Its tubes were observed protruding through the sand, and when
alarmed retreated backward by means of its powerful foot to the depth of several
feet.

Some of the Oolitic Fossils belong to this genus.

Dr. Gray considers the name of Glycimeris, proposed by Klein, 1753, as entitled to
be used for this genus, but the date is anterior to our starting point, viz. the 12th
ed. Linn., 1767.

1. PANOPEA NORVEGICA, Spengler* Tab. XXIX, fig. 1, a — e.

MYA NORVEGICA. Speng. Skrivt. Natu. Silskal, vol. iii, part 1, p. 46, pi. 2, fig. 18.
GLYCIMERIS ARCTICA. Desk. 2d ed. Lamarck, torn, vi, p. 70, 1835.

NORVEGICA. Gray. List Brit. Moll., p. 63, 1851.
PANOPEA GLYCIMERIS. Bean. Mag. Nat. Hist., viii, p. 562, figs. 50, 51.

* Etym. Panope, one of the Nereids. Panopea, Hubn. 1816, a genus of Lepidoptera.

37

282 MOLLUSCA PROM THE CRAG.

PANOPEA ARCTICA. Gould. Inv. Massach., p. 37, fig. 27, 1840.

— — Dekay. Nat. Hist. New York Zool., p. 246, 1843.

— — King. Ann. and Mag. Nat. Hist., vol. xviii, p. 243, 1846.
PANOPEA BIVON^E. J. Smith. Wern. Mem. vol. viii, p. 107, pi. 2, fig. 4, 1839.

_ _ Phil. En. Moll. Sic., vol. i, p. 8, t. 2, fig. 1, a— c, 1836.

SPENGLERI. Falen. Arch, du Mus., torn, i, p. 15, pi. 5, fig. 3, 1839.

Chenu. Illust. Conch. Panopsea, pi. 4, fig. 2, 4, 4 a, 4 b ; pi. 6,

fig. 3, a, b ; and pi. 10, fig. 2, a, b.

NORVEGICA. J. Sow. Min. Conch., t. 610, fig. 2, and 611, figs. 1, 2.
Lovtn. Ind. Moll. Scand., p. 49, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 175, pi. 1 1, 1848.
Middend. Malacozool. Kossica (Mem. loc. cit.), p. 593, t. 20,
fig. 11, 1849.

Spec. Char. Testa crassd, ollongd vel subrhomboidali, plus minusve incequilaterali ;
antice plerumgue breviore,portice truncatd et latiore ; cardine edentulo ? impressione pallii,
interrupta, maculosa.

Shell thick, oblong or somewhat rhomboidal, more or less inequilateral ; anterior
side generally the shorter, posterior truncated and broader ; hinge without teeth ; im-
pression by the mantle interrupted, spotted and irregular.

Length, 3 inches. Height, 2 inches.

Locality. Red Crag, Sutton, Butley.

Mam. Crag, Chillesford, Bridlington.
Clyde Beds, and Sicily.
Recent, North America, Britain, Scandinavia, Russian Lapland, and Sea of Ochotsk.

As yet this shell has been but sparingly obtained from the Red Crag, but it does
not appear to be very scarce in the native bed at Chillesford, where the valves are met
with in their natural position. Although my specimens from the Red Crag do not
amount in number to more than half a dozen, there is a considerable variation among
them.

Our fossils are in general more equilateral, that is to say, the siphonal side of the
shell is less in size, particularly those from Chillesford, than the living specimens, or
those from the newer Tertiaries of Sicily, where the anterior side does not constitute
more than a third of the entire shell ; there is, however, no doubt as to the identity of
the British fossil with the recent species. Among other minor differences may be
mentioned the ligamental fulcra, which in Crag specimens extend half way across the
dorsal margin, giving support to large and powerful ligaments, while in the
living shell this fulcrum is much smaller. The adductor muscle-marks are deeply
impressed, the shell gapes widely on the posterior side, and there is a considerable
opening in the fore part of the ventral margin for the extrusion of the foot : the
surface is much roughened by somewhat irregular lines of growth ; and the centre of
the shell is contracted or depressed, giving it a couple of obtuse ridges which diverge
from the umbo.

BIVALVIA. 283

In the living state it has been only obtained in deep water.

A small obtuse tooth occupies a position immediately beneath the umbo in the
living shell, but in the fossil this is merely rudimentary.

The figure by Middendorff has the siphonal side the larger.

2. PANOPEA FAUJASII, Menard de la Groye. Tab. XXVII, fig. 1, a— -f.

PANOPEA FAUJASII. Men. de la Groye. Ann. du Mus., torn, ix, p. 131, t. 12, 1807.

Dubois de Montp. Conch. Foss. de Wolhyn. Podol., p. 51, pi. 4,

figs. 1 — 4, 1831.
PANOPEA FAUJASII. Bast. Foss. de Bord., p. 95, 1825.

Eronn. Leth. Geog., p. 973, pi. 37, fig. 6, 1838.
Phil. En. Moll. Sic., vol. i, p. 7, t. 2, fig. 3, 1836.
Goldf. Pet. Germ., vol. ii, p. 274, t. 159, fig. 1, a— d.
Valenciennes. Arch, du Mus., vol. i, p. 13, 1839.
J. Sow. Min. Conch., t. 602, figs. 3 — 5.
Chenu. Conch. Illust., pi. 4, fig. 1, 1.
IPSVICIENSIS. J. Sow. Min. Conch., t. 611, figs. 3, 4.

Valenciennes. Loc. cit. sup., No. 36.
REFLEXA. Say. Journ. Acad. Nat. Sc., vol. iv, p. 153, pi. 13, fig. 4, 1824.

Conrad. Foss. Med. Tert., p. 5, pi. 3, fig. 4, 1838.
AMERICANA. Id. Foss. Med. Tert., p. 4, pi. 2.
ALDROVANDI? Phil. En. Moll. Sic., vol. i, p. 7, t. 11, fig. 2.
GENTILIS. J. Sow. Min. Conch., vol. vii, t. 610, fig. 1, 1840.
MYA PANOPJEA? Broc. Conch. Foss. Subap., p. 532, 1814.

Spec. Char. Testa transversd, ovato-oblongd, in/laid ; plus minusve inaquilaterali ;
postice truncatd et valde Jdante ; cardine umdentato.

Shell transverse, ovately oblong, inflated, more or less inequilateral ; posterior side
truncated, and gaping widely ; hinge with one tooth.

Length, 6 inches. Height, 3^ inches.

Locality. Cor. Crag, Sudbourn, Gedgrave, Ramsholt.
Red Crag, Sutton.

This handsome shell is very abundant as a Crag Fossil, though its great size and
comparative thinness has caused it to be somewhat scarce in our Cabinets : at
Ramsholt numerous specimens were found with the valves united. It presents a very
considerable variation, both in regard to its form, and to the degree of gape on the
anterior side, and I am inclined to believe the recent Mediterranean shell called
P. Aldrovandi is merely the descendant of our Crag species somewhat altered by
local conditions : the Sicilian fossil (specimens of which were obligingly given to me
by Madame Power) seems to present some differences ; but they are not, I think, of
sufficient importance for specific distinction ; that shell is, in general, rather more
inequilateral than the Crag one, but not always so ; and, among my British specimens

284

MOLLUSCA FROM THE CRAG.

a considerable variation in that character may be observed. Great reliance has been
placed upon the size of the gape for the foot on the anterior side, but I believe such
distinction to be of very little value, as in some of my specimens it is nearly closed,
while in others it is widely open, and with all intermediate magnitudes. The variety
Ipsviciensis, found at Ramsholt, appears to differ most from the Sicilian shell, and may
be considered its extreme range in variation, being more equilateral and straight ; but
some of my specimens from near Orford, have nearly the same inequilaterality as the
Sicilian fossil, with the like obliquity. In P. Norvegica^ a difference exists between the
comparative magnitudes of the two sides of the recent, as well as between the Sicilian
fossil, and my specimens from Chillesford, equally evident with what may be seen in
this species ; and the comparatively greater depth of the sinus results, I conceive, in
this difference between the two sides, the sinus reaching further back, or apparently
deeper, in those which are more equilateral than where the siphonal side is so much
the larger. Similar differences exist in Mya truncata ; what has been called
M. Uddevattensis has one side of the shell very short, giving a material difference
in proportional dimensions from some undoubtedly of the same- species from the
Coralline Crag, as well as from the more southern portion of the English Coast, as if
a northern locality had induced an alteration in that character.

I have given figures of the specimen from the Red Crag, called P. gentitis (fig. 1,
d, e), which Mr. Sowerby considered as a distinct species. With the exception of its
being a little more elongated, its characters are so similar to those of fig. 1, a, that I
believe it to be only an aberrant form of the one abundant in the Coralline Crag.
The apparent greater depth in the sinus of the mantle-mark, in this specimen, I would
attribute entirely to its elongated and constricted form : a considerable difference in
the siphonal scar may be observed in a large series depending in a great degree upon
the outward form of the shell.

Figs. 3, 4, 5, of the ' Mineral Conchology/ t. 602, are probably fragments of this ;
but figs. 1 and 2, of the same Plate, described under the name of P. Fatijas, belong, I
believe, to another species.

SAXICAVA.* Fleureau de Bellevue, 1802.

MYTILTJS (sp.) Linn. Mont. &c.

SOLEN (sp.) Linn. Mont. &c.

MYA (sp.) Linn. Fair. &c.

DONAX (sp.) Poli.

ANATINA (sp.) Turton.

CARDITA (sp.) Bruguiere.

IRTJS (sp.) Oken.

CHAM^PHOLAS (sp.) Lister.

ARCINELLA (sp.) Phil. 1844. Not Schum.

HIATELLA. Dand. 1800. Gray, 1851,
CLOTHO? Fauj. St. Fond. 1807.
BYSSOMIA. Cuv. 1817.
DIDONTA. Schum. 1817.
PHOLEOBIA. Leach, 1819.
BIAPHOLIUS. Id. 1819.
RHOMBUS. Blainv. 1818.
AGINA. Turt. 1822.
RHOMBOIDES. Blainv. 1825.

* Etym. Saxum, a rock ; and cavo, to make hollow.

BIVALVIA. 285

Generic Character. Shell transverse, inequilateral, oblong, or subrhomboidal,
equivalve, slightly gaping at both extremities, sometimes in front ; hinge with one or
two cardinal teeth, which are generally obsolete when full grown; muscular im-
pressions ovate, strong, and distant ; palleal impression somewhat irregular, with a
small or moderate sinus. Ligament external.

Animal oblong, or club-shaped ; mantle united, except where open in front for the
passage of a digitiform foot, furnished with a byssal groove ; siphons short, separated
at their extremities ; branchial and anal orifices large, margined with cirrhi.

Animals of this genus are generally found located in rocks, as the name imports,
and they are often met with in those situations into which they must have entered at
a very early age, their extrication being effected only by a fracture of the stone from,
depths of sometimes nearly six inches. It is therefore evident this aperture is formed
by the animal itself, and as the crypts are not symmetrical, like those of the Pholades,
the mechanical theory of a rotatory motion, by the rasping of the shell, will not in this
instance satisfactorily explain the modus operandi. They appear endowed with the
power of spinning a byssus, by which they are sometimes moored to the sides of the
cells, and occasionally the ventral opening is of considerable size ; from which
circumstance a genus was formed by Baron Cuvier, under the name Byssomya, for the
reception of those shells possessing this character.

Their peculiar habits producing often great distortion, and their extraordinary
variation, have caused much perplexity to the naturalist; the same species has, I
believe, been placed in five different genera ; and the most distinguished conchologists
of the present day are still at variance, not only in the determination of the species to
which the shells now found on our own coasts should be assigned, but even the generic
limits cannot be agreed upon. A small shell from the Older Tertiaries of this
country is in the Cabinet of Mr. Edwards, probably belonging to this genus ; and
M. Deshayes has described some species from the Paris Basin.

1. SAXICAVA RUGOSA, Pennant. Tab. XXIX, fig. 3, a — g.

MYTILUS RUGOSUS. Penn. Brit. Zool., ed. 1, vol. iv, p. 110, t. 63, fig. 72.
— PHOLADIS. Miill. Zool. Dan., t. 87, figs. 1 — 3.

Chemn. Conch. Cab., vol. viii, p. 154, t. 82, fig. 735.
MYA BYSSIFERA. Otho. Fabr. Faun. Groenl., p. 408, No. 8.
— EUSTICA. Broc. Conch. Foss. Subap., p. 533, t. 12, fig. 11, 1814.
SAXICAVA RUGOSA. Forb. and Hani. Brit. Moll., vol. i, p. 146, pi. 6, figs. 7, 8 ; and pi. F,

fig. 6.

Lyell. Trans. Geol. Soc., 2d series, vol. vi, pi. 16, fig. 7, 1839.
J. Sow. Min. Conch., t. 466.
Phil. En. Moll. Sic., vol. i, p. 20, t. 3, fig. 4, 1836.
STRIATA. Fl. de Bellevue. Journ. de Phys., torn, liv, p. 349, 1802.
— GALLICANA. Desk. 2d ed. Lamarck, torn, vi, p. 162, 1835.

286 MOLLUSCA FROM THE CRAG.

SAXICAVA PHOLADIS. Turt. Brit. Biv., p. 21, t. 2, figs. 11, 1822.

— Hancock. Mag. Nat. Hist., vol. xviii, p. 337.
DISTORTA. (Say.) Gould, Inv. Massach., p. 61, fig. 40.

— STJLCATA. Smith. Phil. Trans., 1835, pi. 2, fig. 25.
PHOLEOBIA RUGOSA. Leach. Ross's Voy. Baff. Bay, p. 174, 1819.
BIAPHOLUS RUGOSUS. Leach MS. An. and Mag. Nat. Hist., vol. xx, p. 272.
BYSSOMYA PHOLADIS. Bowdich. Bivalves, fig. 43.

RHOMBOIDES RUGOSUS. Blainv. Man. Malac., p. 573, 1825.
HIATELLA OBLONGA. Turt. Brit. Biv., p. 25, pi. 2, fig. 13, 1822.
— RUGOSA. Flem. Brit. An., p. 461, 1828.

Spec. Char. Testa variabile, oblongd, vel subrhomboidali transversim striatd, rugosa ;
utraque ecctremitate obtusd, aliquando valvarum angulis binis instruclo: latere antico
brevissimo.

Shell variable, oblong or subrhomboidal, transversely striated, and rugose ; obtuse
or rounded at each extremity ; sometimes furnished with two diverging rows or slightly
imbricated ridges ; anterior side much the shorter.

Length, 1 inch. Height, f inch.

Locality. Cor. Crag, Sutton.

Red Crag, Sutton, Walton Naze.
Clyde Beds, Bridlington.

Recent, Britain, Mediterranean, Scandinavia, N. E. Coast of America,
Nova Zembla, Sea of Ochotsk, and Sitka.

Small specimens of this shell are abundant in the Cor. Crag. In the Red Crag
they are sometimes met with, in loose sand, with the valves united, much distorted, and
with a large, ventral opening. The gigantic specimens obtained in the Clyde Beds,
and in the recent Deposits of Canada, belong, I believe, to nothing more than a variety
of this species, where, apparently under favorable circumstances, it had attained to so
great a magnitude ; but one of my specimens from the Red Crag is not much less,
giving every reason to suppose the simple difference in size, if not merely a difference
in age, may be the result of different conditions ; the Red Crag specimens bearing in
general a sort of intermediate character, as if a reduction in temperature from the
older to the more modern Periods had been favorable to the fuller development of
this species.

Large numbers of individuals are found loose in the Crag, and when in a living
state, probably passed their lives in adhering by a byssus to the roots of Fuel. Mr.
Sowerby, in ' Min. Conch./ speaks of a specimen having been found imbedded in
Septaria, beneath the Red Crag at Holy wells. I have never met with the British
fossils otherwise than in localities where, I believe, they were not excavators. This
species appears to be generally distributed through the Drift Beds in this country, and
it is also found in similar Deposits in Canada, Sweden, and Russia. Mr. Smith, of
Jordan Hill, has recently forwarded to me the drawing by the late Professor E. Forbes,

BIVALVIA. 287

of an individual measuring 1 J inch long, and fths of an inch high, which was thought
to be distinct from rugosa, and called striata. I cannot coincide in that opinion ; it
appears to me to be only a monstrous form of our variable shell.

2. SAXICAVA ARCTICA, Linnaeus. Tab. XXIX, fig. 4, a — b.

MYA ARCTICA. Linn. Syst. Nat., ed. 12, p. 1113.

CARDITA LITHOPHAGELLA. Costa. Fide Phil.

MYA ELONGATA. Broc. Coq. Foss. Subap., p. 529, t. 12, fig. 14, a, b, 1814.

HIATELLA ARCTICA. Daud. Rec. Mem. Moll., 1800.

ANATINA ARCTICA. Turt. Brit. Biv., p. 49, pi. 4, figs. 7, 8, 1822.

SAXICAVA ARCTICA. Phil. En. Moll. Sic., vol. i, p. 20, t. 3, fig. 3, 1836.

Lovtn. Ind. Moll. Scand., p. 40, 1846.

D'Orligny. Moll. Canar., p. 109, No. 195, 1835.

Nyst. Hist. Coq. Foss. Belg., p. 95, pi. 3, fig. 15, a— -c, 1844.
— RTJBRA. Desk. Exped. Alger. Moll., pi. 66, figs. 18, 19.
SAXICAVA RHOMBOIDES. Desh. 2d ed. Lamarck, torn, vi, p. 153, 1835.
SOLEN MiNUTUs. Linn. Syst. Nat., ed. 12, p. 1115, No. 42.

Mont. Test. Brit., p. 53, pi. 1, fig. 4, 1813.
— PURPUREUS. Flem. Brit. An., p. 459, 1828.
HIATELLA MINUTA. Turt. Brit. Biv., p. 24, pi. 2, fig. 12, 1822.

Gray. List. Brit. Moll., p. 89, 1851.

TELLINA RHOMBOIDES. Poli. Test. Sicil., p. 81, t. 15, figs. 12, 13, 15 ; and t. 14, fig. 16.
DONAX IRUS. Olivi. Fide Philippi.

MYTILUS PR^CISUS. Mont. Test. Brit., p. 165, t. 4, fig. 2, 1803.
PHOLEOBIA PR^ECISA. Brown. Illust. Brit. Conch., t. 9, fig. 16.
AGINA PDRPUREA. Turt. Brit. Biv., p. 54, t. 4, fig. 9.
DIDONTA BICARINATA. Schum. Eesai, p. 125, pi. 6, fig. 2, a, b, 1817.
BIAPHOLIUS SPINOSUS. " Leack." Ann. Mag. Nat. Hist., vol. xx, p. 272.
HYPOG^A GIBB A. Poli. Test. Sic., vol. i, p. 25 1 .

Spec. Char. Testa crassd, oUongd, vel rhomboidali, valde inaquilaterali ; concentrice
striata, aut rugosd ; latere antico brevissimo ; biseriatim oblique aculeis instructo: car dine
unidentato.

Shell thick, oblong or rhomboidal, very inequilateral; rugose or irregularly
striated with lines of growth; anterior side very short; ornamented with two
diverging imbricated ridges : hinge with one tooth.

Length, f inch. Height, f inch.

Locality. Cor. Crag, Sutton.
Red Crag, Sutton.
Recent, Canary Islands, Mediterranean, ^Egean, British and Norwegian Seas.

In deference to the malacologists, I have separated these two shells, and placed
them as distinct species, under the names arctica and rugosa, though I believe there is
no ground for the distinction.

288 MOLLUSCA FROM THE CRAG.

The form of the shell, and the inequilaterality of the valves are not to be depended
upon for specific separation, neither can any reliance be placed upon the two diverging
ridges upon the siphonal side, though strongly marked in this, where often these ridges
are imbricated; the same character may generally be detected in the younger portion
of the preceding, becoming obliterated in the older shell, and what is called the exca-
vated lunule,* which is said by the recent conchologists to be the tangible mark of
distinction between the two, is as prominent and evident in the one as in the
other.

The remark made by Dr. Gould upon Saxicava distorta may be also applied to our
fossils : " it is a perfect Proteus, of which no description can be given that is not
liable to mislead." The American shell being probably only a variety of a species
that seems to have a geographical extension reaching from the Mgetm to the northern-
most shores of Finmark, and the N. E. coast of America.

Saxicava bilineata, Conrad, ' Foss. of the Mid. Tert. of the United States/ p. 18,
PL 10, fig. 4, is probably another variety of this species.

The only imprisoned specimen I have ever found in the Crag, was in the interior of
one of the large barnacles. I have a recent individual from the Bay of Smyrna, it
was imbedded in sponge.

3. SAXTCAVA ? FRAGILIS, Nyst. Tab. XXIX, fig. a — e.

SAXICAVA FRAGILIS. Nyst. Coq. Foss. de Belg., p. 97, pi. 4, fig. 10, a, b, 1844.

? — RUGOSA, juv. ? Forb. and Hani. Hist. Brit. Moll., vol. i, p. 149, pi. 6, figs. 1—3,

1848.

— var. Gray. List Brit. Moll., p. 88, 1851.
SPHENIA CYLINDRICA. S. Wood. Catalogue, 1840.

Spec. Char. Testa oblongd, vel snbcylindraced tenui,fragili, inceguilaterali, laevi (prater
strias incrementi irregulares] later e postico obtuse angulato ; cardine unidentato.

Shell oblong, or subcylindrical, thin, fragile, inequilateral, smooth (except the
irregular lines of growth) ; posterior side with an obsolete, angular ridge ; one cardinal
tooth.

Length, f inch. Height, f inch.

Locality. Cor. Crag, Sutton.

Very abundant. All my specimens were found free and loose in the sand with
the valves separated.

Our shell in its young state is furnished with one cardinal tooth, and a depression
for its reception in each valve ; and, like Saxicava, these teeth become obsolete when

' There is no distinct lunule in these shells, the appearance of such is produced simply by an
obsoletely-curved ridge in the shell, on the anterior side.

BIVALVIA. 289

the shell is full grown. There is a small sinus in the mantle-mark, and the impressions
of the adductors are very distinct. Within these, on both sides, a ridge diverges from
beneath the umbo ; that on th« anterior side is the more prominent. The ligament
appears to have been supported upon a prominent fulcrum, while the cartilage was
placed in a depressed line upon the dorsal edge, and there is a small gape on the
siphonal side.

The shell above referred to, in the ' Hist, of Brit. Moll./ may possibly be the
descendant of our fossil, as I had supposed when compiling my Catalogue, (Ann.
and Mag. of Nat. Hist., 1840, p. 245, infra], but several dead valves of the recent
species, since obtained from the beach on Stone Point, at Walton Naze, cast a doubt
upon that identification, the recent shell having the siphonal side much broader than
the anterior, and is not quite so flat.

I have no doubt of our fossil being distinct from Saxicava arctica, nor do I think
there is any good reason for believing it to be the fry of some larger species. It is
difficult to determine where it ought to be placed, but it appears to conform more
nearly with the diagnosis of Saxicava than with any other existing genus. I would
have adopted Arcinella, proposed by Philippi for the succeeding species, but that this
name had been twice previously used in the class Mollusca ; and Sphenia, the genus in
which I had provisionally placed it, has a different hinge with an internal ligament
like that of Mya, placed upon a spatulate projection.

3. SAXICAVA ? CARINATA ? BroccU. Tab. XXIX, fig. 5, a — e.

MYTILUS CARINATUS? Broc. Coq. Foss. Subap., p. 585, t. 14, fig. 16.

1 Gold/. Pet. Gerra., p. 179, pi. 131, fig. 14.
ARCINELLA CARINATA. Phil. En. Moll. Sic., vol. ii, t. 16, fig. 9.
SPHENIA ANGULATA. S. Wood. Catalogue, 1840.

Spec. Char. Testa minutd, transversd, oblongd, valde inaequilaterali^ tenui,fragili ;
antice brevi, postice carinatd, angulatd, productd, granulosd ; cardine unidentato.

Shell minute, transverse, oblong, very inequilateral, thin, and fragile ; anterior side
short, posterior angulated, carinated, and produced, with a granular surface ; hinge
with one tooth.

