Chapter I: Introduction

Conchology or Testaceology is a numerous and beautiful branch of Natural History, treating of the testaceous covering of animals; perhaps none but the department of Flora can vie with it in variety, symmetry of form, and rich colouring. It has ever excited admiration, and obtained a prominent situation in the cabinet; and so great are the facilities afforded at the present day to procure specimens and obtain a knowledge of this science, that it has become one of the requisites of a finished education. Shells are found in all parts of the world, both on land and in water; but the most beautiful and valuable species are found between the tropics.

At first they were regarded as pleasing curiosities, and prized only on that account; but the investigations of scientific men have proved that the study of this science is not only interesting, but useful. Much valuable information has already been obtained, and, from the investigations of modern naturalists, much more may be anticipated.

So intimate is the connexion between Conchology and Geology, that a knowledge of the one is indispensable to the study and acquirement of the other. The geologist will draw much advantage from a close study of the testaceous covering of molluscous animals to aid him in determining the identity or the superposition of the different strata of the earth and the extraordinary changes it has undergone; for, as Bergman elegantly says, “fossil shells, coral, and wood are the only three remaining medals of Creation.” He will see in the innumerable quantity of these animals, succeeding each other from generation to generation in the depth of the seas, one of the evident causes of the growth and increase of islands and continents.

But man may find in the knowledge of Mollusca applications still more direct to his well being in society, both as to the advantages and disadvantages to be derived from them: thus a great number of species are proper for food, as oysters, mussels, &c., which are objects of commercial speculations. The Pinna furnishes the Italians with materials for a rich dress, and the pearl, so much prized by the Orientals, by princes, and particularly by the ladies, as a modest and beautiful ornament, is produced by a disease of the animals in certain species of shells. It was this knowledge which made the celebrated Linnæus imagine that it was possible to form an artificial pearlery in the rivers of Sweden. The mother of pearl, so much employed as an ornament in articles of luxury, is only the interior lining of certain univalve or bivalve shells. Painting draws from some of these animals many colours, valuable not so much for their beauty as their usefulness, as Chinese ink and sepia.

The brightest and richest colour known by the ancients, and used by them for the celebrated Tyrian purple dye, is produced by animals at this time known by the name of Purpura.

The Teredo attacks the wood of our vessels, and often does much injury; therefore the knowledge of its manners, habits, and customs must be of great importance in countries infested with them, so as to be able to provide a remedy against them. Snails and slugs are also enemies much to be dreaded in our gardens.

Lamarck, in his last work, the result of the successive and continual labours of his whole life and those of his contemporaries, has rendered a very great service to science, but especially to conchology, by describing, or, at least, characterizing the numerous species of shells in his own splendid cabinet. It may be proper here to remark, that a part of Lamarck’s cabinet is now in the possession of Isaac Lea, Esq., of Philadelphia, to whom we are much indebted for valuable assistance. To Dr. Comstock, and the Rev. W. Turner, of Hartford, Conn., we are much indebted for kind favours; their aid has greatly facilitated our labours.

In this Manual of Conchology we have endeavoured to give a free translation of Lamarck’s system, as simplified by De Blainville; and, in order to facilitate as much as possible the study of this beautiful and interesting science, we have divested it of numerous technicalities, and divided it into four classes: Annelides, Cirrhipedes, Conchifera, and Mollusca.

To each class we have assigned its various families, to each family its genera, and to each genus its living species; thereby making it plain and within the reach of the meanest capacity. A type of almost every genus is given, excepting only those shells which, from their similarity to other genera, may easily be classed.

It was deemed advisable, as this is intended for an easy introduction to the science, to omit many divisions and subdivisions, which would only serve to perplex and render the attainment more difficult.

As the Naiades, or shells of this country, are given in several valuable scientific works lately published, we have only slightly touched them in the place they are intended to occupy.

We cannot expect that the work now presented to the public is free from imperfections; but we ask for their lenity and kind forbearance to excuse whatever defects there may be in our humble attempts to advance the cause of science. Conchology, like other departments of natural history, is progressing; and that which is given to-day is almost always susceptible of being modified to-morrow; should this work be well received, it is our intention to give, as soon as practicable, an enlarged work, containing even the minute microscopic shells and the fossils, with plates containing types of as many species of the genera as can possibly be obtained.

The plates were drawn and coloured with great care and accuracy from the natural shells in our own cabinet, under the superintendence of Mr. James Ackerman, artist.

T. W.

ARRANGEMENT.

CLASS I.
ANNELIDES.

FOUR FAMILIES.

Fam.

1. _Dorsaliæ._ Two genera.
1. Arenicola. Species 1
2. Siliquaria. “ 4

2. _Maldaniæ._ Two genera.
1. Clymene. Species 1
2. Dentalium. “ 12

3. _Amphitritæa._ Four genera.
1. Pectinaria. Species 2
2. Sabellaria. “ 2
3. Terebella. “ 3
4. Amphitrite. “ 6

4. _Serpulacea._ Five genera.
1. Spirorbis. Species 5
2. Serpula. “ 26
3. Vermilia. “ 8
4. Galeolaria. “ 2
5. Magilus. “ 1

CLASS II.
CIRRHIPEDES.

ONE FAMILY.

1. _Cirrhipedes._ Ten genera.
1. Tubicinella. Species 1
2. Coronula. “ 3
3. Balanus. “ 28
4. Acasta. “ 3
5. Creusia. “ 3
6. Pyrgoma. “ 1
7. Anatifera. “ 5
8. Pollicipes. “ 3
9. Cineras. “ 1
10. Otion. “ 2

CLASS III.
CONCHIFERA.

TWENTY FAMILIES.

1. _Tubicola._ Six genera.
1. Aspergillum. Species 4
2. Clavagella. Species 1
3. Fistulana. “ 4
4. Septaria. “ 1
5. Teredina. “ 2
6. Teredo. “ 2

2. _Pholadaria._ Two genera.
1. Pholas. Species 9
2. Gastrochæna. “ 3

3. _Solenides._ Four genera.
1. Solen. Species 18
2. Panopæa. “ 1
3. Solecurtus. “ 3
4. Glycimeris. “ 1

4. _Myaria._ Two genera.
1. Mya. Species 4
2. Anatina. “ 10

5. _Mactracea._ Seven genera.
1. Lutraria. Species 11
2. Mactra. “ 33
3. Crassatella. “ 11
4. Erycina. “ 1
5. Ungulina. “ 2
6. Solenimya. “ 2
7. Amphidesma. “ 16

6. _Corbulacea._ Two genera.
1. Corbula. Species 9
2. Pandora. “ 2

7. _Lithophagi._ Three genera.
1. Saxicava. Species 5
2. Petricola. “ 13
3. Venerirupis. “ 7

8. _Nymphacea._ Ten genera.
1. Sanguinolaria. Species 4
2. Psammobia. “ 18
3. Psammotæa. “ 7
4. Tellina. “ 54
5. Tellinides. “ 1
6. Corbis. “ 1
7. Lucina. “ 20
8. Donax. “ 27
9. Capsa. “ 2
10. Crassina. “ 1

9. _Conchacea._ Seven genera.
1. Cyclas. Species 11
2. Cyrena. “ 10
3. Galathea. Species 1
4. Cyprina. “ 2
5. Cytherea. “ 78
6. Venus. “ 88
7. Venericardia. “ 1

10. _Cardiacea._ Five genera.
1. Cardium. Species 48
2. Cardita. “ 21
3. Cypricardia. “ 4
4. Hiatella. “ 2
5. Isocardia. “ 3

11. _Arcacea._ Four genera.
1. Cucullæa. Species 1
2. Arca. “ 37
3. Pectunculus. “ 19
4. Nucula. “ 6

12. _Trigonacea._ Two genera.
1. Trigonia. Species 1
2. Castalia. “ 1

13. _Naiades._ Four genera.
1. Unio. Species 48
2. Hyria. “ 2
3. Anodonta. “ 15
4. Iridina. “ 1

14. _Chamacea._ Three genera.
1. Diceras. Species 1
2. Chama. “ 17
3. Etheria. “ 4

15. _Tridacnites._ Two genera.
1. Tridacna. Species 6
2. Hippopus. “ 1

16. _Mytilacea._ Three genera.
1. Mytilus. Species 35
2. Modiola. “ 23
3. Pinna. “ 15