Length, % inch. Height, \ inch.

Locality. Cor. Crag, Sutton.

A few specimens only of this species have come under my observation, and those
are all in my own cabinet.

The shell it most resembles is the preceding, from which, however, it differs in
having the siphonal side much more angular, pointed, and carinated, with also a
roughened or shagreen-like exterior, most distinctly visible on the posterior slope.

38

290 MOLLUSCA FROM THE CRAG.

There is one obtuse tooth, most prominent in the right, with a corresponding depression
in the left valve, and the anterior muscular impression is of an ovate form, deeply

impressed.

I have assigned it, with some degree of doubt, as an identity with the Italian fossil,
depending upon the very imperfect figure by Brocchi. It accords with his description,
except that it is not " smooth/' as he describes it ; but some of my specimens appear
to have lost their granular exterior, and this may have been the case with the sub-
Apennine fossil.

An American shell from the Older Tertiaries, Byssomya petriculoides, Lea, ' Contrib.
to Geol./ p. 48, pi. 1, fig. 16, though evidently distinct, more nearly approaches this
species than Saxicava arctica, to which it has been considered to have belonged.

Philippi has given the representation of a fossil under the name of Arcinella carinata,
which I have considered as this species, and he refers to Mytilus carinatus, Brocchi ;
but there is no description to assist in its determination, and my dependence is entirely
upon his figure. Arcinella laevis, of the same author, vol. ii, p. 54, t. 16, fig. 10,
probably belongs to a different genus ; it looks like the left valve of Montacuta bidentata.

GLYCIMERIS,* Lamk. 1801.
CYRTODABJA. Daudin, 1792. Fide Gray.

Generic Character. Shell equivalved, inequilateral, elongately oblong, thick, strong,
flattish or compressed, gaping widely at each extremity. Hinge edentulous ; ligament
external. In the recent state covered with a thick epidermis. Two deep impressions
by the adductor muscles, with a small sinus in the rugged and irregularly-shaped
mantle-mark.

Animal of the form of the shell, with the lobes of the mantle thick, and the edges,
united, except immediately in front, where there is an opening for the passage of a
small cylindrical foot ; siphons united to their extremities, thick, and fleshy, with a
wrinkled epidermis, and incapable of being withdrawn into the shell ; orifices fringed ;
branchiae long and thick, two on each side.

One recent species only of this genus has yet been noticed, and that has been
long known. It is an inhabitant of the arctic regions, and the N. E. Coast of America,
but not met with in our own seas. The animal of this has been examined by M.
Audouin, and its details published in the 'Ann. des Sc. Nat./ 1833, from which it
appears to have somewhat of an isolated position. M. de Blainville placed it among
the Naiades. In the shell and its hinge-furniture it has considerable resemblance to
Panopea Norvegica.

In Mr. Edwards's cabinet is a species from the lower division of the Older
Tertiaries.

* Etyra. y\vKts, dulcis, and /uep«s, a species so called by Pliny from its sweet taste.

BIVALVTA. 291

1. GLYCIMERIS ANGUSTA, Nyst and Westendorp. Tab. XXIX, fig. 2, a — d.

GLYCIMEBIS ANGUSTA. Nyst and West. Nouv. Rech. Coq. Foss. d'Anv. (Bull, de 1'Acad.

des Sc. de Bruxelles, torn, vi, 1839), p. 4, pi. 1, fig. 1.
Nyst. Coq. Foss. de Belg., p. 55, pi. 11, fig. 1, 1844.
VAGINA. <S. Wood. Catal. of Crag Shells in Ann. and Mag. Nat. Hist., vol. vi,

p. 245, 1840.
= /. Sow. Min. Conch., t. 636, 1844.

Spec. Char. Testa elongato-oblongd. crassd, rugosd, tortd, valde inaquilaterali ; joos-
tice breviore, truncafd, mlangulatd ; antice productd, attenuatd ; valvis intus incrassatis.

Shell elongately oblong, thick, rough and twisted, and very inequilateral ; pos-
terior side the shorter, truncated, and somewhat angular; anterior produced, slightly
pointed ; valves thickened within.

Length, 4 inches. Height, \\ inch.

Locality. Cor. Crag, Gedgrave, Sudbourn, and Ramsholt.
Red Crag, Sutton.

This strong shell is by no means rare in the Coralline Crag, and fragments of it are
not unfrequently met with in the Red Crag. Some differences exist between this and
the recent species, Mya siliqua, Chemn., vol. ii, p. 192, t. 198, fig. 1934; the siphonal
side being shorter in the Crag shell, as well as broader, and the anterior more pointed ;
there is also a greater twist or contortion in the valves, and the muscular impressions
are somewhat different ; that of the anterior adductor is more elongated, increas-
ing in breadth towards the anterior, and extending to the verge of the impression by
the mantle on that side ; the posterior adductor is situated further backward than in
the recent shell, almost touching the extreme edge, below which is the small sinus of
the mantle-mark. The shell is much twisted, so that the valves, when united, touch
only at the hinge and basal edge of the anterior margin. There is a large and pro-
minent fulcrum for the ligament, extending nearly to the posterior extremity of the
shell ; between it and the umbo is a cavity for the cartilage, with a callosity or obscure
tooth immediately under the beak.

There is a slight appearance of erosion at the umbones of some of my specimens,
and the exterior is smooth, with the exception of lines of growth. Traces of irregular
lines may be sometimes seen both longitudinally and transverse ; these were probably
produced by the rugosities of its thick epidermis.

In this, contrary to the generality of Bivalves, the siphonal side is much the shorter
of the two.

A recent species of this Genus is in the cabinet of my friend J. W. Flower, Esq.,
said to be from Moreton Bay. It approaches rather nearer to our fossil than does the
Arctic shell, in having a greater twist, but it differs also slightly in form.

292

MOLLUSCA FROM THE CRAG.

GASTROCH^ENA,* Spengler, 1783.

UPEROTUS (part). Guettard, 1774.
CH^ENA (part). Retzius, 1788.
MYA (sp.) Pennant.
PHOLAS (sp.) Chemn. Poli.

FISTULANA (sp.) Brug. 1792.
TRAPEZIUM (sp.) Megerle, 1811,
GASTROCHINA. Swains. 1840.

Generic Character. Shell equivalve, inequilateral, oval or wedge-shaped, with a
large ventral opening ; hinge linear ; a single laminated obscure tooth in each valve.
Ligament external.

Tube calcareous, pyriform ; posterior opening narrow, with a bipartite or divided
aperture.

Animal cuneiform, siphons united to their extremities, orifices fringed, mantle
closed, with the exception of an opening for a small, finger-shaped, curved, and
pointed foot, sometimes furnished with a delicate byssus.

Animals of this genus are generally enclosed in the thick shelly substance of some
mollusc, or in the centre of a mass of coral, their excavations being produced by an
operation of the animal itself. The mode by which this is effected is not yet satisfac-
torily determined, a difference of opinion still existing as to whether it is caused by
the action of a solvent, or by the mechanical operation of surface abrasion.

Some specimens do not attempt to excavate, but merely to enclose themselves in
their own flask-like cases, to which occasionally foreign materials are added.

Species of this genus have been found in the Oolite Formations, and in the Older
Tertiaries, but nowhere in any abundance.

1. GASTROCHINA DUBIA, Pennant. Tab. XXX, fig. 11, a — d.

MYA DUBIA. Penn. Brit. Zool., vol. iv, p. 82, pi. 44, fig. 19, 1777.

CHAMA PARVA. Da Costa. Brit. Conch., p. 234, 1778.

MYA PHOLADIA. Mont. Test. Brit., p. 28, 1803 ; and Supp., p. 20, 1808.

PHOLAS FABA. Pulteney. Hutchin's Hist. Dorset, p. 27.

GASTROCHINA MODIOLINA. Lamk. Hist, des An. s. Vert., torn, v, p. 447, 1818.

Forb. and Hani. Hist, of Brit. Moll., p. 132, pi. 2, figs. 5 — 8,
pi. F, fig. 5.

PHOLADIA. Turt. Brit. Biv., p. 18, pi. 2, figs. 8, 9, 1822.

LuJcis. Mag. Nat. Hist., vol. vi, p. 404, fig. 52, a — g.

CUNEIFORMS. Phil. En. Moll. Sic., vol. i, p. 2, 1836.

POLII. Id. „ „ „ vol. ii, p. 3, 1844.

HIANS. Flem. Hist. Brit. An., p. 458, 1828.

FULVA. Leach, MS. 1818. Ann. Mag. Nat. Hist., vol. xx, p. 272.

DUBIA. Desh. Traite Ele"m. Conch., pi. 2, figs. 4, 5.

POLIANA. Phil. In Wiegman Archiv. Nat., pi. 7, fig. 1, 1845.

Etym. yaanjp, ventral, and \atvtD, to gape.

BIVALVIA. 293

GASTROCH^ENA FABA. "Leach, MS." 1817. Fide Gray.
MYTILUS AMBIGUUS. Dillw. Cat. of Recent Shells, p. 304, No. 9.
PHOLAS PUSILLA. Poli. Test. Sic., vol. i, p. 50, t. 8, figs. 12, 13, 1791.

Spec. Char. Testa elongatd, cuneiformi, tenui, fragili ; hiatu magno ovato; striis
Incrementi valde conspicuis ; umbonibus subterminalibus vix prominulis ; cardine subcalloso.

Shell elongate, wedge-shaped, thin and fragile, with a large ventral gape ; lines of
growth conspicuous ; beaks nearly terminal, scarcely prominent ; hinge with an obtuse
callosity.

Length, -f inch.

Locality. Cor. Crag, Sutton.

Red Crag, Sutton. Recent, Mediterranean, Britain.

Numerous fragments of the calcareous tube of this species are met with in the
Red as well as in the Coralline Crag ; and I have found the valves imbedded in the
globular masses of coral so abundant in the latter Formation, and also in the thickest
part of the common oyster. These excavations made by the animal appear all to have
been lined with a calcareous coating, as well in the thick shell of the oyster as in the
porous substance of the coral ; and the exterior of this marsupium, or purse-like
envelope, is always more or less granular, wherever it is exposed.' My specimens
present considerable variation in regard to magnitude, some of the valves having
twice the length of others, though all appear to have formed a calcareous lining to
their excavation, and as such, it is presumed, they have attained to full maturity. I
have none so small as to be considered the young, without the lining, assuming it not
to have the power of increase after it has once formed its own envelope.*

This calcareous flask-like covering is terminated posteriorly with a tube for the
protection of the siphons, which project a little beyond the surface of the coral, and
the neck of this is often of considerable thickness. At a distance of about a quarter,
or sometimes half an inch within the tube, a calcareous partition is seen (fig. 1 1 d),
with a linear opening crossed in two places, assuming the form of a double dagger,
each siphonal aperture having the appearance of a cross. This opening appears to be
variable in different species, but whether the form be a good specific distinction I am
not able to say.

* In the case of the Gastrocfuena, it is probable that only when it has attained to full maturity does
it form a lining to its crypt, or a covering to itself ; this being, as it were, exterior and detached from the
vital portions of the animal, may be incapable of alteration, but it probably possesses the power of dissolving
or destroying this case, and constructing another, as occasions require, by the same means it has employed
for the enlargement of its domicile. The prevailing opinion is, that the shell, or exo-skeleton, as it is called,
being extra-vascular, is not susceptible of alteration by interstitial increase, but we know that absorption
does take place ; and the examination of shell-structure by the microscopist shows us clearly its highly
organized condition, permeated with vessels for the conveyance of fluids ; and it is exceedingly difficult to
explain in any other way some of the operations of the Mollusca, more especially the alterations in magnitude
of the hinges of the Bivalves, for example, during the growth of the animal.

294

MOLLUSCA FROM THE CRAG.

In some specimens, the terminal tube projects a little distance beyond the surface
of the coral, and of course, when alive, has its siphons always free. Occasionally the
o-rnwn fastftr_thajijthe_mollusc. or, what is more probable, had con

_ __

tinued to increase after the death of the imprisoned animal, the terminal opening having
been closed up by the growth of the coral.

PHOLAS,* Linnaeus.

DACTYLUS. Pliny.

HYPOG.EA HYPOGEODERMA. Poll, 1791.
ZIRF.EA. Leach, MS. 1817. Gray, 1851.
THOVANA. Id. 1818.

BAKNIA. Leach, MS. 1819.
DACTYLINA. Gray, 1847.
ANCHOMASA. Leach, MS. 1819.

Generic Character. Shell ovate or transversely elongate, equivalved, inequilateral,
externally rough or imbricated, more or less ornamented with radiating ridges, gene-
rally gaping at both extremities, occasionally furnished with accessory valves, and a
reflected callosity over or before the beaks ; a large, curved, testaceous appendage
projects immediately beneath the umbo ; no teeth or hinge ligament ; and the impres-
sion of the mantle is deeply sinuated.

Animal thick and club-shaped ; lobes of the mantle open in front, and reflected
dorsally, by which the accessory valves are formed ; siphonal tube long and extensile,
divided at the extremity, and bordered with cirrhi ; foot thick and truncated.

This is, generally speaking, a marine genus, and most of the species are inhabitants
of shallow water, ranging to about 25 fathoms. Ph. rivicola, Reeves and Adams,
' Voyage of the Samarang,' pi. 25, fig. 5, is said to have been found burrowing in
floating logs at Gunung Taboor, on the Pantai River, twelve miles from the sea, and
where the water was quite fresh. This species is divided by a depressed line or sulcus,
like Ph. crispata, and has, at the pedal opening, a calcareous covering, but without an
accessory cup at the base of the siphons.

It is extremely difficult to define the generic limits of this group of shells. Some
are furnished with an umbonal shield, consisting of several pieces ; some have only
a single dorsal valve, while in others this appendage is rudimentary or absent. These
differences are considered to be only of specific value with' many naturalists, while
others make them generic distinctions.

The name given implies that the habits of these animals are those of excavators,
and they are found to burrow in various materials, sandstone as well as calcareous
rocks, wood, &c. The species do not always confine themselves to one kind for their
habitations, and in all probability the mechanical mode is the one most generally

Etym.

, to burrow, or hide in a hole.

BIVALVIA. 295

employed ; but whether the shell is the instrument used for such a purpose is not so
satisfactorily determined. We sometimes find specimens with the asperities of the
shell worn down, where the animal has located itself in mud ; and at other times
specimens have never had their roughened surfaces at all abraded. We know also
that other animals than those belonging to the Mollusca, such as have no rough or
hardened exterior, are able to penetrate deeply into stone as well as into wood.

1. PHOLAS CYLINDRICA, /. Soiverby. Tab. XXX, fig. 8, a — d.

PHOLAS CYLINDRICA. J. Sow. Min. Conch., t. 198.

Nyst. Coq. Foss. de Belg., p. 41, 1844.

Dale. Hist, and Antiq. of Harwich, p. 295, t. 13, fig. 6, 1730.

Spec. Char. Testa elongatd, subcylindricd, tenui, fragili, valde incequilaterali ; latere
antico abbreviate, postico porrecto, accuminato ; costatd, costis anticis dentato-muricatis,
costis posticis ad extremitatis evanescentibus.

Shell elongate, subcylindrical, thin, and fragile, very inequilateral ; anterior side
short, posterior prolonged, and obtusely pointed ; costated ; ribs on the anterior side
toothed and rough, and on the posterior obsolete towards the extremity.

Length, 3 inches. Height, 1 inch, nearly.

Locality. Cor. Crag, Sutton.

Red Crag, Sutton and Walton Naze.

This species is very abundant at Walton-on-the-Naze, but, from its fragility, speci-
mens are difficult to obtain in perfect condition. In the Coralline Crag I have met
with only a few fragments.

It most nearly resembles the British species, P. _parva, from which it may, however,
be distinguished by its being more inequilateral, the siphonal side occupying at least
two thirds of the entire shell, and the opening for the foot on the ventral portion of
the anterior side is larger and deeper. The shell is reflected over the back, covering
the umbones, but the reflected portion is not partitioned like that of Ph. dactylus, and
there is a tubercle at the middle, flattened by the pressure of the valves ; the large
and subovate impression of the adductor muscle is placed about midway between the
umbo and the posterior extremity, and the line of the mantle-mark extends inwards
a little beyond it ; the plate or tooth curves from immediately beneath the beak, and is
slightly spatulate in form. There is a small opening in the dorsal portion of the
anterior side, which was no doubt covered by an accessory piece. Fragments of such
a valve have been found by myself at Walton, most probably belonging to this species,
(fig. 8, d.)

The figure given by Dale, above referred to, is no doubt our shell, as he says Dr.
Woodward found it in Harwich Cliff; and as it is abundant at Walton Naze, its

296 MOLLUSCA FROM THE CRAG.

proximity to that locality would fairly justify its being so considered, though he refers
to Lister's figure, No. 276, which is Ph. dactylus, not as yet found in the Crag that I am
aware of.

Pieces of indurated clay are occasionally met with at Walton Naze that have been
perforated by this species ; and I have a small portion, little more than two inches
square, and half an inch thick, full of small specimens. These shells had effected an
entrance from both sides, meeting in the middle ; and one side contains almost as
many as the other, showing the probability of the stone having been moved by the
action of the water, to have permitted an ingress at both surfaces. A specimen of
wood in my possession, from the Red Crag, but now in a lapideous state, contains an
individual of this species, which, like Pit. parva, its very near relative, did not appear
to confine itself to one kind of habitation. Some of these shells were at times only half
immersed, as specimens have often the upper portion covered by the remains of a
membranipora.

2. PHOLAS CRISPATA, Linnceus. Tab. XXX, fig. 9, a — c.

PHOLAS CRISPATA. Linn. Syst. Nat., p. 1111, No. 25, 1767.

Penn. Brit. Zool., 1st ed. p. 77, pi. 40, fig. 12, 1776.

Don. Brit. Shells, vol. ii, t. 62, 1801.

Gould. Inv. of Massach., p. 27, 184 1.

Dekay. Hist. New York Moll., p. 247, pi. 32, figs. 506, and 506 a.

Cuvier. Regne Anim., pi. 113, fig. 3, animal.

— BISFRONS. Da Costa. Brit. Conch., p. 243, t. 16, fig. 4, 4.

— PARVA. Id. Brit. Conch., p. 247.

Donovan. Brit. Shells, vol. ii, pi. 69, 1801.

— LATUS. List. Hist. Conch., lib. iii, fig. 379 A, with the animal, 1685.
SOLEN CRISPUS. Gmel. Syst. Nat., p. 3228.

CRISPATA. Gray. List Brit. Moll., p. 53, 1851.

Spec. Char. Testa ovatd, crassd, subaquilaterali, antice dreviore, rostratd, et costatd ;
costis dentato-muricatis, latere postico rotundato ; extremitatis hiantissimis ; sulco unico
submediano, obliquo.

Shell ovate, thick, slightly inequilateral, anterior side the shorter, beaked and
ribbed ; ribs furnished with roughened and prominent denticulations ; extremities
widely gaping : divided by a submedial oblique suture.
Length, 3 inches. Height, \\ inch.
Locality. Cor. Crag, Sutton.

Red Crag, Sutton, Walton Naze.

Mam. Crag, Bridlington. Fossil, Sweden.

Recent, Britain, Scandinavia, and N. E. Coast of America.

Although essentially a boreal species, it lived in the seas of the Coralline Crag, a

BIVALVIA. 297

fragment of a specimen having been there found by myself. It seems to have become
much more abundant in the succeeding Period, as it is by no means rare at Walton
Naze, but difficult to procure, the shells generally separating at the suture. It has also
been found in the Drift Beds in Ireland, and ranges, in the living state, on the N. E.
Coast of America, as far as South Carolina. The characters of this species are well
marked, so as not easily to be confounded with any other. It is found in a very modern
Tertiary Deposit at Bracklesham, where specimens have been obtained measuring
4J inches in length, in company with Ph. Candida.

Ph. dactylus is in Mr. Smith's ' List of Clyde Fossils.'

PHOLADIDEA, Leach, 1819.

PHOLAS. Turton.

MARTESIA. Leach, 1818. Blainv. 1824.
JOUANNETIA? Desmoul. 1828.
PHOLIDEA. Swains. 1835.

Generic Character. Shell ovate or oblong, equivalve, inequilateral, externally
rough or imbricated. Anterior extremity open in the young, but closed in the adult
shell. Posterior extremity truncated and gaping, furnished with a coriaceous or
testaceous cup when full grown.

Animal club-shaped ; mantle closed, except a small opening in front for the passage
of a truncated, sucker-shaped foot. Siphonal tube long, terminating in a disk, sur-
rounded with cirrhi ; terminal openings also fringed.

This genus has been founded upon a species of one of the rock-boring molluscs,
whose great peculiarity is, that when it has arrived at the full stage of existence, it
closes the previously large opening in front with a thin calcareous covering ; and at its
posterior termination there is added a small testaceous cup at the base of the siphons.
If this be entitled to generic distinction it must rest its claim upon the latter character,
as many of the Pholades have a large pedal opening in their young state for the active
employment of that organ, possessing the same habits as the animal of this genus, in
closing the aperture when full grown by a calcified membrane. Some other species
also endowed with this habit, though not strictly according with the diagnosis of this
genus, appear to be very closely related, viz., Pholadopsis, Conrad, and Triomphalia,
Sowerby, but the valves are of unequal magnitude. Other species, possessing two
radiating furrows, have been proposed for a genus by Conrad, under the name Para-
pholas.

The prolongation of the shell at the posterior side appears to be the commencement
of what, in proximate genera, become a lengthened calcareous tube for the protection
of the elongated siphons, as pointed out by Messrs. Forbes and Hanley, when con-

39

298 MOLLUSCA FROM THE CRAG.

sidering this as the connecting link between the Pholas and the Teredo ; and it may be
further remarked, that the habit of closing its anterior opening, when the animal has
attained to full maturity, is very analogous to the closing of the anterior portion of the
tube in the adult or senile species in the Teredo and other tube-forming Bivalves.

Pholades have been found fossil as early as the Lias, and, as it might be supposed,
were present in the Tertiary Formations. One species, in the Paris Basin, forms a
calcareous lining to its burrow.

PHOLADIDEA PAPYRACEA, Solander. Tab. XXX, fig. 10.

PHOLAS PAPYRACEA. Solander, MSS., fide Turton. Portland Cat., p. 82, lot 1828.
Turt. Brit. Biv., p. 2, pi. 1, figs. 1—4, 1822.
G. Sow. Gen. of SheUs, No. 24, fig. 3.
Eeeve. Conch. Syst., pi. 24, fig. 3.
PHOLADIDEA GOODALLII. Diet, des Sc. Nat., t. 37, p. 532.

STRIATA. Guv. An. Kingd. (edit. Griffith), pi. 8, fig. 1 .
LAMELLATA. Turt. Brit. Biv., p. 4, pi. 1, figs. 5, 6.
— LOSCOMBIANA. Goodall in Turt. Conch. Diet., p. 147, 1819.

PAPYRACEA. Forb. and Hani. Brit. Moll., vol. i, p. 123, pi. 5, figs. 3—6.
Gray. List Brit. Moll., p. 52, 1851.

Spec. Char. " P. testa clavatd, later e antico clauso obtusissimo, postico hiante truncato
accessorio producto annulari"

" Shell club-shaped, closed and very obtuse at the anterior end, open and truncate
at the other end, which is furnished with a produced accessorial ring." — Turton.

Length, \\ inch. Height, |- inch.

Locality. Cor. Crag, Sutton. Recent, South Coast of Britain.

A few fragments, in my cabinet, indicate so strong a resemblance to the recent
British shell, that I do not hesitate to refer them to that species. One piece has the
obtuse anterior extremity, with the smooth surface of the enclosed portion of the gape
peculiar to the adult shell ; while two fragments of the siphonal side are truncated, and
marked with concentric lines like the recent species, without any radiating ridges.
They are, however, unfit for description ; and I have therefore copied the diagnosis
from Turton.

TEREDO,* Linnaeus, 1767.

TEREDO. Sellius, 1732. Adamson, 1757.
SIPHONIUM. Brown, 1756.
SERPULA (sp.) Linn. Schroet.
UPEROTUS (sp.) Guettard, 1774.
XYLOPHAGUS. Gronov. 1781.