17. _Malleacea._ Five genera.
1. Crenatula. Species 7
2. Perna. “ 10
3. Malleus. “ 6
4. Avicula. “ 13
5. Meleagrina. “ 2

18. _Pectinides._ Seven genera.
1. Pedum. Species 1
2. Lima. “ 6
3. Pecten. “ 59
4. Plagiostoma. “ 10
5. Plicatula. “ 5
6. Spondylus. “ 21
7. Podopsis. “ 2

19. _Ostracea._ Six genera.
1. Gryphæa. Species 1
2. Ostrea. “ 48
3. Vulsella. Species 6
4. Placuna. “ 3
5. Anomia. “ 9
6. Crania. “ 1

20. _Brachiopoda._ Three genera.
1. Orbicula. Species 1
2. Terebratula. “ 12
3. Lingula. “ 1

CLASS IV.
MOLLUSCA.

TWENTY-TWO FAMILIES.

1. _Pteropoda._ Six genera.
1. Hyalæa. Species 2
2. Clio. “ 2
3. Cleodora. “ 2
4. Limacina. “ 1
5. Cymbulia. “ 1
6. Pneumodermon. “ 1

2. _Phyllidiacea._ Four genera.
1. Phyllidia. Species 3
2. Chitonellus. “ 2
3. Chiton. “ 6
4. Patella. “ 45

3. _Calyptracea._ Seven genera.
1. Parmophora. Species 3
2. Emarginula. “ 4
3. Fissurella. “ 19
4. Pileopsis. “ 4
5. Calyptræa. “ 4
6. Crepidula. “ 6
7. Ancylus. “ 2

4. _Bullacea._ Three genera.
1. Acera. Species 1
2. Bullæa. “ 1
3. Bulla. “ 11

5. _Aplysiacea._ Two genera.
1. Aplysia. Species 3
2. Dolabella. “ 2

6. _Limacinea._ Five genera.
1. Onchidium. Species 2
2. Parmacella. “ 1
3. Limax. “ 4
4. Testacella. “ 1
5. Vitrina. “ 1

7. _Colimacea._ Eleven genera.
1. Helix. Species 107
2. Carocolla. “ 15
3. Anostoma. “ 2
4. Helicina. “ 4
5. Pupa. “ 27
6. Clausilia. Species 12
7. Bulimus. “ 34
8. Achatina. “ 20
9. Succinea. “ 3
10. Auricula. “ 14
11. Cyclostoma. “ 28

8. _Lymnæcea._ Three genera.
1. Planorbis. Species 12
2. Physa. “ 4
3. Lymnæa. “ 11

9. _Melanides._ Three genera.
1. Melania. Species 16
2. Melanopsis. “ 3
3. Pirena. “ 4

10. _Peristomides._ Three gen.
1. Valvata. Species 1
2. Paludina. “ 7
3. Ampullaria. “ 11

11. _Neritacea._ Five genera.
1. Neritina. Species 21
2. Navicella. “ 3
3. Nerita. “ 17
4. Natica. “ 31
5. Janthina. “ 2

12. _Macrostomides._ Four gen.
1. Sigaretus. Species 4
2. Stomatella. “ 5
3. Stomatia. “ 2
4. Haliotis. “ 15

13. _Plicacea._ Two genera.
1. Tornatella. Species 6
2. Pyramidella. “ 5

14. _Scalarides._ Three genera.
1. Vermetus. Species 1
2. Scalaria. “ 7
3. Delphinula. “ 3

15. _Turbinacea._ Seven genera.
1. Solarium. Species 7
2. Trochus. “ 69
3. Monodonta. “ 23
4. Turbo. “ 34
5. Planaxis. “ 2
6. Phasianella. “ 10
7. Turritella. “ 13

16. _Canalifera._ Eleven genera.
1. Cerithium. Species 36
2. Pleurotoma. Species 23
3. Turbinella. “ 23
4. Cancellaria. “ 12
5. Fasciolaria. “ 8
6. Fusus. “ 37
7. Pyrula. “ 28
8. Struthiolaria. “ 2
9. Ranella. “ 14
10. Murex. “ 66
11. Triton. “ 31

17. _Alata._ Three genera.
1. Rostellaria. Species 3
2. Pteroceras. “ 7
3. Strombus. “ 32