TEREDARIUS. Dumeril, 1806.
SEPTARIA. Lamk. 1818.
XYLOTRYA. Leach, MS. 1817.
BANKIA. Gray, 1840.
MALLEOLUS. Gray, 1848.

* Etym. repij5wj', Pliny, a rep//w, to bore.

BIVALVIA. 299

Generic Character. Shell convex, tumid, inequilateral, equivalved, presenting, with
the valves united, an orbicular or nearly spherical outline, having a large angular
opening in front, and a rounded or ovate aperture posteriorly ; covered or ornamented
externally with ridges or striae, caused by the slightly reflected or thickened edges of
the margin ; a testaceous process or tooth, of a somewhat spatulate form, curves and
projects inwardly from beneath the umbo ; one distinct muscular impression ; ligament
obsolete.

Animal worm-shaped ; mantle open in front ; siphons very long, bifurcating at
their extremities ; orifices fringed ; foot rudimentary.

The valves are situated at the anterior extremity of an irregular, subcylindrical,
elongated, and somewhat flexuous testaceous tube, which appears to be formed for the
purpose of lining the cavity made by the animal. This tube, in some species, is large,
thick, and heavy, while in others it is thin and semi-transparent ; the variation, per-
haps, depending upon a necessary protection against lateral pressure. At the posterior
termination are two pennate or palmate opercula, called pallettes by Adanson, or
calumnies by Deshayes, by which the aperture is closed at the will of the animal, one
probably employed as a lid to each siphon ; and this end of the tube, in some species,
is partitioned with segments or semi-camerations, but for what especial purpose has
not been satisfactorily ascertained. The growth of the animal, and necessarily the
enlargement of the valves, causes a corresponding increase in the size of the tube,
which is lengthened at the anterior extremity, while the posterior part is kept on a
level with, or a little beyond, the surface of the wood, so as always to keep the siphons
free.* The addition of calcareous matter is made to the larger end only, which is
kept open until the animal has attained to full maturity, when it is closed with a convex
or dome-shaped termination.

The habits of most of the species lead them to excavate timber of all kinds. T.
corniformis burrows in the husks of the cocoa-nut ; and T. arenaria locates itself in mud.
The tube of the latter animal (figured and described by Mr. Griffiths, in the ' Phil.
Trans.' for 1806, p. 269, from a specimen found on the N. W. Coast of Sumatra) mea-
sured 5 feet 4 inches in length, and 9 inches at its greatest circumference ; the posterior
termination was longitudinally divided into two separate tubes for about 8 or 9 inches,
and the larger end was closed, where the animal had constructed two separate septa
a few inches within. The character of a longitudinal division for the two siphons is
sometimes observable in the European species of this genus, and they terminate di-
vergingly ; but this, probably, is not constant, and only dependent upon circumstances.
The tube of T. arenaria presents, when fractured, a crystalline or radiating structure.
The tubes of our fossil, and other European Teredines, are composed of numerous

* In the kindred genus Xylophaga, the animal does not furnish itself with a calcareous tube, as it
never retreats far from the surface of the wood into which it has penetrated, consequently has no elongated
siphons.

300 MOLLUSCA FROM THE CRAG.

concentric layers, thickened with the age of the animal. If the Sumatra species cor-
respond in all other respects with this genus, it will slightly diminish the value we
have hitherto placed upon structural composition.

This genus is found abundantly imbedded in the fossil wood of the London Clay,
and the fruits or seed-vessels of Sheppey (tfipadites, Bowerbank) are sometimes per-
forated by these animals. The tubes are of various sizes, some of them much smaller
than others, the larger ends of which are generally closed, and consequently presumed
to have attained to the full period of individual existence. The closing of the larger
end is an operation performed also by other genera, such as Clavagella and Aspergillum,
which have a perforated termination, and the valves are fixed or soldered into the sides
of the tubes. This fixing of the valves is only done when the animal constructs the
roof to its dwelling, as, if fixed at an earlier period, they would appear at irregular
distances ; and I believe the valves of these genera, like those of Teredo, are loose and
free while the animals are growing, and only imbedded in the walls of the tubes at the
time they have closed or imprisoned themselves by the construction of their dome-
shaped or perforated disk.

There is no true ligament in this genus for the union of the valves, but a powerful
muscle forms a deep impression upon the shell at the exterior of the dorsal margin,
and is the only hinge on which the valves are moved.

A species has been found in the Lias in dichotyledonous wood.

The natural history of this " calamitas navium," as it was called by Linnaeus, is
graphically given by the authors of the ' Hist, of Brit. Moll.,' with the various opinions
respecting these wood-eating animals, and their allies, the stone-eating Pholades. This
subject is far from being exhausted, differences of opinion as to the modus operandi
exist at the present day, and have done so ever since the time of Pliny, who imagined
the animal of the Teredo to be a worm, and its two valves the formidable jaws by which
it was capable of inflicting upon mankind such dire calamity. The species are not
numerous, even in the recent state, but the individuals have multiplied to an alarming
extent, and at one time threatened! to submerge the States of Holland.

TEREDO NORVAGICA, Spengler. Tab. XXX, 12, a — d.

TEREDO NORYAGICUS. Spengler. Skrivt. af Naturh. selsk., vol. ii, part 1, p. 102, pi. 2,
figs. 4—6 B, 1792.

— NORVAGICA. Loven. Ind. Moll. Scand., p. 50, 1846.

Forb. and Hani. Hist. Brit. Moll., vol. i, p. 67, pi. 1, figs. 1 — 5,
1848.

— NORVEGICA. Thompson. Ann. and Mag. Nat. Hist., vol. xx, pp. 157, 163.

Adanson. Acad. Scien. Par., t. 9, figs. 1 — 8.

— NAVALIS. Mont. Test. Brit., p. 527 ; and Supp., p. 7.

BIVALVIA. 301

TEREDO NAVALIS. G. Johnston. Mag. Nat. Hist., vol. ii, p. 23, fig. 7, b, 1829.

Dekay. Nat. Hist. New York, p. 34, fig. 325.
— BRUGUIERI. Delle. Chiaje. Mem., vol. iv, pi. 54, figs. 9 — 12.

Phil. En. Moll. Sic., vol. i, p. 2 ; and vol. ii, p. 3.J

Spec. Char. Testa tumidd, convexd ; angularibus striatis ; utraque hiante, hiatu postico
magno angulato ; antico ovato.

Shell tumid, convex, subspherical ; marked externally with angular striae ; gaping
widely on both sides ; posterior with a large angular opening ; anterior ovate.

Diameter, J inch.

Locality. Cor. Crag, Sutton, Ramsholt.

Red Crag, Sutton. Recent, Norway, North America, Britain,

Mediterranean, and Black Sea.

A single valve, in my cabinet, is all that I have seen from the Crag, and this I
believe to be navalis of Mont. Fig. 1 2, c, represents a fragment of the posterior por-
tion of the tube, probably of this species, showing the camerated structure ; but there
is no appearance of longitudinal division. It is, however, too imperfect for any safe
reliance in that respect.* Fragments of tubes are not unfrequently met with in the
Red, as well as in the Coralline Crag, perhaps belonging to the same animal. They
are thick and strong, with a diameter varying from ^-th to |th of an inch.

The valves of the different species of this genus preserve a great similarity, and it
is said they can only be determined specifically by the pallets or styles at the posterior
orifice, and as these have not, that I am aware of, been found in the Crag, the present
appropriation, if the above be true, may be considered doubtful.

This portion of the Monograph contains the descriptions of forty-six species of
Bivalves from the Lower or Coralline Crag Formation. Of this number, there are
thirty-two identical with forms still in existence. From the Red Crag are described
thirty-nine, out of which I have considered twenty-five as living species. Hence it
will be seen that the former gives an amount of identification as high as 69 per cent.,
with a consequent extinction of 31 ; while the latter (Red Crag) has an amount of
extinction as high as 36 per cent., giving, by this estimation, a greater antiquity to the
higher or newer of the two Formations ; and even presuming a better examination
might bring the Red Crag on to an equality with the Coralline, the two Formations
do not appear by this test to be capable of separation.

May it not be asked whether it is necessary, in order to ascertain the age of a
Tertiary Formation by the per centage system, and to assign it to one of the tripartite
or quadrupartite divisions of the Cainozoic series, we are to take the whole of the

* This part of the tube, according to Montague, affords little or no assistance in the determination of
the species : the number of these camerations or partitions vary from four to as many as twenty; indeed,
in one specimen he examined, he counted not less than twenty-nine.

302 MOLLUSCA FROM THE CRAG.

Marine Fauna of the entire deposit, or may we be permitted to select a part only for
such examination, and if so, what part ?

The Mollusca herein described bear so close a resemblance to animals now living in
our own seas, as to give good reason to believe their geological relationship to be much
nearer to the present Period than to the Eocene ; and if an amount of extinction of
more than one half of its species be necessary to entitle a Deposit to be considered as
belonging to what is called the Miocene or Middle Tertiary, our present identifications
do not fulfil those required conditions, even for the lowest or oldest (by position) of the
Crag Formations.

Assuming that a different construction might be put upon a few of the specific
determinations, in opposition to the conclusions I have arrived at, I much doubt
whether the Coralline Crag could possibly be made to contain more than 50 per cent,
of extinct species of Mollusca ; while the connection zoologically between this Deposit
and those of the Eocene is so small as to have an identity of less than 1 per cent, that
have transmitted their posterity unaltered from those Periods into the Crag; and
although a considerable difference of conditions probably existed under which the
Formations were deposited, Tropical forms are by no means wholly excluded from
the Coralline Crag Sea, neither are sub-Arctic genera, such as Glycimeris, Astarte, and
Cyprina, absent from the Older Tertiaries.

When the present work was begun, I had purposed to call it simply ' A Monograph
of the Crag Mollusca;' but this title had to be submitted to the Council of the
Palaeontographical Society for their approval, when the term " Crag " was thought by
some of the members of that body to be of too local or technical a significance, and
would not be fully understood by foreign geologists ; and the explanatory addition of
' Descriptions of Shells from the Middle and Upper Tertiaries of England ' was then
suggested, and acceded to by myself.

A more complete examination of these Deposits, during the progress of the work,
has induced me to believe the term " Middle" to have been incorrectly introduced,
there being no remains of a Formation in Great Britain referable to that Period, more
especially if we are to depend, for such determination, upon the amount of extinction
by the per centage mode of valuation ; it is therefore requested to erase the words
Middle and Miocene from the title-pages and other parts of the work formerly given,
as I believe the Formations I have been here attempting to illustrate belong with more
propriety to the Upper Tertiaries.

CEPHALOPODA.

SINCE the publication of the first part of this work, the Red Crag "diggings" have turned up portions
and segments of Nautilus and Ammonites, but these, like the Belemnites, are derivative fossils, and may be
traced to antecedent Formations ; the Nautilus apparently to the London Clay, and the Ammonites to one
of the middle Secondary Periods.* The Cephalopods living in our own seas, and even in those of more
southern latitudes, like the Mediterranean, in association with a Marine Fauna similar to that of the
Coralline Crag, are of such a perishable nature, and possess so little of preservable material, that, except
under very favorable protection, should we be likely to find any portion of their remains. What are called
the Tetrabranchiata, with strong calcareous shells, such as those from the Middle Tertiaries of Bordeaux
and Dax, do not appear to have extended their existence into the sea of the Coralline Crag, although the
Pynda and Pholadomya (tropical forms), when first obtained in the Deposit of that Period, gave a slight
hope that the Nautilus might also there be met with.f

" In my cabinet are casts also of several species of Univalves and Bivalves, which, so far as such
fossils will permit of an identification, are of shells belonging to the Older Tertiaries ; and I will here men-
tion that, although a few of the extraneous organic remains of the Red Crag may be traced to the Chalk
and Older Secondaries, the great majority I believe to have been derived from the Eocene Deposits, and
principally from the London Clay proper, along with the phosphatic nodules ; and I would assign to the
same source (the Older Tertiaries) the marine Vertebrata, Carcharodon, Lamna, Myliobates, Pycnodus,
Phyllodus, Edaphodon Pristis, &c. &c., as well as the Cetacea, recently found in such abundance, and the
Crustacea (Zanthopsis, &c.), — the abrasion, by coast action, being, in my opinion, sufficient to produce all
the effects now visible in the Red Crag, with the sea of that period opening to the northward. Christchurch
Bay, between Handfast Point and the Needles, may perhaps furnish us with a parallel.

f In the second part of the ' Eocene Mollusca,' by F. E. Edwards, Esq., is an address to the subscribers
of the Palseontographical Society, respecting the Siphuncular Theory of the Cephalopoda. The author,
when treating of the tube which perforates the chambers of the shells in that class of animals, attributed to
myself the priority of pointing out a new explanation of the function of that organ, one which seems now
to be generally admitted, and published in his own and better language the statement I had given him of
my opinion, and the arguments used in support of it. This priority has, it seems, been laid claim to in
the sentence quoted in that address. I have, until now, remained silent upon the subject, and would
gladly have continued to do so, had not some of my friends expressed a desire that I should defend myself
from what, to them, appears to be capable of being interpreted into an appropriation of the discovery of
another as my own idea. The only defence that can now be offered is, that I was wholly unconscious of
any other function than that of a hydrostatic balance having ever been attributed to this tube, and I con-
fess to my having been unacquainted with the paragraph referred to.

The necessity of maintaining an integrity of character, and the preservation or permanence of adhesion
in the inorganic elements in these Cephalopods, occurred to me from the especial study of Bulimus decol-

304 APPENDIX.

GASTEROPODA.

The following land and fresh-water shells are from the Formations belonging to the Uppermost or
Newest Tertiaries of Great Britain. These shells are all, with the exception of four, undoubtedly identical
with species still in existence in England, and it is thought an insertion of their names alone, with a
reference to where they have been recently well figured and described, will be sufficient. The exceptions,
though here extinct, are still existing in other parts of Europe ; and as they were formerly inhabitants of
where their remains are now found, they claim a place in the Monograph of the Upper Tertiaries of the
British Isles.

I am indebted to Mr. John Brown, of Stanway, for the list of species from Copford and from Fisherton.

latus and other decollated, or rather decapitated, shells, which appeared to have become so from the want
of the necessary connection between the shell and the more vital parts. It is to Dr. Fleming, perhaps,
that the real priority of the idea should be awarded. In his 'Philosophy of Zoology' there is a very
significant passage, where he speaks of the vitality of the shell when in intimate contact with the fluids of
the animal, foreshadowing there the belief, now generally entertained, that the calcareous portions of the
Mollusca are far from being inert matter, secreted merely as protective coverings to the softer parts (a
considerable section being wholly destitute of such coverings), but that they are truly constituent and
integral portions of the animals themselves, only with a larger amount of inorganic elements.

It is well known that, in some of the extinct species of Cephalopods, the tube is protected throughout
its entire length by a rigid, continuous, and inflexible covering, and one can scarcely refrain from an
expression of astonishment that naturalists, who have purposely studied, and largely published their views
upon the Nautilus and its congeners, should not have discerned the now presumed use of the siphuncle.
If seen, it is perhaps still more extraordinary that this silver cord should have had with it so little
explanation.

My friend Mr. Edwards has (I think wisely) left the determination of the claim to priority to the
judgment of the members ; but an ulterior question arises, which is, whether the paragraph quoted by
Mr. Edwards in his address amounts to more than the suggestive passage by Dr. Fleming, similar in its
purport, to which I have referred.

The two passages are here subjoined : —

" The shell cannot be considered as dead matter so long as it remains in connection with the living
animal. In those animals in which the shell is external, there are muscles which connect the animal with
its external surface, and the bond of union being a substance soluble in water, the muscles can be detached
by maceration. The analogy between shell and bone is here obvious, although in the one case the con-
nection between the muscle and the bone is permanent, in the other between the muscle and the shell
temporary, or frequently changed during the life of the animal. But the vitality of the shell, if I may use
the expression, is demonstrated from the changes which it undergoes when detached from the animal. The
plates of animal matter harden, the epidermis dries, cracks, and falls off, and in many cases the colours
fade or disappear. We confess ourselves unable to point out the means employed by the animal to prevent
these changes from taking place by any process similar to circulation." — Phil. ofZool., by Dr. Fleming,
vol. H, p. 405, 1822.

"Whatever additional advantage the existing Nautilus might derive by the continuation of a vascular,
organized membranous siphon through the air-chambers, in relation to the maintenance of vital harmony
between the soft and testaceous parts, such likewise must have been enjoyed by the numerous extinct
species of the Tetrabranchiate Cephalopods, which, like the Nautilus, were lodged in chambered and
siphoniferous shells."— Lectures upon the Invertebrata, by Professor Owen, p. 331, 1843.

APPENDIX. 305

Mr. Pickering has furnished me with those from Grays and the Kennet Valley; Mr. Woodward has
supplied the Maidstone one; and the Cropthorn list was published by the late Mr. Strickland. The
species from Clacton and Stutton were obtained by myself, and for which I am responsible.

Land or fresh-water shells have also been found at Bacton («), Brentford, Cambridge (6), Casewick,
Charing (6), Chislet, Clapton, Cuxton (b), near Stroud, Erith, Faversham, Folkestone, West Hackney,
Harwich, Hemingford Abbots, Herne Bay, Ilford, Isle of Wight, Littleport (5), (Isle of Ely), Market
Weighton, Mundesley, Peterborough, Eain near Braintree, Runton, Stamford, Valley of the Nar (b),
Witham, and Yeovil ; perhaps elsewhere, but the localities are too numerous to have here a separate and
distinctive catalogue, (c) These Lacustrine or Fluviatile Beds appear to be principally'confined to the middle
and southern portions of England ; and although they may, perhaps, exist in Scotland or in Ireland, I
have been unable to procure, for insertion here, the name of any locality that might be considered as
analogous or synchronous with the older of these deposits. The fresh-water fossils that have come under
my observation from either of those kingdoms, or from the Isle of Man, were found in peat bogs.

By the following table it will be seen that the species of fresh-water shells fall short of those which
live exclusively on land, although the individuals of the former generally outnumber those of the latter,
as we see amongst the same group of Mollusca of the present day. In the Uppermost Tertiaries we have
about fifty-five species of land shells, with about forty-four fresh-water ones. In the latter are included eleven
species of Bivalves, and the amphibious Succinea. Our catalogues of the land and fresh-water Mollusca
existing in England enumerate about seventy-two of the former, with fifty-one of the latter, giving a slight
difference in the proportions between the recent and fossil species ; but the excess in number at the present
day is greater than can be made up by the extinct species of these deposits, showing that, if we really have
obtained all the species belonging to those past periods, the incomers exceed those which have here gone
out of existence, giving a considerable increase to the existing Fauna, making the insular condition of
England better tenanted than when it is supposed to have formed a part of the Continent.

(a) Bacton is considered by Mr. Prestwich (from position) to be the oldest of all these fresh-water
deposits ; it is most probably synchronous with the Marine and Estuary Beds of Chillesford and Bramerton.
I much regret my list of Mollusca from this locality is so insignificant as to be unworthy of a separate
insertion. Chislet, Ilford, and Mundesley contain one or more of the extinct species, and these may be
assigned to the age of Stutton, Grays, &c.

(5) These are probably the most modern.

(c) The uppermost Tertiaries, or those above the Crag in these islands, have, with every degree of
probability, been separated into four distinct Geological Periods, and our able coadjutor, Mr. Prestwich,
has, I believe, come to the conclusion that an addition must even be made to this number. Their separa-
tion has, however, been founded exclusively upon geological evidence ; and it is with the hope that palaeon-
tological aid may afford some slight assistance to their correct determination that I have made a separate
enumeration of the contents of several of our most important fresh-water localities. Existing species cer-
tainly extend through all, but they are not equally disseminated.

The want of permanence presented by the more recent Formations in the duration of the specific
existence of their Fauna, compared with those of more ancient Deposits, is probably owing to the greater
variety and more rapid alterations of the conditions under which the organisms have their existence in recent
epochs than in those more remote.

40

306

APPENDIX.

p

3,

f

5

10

i;

2(

2;

30
3;

PULMONATA.

Stutton. 1

Clacton.

o

!

o

_o

5"

0

0

0
T3

Fisherton.

Maidstone. 1

i Newbury. 1

i • ~MT".n»~ „.,',/,? 17 ST TT TTiof TCvif TVTnll •+• vnl iv r» 1 nl "n ~n T> fio1 4

• •

*

*
*

*
*
*
*
*
*

Limax agrestis, W. „ vol. iv, p. 13, pi. DDD, fig. 2 .
— Sowerbyi, Ferrussac „ vol. iv, p. 22, pi. E E E, fig. 3 .
Helix aspersa/Mz</ter „ vol. iv, p. 44, pi. 116, fig. 1 .
— nemoralis, Linnceus „ vol. iv, p. 53, pi. 115, figs. 1-4 .
— — var. hortensis, Miil. ,, ... .
— arbustorum(a), Linnceus „ vol. iv, p. 48, pi. 115, figs. 5, 6
— fruticuin, Miiller, vide p. 308 ... . .
Cantiana(6), Montague, v. Ht. Brit. Moll., vol. iv, p. 50, pi. 116, figs. 8, 9

*

*

*

*

•

*
*

*
*
*

*

*
*

. .

*
*
*

*

*

*
*
*

*
*

*
*

*
*
*

*

*
*

— rufescens, Pennant „ vol. iv, p. 66, pi. 1 18, figs. 4, 7, 10
— sericea, Draparnaud „ vol. iv, p. 71, pi. 118, figs. 5, 6
— hispida(e?), Linnceus „ vol. iv, p. 68, pi. 118, figs. 1-3
— — var. plebeia, Jeffreys „ .."".'
— — var. concinna, Id. „
— — var. depilata, Alder „ . . . .
— incarnata ? Miiller, vide p. 309 . .

trirrrotn T)n f.niffl f» Hist RHt TVToll Vol IV T) 57 T)l 117 fiff 10

*

*

*

*

*
*

*

*
*
*

*
*

*
*

. .

— lapicida, Linnceus „ vol. iv, p. 65, pi. 116, figs. 3, 4
— lamellata, Jeffreys „ vol. iv, p. 73, pi. 117, figs. 8, 9
— pulcbella, Miiller „ vol. iv, p. 78, pi. 119, figs. 8-10
— — var. costata, Id. ,, ......
— aculeata, Id. „ vol. iv, p. 74, pi. 117, figs. 5, 6
— fulva, Id. „ vol. iv, p. 75, pi. 118, figs. 8, 9
— ruderata, Studer, vide p. 309 . . •
— rotundata, Miiller, v. Hist. Brit. Moll., vol. iv, p. 80, pi. 119, figs. 6, 7
— fusca, Montague „ vol. iv, p. 77, pi. 119, figs. 4, 5
— cellaria, Miiller „ vol. iv, p. 33, pi. 120, figs. 1-3
— alliaria, Id. „ vol. iv, p. 34, pi. 120, figs. 5, 6
— nitidula, Draparnaud „ vol. iv, p. 36, pi. 120, figs. 8-10
— radiatula, Alder „ vol. iv, p. 38, pi. 121, fig. 1
— nitida, Miiller „ vol. iv, p. 39, pi. 120, figs. 4, 7
— pura, Alder „ vol. iv, p. 37, pi. 121, figs. 5, 6
— pygmsea, Draparnaud „ vol. iv, p. 83, pi. 121, figs. 9, 1(
— crystallina, Miiller „ vol. iv, p. 41, pi. 122, figs. 1, 2
— excavata, Bean „ vol. iv, p. 40, pi. 121, figs. 2-4
Succinea putris, Linnceus „ vol. iv, p. 132, pi. 131, figs. 1-5
— var. Pfiefferi, Rossm. „ . . . . '» .
— oblonga, Draparnaud ,, vol. iv, p. 137, pi. 131, figs. 6, 7

*

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f The references in this list are made to the ' History of British Mollusca,' by Messrs. Forbes and Hanley, except where
otherwise particularly expressed.

(a) Tab. XXXI, fig. 22, is the representation of a monstrous form of this species. A small fracture, in infancy, has caused
the angle of volution to he slightly altered, by which the shell became elongated. At the upper corner of the aperture on the
body whorl is a small tooth or calcareous deposit, forming a sort of excurrent canal, an accidental character produced probably
by its abnormal form, as I have never seen the like in any existing specimen. This was found at Cherry Hinton Jiy the Rev.
Osmond Fisher, in what appears, he says, the site of an old moor or fen. With it were several other shells, H. ericetorum,
Limncea, Planorbis, Succinea, &c. From the same locality Mr. Fisher kindly forwarded to me, with the above, the fragment of
Cardium edule. He says, " I suppose this to have been brought by a sea-gull, or to have accidentally been dropped on the spot
by some extraneous means." This fragment does not look as if it belonged to a recent specimen, and I am inclined to believe it
to be a genuine fossil of the locality. Estuary or tidal conditions might have prevailed over the Bedford Level as high as
Cambridge, by the sinking of the eastern coast only a few feet, such as we may fairly assume to have been the case when
the Inland Cliff at Lowestoff, for example, was washed by the sea ; and although the deposits at Littleport and Cherry Hinton
are probably very modern, the introduction here of these shells as fossils is upon the assumption that they belong to an ante-
human period.

(b) This is in a list of Pleistocene shells in my possession as from Faversham, but upon whose authority I do not now know.

(c) From Cherry Hinton and Bostol.

(d) H. conoidea, Sowerby, figured in the ' Mag. Nat. Hist.,' vol. vii, p. 429. pi. 2, figs. 4, 5, to accompany Mr. Brown's
Paper on the Clacton Fossils. I have not been able to see this specimen ; but, judging from the figure, it does not appear to be
anything more than a variety of H. hispida. This species, when frequenting marshy places, does assume an elevated form.

The asterisks denote the presence of the species.

APPENDIX.

307

2

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PULMONATA.

Stutton.

Clacton.

c
'I

Cropthorn.

Copford.

Fisherton.

Maidstone.

n
c
•3

10

4;>

50

55

no

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70

73

Bulimus Lockhamensis(a), Mont., v. Ht. Bt. Moll., vol. iv, p. 89, pi. 127, fig. 6

— acutus(fi), Mutter ,, vol. iv, p. 86, pi. 128, fig. 5

— obscurus(e), Id. „ vol. iv, p. 90, pi. 128, fig. 7
lubricus, Id. „ vol. iv. p. 125, pi. 125, fig. 8 .
tridens, Pulteney ,, vol. iv, p. 128, pi. 125, fig. 9 .
Achatina acicula(«f), Mutter „ vol. iv, p. 130, pi. 128, fig. 4 .
Pupa umbilicata, Draparnaud ,, vol. iv, p. 95, pi. 129, fig. 7
- anglica Ferussac „ vol. iv, p. 99, pi. 129, fig. 6
— muscorum, Linnaeus „ vol. iv, p. 97, pi. 129, figs. 8, 9
• edentula, Draparnaud ,, vol. iv, p. 103, pi. 130, fig. 1 .
— minutissima, Hartmann „ vol. iv, p. 104, pi. 130, fig. 2 .
pygmsea, Draparnaud „ vol. iv, p. 106, pi. 130, figs. 4-6
Id. var. alpestris ,, .
• sexdentatus, Montague „ vol. iv, p. 108, pi. 130, fig. 3 .
pusilla, Mutter „ vol. iv, p. Ill, pi. 130, fig. 8 .
— antivertigo, Draparnaud ,, vol. iv, p. 109, pi. 130, fig. 7 .
— angustior, Jeffreys ,, vol. iv, p. 112, pi. 130, fig. 9 .

:'f

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Balea fragilis(e), Linnaeus „ vol. iv, p. 114, pi. 128, figs. 8, 9
Clausilia biplicata, Montague „ vol. iv, p. 118, pi. 129, fig. 4 .
— bidens, Miiller „ vol. iv, p. 116, pi. 128, fig. 10
— nigricans, Mat. andBack. „ vol. iv, p. 121, pi. 129, figs. 1, 2
— plicatula, Draparnaud ,, vol. iv, p. 120, pi. 129, fig. 3 .

*

•
•

-

*

Carychium minimum, Miiller „ vol. iv, p. 198, pi. 125, fig. 6 .
Conovulus denticulatus(y), Montague ,, vol. iv, p. 194, pi. 125, fig. 3 .

•

*

I

•

*

:;-•

*

*

Limnsea stagnalis(#), Linnaeus „ vol. iv, p. 174, pi. 124, figs. 4, 5
auricularia, Id. „ vol. iv, p. 169, pi. 123, figs. 1, 2
peregra, Miiller „ vol. iv, p. 165, pi. 123, figs. 3-7
palustris, Linnceus „ vol. iv, p. 180, pi. 124, fig. 2 .
— truncatulus, Miiller „ vol. iv, p. 177, pi. 124, fig. 3 .
— glaber(A), Id. „ vol. iv, p. 178, pi. 124, fig. 1 .

f

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— glutinosa(z), Id. ,, vol. iv, p. 182, pi. 124, figs. 6, 7
Ancylus fluviatilis, Id. „ vol. iv, p. 186, pi. 122, fig. 4 .
lacustris, Id. „ vol. iv, p. 188, pi. 122, fig. 5 .
Physa fontinalis(^), Linnceus ,, vol. iv, p. 140, pi. 122, fig. 9 .

*

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— hypnorum, Id. „ vol. iv, p. 143, pi. 122, figs. 6, 7
Planorbis corneus, Id. „ vol. iv, p. 147, pi. 126, figs. 4, 5
spirorbis, Id. „ vol. iv, p. 159, pi. 127, figs. 9, 10
vortex, Id. „ vol. iv, p. 157, pi. 127, figs. 6-8
— contortus, Id. „ vol. iv, p. 160, pi. 126, fig. 3 .
— albus, Miiller „ vol. iv, p. 149, pi. 126, figs. 1, 2
— glaber(/), Jeffreys „ vol. iv, p. 150, pi. 126, figs. 8,9

*
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(a) A fragment of what appears to be this species is in my cabinet, and the name is also in Mr. Trimmer's Paper on the
Orton Gravel. — Quart. Journ. Geol. Soc., vol. x, p. 346.
(£) A fragment, on the authority of Mr. Pickering.

(c) In Mr. Brown's List.

(d) Professor Morris, in his ' Catalogue,' gives this from Clacton. May not the burrowing habits of the living animal have
introduced it amongst the fossils ? I have frequently found dead specimens when examining the Cor. Crag sand.

(e) I have been unable to obtain any satisfactory evidence of the fossil state of this species. An imperfect Clausilia much
resembles it, and may possibly have been mistaken as such.

(/) From the Valley of the Nar. (C. B. Rose.)

(g) My cabinet contains only a fragment, from Clacton, of what may be this species.

(A) This is given with a ?, in Mr. Prestwich's Paper, Quart. Journ. Geol. Soc., vol. xi, p. 110, loc. Shacklewell Lane. It is
mentioned also in Mr. Trimmer's Paper on the Orton Gravel, loc. cit. ante.

(i) From Sir Charles Lyell's Paper on the Mundesley Fresh-water Beds. — Phil. Mag., vol. xvi, p. 365.

(k) The fragment of a Physa, from Clacton, is in my cabinet, but not perfect enough to determine the species.

(/) PI. lavis is mentioned in Sir Charles Lyell's Paper from Mundesley. I presume it is this species.

308

APPENDIX.

75

88

PULMONATA.

Planorbis nautileus, Linnceus, v. Hist. Brit. Moll., vol. iv, p. 152, pi. 126, figs. 6, 7

— nitidus, Miiller

— marginatus, Draparnaud

— carinatus, Miiller

— lacustris, Lightfoot
Cyclostoma elegans(o), Miiller

80 Acicula lineata, Draparnaud

Id. var. perversa

vol.iv,p. 161, pi. 127, figs. 11, 12
vol. iv, p. 155, pi. 127, figs. 1-3
vol. iv, p. 152, pi. 127, figs. 4, 5
vol. iv, p. 162, pi. 128, figs. 1-3
vol. iv, p. 201, pi. 122, fig. 3
vol. iv, p. 204, pi. 125, fig. 7

PECTINIBRANCHIATA.

Veritina fluviatilis, Linnceus, v. Hist. Brit. Moll., vol. iii, p. 3, pi. 71, figs. 1, 2
Paludina vivipara(6), Id. ,, vol. iii, p. 11, pi. 71, figs. 14, 15

— marginata, Miehaud, vide p. 320 .......

Bitbinia teutaculata, Linnceus, v. Hist. Brit. Moll., vol. iii, p. 14, pi. 71, figs. 5, 6 .

— ventricosa, Gray
Rissoa Thermalis? Linnceus, vide p. 319
Valvata piscinalis, Miiller, v. Hist. Brit. Moll.,
— Id. var. antiqua, Morris „

— cristata, Miiller

vol. iii, p. 16, pi. 71, figs. 7, 8

vol. iii, p. 19, pi. 71, figs. 9, 10
vol. iii, p. 21, pi. 71, figs. 11-13

C

* 2?

£>. 2

f*>. •** .

(a) Specimens of this species, with H. ericetorum and other land shells, are found at Bostol, near Woolwich, in a deposit of
several feet in thickness (8 — 10), probably a talus from the chalk. A similar bed, containing numerous species of land shells, is
mentioned as resting upon the Greensand at Gore Cliff. (Bowerbank, ' Proc. Geol, Soc.', vol. ii, p. 449.) I have met with this
species (C. elegans) in like situations over the Crag, though I have never seen it in a living state in the eastern part of Suffolk.
Mr. Woodward gives it from the Caves of Torquay.

(£) This is given in Sir Charles Lyell's Paper on the Mundesley and Runton Beds, lac. cit. ante.

HELIX FRUTICTJM, Miiller. Tab. XXXI, fig. 19, a, b.

HELIX FRUTICUM. Mull. Verm. Terr, et Fluv. Hist., p. 71, No. 267, 1773.

Schroter. Erdconch., p. 178, t. 2, fig. 19, Nos. 55—59, 1771.
Chemn. Conch. Cab., vol. ix, p. 150, t. 133, fig. 1203, 1786.

— Drop. Hist. Nat. des Moll. Ter. de la France, p. 83, No. 10, pi. 5,

figs. 16, 17, 1805.

Brard. Hist, des Moll., p. 58, No. 14, pi. 2, fig. 13, 1815.
Pfieff. Deutsch Land und Sussw. Moll., p. 23, No. 3, pi. 2, figs. 3—5,

1821.

— Rossmasl. Icon, der Lund, und Sussw. Moll., p. 61, pi. 1, fig. 8.

— CINEKEA. Poiret. Prodr., p. 73, No. 8. Fide Deshayes.

— TERRESTRIS ? Gmel. ex Drap.

Spec. Char. "Testa orbiculato-convexa, umbilicatd, tenui, pellucidd, obsolete-striatd, albidd ; spird
subprominuld, labro margine reflexo"

Shell roundedly convex, umbilicate, thin, pellucid, obsoletely striated, white ; spire slightly prominent ;
outer lip reflexed.

Diameter, f inch.

Locality. Fossil, Stutton.

Recent, Denmark, France dans la Bresse (Depart, de 1'Aisne), Saleve near Geneva (Je/reys).

APPENDIX. 309

One specimen only of this species, obtained by myself, is all that I have seen. It appears to be full
grown, though its sharp and reflexed outer lip is destroyed, but in all its other characters it perfectly
resembles the recent shell.

HELIX INCARNATA? Muller. Tab. XXXI, fig. 17, a, b.

HELIX INCARNATA. Miill. Loc. cit., p. 62, No. 259, 1773.

Drop. Loc. cit., p. 100, No. 29, pi. 6, fig. 30, 1805.

Pfieffer. Deutsch Landund Sussw. Moll., p. 33, pi. 2, fig. 15, 1821.

Rossm. Loc. cit., p. 35, t. 26, fig. 361.

Desk. Exped. de Moree, p. 160, No. 231.

Brown. Geol. Journ., vol. viii, p. 190, fig. 4, a — c, 1852.

Spec. Char. "Testd subglobosd, depressiusculd, perforatd, pellucidd, corned; spird prominuld ; labro
margine rufescente, subreflexo."

" Shell subglobosa, slightly depressed, perforated (umbilicated), pellucid, and corneous ; spire slightly
prominent ; margin of lip reflexed and reddish."

Diameter, % inch.

Locality. Fossil, Copford. Recent, France, and Belmont near Lausanne.

Two or three specimens only of what most probably belonged to this species are all that I have seen.
They were obtained at Copford by Mr. John Brown, who has obligingly permitted me to have them
described ; they are unfortunately not in a very good state of preservation. The best specimen appears to
correspond with the recent shell ; but not being full grown, it has only five volutions instead of six, and is
evidently an immature individual, consequently wants the reflexed lip, the character of maturity. It differs
from rufescens, which is more depressed ; and from hispida in having a smaller umbilicus ; and our fossil is
more globose than either. The identification is not, however, perfectly satisfactory, and it would be desirable
to see a few more and better specimens.

HELIX RUDERATA, Studer. Tab. XXXI, fig. 15, a, b.

HELIX RUDERATA. Stud. Systemat. Verz. der Schweiz. Conch, s. 86, 1820.

Hartman. Erd. et Sussw. Moll., No. 57, t. 11, fig. 11, 1821.
Pfief. Deutsch Land und Sussw. Moll., p. 31, t. 4, fig. 26, 1824 ?
Rossm. Icon. Land and Sussw. Moll., p. 13, t. 32, fig. 455.
Brown. Geol. Journ., vol. viii, p. 190, fig. 4, d, e, 1852.
— ROTUNDATA, var. |8. Nils. Hist. Moll. Suec. Terr, et Fluv., s. 31, 1822.

Spec. Char. "Testd perspective-umbilicatd, depressd, lutescente-cornea, concolor, subtilissime costulato-
striatd, spird convexd, anfractibus 4 — 5 subteretibus ; aperturd ovali ; peristomate recto, simplici, acuto."
— Rossmasler.

" Shell perspectively umbilicated, depressed, of a clouded or dirty-horn colour, very finely striated by
elevated lines of growth ; spire convex, volutions 4 — 5, tapering ; aperture ovate ; perietome plain, simple,
sharp."

Diameter, % inch.

Locality. Fossil, Clacton, Grays, Copford.

Recent, Sweden, Finland, Russia, Styria, Switzerland, and Cincinnati, U. S.

310 ' APPENDIX.

This is not very rare at Clacton ; at Copford, Mr. Brown tells me, it is so. It closely resembles H.
rotundata in its large umbilicus and elevated ridges, but is justly separated from that species by well-marked
characters, having large volutions, which are fewer in number, and the aperture is consequently more open.
H.striatella, Anthony, 'Bost. Journ. Nat. Hist.,' vol. iii, p. 278, pi. 3, fig. 2, an existing species in the United
States, is now admitted to be the same as the above ; and H. perspectives is, perhaps, only a variety. A
species, with a geographical range extending from Russia and Switzerland to Massachusets and Ohio,
might be expected to possess considerable variation.* In my List of Land and Fresh-water Shells from the
Older Tertiaries, at Hordwell, published in the 'Lond. Geol. Journ.,' vol. i, p. 118, I had considered a species
found there to have prolonged its existence unchanged to the present time, and that the one above referred
to (striatella) was its specific descendant. Mr. F. Edwards, in his 'Monograph of the Eocene Moll.
Pulmonata,' p. 66, gives his opinion adverse to that decision ; and I am now inclined to think he is correct.
H. labyrinthica was given in my list as one of the species existing at the present time, while two others
were also inserted there, but with a doubt. I was at one time impressed with the idea that an air-breathing
mollusc, being less exposed to a variation of conditions, was enabled to preserve a specific existence longer
than its marine brethren ; and I fear it gave a slight bias to my determinations. Mr. Edwards has bestowed
upon the labyrinthica a very critical and a very able examination, and has pointed out some differences
between the Hordwell fossil and the existing American shell ; but they were not, he considered, sufficient to
invalidate their identity, more especially as the living shell is itself subject to considerable variation ;
assuming, also, that if we possessed a large series of fossil specimens, these differences would probably
disappear : is it really certain that the possession of a larger series must necessarily bring the recent and
fossil nearer together ? This species of mollusc appears to stand almost, if not entirely, by itself, as dating
its existence from the Older Tertiaries ; and, as we are obliged to depend exclusively upon the restricted
characters of the shell alone, we are compelled to admit its identity, from the impossibility of pointing out a
dissimilarity such as is generally considered sufficient for specific separation. Might it not be possible
that the combined characters of the entire animal, could they be possessed, would exhibit a difference so as
to prevent its coming within the definition of a species in the present acceptation of that term? If this
Hordwell fossil be really still an existing shell, it militates somewhat against the hypothesis that a species
with a very prolonged existence in regard to time, would, if still in being, have a more extended geo-
graphical range, and vice versa ; it does not appear so in regard to Helix, when labyrinthica is compared
with ruderata.

SIPHONOSTOMATA.
MITRA EBENUS, Lamarck. Tab. XXXI, fig. 7.

MITRA EBENUS. Lam. Ann. du Mus., vol. xvii, p. 216, No. 58, 1822.
Phil. En. Moll. Sic., vol. i, p. 229, t. 12, figs. 8—10.

— Bellardi. Monog. delle Mitre Foss. del Piedmonti, p. 23, t. 11, figs.

20—23, 1850.

— PYRAMIDELLA. Bronn. var. /3. Ind. Palseonth., p. 733, 1848.

— PLUMBEA. Lamk. Hist, des An. s. Vert., torn, vii, No. 73, 1822.

* This is the only one of the six extinct species belonging to these Fluviatile deposits that has its range
to the westward ; the others belong to the European Continent, with the exception of Cyrena consobrina, now
an inhabitant of the Nile. The Mollusca of these beds do not appear to have any connection with the
peculiar, and probably more recent, Faunas of the Canaries, Madeiras, or the Azores.

APPENDIX. 311

MITRA L^VIS ? Dubois. Wolhyn. Pod., t. 1, figs. 2, 3. Fide Phil.
DEFRANCII. Payr. Cat. Moll. Cors., p. 166, t. 8, fig. 22.

— CORNICULA. Sismond. Syn. Meth. an. Invert. Fed. Foss., p. 41.
VOLUTA PLICATULA. Brocchi. pp. 318 and 646, t. 4, fig. 7.

— CORNICULA. Linn. Syst. Nat., ed. 11, p. 1191-

Spec. Char. Testd turritd, sublcevigatd, aut obsolete costatd ; anfractibus convexiusculis ; aperturd
spiram cequante ; columella triplicatd sive quadruplicatd.

Shell turreted, nearly smooth, with obsolete ribs ; whorls slightly convex ; aperture the length of
the spire; columella with three or perhaps four folds.

Length, f inch.

Locality. Cor. Crag, Gedgrave. Recent, Mediterranean. Fossil, Apulia and Piedmont.

A single specimen of this genus has been obligingly presented to me by Mr. Charlesworth, and this
is the only one I have seen. It is not quite perfect, the outer lip being slightly broken, but it is otherwise
in good condition ; and there is every reasonable probability of its belonging to one of the variable forms of
ebenus. It most resembles the variety with the upper volutions somewhat obscurely costated, having the
body one smooth. My specimen has seven volutions, and three distinct folds upon the columella ; the
upper two folds large and distant, the third smaller and closer, with a very minute one lower down, perhaps
invisible if the lip were perfect. There is a slightly depressed mark around the upper part of the volution,
and, in the living state, probably corresponded with Philippi's description, "infra suturas linea albida
obscure cinctis."

A specimen of Mitra is mentioned, in the {Mem. of the Geol. Survey,' vol. i, p. 429, as having been
found in the Glacial Beds of Wexford, and referred to M. cornea, Lamk., with doubt.

MITRA PLICIFERA. 8. Wood. Crag Moll., vol. i, p. 21, t. XXXI, fig. 8.

Not having been able to obtain anything more perfect than what have been so long in my cabinet, I
have had my best specimen figured, in order to call attention to its existence in the Coralline Crag. It
appears too strongly costated to be a variety of ebenus, and the apex is more obtuse than in that species. It
must, therefore, remain for the present with its provisional name.

PYRULA ACCLINIS, S. Wood. Tab. XXXI, fig. 6, a, b.

PYRULA RETICULATA, Lam., vide. Crag Moll., vol. i, p. 42, t. 2, fig. 12.

A better knowledge of the various recent shells of this genus give reason to believe the differences
previously pointed out between the fossil and the recent species, to which it was assigned, are sufficient to
entitle it to specific distinction ; I therefore propose for the Crag shell the above name.

Edward Acton, Esq., of Grundisburgh, has, out of his rich collection, presented me with a cast in sand-
stone of what most probably was this species, obtained from the Red ,Crag of Sutton, which appears to
present a still greater difference from the recent reticulata than do either of my own specimens, from which
the assignment had previously been made. This cast (fig. 6, a) shows a greater elevation of spire than
either the recent shell or my own fossils, which might perhaps be expected ; but the excess in height is
more than would arise simply from its being a cast, and it shows also more particularly that the shell from
which it was taken had a shorter canal than the true reticulata : the latter character is, I think,
sufficient to separate our fossil from the existing species, and I am the more readily induced on that account
to change the name previously given.

This is in a sandstone nodule, similar to what has been spoken of at p. 69, and the cavity left by
the withdrawal of the shell is imperfectly filled by carbonate of lime in a crystallized state, the crystals

312 APPENDIX.

being deposited upon the internal cast ; while upon the matrix is exhibited the sculpture of the exterior
on which also are deposited similar crystals. Besides the present species, Mr. Acton has kindly given
me a specimen of Nassa conglobata in the same state ; and although the last has not yet been found
in the Coralline Crag, I think there is every reason to believe the cast of this species, as well as the other
sandstone nodules previously noticed, are the littoral remains of a destroyed portion of what might have
been a purely sandy deposit of the age of the Older Crag.

TROPHON NORVEGICUM, Chemnitz, Tab. XXXI, fig. 1, a, b.

STROMBUS NORVEGICUS. Chemn. Conch. Cab., vol. x, p. 218, 1. 157, figs. 1497, 1498, 1788.
Fusus NORWEGICUS. Turt. Mag. Nat. Hist., vol. vii, p. 351, 1834.
— NORVEGICUS. Howse. Ann. and Mag. Nat. Hist., vol. xix, p. 162, pi. 10, figs. 1 — 4,

1847.
Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 428, pi. 107 and 108,

%. 7.

TRITONIUM NORVEGICUM. Midd. Malaco. Rossica., part 2, p. 147.
— Lovtn. Ind. Moll. Scand., p. 11, 1846.

Spec. Char. " T. oblongd, subulatd, albd, anfractibus sex teretibus ; aperturd patuld ovatd, caudd
subadscendente, fauce churned" — Chemnitz.

" Shell smooth, volutions six, rather flat, the lower one ventricose ; aperture twice the length of the
rest of the shell, and pure white ; outer lip much dilated, and smooth on the inner margin ; the edge sharp
and slightly reflected ; pillar smooth."

Length of recent shell, 4^ inches.

Locality. Red Crag, Sutton and Felixstow. Recent, British and Arctic Seas.

A few fragments, or the young state of this species, have been for some time in my cabinet, but their
very imperfect condition rendered an assignment doubtful ; and until the discovery of the larger specimen,
which was obtained at Felixstow by Mrs. Henry Bartlet, of Ipswich, who has obligingly entrusted it to my care
for examination and representation, I was fearful to introduce the name into the List of British Fossils ; but
there is now very good reason to believe the above-named species was an inhabitant of our seas during the
period the Red Crag was deposited. Mrs. Bartlet's specimen (fig. 1, a) consists of a considerable portion of
the shell, with the outer lip and anterior canal destroyed : what remains corresponds so closely with the
existing species, that there is every probability of its identity. Our shell is thin, has lost its outer coating,
and the suture in consequence is deepened ; upon the shell are still visijble numerous, but somewhat obsolete
striae. The fracture of the specimen appears to have been produced or accelerated by the inroads of a Cliona
— a means of destruction not uncommon with the shells of the Crag. Being unable to give a detailed
description, I have taken the diagnosis from Chemnitz ; he refers to * Seba Thesaur,' vol. iii, t. 52, fig. 9 ?
1758, who was probably the first to notice the species. It is said to have been found in the Newer Tertiaries
of Sweden.