18. _Purpurifera._ Eleven gen.
1. Cassidaria. Species 5
2. Cassis. “ 25
3. Ricinula. “ 9
4. Purpura. “ 50
5. Monoceros. “ 5
6. Concholepas. “ 1
7. Harpa. “ 8
8. Dolium. “ 7
9. Buccinum. “ 58
10. Eburna. “ 5
11. Terebra. “ 24

19. _Columellaria._ Five genera.
1. Columbella. Species 18
2. Mitra. “ 80
3. Voluta. “ 44
4. Marginella. “ 24
5. Volvaria. “ 5

20. _Convoluta._ Six genera.
1. Ovula. Species 12
2. Cypræa. “ 68
3. Terebellum. “ 1
4. Ancillaria. “ 4
5. Oliva. “ 62
6. Conus. “ 181

21. _Nautilacea._ Two genera.
1. Spirula. Species 1
2. Nautilus. “ 2

22. _Heteropoda._ Two genera.
1. Argonauta. Species 3
2. Carinaria. “ 3

CONCHOLOGY.

CLASS I.
ANNELIDES.
CONTAINS FOUR FAMILIES.

FAMILY I.
DORSALIÆ. Two genera.

1. Arenicola. Has no shell. One species.

A. piscatorium.

2. Siliquaria. Four species.

Shell very thin, conical, tubular, involuted in a loose and irregular spiral manner; aperture circular, edges sharp, interrupted in the middle by a notch prolonged like a slit through nearly all its length, stopped abruptly at some distance from the summit.

Siliquaria anguina.
S. muricata.
S. lævigata.
S. lactea.

_S. anguina._ The Snake Siliquaria. Pl. 33, fig. 4.

Shell tapering, undulating, spiral at the extremity.

_S. muricata._ The Prickly Siliquaria.

Species armed with short spines or prickles; aperture sometimes margined; usually of a rosy or pink colour.

FAMILY II.
MALDANIÆ. Two genera.

1. Clymene. One species.

_C. amphistoma._ The double-mouthed Clymene.

Tube thin and slender, open at both ends; incrusted externally with sand and fragments of shells.

2. Dentalium. The Tooth Shell. Twelve species.

This genus took its name from its resemblance to an elephant’s tooth. It is an attenuated conical tube, slightly bent, and open at both ends.

Shell tubular, regular, symmetrical, lightly curved longitudinally, conic, attenuated insensibly posteriorly, and open at each extremity by a round orifice.

Dentalium elephantinum.
D. aprinum.
D. fasciatum.
D. entale.
D. Tarentinum.
D. corneum.
D. octoganum.
D. novemcostatum.
D. dentale.
D. nigrum.
D. politum.
D. eburneum.

_D. elephantinum._ The Elephant’s Tooth Shell.

Species in which the tube is striated or ribbed longitudinally; the ribs are generally ten in number; green colour.

_D. entale._ The common Dentalium. Pl. 33, fig. 1.

Species very minutely striated; white or yellowish colour.

_D. pellucidum._ The pellucid Dentalium.

Species narrow and thin; pale topaz colour.

_D. politum._ The ring-striated Tooth Shell.

Species finely pointed, solid, striated annularly; generally rosy or pink colour.

_D. rectum._ The straight Tooth Shell.

Species entirely straight, with longitudinal ribs.

_D. eburneum._ The Ivory Tooth Shell.

Species of a reddish or pale yellow colour, with the tip frequently tinged with orange or pink.

FAMILY III.
AMPHITRITÆA. Four genera.

The similarity of the four genera comprising this family is such, that it was thought sufficient to give only one type (the sabellaria crassissima), as the student may easily recognise the others.

1. Pectinaria. Two species.

A membranous or papyraceous tube, in the form of a reversed cone; unfixed; exterior covered with sandy adhesions.

Pectinaria Belgica.
Pectinaria capensis.

_P. Belgica._ The Belgic Pectinaria.

Tube inversely conic, membranous, and covered with sand.

2. Sabellaria. Two species.

The covering of the animal belonging to this genus is composed of fragments and particles of marine substances, adhering to a tubular membrane; some are detached and others are fixed. The tubes are cellular at the base, and the orifice expanded.

Sabellaria alveolata.
Sabellaria crassissima.

_S. alveolata._ The Honeycomb Sabellaria.