Mr. Howse states having dredged the living shell, in sixty fathoms water, off the Durham coast.

TROPHON TURTONI, Bean. Tab. XXXI, fig. 2.

Fusus TURTONI. Sean. Mag. Nat. Hist., vol. vii, p. 493, fig. 61.

— Howse. Ann. Nat. Hist., vol. xix, p. 163, pi. 10, figs. 6 — 10.
Reeve. Conch. Icon. Fusus, vol. iv, pi. 20, fig. 83.

— Forbes and Hanley. Hist. Brit. Moll., vol. ii, p. 431, pi. 105, figs. 3, 4, and

pi. 106, figs. 2—4.

APPENDIX. v 313

CAar. " Testa ovato-turritd, crassiusculd ; spirit enormiter acuminato-productd, apice papillari ;
anfractibus spiraliter striatis, superne concavis, vix angulatis ; aperturd ampld, labro incrassato subreflexo ;
albida" — Reeves.

" Shell ovately turreted, somewhat thick ; spire enormously produced, with a mammillated apex ;
whorls spirally striated, concave on the upper part, scarcely angulated ; aperture large, with a thickened,
slightly reflexed outer lip."

Length (of the recent shell), 5 inches.

Locality. Red Crag, Ramsholt. Recent, British Seas.

The fragment of a shell in my cabinet corresponds with the young or spiral portion of the above-
named recent species, and this is all that I have seen; it is thin and fragile, having lost its outer coating,
and is quite smooth, and it is placed provisionally in this position.

TROPIION PROPINQUUM? Alder. Tab. XXXI, fig. 3, o, b.

Fusus PROPINQUUS. Alder. Catal. Moll. Northum. and Durh., p. 63.

Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 419, pi. 103, fig. 2.
— SABINI. Forbes. Mem. Geol. Surv. Grt. Brit., vol. i, p. 426.

The British conchologists appear to consider they have well-defined characters for the separation of
T. Islandicum and T. propinquum, the former having a mammillated apex, while in the latter the volution is
commenced from a much smaller point ; the pullus of each being sufficient to determine the species. In
addition to which the propinquum is said to be comparatively much shorter and more tumid, or less
elongated than the other. My Coralline Crag specimens appear to preserve a sort of intermediate character,
and I have thought it necessary to give an enlarged representation of the spire of our shell, which is
certainly not mammillated, and corresponds in its elongated and elegant form with T. Islandicum, having
eight volutions, with a length of one inch and a quarter, and its greatest diameter -y^ths of an inch : thus
appearing to unite the distinguishing characters of the two recent species. The specimens from the Red
Crag are tolerably abundant, but the apex — the character by which it is said to be distinguished — is generally
more or less injured. It has been found at Bridlington, and in the Drift in Ireland.

TROPHON FABRICII, Beck. Tab. XXXI, fig. 4.

TROPHON FABBICII. (Beck) ex Moller. Ind. Moll. Groenl., p. 14, 1842.
TRITONIUM CRATTCTJLUM. Fabridus. Faun. Groenl. Fide Moller.
Fusus FABRICII. Forbes. Mem. Geol. Surv., vol. i, p. 425.

Spec. Char, Testd ovato-turritd, vel ventricoso fusiformi; costatd, costis acutis, angulatis; transversim
striatd, striis prominulis remotis ; aperturd ovatd ; labro incrassato, intus Icevi ; caudd brevi ; columella
pland.

Shell ovately turreted, or ventricos^ly fusiform ; costated, ribs sharp and angulated ; transversely
striated, strise slightly prominent and remote ; aperture ovate ; outer lip thickened, smooth within ; canal
short ; columella plain.

Length, -f inch.

Locality. Drift Beds, Wexford (Forbes). Recent, Greenland.

" This beautiful species, which was not observed in the Drift Beds until found in Ireland by Captain
(Major) James, is intermediate in its character between Fusus scalariformis and Fusus Barvicensis. It has
the general form and ventricose whorls of the former, with the fimbriated ribs of the latter." — Forbes.

The figure is from the only specimen that I have seen. It is in the Museum in Jermyn Street.

41

314 APPENDIX.

Fusus FOK.BESI. Strickland.

"According to Mr. G. B. Sowerby, identical with Fusus cinereus, Say, an American species, synonymous
with BuccinumplicosumofMenke." — Forbes, 'Mem. Geol. Surv.,' vol. i, p. 426.
Locality. Isle of Man.

"Fusus B-AUViCENSis. Johnston.

" Locality. Fossil, Irish Drift.

Living, Northern Coasts of Britain."

"Fusus BAMFFIUS. Donovan.

"Locality. Fossil, one of the most generally diffused and abundant species in the British and Irish

Glacial Beds.

Living, Northern and Arctic Regions of the European Seas, common on the Scottish
Coasts, Greenland, Seas of Boreal America." — Forbes, 'Mem. Geol. Surv.,' vol. i, p. 425.

"Fusus CURTUS. Smith. MS. Tert. Dep. of the Basin of the Clyde, Trans. Geol. Soc., 2d ser., vol. vi,

p. 156, No. 26.

" F. Testdoblongd, crassiusculd, Icevigatd, spiraliter striatd ; anfractibus subrotundatis quinque, ultimo
majori ; aperturd oblongd, magnd ; canali brevissimo obtuso. Long. 0'3, lat. 0-12, poll."

"This species has the form of many Pleurotomata, particularly of PL filosa, but it has not the notch
near the posterior part of the outer lip which characterises that genus. I have, therefore, found it necessary
to place it with the Fusi ; the very short, scarcely evident canal, however, tends to separate it from the more
typical species of Fusus."

The above description of the Clyde Beds fossil has been obligingly forwarded to me by Mr. Smith, of
Jordan Hill ; it was drawn up by the late Mr. G. B. Sowerby. From what I can learn of this shell, which
I have not been able to see, it probably belonged to PI. reticulata, Brown. PL Trevellianum, Turt.
Mangelia Trevelliana, Forbes and Hanley.

" Fusus nov. sp. ? or variety of F. CRISPUS, Brocchi (?).

"A shell measuring above an inch in length, fusiform, the whorls narrow, and crossed by prominent
ribs, which are traversed by raised spiral ridges. The characters are those of F. crispus, of which it is
probable an extreme form ; but more perfect specimens are required for accurate determination. It is very
distinct from any recorded Drift fossil.

"Locality. Fossil, Wexford.*

Living, F. crispus is at present a Mediterranean species.

"It occurs fossil in the Sub-Apennine beds." — Forbes, 'Mem. Geol. Surv.,' vol. i, p. 426.

There is a specimen from the Red Crag in my cabinet, which resembles this species ; but it is in a
worn and mutilated condition, and undeterminable. F. crispus is figured by Michalotti, ' Desc. des Terr.
Mioc. de 1'Ital. Septen.,' p. 272, No. 3, pi. 9, figs. 17, 18, who refers to Borson, ' Oritt. Piemont,' p. 317.

It is not mentioned by Brocchi.

* Every possible assistance has been most obligingly rendered to me by the officers of the Geological
Survey, in their endeavours to discover this and some other Fossils, but all their exertions have been
unsuccessful. Not anticipating the calamity that has deprived us of our lamented associate and friend,
the late Professor E. Forbes, I did not think it necessary to apply to him respecting these species until I
began to work upon the Appendix, knowing his ever-ready willingness to assist whenever occasion might
require. My application has been thus unfortunately delayed, which I should the more regret were it not
that his authority for the existence and correct determination of these species is quite sufficient without any
endorsement I could give them.

APPENDIX. 315

NASSA PYGM^EA, Lamarck. Tab. XXXI, fig. 5.

RANELLA PYGM^EA. Lamk. Hist, des An. sans Vert., 2d ed., vol. ix, p. 550, No. 14.

Kiener. Coq. viv. (Ranel), p. 33, pi. 10, fig. 2.

TRITONIA VARICOSA. Turt. Zool. Journ., No. 7, p. 365, t. 13, fig. 7.
NASSA INCRASSATA, var. Flemg. Brit. An., p. 340, 1828.

— PYGMJBA. Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 394, pi. 108, figs. 5, 6.

Spec. Char. Testa turrit d, costatd et spiraliter striatd, costis numerosis, striis creberrimis decus-
santibus ; saepe varicibus in anfractibus superioribus ; aperturd ovatd, labro extus incrassato, varicoso.

Shell turreted, costated, and spirally striated, ribs numerous, with close-set striae ; upper volutions
often bearing thickened ribs or varices ; aperture ovate ; outer lip thickened externally.

Length, f inch.

Locality. Cor. Crag, Sutton. Recent, Britain.

A single specimen, but not in good condition, is in my cabinet, and appears to correspond with what
the British conchologists have confidently proposed as a distinct species. I believe the Crag fossil to be
identical with the living shell.

I have withheld a notice of this, as well as a few other imperfect specimens from the Crag, up to the
present time, in the hope of being able to procure something better to represent than what I am now only
able to give.

NASSA MONENSIS, Forbes, MS.

NASSA MONENSIS. Strickland. Proc. Geol. Soc., vol. iv, p. 8.

In the first volume of my Monograph, p. 31, t. 3, fig. 5, a Red Crag shell was considered to have
belonged to the above species, and it was inserted as such upon the authority of the late Professor E.
Forbes. Mr. Smith has recently sent me a MS. note, accompanied with a sketch, by the original
discoverer, of what is there called N. Monensis. " Nassa differing from N. macula in having the spire less
produced, the body whorl much more ventricose, and the longitudinal ribs fewer. It appears intermediate
between N. macula and N. ambigua." Forbes. The figure presents some considerable differences from the
Crag shell, and I regret my inability to obtain a sight of the Manx specimen ; they must, therefore, remain
united for the present.

NASSA PLIOCENA. Strickland. Proc. Geol. Soc., vol. iv, p. 9.

Locality. Isle of Man.

This shell I have been unable to obtain a sight of.

Nassa reticulata is enumerated in Mr. Smith's 'List of the Clyde Fossils,' 'Proc. Geol. Soc.,' vol. iv, p. 9.

" BUCCINUM CILIATUM. Fabricius.

" Syn. (a variety.) Buccinum Humphreysianum, Bennett. Possibly, Buc. fusiforme, of Broderip, may
be an extreme form of this species.

"Locality. Fossil, North of England and Scotland.

Living, very rare in the British Seas, common in Arctic Seas and on the Banks of

Newfoundland." — Forbes, ' Mem. Geol. Surv.,' vol. i, p. 427.
This is another recorded British Tertiary fossil that I have been unable to obtain a sight of.

316 APPENDIX.

CANCELLABIA SCALABOIDES, S. Wood. Tab. XXXI, fig. 9.

CANCELLABIA COBONATA. S. Wood. Crag. Moll., part 1, p. 64.

I have here introduced the figure of a specimen from the Coralline Crag, at Sudbourne, given
to me by Mr. Charlesworth, since the publication of my first part, and as it presents a variation
in character from those previously in my possession from the Red Crag, it is desirable it should be
represented. From this more especially, and from a further examination of the other specimens, I am
induced now to believe the Crag shell to be distinct, and to be intermediate between C. varicosa, Broc., and
C. coronata, Scacchi. In this Coralline Crag specimen the costae are very few, not more than seven in the
last volution, like those of varicosa, but the upper part is more angular than in that species, and it differs
from coronata in not only having fewer costse, but the outer lip of our shell is furnished with numerous
ridges or teeth, about ten, apparently at all ages ; and there are three distinct folds upon the columella, the
upper one small, the middle one the largest ; while in varicosa the upper one is the large one. The form of
the aperture is also different from what is represented by Philippi in the figure he has given of C. coronata.
The form of our shell approaches that of Fusus, the proportions of the aperture being little more than one
third of its entire length : although these dimensions may vary in several specimens, and is a character of
no very great importance, but, united with other differences, give reason to believe our shell to be entitled
to an isolated position. The Red Crag shell is probably the prolonged existence of the Coralline Crag
species.

LACUNA VINCTA, Montague. Tab. XXXI, fig. 13, a, b.

TUBBO VINCTUS. Mont. Test. Brit., vol. ii, p. 307, pi. 20, fig. 3, 1803.
LACUNA VINCTA. Turt. Zool. Journ., vol. iii, p. 192.

Gould. Inv. Massach., p. 262, fig. 178*.

— CANALIS. Turt. Zool. Journ., vol. iii, p. 192.

— QUADBIFASCIATA. Id. Zool. Journ., vol. iii, p. 191.

Loven. Ind. Moll. Scand., p. 22.

— DIVABICATA. Id Ind. Moll. Scand., p. 23.

— PEBTUSA. Conrad. Journ. Acad. Nat. Sci. Philadelph., vol. vi, p. 266, pi. 11,

fig. 19.
PHASIANELLA BIFASCIATA. Brown. Illust. Brit. Conch., pi. 46, fig. 47, 1827.

Spec. Char. Testd ovato-conoided, tenui ; anfractibus convexiusculis, rotundatis ; labro tenui, simplici ;
columelld late angustd, excavatd, arcuatd.

Shell ovately conical and thin, with about four slightly convex or rounded volutions ; outer lip thin
and simple ; columella elongated, curved, and excavated.

Length, \ inch.

Locality. Mam. Crag, near Norwich.

Clyde Beds. Recent, Britain, Norway, and North America.

The shell, in the living state, to which my fossil is assigned as an identity, indulges in such con-
siderable variation, that I have placed it there as its most probable position, and the longitudinal propor-
tions between the varieties called gracilis and quadrifasciata would give a mean with which our fossil
appears to correspond, approaching, however, rather nearer to the latter (like the fig. 169, Gould);
but the three specimens in my possession are not in good preservation, and have lost the greater
portion of the outer coating, by which the form is altered. One specimen presents a somewhat square
outline to the aperture, resembling, in that character, L. crassior. The recent shells of this genus have

APPENDIX. 317

greatly perplexed the conchologist, and the condition of my fossils presents greater difficulties in their
determination.

In the 'Memoirs of the Geological Survey,' vol. i, p. 423, Lacuna Montacuti is quoted as having been
found in the Drift Beds of Ireland.

Littorina ? suboperta, 'Crag Moll.,' vol. i, p. 118, t. 10, fig. 13. Since the figure here referred to
was made, I have obtained a rather better specimen, which shows a flattened or slightly concave columella,
the characteristic distinction of the genus Lacuna. It may, perhaps, with more propriety be called Lacuna

suboperta.

Littorina neritoides, rudis, and palliata, are enumerated in the ' List of Clyde Fossils.'

FOSSARUS SULCATUS, S. Wood.

PHASIANEMA SULCATA. 8. Wood. Catalogue, 1840. loc. cit.
FOSSARUS CLATHRATUS. Id. Crag Moll., vol. i, p. 121.

The Crag shell was considered by myself as an id entity with the Mediterranean species, which subse-
quent examination gives reason to believe is not correct ; I have, therefore, ventured to restore to it the
provisional name given in my 'Catalogue.' It resembles a recent British shell which I believe belongs to
this genus, Odostomia dolioliformis, 'Hist. Brit. Moll.,' vol. ii, p. 301, pi. 97, fig. 5. Our fossil is, however,
specifically distinct, and seems to preserve an intermediate character between dolioliformis and clathratus,
being larger than the one, and smaller than the other, and more elongated than either. The ridge upon
the columella is at times invisible, and is a character not to be depended upon.

ODOSTOMIA UNIDENTATA, Montague. Tab. XXXI, fig. 11.

TURBO UNIDENTATUS. Mont. Test. Brit., p. 324, 1803.

VOLUTA UNIDENTATA. Mat. and Rack. Trans. Lin. Soc., vol. viii, p. 121.

JAMINIA UNIDENTATA. Brown. Illust. Brit. Conch., pi. 50, figs. 34, 35, 1827.

ODOSTOMIA UNIDENTATA. Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 264, pi. 95,

figs. 7, 8.
PLICATA. Flem. Brit. An., p. 310, 1828.

Spec. Char. Testd minutd, ovato-conoided, Icevigatd, anfractibus 5 — 6 convexiusculis , spird paulo
longiore, aperture ovatd, labro simplici, columelld unidentatd.

Shell small, ovately conical, smooth, with about five or six volutions, slightly convex ; spire a little
longer than the aperture, which is ovate, with a simple lip ; columella toothed.

Length, T'ff inch.

Locality. Red Crag, Walton Naze. Recent, Britain.

A solitary specimen of a shell of this perplexing genus has been recently obtained by myself from
the Red Crag, and it appears to accord best with the shorter variety of the above-named recent British
species, although it differs slightly in having the volutions at the base rather more rounded.

In the former part of my Monograph, Od. plicata and Od. conoidea are united as one and the same
species, which I now believe to be distinct, as pointed out by the authors of the ' Hist, of Brit. Mollusca.'
Both these species were in existence during the Crag Periods, the latter in the Coralline, and the former
in the Red Crag.

A shell in my cabinet, from the Coralline Crag, strongly resembles Od. eulimoides ; but the specimen
is not in sufficiently good preservation for figure or description.

318 APPENDIX.

ODOSTOMIA TRUNCATULA? Jeffreys. Tab. XXXI, fig, 16.

ODOSTOMIA TRUNCATULA. Jeff. Ann. Nat. Hist., new ser., 1850, p. 150.

— Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 294, pi. 96, fig. 8,

1850.

Spec. Char. Testa elongatO'turritd, subulatd vel subcylindraced, leevigatd, pellucidd? tenui ; anfractibus
5 — 6 convexiusculis ; aperturd ovatd, labro acuto ; umbilico parvo ; columelld obsolete unidentatd.

Shell elongately turreted, tapering, or nearly cylindrical, smooth, thin, and transparent ? volutions
5 — 6, somewhat flattened ; aperture ovate ; outer lip sharp ; columella with an obsolete tooth, and small
umbilicus.

Length, i inch.

Locality. Cor. Crag, Sutton. Recent, Britain-

Three or four specimens in my possession appear to correspond with the recent shell above referred to.
In comparing my fossils with some specimens of the recent shell, obligingly presented to me by Mr. Barlee,
the greatest difference appears to be in the apex, which, in the living shell, is somewhat flatter and more
obtuse than in my fossil, whose apex is blunt or obtuse, but not flat, neither does it appear to have been
reversed. My specimens unfortunately are not in the best state of preservation.

Assiminea Grayiana is enumerated as a fossil by Mr. Dixon, in his ' List of Shells from the Upper
Tertiaries of Bracklesham.'

RISSOA SOLUTA, Philippi. Tab. XXXI, fig. 10.

RISSOA SOLUTA. Phil. En. Moll. Sic., vol. ii, p. 130, pi. 23, fig. 18, 1844.
— ? Jeffreys. Ann. Nat. Hist., vol. xx, p. 16.

? Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 131, pi. 75, figs. 3, 4, 1850.

Spec. Char. Testd minima, elongato-turritd, Icevigatd, anfractibus (quatuor vel quinque) rotundato-
ventricosis, suturis profundis ; aperturd suborbiculari.

Shell minute, elongately turreted, smooth ; whorls (four or five) roundedly ventricose, sutures deep ;
aperture nearly orbicular.

Length, ^ inch.

Locality. Cor. Crag, Sutton. Recent, Mediterranean.

I have found, in the Sutton sand, a single specimen of a shell which corresponds closely with the
figure and description by Philippi, above referred to.

Messrs. Forbes and Hanley, p. 131, supra, have expressed great doubt respecting the existence of
Philippi' s species, and they have appropriated his name to the British shell. I fully participate in their
doubt respecting the identity of the Mediterranean form with that found in our own seas ; but, judging
from the fossil now figured, I am much inclined to believe the Mediterranean shell to be a valid species ;
and in the event of its being hereafter so determined, I would suggest the name of intersecta for the recent
British shell, as in that case soluta must be retained for the one to which it was first given.

The Crag shell may be more particularly described as being somewhat thin, and now opaque, though
perhaps transparent in the living state ; quite smooth, without appearing to have lost its outer coating ;
although somewhat elongate in the spire (differing therein from the recent British shell), the apex is obtuse,
with at least four volutions, and a deep suture, particularly the last (but not "disjoined"), and with a
distinct and deep umbilicus. The outer lip is simple, not thickened by a ridge, neither is it toothed
within ; the aperture somewhat rounded, but the diameter of the opening is rather greater in a longitudinal
direction, and is about two fifths the entire length of the shell, with the lower part slightly effuse.

APPENDIX. 319

RISSOA THERMALIS? LinncBus. Tab. XXXI, fig. 12, a, b.

TURBO THERMALIS. Linn. Syst. Nat., 12th ed., p. 1237, No. 629.
— MURIATICUS? Beudant. Ann. du Mus., torn, xv, p. 201.

Spec. Char. " T. umbilicatd oblongiusculd, obtusd, anfractibus teretibus Icevibus." — Linnseus.

Shell elongately conical or subulate, naked, smooth, and glossy ; volutions six, slightly convex ;
suture distinct and deep ; apex obtuse, depressed ; aperture ovate ; inner lip adpressed, giving a pointed
termination at the upper part; umbilicus small.

Length, ^ inch. Diameter, f of the length.

Locality. Clacton.

It is now most difficult, perhaps impossible, to say what Linnseus intended for the type of his Turbo
Thermalis, as there are two or three species that might, with a moderate allowance of latitude in variation,
be made to accord with the diagnosis of his shell, and, it is to be feared, have already been done so. I am
unwilling to make " confusion worse confounded," so have introduced our shell with the above name
instead of imposing a new one, though not without great misgivings upon the propriety of doing so,
particularly as Linnaeus, in his description, says, " T. semine Brassicse paulo major."

Our fossil is by no means rare at Clacton, but the majority of my specimens were obtained from the
clay or estuary portion of the deposit at that locality in association with marine or rather estuary species :
Cardium edule, Tellina Balthica, Trigonella plana, Mytilus edulis, and Balanus. I have also found
specimens in the sandy and purely fresh-water part of the cliff, with land and fresh-water shells, so that
probably its animal inhabitant was capable of residing in water that was either fresh or brackish. Mr.
John Pickering has presented me with some specimens of a recent shell identical with our fossil, and these,
he tells me, were obtained in the ditches of brackish water near Gravesend, in Kent. Similar specimens
were pronounced by Messrs. Forbes and Hanley, vol. iv, p. 267, to be only varieties of R. ventrosa, in which
opinion I cannot coincide ; and I am permitted by Mr. Pickering to say he believes the two shells to be
specifically distinct.

This shell, or something very like it, was found by MM. Ehreuberg and Von Hemprich, " in fontibus
Oasis Jovis Hammonis inter Alexandriam et Rosettam."

JEFFREYSIA? PATULA, S. Wood. Tab. XXXI, fig. 14, a, b.

NATICA DEPRESSULA. S. Wood. Catal. of Crag Shells, Ann. and Mag. Nat. Hist., 1840,

p. 530.

Spec. Char. Testd minuld, subglobosd, Icevigatd, politd, tenui, vitred, pellucidd? umbilicatd; apice
obtuso ; anfractibus paucis 1 — 2 depressis ; suturis profundis, excavatis ; aperturd magnd, ovatd, dilatatd ;
labro simplici acuto.

Shell small, subglobose, smooth, glossy, thin, vitreous, pellucid? umbilicated; apex obtuse; volutions
few, 1 — 2, depressed ; suture deeply excavated ; aperture large, ovate, expanded ; outer lip thin and
sharp.

Diameter, ^ inch.

Locality. Cor. Crag, Sutton.

Three specimens of a small species were found by myself many years since, and reserved to the present
time. They are now assigned provisionally to the above genus, more from the difficulty of finding a better
position than from a satisfaction of their correct appropriation. They appear to differ from Natica, where

320 APPENDIX.

they were first placed, in having an obtuse instead of an acute apex, like all the species in that genus that I
have examined, and the texture of the shell is vitreous and clear, and when living was probably quite
transparent. The form much resembles that of Natica, but the peristome is continuous, and not impressed
by the body whorl, nor is the inner lip spread out as in the species of that genus. I know of nothing
strictly resembling it, and if the determination of the genus depend, as it is said, entirely upon the form of
the operculum, it will probably be long ere it is correctly determined by that character.

PALUDINA PABILIS, S. Wood.

PALUDINA LENTA. S. Wood. Crag. Moll., vol. i, p. 110.

Since the publication of my first volume, wherein I had assigned the Crag shell as an identity with the
fossil from the Older Tertiaries, and considered them both as the progenitors of a shell now living in the
Nile, I have given to them a more extended examination, with an increased number of specimens, and have
reason to believe they are all three distinct.

1 therefore propose the above name for the British Upper Tertiary Fossil, in lieu of the one it has
hitherto borne.

PALUDINA MARGIN ATA, Michaud. Tab. XXXI, fig. 18, c, b.

PALUDINA MAKGINATA. Mich. Comple. de 1'Hist. Nat. des Coq. Terr, et Fluv. de la France,

p. 98, No. 11, t. 15, figs. 58, 59, 1831.
Lyell. Man. Elem. Geol., p. 127, fig. 112, 1851.
MINUTA. Strickland. Silur. Syst., p. 555.

Lyell. On the Boulder Formations and F. W. Deposits of Eastn. Norf.,
Phil. Mag., ser. 3, vol. xvi, No. 104, p. 354, fig. 4, 1840.

Spec. Char. " Testa minima, pellucidd ovata, nitidd, albidd, longitudinaliter substriatd ; anfractibus
quinis, rotundatis ; aperturd ovato-rotundatd ; labro extus marginato ; apice obtuso, papillato. Operculum
ignotum." — Michaud.

Shell small, pellucid, ovate, naked, white, slightly striated longitudinally ; volutions five, rounded ;
aperture roundedly ovate ; outer lip outwardly marginated ; spire obtuse, papillated. Operculum unknown.

"Dimensions, f and £ line."

Recent, Draguignan, South of France, Carouge, near Geneva (Jeffreys).

This species is, I believe, abundant at each of the localities in which it is found, and particularly so at
Clacton. The generality of specimens do not exceed the dimensions given by Michaud to the recent shell,
though some few of my fossils have attained to the tenth of an inch in length, from the elongation of the
spire, without increasing the number of volutions, in which case the suture is much deepened. The apex is
very obtuse, the vertex being flattened, with the apical or embryonic portion broad and inflated. The
outside of the aperture is strengthened by a thickened whitish rib, generally at a short distance from the
margin, which is sharp and plain ; the aperture is ovate, with the major axis in a longitudinal direction,
scarcely at all impressed by the body whorl.

This is not now found living in Britain, and I have been unable to obtain any information respecting
the soft parts of the animal. The thickened margin would rather indicate its having a calcareous operculum,
like the genus Bithinia, but I have never found one, although the shell is very abundant.

APPENDIX. 321

NATICA SMITHIT, Brown.

BTJLBUS SMITHII. Brown. Mem. Wern. Soc., vol. viii, p. 104, pi. 1, fig. 18, 1838.
NATICA — Forbes. Mem. Geol. Surv., vol. i, p. 430.

" The only specimen ever met with of this most interesting shell, a member of the division of
ampullariform Naticse, was found by the Duchess of Argyle in the Pleistocene Beds at Ardincaple. That
specimen was presented to Mr. Smith, and was figured and described by Captain Brown, in the eighth
volume of the 'Wernerian Transactions.' It has since, unfortunately, been destroyed. From its delicacy
it is not likely to occur in the more disturbed beds of the Drift, but should be looked for in the Clyde Beds.
It is extremely probable that when an opportunity for comparison may occur, the Bulbus Smithii will be
found to be identical with Natica flava, of Gould ; a rare living inhabitant of the Newfoundland Bank."
— Forbes.

Mr. Smith, of Jordan Hill, to whom I have applied in the hope of being able to add something to the
above remark, expresses his deep regret at the loss of the specimen referred to, which, he says, is the only
one he has either seen or heard of.

NATICA BOWERBANKII, Forbes. MSS. Mem. Geol. Survey, vol. i, p. 430.

" In Mr. Bowerbank's Bridlington Collection there is an imperfect specimen of a very distinct species
of Natica, which does not agree with any living or fossil species known to me. It has a smooth, ventricose
body whorl, angulated above, and a depressed spire. It equals Nat. monilifera in size." — Forbes.

This is another, at present uncertain, species upon which, I regret to say, my endeavours to add a little
information have not been crowned with success. Mr. Leckenby, who is well acquainted with the
Bridlington fossils, kindly undertook to make inquiry for another specimen, but was equally unsuccessful.
The shell in Mr. Bowerbank's Museum is in that condition from which a determination would not be at all
satisfactory.

NATICA ALDERI, Forbes.

(NATICA NITIDA, Donovan.)

This is said to have been found in the Drift Beds of Ireland and Scotland.

TROCHUS CRENULARIS. Crag Moll., vol. i, p. 123, t. 13, fig. 7.

The specimen figured under this name at the above reference, I am now inclined to believe is a
foreigner, and that the species does not belong to the Coralline Crag.

TROCHUS MAGUS, Linn.

Found in the Irish Drift Beds.

MARGARITA UNDULATA, G. B. Sowerby.

TROCHUS INFLATUS. Smith. Mem. Wern. Soc., vol. viii, pi. 1, figs. 10, 11.

Found in the Irish Drift and in the Clyde Beds.

42

322 APPENDIX.

BULLA CONUL01DEA, S. Wood.

The shell called B. conulus, S. Wood, 'Mon. Crag. Moll.,' part 1, p. 173, t. 21, fig. 2, is, I now believe,
distinct from the Paris Basin shell, to which I had assigned it. A better examination with more specimens,
some of which were obligingly forwarded to me by M. Deshayes, have shown that although the two shells
are very closely allied, the differences are such as to warrant a specific separation. I therefore propose the
above alteration for the Crag shell. The species from the Basin of the Adour, called by Grateloup, B.
conulus and B. angistoma, which I had considered synonymous, I have been unable to examine whether
they be more nearly related to the Older Tertiary or to the Crag species.

BULLA HYDATIS, Linn.

This is enumerated in Mr. Dixon's 'List of the Upper Tertiary Fossils at Bracklesham.'

BULLA AMPULLA.

Mentioned in Sir E. Murchison's * Silur. Syst.,' p. 533, as a Tertiary fossil, found at Kempsey, near
Worcester. I am unable to say whether these two be the same or different species.

BULLA ACUMINATA. S. Wood. Crag. Moll., vol. i, p. 174.

In the Synoptical Table at the end of the first volume of the 'Crag Mollusca' is a x against this name in
the line of Eocene fossils, as if intended to denote the presence of the recent species, acuminata, during the
Period of the Older Tertiaries.* This is a misprint ; no mention is made of such existence in the text at the
above reference. An unfigured species has, however, been found at Barton, closely resembling the recent
shell in having a pointed or acuminated termination, with the spire enveloped, but the Older Tertiary fossil
is evidently distinct.

Systematists appear to labour under great difficulties in the generic divisions of the Bullee, the form of
the shell appearing almost alone to determine the distinctions. Our little species rejoices in the title of
several generic aliases. Prefessor Loven has removed it from Bulla into a proposed genus called Cylichna.
Messrs. Forbes and Hanley placed it (with a doubt) in Ovula. It was called Folvula by Adams ; and Mr.
Woodward has united it with Tornatina. A knowledge of the animal, when possessed, will assist in its true
assignment, and may possibly justify, a different position ; but at present the shell alone is all we have to
guide us as to its true relations, and from this it appears to differ only as a species from Bulla cylindracea,
and other cylindrically convoluted shells, and whatever may be considered more essential distinctions for
generic separation in such inflated species as Bulla ampulla, &c., the simple difference in this, at least from
the cylindrically formed shells, is merely a greater elevation of the outer lip, so as to conceal the turns of the
spire : or perhaps it would be more correct to speak of it as a prolongation of the outer lip into a pointed
termination for the excurrent canal, instead of being at the junction or suture of the volution ; an
approximation to this may be seen in those species, such as B. umbilicata, &c., in which the outer lip is
extended retreally or retreatingly, so as to cause a concavity where the spire is depressed but not
hidden.

* This column contains also a few other crosses, intimating the supposed existence during the Eocene
Periods of those species against which they are attached. Since that table was published I have given to
them a more special examination, and although there are two or three (particularly the species of
Pleurotoma) that present many characters in common, there is not ,one therein included that can be
undoubtedly said to have lived during the joint Periods of the Older Tertiaries and the Crag.

APPENDIX. 323

APLYSIA? ASCIOLA, S. Wood. Tab. XXXI, fig. 24 a, b.

Locality. Cor. Crag, Sutton, Sudbourne.

This fossil has been in my possession for the last twenty years, with the above doubtful generic name,
and my endeavours to obtain information as to its true character have hitherto been unsuccessful. There is
a strong resemblance between it and one of the opercular valves of a Barnacle (tergum)> but, with all my
search, I have never been able to find what might be considered as its opposing portion — all my specimens
have the point or apex inclining in the same direction ; still I thought it might possibly belong to the
Cirripedia ; I therefore requested Mr. Darwin would be kind enough to give me his opinion upon them,
but they were rejected by him as not belonging to any animal in the group he has so ably
investigated.

Its form is that of a "little hatchet," and I have assumed it to be the calcareous portion of an internal
shell, belonging, probably, to the section called Aclesia by Rang, and have placed it provisionally in the
above generic position. At least fifty specimens have been found by myself, and these present considerable
variation inter se, but I think they may be all referred to the same specific animal. One specimen is from
Sudbourne ; and this, though more than double the size of those from Sutton, was probably only from a
larger individual, varying in that respect like the specimens of Scalpellum, as well as a few of the Mollusca
from the same two localities.

Two fossils from the Upper Tertiaries of Sicily have been doubtingly described as species under the
above generic title.

The inner portion or lining of Pectunculus glycimeris sometimes separates from the rest of the shell,
and is occasionally found in the Red Crag ; and when in that condition it strongly resembles the figure of
Aplysia grandis, Philippi, ' En. Moll. Sic.,' vol. ii, t. 18, fig. 10, a, b ; but I have not been able to see the
Sicilian fossil.

PECTEN MAXIMUS. Tab. XXXI, fig. 25.

PECTEN MAXIMUS. S. Wood. Monog. of Crag Moll., ante, p. 22.

A single specimen of the flat valve of a species in this genus has lately been given to me by Mr.
Whincopp, who obtained it from Sutton.

Although a considerable amount of variation is exhibited in my large series of specimens of what I have
considered as P. maximus from the Coralline Crag, I have not seen anything quite so anomalous as is
presented by this Red Crag specimen, and confess to be somewhat perplexed respecting it ; still there is
something peculiar in the arrangement of the ribs of this shell to warrant the belief that there has been a
failure in their number of about one half, perhaps caused by what might be called a duplicature or union of
the organs by which they were produced, and that it is nothing more than a monstrous form of the common
British species.

There are six, or perhaps eight ribs, including those irregular ridges at the shoulders, rounded and
smooth, probably made so by attrition ; between them are some smaller rays, varying from two to five. In
the recent shell these intermediate rays are also variable, and, in some specimens, they are very distinct and
prominent, both between and upon the ribs, while in others they are entirely absent.

In order, therefore, to avoid the introduction of a species upon the slender evidence afforded by this
specimen, I have called it P. maximus, var. larvatus.

324 APPENDIX.

PECTEN POLYMORPHUS, Bronn, Tab. XXXI, fig. 20.

PECTEN POLYMORPHUS. Bronn. Reise, p. 627, sec. Phil.

— STRIATUS. Marcel, de Serr. Geog. des Terr. Tert. du Midi de la France, p. 131.

— STRIATULUS. Lamarck. Sec. Philippi.

— INJEQUICOSTALIS. Id. Sec. Philippi.

— ISABELLA. Lamarck. Sec. Philippi.

— FLAGELLATUS. Id. Sec. Philippi.

— FLEXUOSUS. Id. Sec. Philippi.

— POLYMORPHUS. Phil. En. Moll. Sic., vol. i, p. 79, t. 5, figs. 18 — 21.

Dixon. Geol. of Sussex, p. 16, fig. 3, 1850.
Sismond. Syn. Meth. Inv. Fed., p. 13, 1847.
OSTREA STRIATA? Brocchi. Conch. Foss. Subap., p. 577, t. 16, fig. 17.

— DISCORS. Id. Conch. Foss. Subap., p. 581, t. 14, fig. 13.

— COARCTATA. Id. Conch. Foss. Subap., p. 574, t. 14, fig. 9.

— PLICA. Poli. Utr. Sic., t. 28, figs. 1 — 5.

Spec. Char. " Testa subeequivalvi, suborbiculari, latiore quam longd, longitudinaliter undulato-
plicatd, striatd aut Icevi, plicis 5 — 12, auriculis amplis subcequalibus, utraque basi angustatd ; i.e., sinu
angulum rectum formante a lateribus divisd." — Philippi.

Shell nearly equivalve, suborbicular, broader than long, longitudinally ribbed or plicated ; ribs 5 — 12 ;
auricles large and slightly unequal, and angulated at the base on each side.

Diameter, 1 inch.

Locality. Bracklesham.

This shell is, I believe, not very rare at the above locality, to which place, as far as I know, it appears
to be restricted, as a British fossil.

It much resembles P. Danicus, and is, like it, subject to great variation ; it differs, however, more
especially in its auricles, which are larger and more equal.

This is a living species in the Mediterranean, and is found fossil at Gravina, according to Philippi.

The specimen figured is in the British Museum.

LIMOPSIS PYGM^A. Ante, p. 71.

This is no longer an extinct species ; it has been recently obtained alive by Mr. M 'Andrew in the
Arctic Regions.

LUCINA COLUMBELLA. Ante, p. 143.

I have been unable to obtain any further information respecting the integrity of this species. Its claim
to the Red Crag is, I suspect, very doubtful.

CRYPTODON SINUOSUM. Ante, p. 134.

At the above reference the Older Tertiary shell, Lucina Goodallii, was considered only as a variety, as
also the Boom shell, Axinns Benedenii, De Koninck, and both were introduced as synonyms to the above
Crag fossil. A better examination with fresh specimens induces me now to believe them distinct.

APPENDIX. 325

MACTRA TRIANGULATA, S. Wood. Tab. XXXI, fig. 21 a — d.

Spec. Char. Testa parvd, ovato-triangulatd, utroque obtusissime carinatd, crassd, striatd out
sulcatd ; dentibus lateralibus magnis, perpendicularibus striatis.

Shell small, ovately and broadly triangular; both sides obtusely keeled, thick, striated, or rather
sulcated ; lateral teeth large, perpendicularly striated.

Length, f inch.

Locality. Cor. Crag, Sutton.

Small specimens of this species are abundant, but they are always more or less decorticated, and, as the
principal distinction is in the sculpture, they have until now remained in my cabinet as varieties of M. ovata.
Two or three individuals have recently been obtained with a sufficiency of the outer surface to show that a
difference existed between it and the recent shell, M. ovata (M. elliptica, F. and H.), such as, I now believe,
will entitle this to a separate specific position : instead of being covered with numerous, fine, irregular, and
sometimes inosculating striae, like those upon the recent British shell, our fossil is ornamented with regular
and distinct ridges, and deep sulci between them, corresponding in that character with Brocchi's description
of M.triangula, Renieri, "transversim sulcata ;" but Messrs. Forbes and Hanley have determined the
triangula, Phil., (M. lactea, Poli, which I presume to be the same,) to belong to M. subtruncata, Mont.
With these discrepancies, and not having been able to see the Subapennine fossil, the above name is given
provisionally until it can be better determined.

LUTRARIA RUGOSA, Chemnitz. Tab. XXXI, fig. 26 a, b.

MACTRA RUGOSA. Chemn. Conch. Cab., vol. vi, p. 236, t. 24, fig. 236, 1782.
LUTRARIA RUGOSA. Lamk. Hist, des An. s. Vert., torn, v, p. 469.

Desh. Trait. Elem. Conch., t. 10, fig. 7.

Sismonda. Syn. Meth. Fed. Foss., p. 23, 1847.

Dixon. Geol. of Sussex, p. 17, 1850.

Ency. Method., pi. 254, fig. 2 a, b.

Spec. Char. " Testd ovato-oblongd, longitudinaliter dense striatd, et quasi costatd ; area anticd et
posticd glabratd, obsolete transversim striatd; margine exteriore crenulato ; colore extus ex albido Jlaves-
cente, intus calcareo." — Chemn.

Shell ovately oblong, striated and costated ; anterior and posterior areas generally smooth ; lines of
growth visible ; outer margin crenulated or wavy.

Diameter, 2 inches.

Locality. Bracklesham. Recent, Coast of Portugal and Mediterranean.

This species, as a British fossil, appears to be confined to the above locality, where, I believe, it is not
very abundant. This, like Pecten polymorphus, is no longer an inhabitant of our own shores. It is said
to be found fossil at Astigiani. The specimen figured is in the museum in Jermyn Street.

Lutraria solenoides (oblonaa) is enumerated in Mr. Dixon's 'List of Upper Tertiary Fossils at
Bracklesham.'

326 APPENDIX.

PHOLADIDEA ? Tab. XXXI, fig. 23.

This is the representation of a specimen obtained by Mr. John Middleton from the Crag " Diggings,"
near Woodbridge, and obligingly put into my hands for publication by Mr. Woodward, who considers it a
genuine fossil of the Red Crag. It appears strongly to resemble the calcareous case of a species of boring
Mollusc, and the generic position he has chosen for it is probably the correct one, belonging to the
section Martesia, Gray. The interior is filled with mud or clay, and particles of sand, but the valves are
gone. The exterior presents concentric ridges or elevations (about a dozen) : these are in relief, and
correspond with the depressions or furrows often seen in the cavities formed by the Pholades.

In my cabinet are some crypts of a similar form, excavated in a nodule of chalk found in the Red
Crag, evidently the production of a boring Mollusc. In my specimens the valves are gone, and the walls
in some of the cells are marked with concentric ridges.

The following existing British species, not found in any of the Crag Formations, are enumerated as
belonging to the Upper Tertiaries of these kingdoms, in accordance with the authorities attached :*

PATELLA PELLUCIDA.

Irish Drift Beds. (Forbes.)

LUCINOPSIS (LUCINA) UNDATA.

Clyde Beds. (Smith.)

CARDIUM ACULEATOM.

Clyde Beds. (Smith.)

CYPRINA pROPiNQUA.f

Clyde Beds. (Smith.)

CYTHEEEA L^viGATA.f

Clyde Beds. (Smith.)

VENUS VERRUCOSA.
— STRIATULA (&ALLINA).

Clyde Beds. (Smith.)

* When the Palseontographical Society was first established the Crag Formations were the allotted
portions for my Monograph, while the more recent deposits of the British Isles were intended to form the
subject of a separate work by James Smith, Esq., of Jordan Hill ; and it was not until after the publication
of my first volume that any alteration was made in this arrangement. Mr. Smith found the fossils of these
Uppermost Tertiaries were, with so few exceptions, identical with existing species, that he thought they were
not of sufficient importance for a distinct work : it has therefore devolved upon me to mention those few
that have become extinct upon our own coasts, and this will in some degree explain the irregular and imperfect
manner in which I have introduced the species ; and as this has taken me rather beyond my original
intention, it has affected the correctness of my former title-page, and rendered it necessary to substitute a
new one.

f These two species, noticed by Mr. Smith in his paper upon the ' Post-Tertiary Deposits of the Basin
of the Clyde,' ' Trans. Geol. Soc.,5 2d series, vol. vi, p. 155, he still thinks are decidedly distinct, and such

APPENDIX. 327

TAPES PULLASTRA (VENERUPIS PERFORANS).
— DECUSSATA.

Clyde Beds. (Smith.) Bracklesham.* (Dixon.)

CERATISOLEN (SOLEN) LEGUMEN.

Clyde Beds. (Smith.)

ANATINA CONVEXA.

Irish Drift Beds. (Forbes.) Clyde Beds. (Smith.)

The woodcut (p. 328) is the representation of a specimen belonging to Mr. Acton, who kindly put it
into my hands for illustration as a new species, but I have no doubt of its true position, and it is placed
unhesitatingly in specific association with the characteristic shell of the Red Crag.

This extraordinary individual is the widest deviation from the normal condition of a species that has
ever come under my observation, for although it is not very uncommon to see a fresh-water discoidal shell,
owing to a little deflection in its spiral, assume a turriculated or conical character, it is exceedingly rare to
see an elevated or turriculated shell become depressed into a discoidal form, with its volution upon a
horizontal axis. My old friend Littorina littoreus has indulged in extraordinary vagaries, but our present
specimen has carried its divergence to an extreme of deformity, emphatically showing that in the practical
study of the Univalve Mollusca little real aid is to be derived from any mathematical accuracy in the angle
of volution.

There is, it is well known, an inherent tendency to variation in some species, and this, though not
wholly dependent upon external conditions, may be aggravated by what is unfavorable to a healthy develop-
ment. The abnormous forms of Littorina littoreus, Purpura lapillus, and Cardium edule, found in the
Estuary Deposits near Norwich, arose, I imagine, from the latter circumstance, as a very large number of
individuals in this locality have become more or less distorted ; and as these species in the recent state are
rarely eccentric, their deformities were attributed by myself to some extraordinary alteration of the medium
in which the animals lived, probably from changes produced by ice or by an excess of outflow whereby the
saline properties of the water were prejudicially and suddenly diluted ; but the varieties of a species in the

was, he says, the opinion of the late Professor E. Forbes, in whose hands they were placed : unfortunately
they are not now to be found.

In the report of the twenty-fourth meeting of the British Association, held at Liverpool, September,
1854, p. 78, 'Geol. Sect.,' is a communication by Mr. P. P. Carpenter, respecting some land, fresh-water,
and marine shells, obtained by Miss Bright from the depth of one hundred feet in the sinking of a well on
the banks of the Avon, at Birlingham, Worcestershire. Among the fresh-water shells is mentioned Limnaa
glutinosa ; and with the marine ones are " two minute undetermined Bivalves, quite distinct from any known,
either recent or in the Crag. One is an Astarte, very flat and triangular, with sharp ribs like Gouldia
Pacifica, C. B. Ad.; the other is a ? Lucina, somewhat the shape of L. columbella, with a deeply cut lunule
as in Opis, beginning with concentric ridges, then suddenly changing into radiating ribs."

* Some of the fossils at this locality appear to exceed considerably in dimensions the same species
still in existence in our own seas. A specimen of T. decussata, given to me by Mr. Bristow, has attained
the length of 3 inches. I have lately seen a fine specimen of Pholas crispata, measuring 4 inches, and am
informed they have been found in this Deposit nearly 5 inches in length.

328

APPENDIX.

Red Crag may with less probability be assigned to such a cause, as there is no good reason to believe that
the Mollusca in the remains of that Formation resided in very close proximity to the regions of fresh water.
The unnatural condition of the present specimen appertains more to the individual than either to a species
or to a colony, and may have arisen from some accidental circumstance, or from unsuitable food, or, what is
perhaps more likely, the unlucky animal may when young have been caught and retained in some confined
position, preventing its growth in a natural direction. It is an immature individual, although it has no
doubt been "curtailed of its fair proportions" in consequence of its deformity.

Trophon antiquum, var. contrarium planorbulum.
From the Red Crag, Sutton.

INDEX TO VOL. II.

BIVALVES.

Abra alba

fabalis .

obovalis

prismatica

Acardo

Acephala testacea

Actinobulus .

Agaria

Agina purpurea

Alasmodonta

Aligena

Aloides

Amblema

Amphidesma .

Amusium

Amygdalum .

Anatina

Anchomasa

Andaria

Anodon

Anodonta anatina
cygnea
intermedia
piscinalis
ventricosa

Anomalocardia

Anomia aculeata
ccepa .
cost at a
ellipticus

PAGE

237

Anomia ephippium

238

lens .

240

margaritacea

239

patelliformis

160.

radiata

1

ruffosa

164

squamula

97

striata

164

striolata

284

sulcata

97

un dul at a

117

undula tim-stria ta

273

Anomya

97

Anonica

237

Antigone

20

Aphrodita

75

Appius

258

Area Britannica

294

cardissa .

75

flammulata

101

fluviatilis

102

fusca

102

Gaimardii

102

lactea

102

lactanea .

102

modiolus

75

navicularis

9

noai

8

nodulosa

8

papillosa

8

pectunculoides

PAGE

8

8

8

9

8

11

8

11

9

8

10

11

6

51
209
160
101
76
76
67
93
76
76
77
78
77
76
76
78
76
79

43

330

INDEX.

Area perforans
pusilla .
Quoyi
raridentata
tetragona

Arcinella carinata

Arcopagia

Arctica

Arctoe

Arcturus

Arenaria

Argina

Argus

Artemis compta

exoleta •
ferruginosa
lentiformis
lincta
sinuata

Asa

Astarte angulata
antiquata
Arctica
Banksii
Basterotii
bipartita
borealis
Burtinii
compressa
cor rug at a
crebricostata
crebrilirata
cyprinoides
Damnoniensis
digitaria
elliptica
excurrens
Gairensis
Galeotti
gracilis
imbricata
incerta
incrassata
lactea
Icevigata
lirata
multicostata

77
79
78
79
76
289
224
196
214
164
235
75
20
216
215
135
215
215
216
214
183
182
176
183
177
180
175
188
183
176
186
184
176
182
190
181
191
181
185
185
212
186
176
176
174
185
183

Astarte mutabilis
nitida
nitidula
obliquata
oblonga
O'Malii
ovalis
parva
parvula
pallida
pisiformis
plana
planata
propinqua
pulchella
pygmaea
rugata
Scotica
semisulcata
striata
subtrigona
sulcata
triangularis
vulgaris

Atrina

Auriscalpium

Avicula aculeata
Anglica
Atlantica
hirundo
Tarentina

Axincea

Aximedia

Axinw

Azor variabilis

Banfcia

Barnia

Barbatia

Beguina

Bequania

Biapholius

Bontcea

Bornia

Brachydontes

Bucardia

Byssoarca

Byssomya

PAGE

179

177

178

189

180

180

182

192

175

182

188

176

179

185

183

187

180

182

176

183

173

182

173

182

49

263

51

51

51

51

51

65

97

133

223

298

294

75

164

133

284

263

117

55

193

75

284

INDEX.

331

Calceola . .

Calcinella . .

Callista . .

Callitriche . ..

Calopodium . .

Canthyria . ,

Capsa

Capisteria

Cardissa

Cardita analis

chamaeformis
corbis
Dunkeri

exigua ,

minuta

nuculina .

orbicularis
scalar is

senilis ,

squamulosa
tuberculata
Carditamera ,
Cardium angustamtm
angustatum
anodonta
arcuatum
Balticum
boreale
clodiense
crenulatum
decorticatum
discrepans
echinatum
edentulum ,
edule
edulinum
Eichwaldii
fragile
glaucum
Groenlandicum
interruptum
Lamarckii
mucronatum
nodosum
nodosulum
oblongum
obliquum

PAGE

97
235
201
52
262
97
218
218
151
168
167
168
168
169
169
169
167
166
165
165
166
164
156
157
160
155
156
160
156
155
159
152
152
160
155
155
156
159
156
160
159
156
152
153
154
159
156

Cardium Parkinsoni

pectinatum

rusticum

scabrum

spinosum

strigilliferum .

tenue

venustum

vulgare

zonatum
Cepa
Cerastes
Chama bicornis
cornuta
gryhina
gryphoides
lacerata
sinisfrorsa
unicornis
Chamcepholas
Cheena
Chion
Chione
Chimeera
Chironia
Chlamys
Cibota
Circe minima .

triangularis
Circomphalus .
Clausina
Clotho
Cochlodesma complanatum

prsetenerum
Complanaria .
Concha rupium
Conchce
Conchifera

Coralliophaga cyprino'ides
Corbicula
Corbula bicostata

complariata

cuspidata

donaciformis

elegans

gibba

granulata

PAGE

158
155
155
153
152
154
155
160
155
155

6

151
163
163
163
162
163
163
163
284
292
218
206

49
117

20

75
198
198
214
150
284
263
264

97

162

1

1

200
103
274
275
273
275
274
274
268

332

INDEX.

Corbula incequivalvis
nucleus
Olympica
planulata
rotundata
striata
sulcata

Corbulomya complanata

Cormopoda

Cornea

Corneocyclas .

Crassina bipartita
borealis
compressa
convexiuscula
corrugata
Damnoniensis

elliptica
incrassata
Gairensis
minima
minutissima
Montagui
multistriata
nitida
obliqua
Omalii
ovata
Scotica
semisulcata
striata
sulcata
triangularis
Crenella
Cristaria

Cryptodon bisinuatum
ferruginosuQi
flexuosum
rotundatum
sinuosum
verticordia
Cuculleea
Cultellus tenuis

cultellatus

Cuneus . . .

Cunicula

PAGE

274

Curvula

274

Cuspidaria

274

Cyamium eximium

274

Cyanocyclas .

274

Cyclas appendiculata

274

cornea

272

Jlavescens

275

fontinaKs

1

gibba .

106

palustris

106

pusilla

180

rivalis

176

rivicola

176

Cycladina

183

Cynetodonta .

176

Cyprina Arctica

182

angulata

181

Defrancii

181

equalis

176

Islandica

181

Islandico'ides

174

Lajonkairii

174

maxima

183

rustica

183

tumida

177

vulgaris

183

Cyphoxis

180

Cyrachcea

181

Cyrena consobrina

182

Duchastellii

176

Gemmellaria

183

triffonula

182

Cyrtodaria

174

Cyrtosolen

55

Cytherea apicalis

97

Chione

134

Cyrilli

135

cycladiformis

134

filosa

135

leevis

134

lamellata

150

lenticula

75

minima

258

minuta

258

nitens

218

pusilla

97

rudis

49
271
152
103
110
107
107
112
112
109
112
107
107
117
258
195
196
197
196
196
196
197
196
197
197
196

75
138
104
104
104
104
290
252
198
207
198
208
208
207
210
198
198
198
207
198
208

INDEX.

333

Cytherea sulcata

triangularis

trigona

Venetiana

Dacromya
Dactylina
Dactylus
Daphne
Decadopecten .
Dendostrea
Dentipecten .
Dicer atia
Didacna
Didonta
Diodonta
Dione
Diplasma

Diplodonta Astartea
dilatata
parvula
rotundata
Dipsas
Dithyra
Ditoma
Donax anatinus

complanata

glabra

irus

longa .

politus

ruber .

striatella

truncata

trunculus

vittatus
Dosina
Dosinia ' . "

EcMon
Egeria
Egesta

Elatobranchia
Ellipsaria
Elliptic
Embla Korenii
Endocephala .

FAtiK

Ensatella

198

Ensis complanatus

198

Erycina trigona

208

Erycinella ovalis

Euglesia

87

Exoleta

294

294

Fenestella

75

20

Galaxura

12

Galeomma

20

Galileja

193

Gari

151

Gastrana laminosa

284

Gastrocheena cuneiformis

217

dubia

206

faba

97

fulva

146

Mans

145

modiolina .

146

pholadia

144

Poliana

101

Geloina

1

Glans

1

Glaucion

219

Glaucus

220

Globus

220

Glossus

205

Glycimeris angusta

220

arctica

220

Norvegica

219

vagina

233

Gobrceus

219

Goodallia

219

Gryphus

219

209

Hecuba

214

Hemicardium

Hemimactra .

6

Hemiodon

218

Heteroconcha

209

Hiatella

1

Hinnites Corteseyi

97

Dubuissoni

97

irregularis

268

pusio

1

Hinnus

PAGE

254
255
275
171
108
214

263
123
108
221
217
292
292
293
292
292
292
292
292
103
164
42
42
162
193
291
281
281
291
221
172
151

218

151

240

97

206

284

19

19

33

33

18

334

INDEX.

Hippagus acuticostatus

verticordius
Hypogcea . •
Hyridella

Iphigenia

Iridea

Irits

Isoarca

Isocardia cor .
crassa
fraterna
globulosa
Hibernica
lunulata
Markoei
rustica
ventricosa

Ixartia

Janira
Jatronus

Kellia ambigua
coarctata
cycladia
deltoidea
dubia .
elliptica
flexuosa
lactea .
nitida .
orbicularis
pumila .
rubra .
suborbicularis

Lacinia

Lamellibranchiata

Lampsilis

Lamproscapha

Lanistes

Lanistina

Lasea

Lasmonos

Lasmigona

PAGE

150

150

254

97

218
97
204
75
194
194
194
194
194
194
194
194
194
258

20
161

120
123
122
115
120
121
121
118
116
120
124
125
118

161

1

97

101
55
55

117
97
97

Lastena .,
Latona . .

Laturnula
Lavignon
Lazarus
Leda arctica .
caudata .
lanceolata
minuta .
myalls .
oblonga .
pernula .
pygmsea
rostrata
semistriata
Thraciseformis
truncata
Lembulus
Lentidium
Leptodea

Lepton deltoideum
depressum
nitidum
squamosum
Ligula alba

Boysii
donaciformis
prismatica
Ligumia
Lima aperta .
bullata .
elongata
exilis
fragilis .
liians
inflata .
Loscombii
oblonga
ovata
plicatula
subauriculata
sulcata ,
sulculus
tenera .
vitrina .
Limatula
Limicola carnaria

PAGE
101
218
263
235
161

INDEX.

335

Limopsis aurita

pygmaea

Limnopsis

Limula

List era

Loripes divaricata
ellipticus
undularia

Lucina alba .

antiquata
arcuata
balaustina
borealis
columbella
commutata
contracta
crenulata
curviradiata
decorata
dentata
digitalis
digitaria
divaricata
femiginosa
Flandrica
flexuosa
mitis .
oblonga
radula
Sarsii .
sinuata
sinuosa
squamosa
striatula
trifaria
vulnerata

Lucinopsis Lajonkairii

Lunaria

Luticola

Lutricola

Lunulacardium

Lutraria elliptica
vulgaris

Lux

Lymnadia

Macha strigillata

PAGE

70
71
69
42
235
137
121
137
139
139
137
227
139
143
137
139
140
190
141
140
190
190
137
135
139
134
139
121
139
134
134
134
141
140
137
143
148
75
97
235
151
251
251
221
97

253

Mactra arcuata
artopta
cinerea
congesta
crassa .
crassatella
constricta
cuneata
deaurata
denticulata
dubia .
elliptica
Euxinica
glauca
helvacea
incequilatera
lactea
limbata
magna
modicella
Neapolitana
obtruncata
ovalis .
procrassa
solida
straminea
striata
stultorum
subtruncata
truncata
vulgaris

Macoma

Mactrina

Mactro'idea

Macrophyllum

Malleolus

Mantellum

Margaritifera

Megadomus

Meretrix

Mesodesma Jauresii

Met apt era

Modiola asperula
barbata
costulata
cylindrdides
discors

PAGE

244

244

241

247

245

245

249

248

249

249

247

247

248

241

241

249

241

248

241

249

241

248

247

245

246

241

247

241

248

245

246

224

172

172

151

298

42

51

97

206

250

97

64

58

60

60

63

336

INDEX.

Modiola discrepant
Europea
Gibbsii
grandis
hyalina
marmorata
modiolus
j papuana

Patagnce
phaseolina
Prideauxiana
rhombea
sericea
tumida
vulgaris
Modiolaria
Modiolarca .
Modiolopsis .
Monocondylea
Monodacna
Montacuta bidentata
cylindrica
donacina
ferruginea
ferruginosa
glabra
oblonga
ovata
pumila
substriata
tenella
truncata
Mulinia
Musculus
Mya acuta

arenaria .
I at a

mercenaria
ovalis
pullus
sub ovata
subtruncata
Swainsoni
truncata .
Uddevallensis
Myalina
Myrtea

PAGE

63

Mysca

62

Mysia Americana

58

Montagui

57

ornata

61

Mytilus abbreviatus

62

affinis

57

alceformis

57

angulatus

60

antiquorum

59

barbatus

64

borealis

64

curtus

61

curvirostris

62

densatus

57

dilatatus

55

edulis .

55

elegans

55

Jlavus .

97

galloprovincialis

151

hesperianus

126

incurvatus

131

notatus

131

pellucidus

130

plebeius

129

retusus

129

sericeus

129

sagittatus

130

solitarius

124

subsaxatilis

128

umbilicatus

130

vulgaris

127

Mytilicardia .

240

52

279

Naia

279

Naidea

279

Navicula

279

Nesera brevirostris

278

cuspidata

278

jugosa

279

Neithea

279

Nicania

278

Nucinella miliaris

277

Nucula argentea

278

Cobboldise

117

corbulo'ides

138

decipiens

PAGE

97
146
144
148
53
53
53
53
53
57
53
57
57
55
53
52
52
53
53
55
52
53
52
53
53
61
53
53
53
57
52
164

97

97

75

273

273

272

20

172

73

85

82

95

84

INDEX.

337

Nucula depressa
gibbosa
hyperborea
Jacksoni
laevigata
lenticula
lucida

maryaritacea
minuta
nitida
nucleus
oblonga
oblongo'ides
Philippiana
pygmeea
rostrata
Ryckholtiana
Thraciceformis
tenera
tenuis
tenuisulcata
trigonula
truncata

Nuculina

Nux

Obliquaria

Obovaria

Odatelia

Odoncinetus .

Omala

Orbiculus

Oreada

Ortygia

Osteodesma

Ostrea borealis

deformis

denticulata

edulis

foliosa

Mppopus

lamellosa

parasitica

princeps

spectrum

undulata

ungulata

91 Oxysma . •
95

90 Palliolum

93 Pandora glacialis

81 inaequivalvis

95 margaritacea

84 obtusa

85 Pinna

92 rostrata

9 1 Panopsea Aldrovandi

85 Americana

93 arctica
90 Bivonce
95 Faujasii

95 gentilis

92 glycimeris
84 Ipsviciensis

96 Norvegica
84 Spengleri
84 reflexa

93 Paphia deaurata

86 Papyridea

94 Parallelopipedum
72 Partularia

106 Paxyodon

Pecten aspersus

97 Audouinii
97 Bruei .

101 complanatus

258 Clintonius

224 Danicus

214 distortus

172 domes ticus

209 dubius

258 Dumasii

13 elongatus

13 jlavus .

13 f rag His

13 Gerardii

13 glabris

1 3 gloria-maris

13 gracilis

13 grandis

1 7 Islaudicus

1 3 Jamesoni

1 7 Lamalii
13

PAGE

49

21

271

270

271

271

271

271

283

283

282

282

283

283

281

283

281

282

283

250

151

75

101

97

30

35

29

23

31

30

33

27

38

30

33

35

45

24

30

33

37

23

40

30

29

27

44

338

INDEX.

Pecten limatus
lineatus
Malvinte
maximus
medius
monotis
muricutus
obsoletus
opercularis
Pandoras
parvus
Pealii .
pictus .
plebeius
Princeps
Pseudamusium
pulchellinus
pusio .
pygmaus
radians
reconditus
rectangulus
scabrellus
septemradiatus
serratus
similis
sinuosus
Sowerbyi
spinosus
squamulosus
stria tus
sublcevigatus
subdiaphanus
subrufus
sulcatus
tigrinus
triradiatus
tumescens
tumidus
varius
ventilabrum

Pectunculina .

Pectunculus decussatus
glycimeris
latiarca
nummarius

PAGE
33
35
35
22
23
41
38
27
35
29
27
40
29
35
31
30
35
33
25
35
35
35
38
30
33
23
33
35
33
33
33
31
24
35
35
27
30
38
25
41
38
35
69
67
66
67
67

Pectunculus nummiformis
pilosus
polyodonta
pulvinatus .
pusillua , .
pygmceus
subobliquus
sulcatus
transversa .
undatus
variabilis .
Pelecypoda
Pennaria
Pera
Peroncea
Perlamater
Petasunculus .
Fetricolarius .
Petrifora

Phaco'ides . .

Pholadidea Loscombiana
papyracea
striata

Pholadomya candido'ides
Esmarkii
hesterna

Pholas bifrons .

crispata .

cylindrica .

lamellata .

papyracea .

parva . .

Pholidea . .

Pholeobia . ,

Pinna ingens . .

pectinata ' .

Pisidium amnicum «

fontinalis .

Henslowianum

obliquum ,

pulchellum

pusillum ,

Pisum . ,

Plagiola . .

Plagiostomus . ,

Pleurobema .

Pleuronectes . ,

PAGE

67
66
67
67
67
71
67
182
67
67
67
1

49

108

172

51

224

205

204

138

293

293

298

266

266

266

296

296

295

298

298

296

297

284

50

50

109

111

110

109

111

112

108

17

, 42
17
20

INDEX.

339

Pleurodon

Polyodonta

Poromya anatinoides
granulata

Poronia rubra

Potamida

Potomomya

Prisodon

Prop t era

Psammobia affinis

Dumontii
Ferroensis
florida
leevis
muricata
tellinella
vespertina

Psammocola .

Psammophila .

Psammosolen .

Psammotcea .

Pseudamusium

Psilopus

Pteria

Ptychina

Pullastra

Puschia

Pyxis

Quadrula

Rhombo'ides

Rhombus

Rotundaria

Sanguinolaria fusca

Saxicava arctica
carinata
distorta
fragilis
gallicana
pholadis
rhombdides
rubra
rugosa
striata
sulcata

PAGE

72

Scacchia elliptica

80

ovata

268

Scalinaria

268

Scapharca

125

Scaphula

97

Scaphura

273

Scrobicularia .

97

Semele

97

Senilia

222

Serripes

222

Serrula

222

Siphonium

223

Solecurtus

222

Solena

222

Solenarius

223

Solen candidus

223

curvus .

221

ensis

250

ensiformis

252

gladiolus

221

Hausmanni

20

ligula .

160

novacula

51

siliqua .

133

strigellatus

201

tennis .

172

Sphsenia angulata

20

Binghami

costulata

97

cylindrica

Sphcerella

284

Spharium

284

Swainsoni

97

Spisula truncata

Stola

231

Strophilus

287

Symphynuta .

239

Syndosmya

286

Syntoxia . .

288

285

Tapes aurea .

286

perovalis

287

texturata

287

virginea

285

Taras

285

Tellimya

286

Tellina Balthica

PAGE
121

123

97

75

75

75

235

235

75

151

218

298

252

254

254

253

256

256

256

255

256

256

256

256

253

258

289

276

128

288

143

106

278

245

161

101

112

237

97

202
203
204
201
136
119
231

340

INDEX.

Tellina balaustina

Benedenii

calcarea

carnaria

crassa .

discors

donacilla

donacina

edentula

fabula .

Groenlandica

inconspicua

lata .

Llantivyi

lusoria

maculata

obliqua

obtusa .

ovala .

ovalis .

ovaloides

prsetenuis

proximo

riaida .

rubra .

sabulosa

scabra .

semistriata

solidula

sordida

subcarinata

subrotunda

tenera .

tenuilamellosa

triangularis

trifasciata

variegata

zonaria

sonata
Teredarius
Teredo Bruguieri

navalis

Norvegica
Tetraplodon
Thovana

Thracia Conradi
convexa

PAGE

227

Thracia inflata

230

phaseolina

228

pubescens

231

ventricosa

226

Timoclea ovata

232

Thyatira . "-.,

234

Thyatisa

233

Theliderma

228

Trigonella plana

232

Trigonoccelia sublamgaia

231

Tridonta . .

231

Triquetra . .

228

Trisidos

233

Trisis

233

Truncilla

226

Trutina

228

Tuceta . .

226

Turtonia

228

228

mtmtO

Ungulina , '

227

Unio antiquior

230

granosus

228

incurvus

226

littoralis

231

nana

228

ovalis

226

Pianensis

232

pictoreum

231

subtetragonus

228

rostrata

233

tumidus

226

228

Uniopsis

227

Uperotus

228

Urynia

233

233

Vagina

230

Fenericardia antiquata .

231

anceps

298

chameeformis

301

corbis

300

intermedia

300

orbicularis

97

scalaris

294

senilis

261

Venerirupis

261

Venerupis irus

PAGE
261

260

259

252

213

133

133

97

235

67

172

97

75

75

97

269

65

132

136
98
98
98
98
98
99
98

100
98
99
99
97

298
97

254

165
169
167
169
165
167
166
165
204
205

INDEX.

341

Venerupis Lajonkairei
Venus jEnea .

aurea .

Brogniarti

bucardium

casina

casinula

chione

circinata

cincta

compressa

Cyrilli

cydadiformis

Damnonia

discina

equalis

exoleta

fasciata

fragilis

gallina

gibbosa

imbricata

incrassata

Islandica

lactea .

leeta .

lentiformis

lincta .

literata

Lupino'ides

lupin a

mercenaria

minima

Montagui

multilamellosa

nebulosa

nitens .

PAGE

. 148

Venus ochropicta

. 202

ovata .

. 202

Paphia

. 211

pectinula

. 196

pectunculus

. 210

pumila

. 210

radiata

. 207

reflexa

. 139

rhomboides

. 210

Rusteruccii

. 175

rustica

. 198

rudis ,

. 208

rupestris

. 182

sarniensis

. 210

senilis .

. 196

similis .

. 215

sinuata

. 211

Scotica

. 145

spadieea

. 210

sulcata

. 210

texturata

. 212

triangalaris

. 178

turgida

. 196

Venetiana

. 213

virago .

. 201

virginea

. 215

Venulites

. 213

Velorita

. 203

Verticordia

. 148

Volsella

. 213

. 196

Xylophagus .

. 198

Xylotrya

. 183

. 210

Yoldia

. 202

. 202

Zirfcea crispata

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PAGE

208
213
211
213
208
198
213
210
201
210
197
208
205
201
210
210
213
182
213
210
204
198
210
208
202
201
209
103
149
55

298
298

87
296

INDEX TO APPENDIX.

Anatina convexa
Aplysia? asciola
Assimiuea Grayiana

Buccinum ciliatum
Bulla acuminata

ampulla

conulo'idea

hydatis .

Cancellaria scalaro'ides
Cardium aculeatum
Ceratisolen legumen
Crassina propinqua
Cryptodon sinuosum
Cytherea Isevigata

Fossarus sulcatus
Fusus Bamffius

Barvicensis

crispus ?

curtus .

Forbesii

Helix fruticum
incarnata
ruderata

Jeffreysia? patula

Lacuna vincta
Limopsis pygmsea
Littorina nerito'ides
rudis
palliata
suboperta
Lucina columbella
Lucinopsis undata
Lutraria rugosa

soleno'ides

PAGE

. 327

Mactra triangulata

. 322

Margarita undulata

. 318

Mitra cornea .

ebenus

. 315

plicifera

. 322

. 322

Nassa Monensis

. 321

Pliocena

. 322

pygmsea

reticulata

. 316

Natica Alderi .

* . 326

Bowerbankii

. 327

Smithii

. 326

. 324

Odostomia cono'idea

. 326

eulimoides

truncatula

unidentata

. 317

. 314

. 314

Paludina marginata

. 314

parilis

. 314

Patella pellucida

Pecten maximus

. 314

polymorphus

Pholadidea

308

• cJ vC/

Pyrula acclinis

. 309

. 309

Rissoa soluta

Thermalis

. 319

Tapes decussata

. 316

pullastra

. 324

Trochus crenularis

. 317

magus

. 317

Trophon Fabricii

. 317

Norvegicum

., 317

propinquum

. 324

Turtoni

. 326

. 325

Venus gallina

. 325

verrucosa

PAGE

324
321
311
310
311

315
315
315
315
321
321
321

317
317
318
317

320
320
326
323
323
325
311

318

319

327
327
321
321
313
312
313
312

326

326

J. B. ADLASD, PKINTEK, BAKTliOLOXIEW CLOSE.

fiT-"- --

H A H ~i

TAB. I.

Fig.

1. Ostrea Princeps, page 17.

a. inside view of lower valve.

b. outside ditto of upper valve.

2. Anomia aculeata, p. 9.

a. outside view of upper valve.

b. ditto ditto var. striolata.

3. Anomia ephippium, p. 8.

a. upper valve of a specimen of var. squamula, showing the radiating costae

produced by the animal adhering to the umbonal region of a Pecten.

b. id., specimen formed on the central portion of a Pecten.

c. id., outside view of var. cylindrica.

d. the testaceous plug, or lapideous portion of the adductor muscle, commonly

called the operculum.

4. Anomia patelliformis, p. 10.

a. outside of upper valve.

b. ditto ditto var. undulata.

The lines indicate the size of the specimens.

2 £L

3 b.

I b

Sower~by

TAB. II.

Fig.

1. Ostrea edulis, page 13.

a. specimen with united valves.

b. outside of lower valve of var. sinuata.

c. specimen with united valves, var. spectrum.

2. Ostrea Princeps, p. 17.

a. outside of lower valve.

b. ditto of young specimen.

3. Anomia striata,jo. 11.

outside of upper or imperforate valve.

TAB.

2 b.

Sswerby.

TAB. III.

Hinnites Cortesyi, page 19.

TAB. 112

G-f-crac Soweriy

TAB. IV.

Fig.

1. Pecten maximus, page 22.

a. outside of lower valve of var. vulgaris.

b. id., upper valve, var. complanatus.

2. Pecten Danicus, p. 30.

3. Pecten dubius, p. 38.

Fig.

TAB. V.

1. Pecten Islandicus, page 40.

2. Pecten tigrinus, p. 27.

a, var. Isevis, left valve, outside view.

b.
c.
d.

e.

S. right valve, ditto.

/3. right valve, ditto.

y. right valve, ditto.

y. left valve, ditto.

7. id., showing a different mode of growth-

exoletus, right valve.

3. Pecten Bruei, p. 29.

a. right valve.

b. left valve.

4. Pecten similis, ^.25.

a. left valve, with a single divergence of coloured lines.

b. id., with zigzag lines.

c. right valve.

5. Pecten Gerardii, p. 24.

a. right valve.

b. left valve.

The lines indicate the size of the specimens.

<? a/.

J b.

TAB. VI.

Fig.

1 . Pecten Princeps, page 3 1 .

2. Pecten opercularis, p. 35.

a. left valve of var. lineatus.

b. id. var. reconditus.

c. id. var. scabrotus.

d. specimen with united valves, var Audouinii.

3. Pecten dubius,/>. 38.

left valve of var. partim imbricatus.

4. Pecten pusio, p. 33.

a. specimen with united valves of var. striatus.

b. left valve, var. limatus.

c. right valve, var. striaturus.

5. Pecten gracilis, p. 37.

The lines indicate the size of the specimens.

TAU.

TAB. VII.

Fig.

1. Lima Loscombii, page 45.

2. Lima hians,j». 44.

3. Lima subauriculata, p. 47.

a. three views of specimen, natural size.

b. enlarged view of hinge line of young individual with minute

crenulations.

c. var. elongata.

4. Lima plicatula, p. 46.

Small figure the natural size .

5. Lima ovata, p. 48.

Small figure the natural size.

6. Lima exilis, j». 43.

7. Pecten maximus, var. grandis, p. 22.

a. lower valve.

b. upper valve.

Tab.?

t.l

3. a

J.6

6.c

r, ', ••,

TAB. VIII.

Fig.

1. Modiola modiolus, page 57.

a. outside view of var. vulgaris.

b. inside ditto.

c. inside ditto, elongated var.

2. Modiola barbata, p. 58.

3. Modiola sericea, p. 61.

4. Modiola phaseolina, p. 59.

c. inside view of young specimen, showing a crenulated margi

5. Modiola discors, p. 60.

6. Modiola costulata, JP. 60.

a. outside view of elongated var.

b. inside ditto var. Petagnse.

7. Modiola marmorata, p. 62.

8. Modiola rhombea, p . 64.

Outside view of two varieties.

9. Mytilus edulis, p. 52.

a. var. elegans.

b. ,, anti quorum.

c. „ incur vatus.

d. „ saxatilis.

e. alseformis.

55

10. Mytilus hesperianus,jo. 55.

11. Pinna pectinata, p. 50.

The lines indicate the size of the specimens.

Tat . V.

TAB. IX.

Fig.

1. Pectunculus glycimeris, page 66.

a. outside view of transverse var.

b. inside ditto of ditto

c. hinge line of antiquated specimen, showing the obliteration of denticles

by the advance of the ligament.

d. outside of elongated var.

e. magnified view of the young shell showing one tooth only, on each side

of the dental area.

/. outside view of a young specimen, with distinct and elevated costse.
y. hinge with full complement of teeth.
h. inside view of var. subobliquus.
i. outside ditto of ditto.

2. Limopsis aurita, p. 70.

c. var. ft.

3. Limopsis pygmsea, jy. 71-

c. hinge magnified.

T.,1, IX.

TAB. X.

Fig.

1. Area tetragona, page 76.

a. outside view of specimen from

Red Crag.

b. inside view of the same.

c. outside of abraded specimen,

with a sinuate d form of ven-

»

tral margin (Bissoarca).

d. inside of var. Britannica.

2. Area lactea,j». 78.

a. outside, left valve.

b. inside of the same.

3. Area pectunculoides, jo. 79.

a. outside of var. brevis.

b. inside of var. elongata.

4. Nucinella miliaris, jy. 73.

a. inside of right valve.

b. inside of left valve.

c. united valves, showing the posi-

tion of the ligament.

5. Nucula tenuis, p. 84.

6. Nucula nucleus, p. 85.

Fig.

8.

9.
10.
11.

12.
13.
14.
15.
16.

17.

Nucula trigonula, p. 86.
Nucula Isevigata, j». 81.
Nucula Cobboldiae, p. 82.
Leda semistriata,jo. 91.

Leda pygmsea, j». 95.

a. inside view of an acuminated

specimen.

b. outside of a specimen of a

more rounded form.

Leda caudata,jo. 92.
Leda pernula, p. 93.
Leda truncata, p. 94.
Leda Thraciseformis, p. 96.
Leda lanceolata, j». 88.

Leda myalis, p. 90.

c. outside view of elongated var.

The lines indicate the size of the specimens.

UNIVERSITY

TAB. XL

Fig.

1. Pisidium amnicum, page 109.

a. inside of elongated specimen

from Stutton.

b. ditto of var. sulcatum from

Grays.

2. Cyclas cornea, p. 107.

a. outside of var. tumida.

b. ditto of var. compressa.

3. Montacuta donacina, p. 131.

b. inside of left valve.

c. outside of the same.

a. inside of var. cylindrica.

4. Kellia cycladia, p. 122.

5. Cyamium? eximium,jo. 132.

6. Lepton depressum, p. 116.

Fig.

7. Lepton nitidum, jo. 116.

8. Lepton squamosum, p. 114.

9. Lepton deltoideum, p. 115.

c. hinge of left valve slightly

enlarged.

d. ditto right valve ditto.

10. Kellia rubra,j». 125.

11. Anodonta cygnea,jy. 102.

12. Uniolittoralis,j0. 98.

13. Unio tumidus, jt?. 99.

14. Lucinopsis Lajonkairii, p, 149.

15. Cyrena consobrina, p. 104.

c. specimen of a more trigonal
form.

The lines indicate the size of the specimens.

lab M

/:' a

IX. h

HSITY 1

TAB. XII.

Fig.

1. Lucina borealis, j»<zye 139.

2. Diplodonta astartea, p. 146.

3. Diplodonta rotun data, p. 144.

4. Loripes divaricata, p. 137.

5. Diplodonta dilatata, p. 145.

6. Lucina decorata, JP. 141.

7. Lucina crenulata, p. 140.

8. Kellia suborbicularis, p. 118.

a. orbicular variety, left valve.

b. transverse ditto, right valve.

9. Kellia orbicularis, p. 120.

a, b. interiors of both valves mag-
nified.

c. outside view, natural size.

10. Kellia coarctata, p. 123.

Fig.

11. Kellia ambigua,jfl. 120.

a. trigonal variety.

b. elliptical ditto.

12. Montacuta substriata, p. 128.

13. Kellia elliptica, p. 121.

b. united valves, showing the sinu-
ated form of hinge margin.

14. Montacuta ferruginosa, j». 129.

15. Kellia pumila,jo. 124.

16. Montacuta truncata, j0. 127.

17. Montacuta bidentata, jo. 126.

18. Hippagus verticordius, p. 150.

19. Cryptodon ferruginosum, j». 135.

20. Cryptodon sinuosum, /». 134.

The lines indicate the size of the specimens.

Tab.

a 7>

7

,9

22

a. 24

15

r-\v

a

Jfl

TAB. XIII.

Fig.

1 a — d. Cardium Groenlandicum, page \ 60.

2 a, b. „ venustum, jo. 160.

3 a, b. „ nodosulum, j». 154.

c. „ „ portion of surface magnified.

4 a, b. „ nodosum,jo. 153.

c. „ „ portion of surface magnified.
50, b. „ strigilliferum, j». 154.

d. „ „ portion of surface magnified.

c. „ „ young specimen, showing the introduc-

tion of an intermediate ray.

6 a — c. „ angustatum, p. 157.
70, b. „ Parkinsoni,jo. 158.

The lines indicate the size of the specimens.

'I at.

i Strwtrl

TAB. XIV.

Fig.

1 a — c. Cardium decorticatum, page 159.

d. „ „ (tenellum)

2 a — g. „ edule,j». 155.

a. Var. vulgaris.

b. „ umbonatum, from Bramerton, Mam. Crag.

c. „ edulinum, from Sutton, Cor. Crag.

d. „ multicostatum, with 28 ribs ; from Sutton, Red Crag.

e. „ clodiense, from Sutton, Red Crag.

/. „ inhabile, with 20 ribs ; from Sutton, Red Crag.

g, „ paucicostatum, 18 ribs; Bramerton, Mam. Crag.

3 a, b. Cardium echinatum, p. 152.

4 a, 6. „ interruptum, p. 159.

Ta.b.Z

UNIVERSITY

»8LfiAuFQ!2a>

TAB XV.

Fig.

1 a— -f. Cardita senilis, page 165.

2 a, b. „ corbis, var. nuculina, JP. 168.
c, d. „ „ „ exigua.

3 a. b. „ chamaeformis, p. 167.

4. „ orbicularis, p. 167.

5. „ scalaris, p. 166.

6. „ analis,jo. 168.

7 a — d. Coralliophaga cyprinoides, p. 200.

b, c. „ „ var. elongata.

d. „ „ slightly enlarged view of the hinge.

8 a — d. Chama gryphoides, p. 162.
9#, b. Isocardia cor,j». 193.

10 a — d. Erycinella ovalis, jo. 171.

e,f. Enlarged views of the hinge, showing a central cavity of the
ligament.

The lines indicate the size of the specimens.

J.I.

2. d .

TAB. XVI.

Fig.

1 a— -f. Astarte mutabilis, page 179.

c, d. „ „ var. deformis.

e^-f, J3 „ specimen from Bridlington.

2 a, b. „ crebrilirata,^. 184.

3 a — d. „ borealis,j». 175.

c, d. „ „ var. Withami.

4,0 — </. tt obliquata, p. 189.

5 a, b. „ sulcata,jo. 182.

6 a, b. „ incrassata, jo. 178.

7 „ elliptica, p. 181.
80 — c. • „ compressa, p, 183.

T<a> .

6.0.

TAB. XVII.

Fig.

1 a—f. Astarte Omalii, p. 180.

c. „ „ var. undulata.

d. „ „ „ bipartita.

e. „ „ „ acuminata.
/. „ „ „ elliptica.

2 a — d. „ Basterotii, p. 177.

3 a — e. „ gracilis,jo. 185.

e. „ „ var. multilineata.

4. „ incerta,j». 186.

5 a — d. „ Burtiniijjo. 188.

6. „ crebricostata 1 p. 186.

7 a, b. „ pygmsea,j0. 187.

8 a — d. „ digitaria, p. 190.

9 0, 6. ,, excurrens, p. 191.
10 a — d. „ triangularis, p. 173.

a, b. „ „ var. trigona.

lla, #. „ parvula,jo. 175.

12 a, b. „ parva,jo. 192.

The lines indicate the size of the specimens.

3.T,

1C. a.

2O. b

TL.a

12.a,

UNIVERSITT

TAB. XVIII.

Fig.
1 a — e. Cyprina rustica, page 197.

a, c, e. „ „ var. tumida.

6, d. „ „ „ elongata.

2a — d. „ Islandica, p. 196.

c, d. „ „ var. orbicularis.

a, b. „ „ „ transversa.

Saw

TAB. XIX.

Fig.

1 a—f. Venus casina, page 210.

2 a — d. Circe minima, p. 198.
3a—f. Venus imbricata, jo. 212.

4 a — d. „ ovata,j». 213.

5 a — c. „ fasciata, j&». 211.

6 a — b. Venerupis irus, p. 205.

7 a — d. Tapes perovalis, p. 203.

George, Sff

TAB. XX.

Fig.

1 a — e. Tapes virginea, page 201.

c, d. „ „ from Mam. Crag, Bramerton.

e. View of sculpture, enlarged two fold.

2 a, 6. Tapes aurea, p. 202.

3 a — c. „ texturata r p. 204.

e. View of sculpture, enlarged two fold.

4 a, b. Cytherea chione, p. 207.
5# — d. „ rudis,jo. 208.

6 a — d. Artemis lincta,j». 215.

7 a — c. „ lentiformis, p. 215.

TAB. XXL

Fig.

1. Tellina crassa, p. 226. From Red Crag, Sutton.

e, portion of surface enlarged.

2. Tellina Benedenii, p. 230. From Red Crag, Sutton.

a, &, show similarity of form in siphonal scar.
d, shows the equal tumidity of the two valves.

The siphonal side of fig. 2 a, was filled up by mistake ; the specimen from which
the figure was taken is imperfect, extending only to the fracture.

3. Tellina fabula, right valve, p. 232.

4. Tellina balaustina, p. 227. From Coralline Crag, Sutton.

d, enlarged portion of surface.

5. Tellina prsetenuis, p. 230. From Red Crag, Sutton.

6. Tellina lata, p. 228.

7. Tellina obliqua, p. 228. „ „

6, c, show the dissimilar forms of the siphonal scar.

Note. This plate was engraved March, 1854.

TAB. XXII.

Fig.

1. Tellina Balthica, p. 231.

a, b, specimen from Clacton, found in clay, with Unio littoralis.
c, specimen from Mam. Crag of Norfolk.

2. Psammobia vespertina, p. 222.

a, d, representation of a monster valve from Sudbourne.
c, d, specimen from Ramsholt.

3. Psammobia Ferroensis, p. 221. From Coralline Crag, Sutton.

4. Psammobia Tellinella, p. 223. „ „

5. Tellina donacina, p. 233. „ „

6. Tellina donacilla, p. 234. „ „

7. Donax vittatus, p. 219. From Mam. Crag, Bramerton.

8. Donax trunculus, p. 219. From Red Crag, Sutton.

9. Donax politus, p. 220. From Coralline Crag, Sutton.

10. Abra alba, p. 237. „ „

c, enlarged hinge of right valve.

11. Abra obovalis, p. 240.

c, enlarged hinge of right valve.

12. Abra fabalis, p. 238. From Red Crag, Walton Naze.

13. Abra prismatica, p. 239. From Coralline Crag, Sutton.

14. Trigonella plana, p. 235.

a, c, show difference of form in palleal impression.

TAJ3 ..

9.0.

JO.c

2O.

9.b

JLa.

13.0,

22.1

23. T,

£. So we.

TAB. XXIII.

Fig.

1. Mactra ovalis, p. 246.

a, b, specimen from Mam. Crag, Chillesford.
c, d, specimen from Red Crag, Button.

2. Mactra glauca, p. 241. From Red Crag, Newbourne.

3. Mactra stultorum, p. 242. „ Sutton.

4. Mactra artopta, p. 244. „ Sudbourne.

5. Mactra arcuata, p. 243.

a, specimen from Ramsholt, Cor. Crag.

b, c, specimen from Walton Naze, Red Crag.

ZAB. X2

TAB. XXIV.

Fig.

1. Lutraria elliptica, p. 251. From Coralline Crag, Ramsholt.

2. Mactra truncata, p. 245.

3. Mactra subtruncata, p. 247.

a, specimen from Sutton.

b, specimen from Bramerton.

4. Mactra solida, p. 245. From Red Crag, Sutton.

c, a triangular variety probably of this species. It much resembles M. striata,
Smith, 'Wern. Trans./ vol. viii, pi. 1, fig. 22, but it has the two sides more
equal.

5. Mactra obtruncata, p. 248. From Red Crag, Sutton.

6. Mactra constricta, p. 249. „ „

7. Mactra deaurata, p. 249.

8. Mactra procrassa, p. 244.

l.a,

TAB. XXV.

Fig.

1. Gastrana laminosa, p. 217. From Coralline Crag, Sudbourne.

d, e, specimen distorted. From Red Crag, Walton Naze.

2. Cultellus tenuis, p. 258. From Red Crag, Walton Naze.

c, d, hinge of both valves slightly enlarged.

3. Macha strigillata, p. 252. From Coralline Crag, Sutton.

4. Pandora Pinna, p. 270.

5. Pandora insequivalvis, p. 270.

6. Solen ensis, p. 256. From Red Crag, Walton Naze.

a — d, various specimens showing different proportionate dimensions.
e,f, exhibit muscular impressions.

7. Solen siliqua, p. 255. From Red Crag, Sutton.

b, d, interior view, to show difference in muscular impressions.

c, a small elongated specimen, with valves united.

8. Solen gladiolus, p. 254. From Red Crag, Walton Naze.*

* In support of the presumption assumed in th'e note at page 255, that the Red Crag is not wholly
derivative, it may be further remarked, that at the part of the cliff -whence this specimen was obtained,
there are no extraneous fossils whatever, at least none that I have been able to discover, which could be
decidedly said were foreign to the deposit. The shells here rest immediately upon the London Clay, and
are in the highest state of perfection ; not only are there many Bivalves in their natural position, but the
numerous specimens of the reversed variety of Trophon antiquum have the fragile apex or pullus seldom or
never removed. Many species are also found that are not met with in the Coralline Crag ; though this
latter evidence is not of itself conclusive, it helps to sustain the argument deduced from the perfection of
the specimens. The whole aspect of the Fauna at this locality differs from that of the White or Coralline
Crag ; the same also may be said of its lithological character, and, in my opinion, the probabilities are greatly
in favour of the Red Crag, certainly at Walton-on-the-Naze, being pure and genuine, and of an Age
geologically subsequent to the Coralline Crag.

TAB. XXVI.

Fig.

1. Thracia pubescens, p. 259. From Coralline Crag, Sudbourne.

e, a distorted specimen, probably the young of this species. (Thracia detrun-
cata, 8. Wood. ' Catalogue of Crag Shells.')

2. Thracia phaseolina, p. 260. From Coralline Crag, Button.

c, a short var., or perhaps the young of pubescens.

3. Cochlodesma complanatum, p. 263. From Red Crag, Walton Naze.

4. Cochlodesma praetenerum, p. 264. From Coralline Crag, Sutton.

5. Thracia ventricosa, p. 262. ,, Ramsholt.

6. Thracia inflata, p. 261. „ Sudbourne.

TAB . TTV7

TAB. XXVII.

Panopea Faujasii, p. 283.

a, b, c, from the Coralline Crag, Sudbourne.
d, e, var. gentilis. From the Red Crag.

TXV22

I.c

e. 3. Sc w er~b :

TAB. XXVIII.

Fig.

1. Mya truncata, p. 277.

a, b, from Coralline Crag, at Ramsholt.

c, var. Uddevallensis. From the Clyde Beds.

d, e, var. pullus. From the Red Crag, at Butley.

2. Mya arenaria, p. 279.

a, I, from the Red Crag, Sutton.

d, e, var. lata. From the Red Crag, Sutton.

c, distorted specimen, from the Mammaliferous Crag, Bramerton.

/, cartilage plate of var. lata.

TAB . .1X17777.

TAB. XXIX.

Fig.

1. Panopea Norvegica, p. 281.

a, b, d, specimens from Chillesford, showing the siphonal side considerably

the shorter of the two.
c, specimen from the Red Crag, Sutton, siphonal side the larger.

2. Glycimeris angusta, p. 291.

a, c, d, from the Coralline Crag, Sudbourne.

b, specimen rather more elongated, and less twisted, from the Red Crag, Sutton.

3. Saxicava rugosa, p. 285.

a, b, var. sulcata. Bridlington.

e, var. rustica. Valves united ; from the Red Crag, Sutton.
/, var. distorta. Coralline Crag, Sutton.
g, var. cylindrica. Red Crag, Butley.

4. Saxicava arctica, p. 287.

a, (Mytilus prsecisus, Mont.} Coralline Crag, Sutton.

b, (Sol en minutus, Mont.} „ „

c, (Agina purpurea, Turt.) „ „

5. Saxicava ? carinata ? p. 289. ,, „

a — d, figures enlarged ; e, natural size.

6. Saxicava ? fragilis, p. 288. Coralline Crag, Sutton.

a — d, figures enlarged ; e, natural size.

7. Sphenia ? Binghami ? p. 276. Figure enlarged. Coralline Crag, Sutton.

TAB. .XXZ.

Z.d,

TAB. XXX.

Fig.

1. Pholadomya hesterna, p. 266. From Coralline Crag, Ramsholt.

c, hinge ; d, portion of shell magnified to show the granulated or shagreen
surface.

2. Corbula complanata, p. 275. From Red Crag, Sutton.

3. Corbula striata, p. 274. From Coralline Crag, Sutton.

4. Corbula rosea ? p. 275. „ „

5. Poromya granulata, p. 268. ,, „

e,f, hinge of both valves magnified, to show the fosse for internal ligament.

6. Nesera cuspidata, p. 273. A fragment only. The outline is imaginary. From

Coralline Crag, Sutton.

7. Nesera jugosa, p. 272. The line denotes the natural size. From Coralline Crag,

Sutton.

8. Pholas cylindrica, p. 295. From Red Crag, Walton Naze.

dt accessory valve, probably of this species.

9. Pholas crispata, p. 296. From Red Crag, Walton Naze.

10. Pholadidea papyracea, p. 298. Figured from two fragments connected by an

outline. From Coralline Crag, Sutton.

1 1 . Gastrochsena dubia, p. 292. From Coralline Crag, Sutton.

c, incrassated portion of the neck of its flask-like envelope.

d, represents the siphonal apertures.

12. Teredo Norvagica, p. 300. From Coralline Crag, Sutton.

c, posterior portion of tube, showing camerated partitions.

d, fragment of a thick tube ; natural size.

"... - I

&.O.

APPENDIX. TAB. XXXI.

Fig.

1. Trophon Norvegicum

2. Trophon Turtoni

3. Trophon propinquum ?

b, apex enlarged.

4. Trophon Fabricii

5. Nassa pygmsea

6. Pyrula acclinis

b, a portion of the matrix,
with impression of the ex-
terior surface.

7. Mitra ebenus, nat. size

8. Mitra plicifera

9. Cancellaria scalaro'ides

10. Rissoa soluta

1 1 . Odostomia unidentata

12. Rissoa Therm alis ? .

b, apex enlarged.

13, a, b. Lacuna vincta .

14, a, b. Jeffreysia? patula

15, a b. Helix ruderata .

312
312
313

313
315

311

310
311
316
318
317
319

316
319
309

Page

318
309
320
308
323
324

16. Odostomia truncatula •

17. a, b. Helix incarnata

18. a, b. Paludina marginata

19. a, b. Helix fruticum .

20. Pecten polymorphus

21. Mactra triangulata .

d, hinge of right valve enlarged.
a, exterior slightly enlarged to
show regularity of ridges.

22. Helix arbustorum . . 306

23. Pholadidea . . 325

24. Aplysia ? asciola . .322

a, b, outside and inside views.

25. Pecten maximus . . 323

var. larvatus.

outside view of flat valve.

26. Lutraria rugosa . . 325

a, inside view of left valve.

b, outside view of right valve.

Note. The lines denote the size of specimens.

3.1

2f.l

Georae

•> 79

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