Consists of numerous parallel tubes, nearly straight, communicating by an aperture, forming when in mass the appearance of a honeycomb; it adheres to rocks in clusters.

_S. crassissima._ The very thick or strong Sabellaria. Pl. 33, fig. 2.

Species incrusted with small stones; sometimes found thick and of a large size.

3. Terebella. Three species.

Tube elongated, cylindrical, membranous, attenuated and pointed at the base, with adhesions of sand.

Terebella conchilega.
T. cristata.
T. ventricosa.

_T. conchilega._ The shelly Terebella.

Tube covered with numerous fragments of broken shells.

4. Amphitrite. Six species.

Nearly the same as the Terebella, but of a tougher membranous texture, and generally without adhesions.

Amphitrite ventilabrum.
A. penicillus.
A. magnifica.
A. vesiculosa.
A. volutacornis.
A. infundibulum.

_A. ventilabrum._ The Fan Amphitrite.

Tube subulate, smooth, of a yellowish colour.

FAMILY IV.
SERPULACEA. Five genera.

1. Spirorbis. Five species.

Tube testaceous, spirally twisted on a horizontal plane, with terminal aperture rounded or angular, attached by the lower part to marine substances.

Spirorbis Nautiloides.
S. spirillum.
S. carinata.
S. lamellosa.
S. tricostalis.

_S. Nautiloides._ The Nautilus-shaped Spirorbis.

White, transversely wrinkled and minute.

2. Serpula. The Worm Shell. Twenty-six species.

The name of this genus is derived from the Latin word serpo, to creep, on account of the vermiform character of some of its species.

They are invariably tubular, sometimes solitary, but more frequently in clusters spirally entwined, adhering to marine substances. In colour they are brown, purple, yellow, tawny, pink or white, and sometimes tinged with green.

Tube solid, calcareous, irregularly twisted, fixed to other substances.

Serpula vermicularis.
S. fascicularis.
S. intestinum.
S. contortuplicata.
S. plicaria.
S. glomerata.
S. decussata.
S. protensa.
S. infundibulum.
S. annulata.
S. cereolus.
S. filograna.
S. vermicella.
S. filaria.
S. pellucida.
S. intorta.
S. cristata.
S. spirulæa.
S. quadrangularis.
S. minima.
S. echinata.
S. sulcata.
S. costalis.
S. dentifera.
S. sipho.
S. arenaria.

_S. vermicularis._ The wormlike Serpula.

White, cylindrical, tapering, rugged, variously curved and twisted.

3. Vermilia. Eight species.

Tube testaceous, cylindrical, more or less twisted, gradually attenuated posteriorly; opening round, the margin with one, two, or three teeth; shell adhering by the side to other substances; provided with a convex operculum.

Vermilia rostrata.
V. triquetra.
V. bicarinata.
V. eruca.
V. subcrenata.
V. plicifera.
V. scabra.
V. tæniata.

_V. triquetra._ The three-sided Vermilia.

White or reddish, rugged, twisted and triangular, carinated along the back.

4. Galeolaria. Two species.

Distinguished from the Vermilia by a very peculiar operculum. Found in groups, adhering together at the base.

Tube open at the summit; aperture orbicular, terminated on the side by a spatulous tongue; operculum orbicular, squamose, consisting of from five to nine testaceous parts or valves, all attached to one side of the operculum; the middle one dentated at the truncated part of its summit, the others a little toothed on their internal edge.

Galeolaria cæspitosa.
Galeolaria elongata.

_G. elongata._ The elongated Galeolaria.

Whitish, existing in congregated masses; operculum as above.

5. Magilus. One species.

A very singular shell, greatly resembling a petrified body, composed of a testaceous white substance like alabaster. The base is bent into a short spire, with about four contiguous whorls; the last prolonged and nearly straight. The animal, as it increases in size, abandons the spiral part by increasing the tubular part, filling up the part it quits with calcareous matter, which proves that it advances gradually.

Tube partially involuted, convex in its upper exterior part, the lower side flattened, platted, carinated, and somewhat angular; the spire short, helix-formed, and prolonged through the rest of its extent in nearly a right line; aperture entire, oval, with a sort of sinus or gutter in the middle line, producing the keel of the shell.

_M. antiquus._ The antiquated Magilus.

Answers to the above description; colour pale yellowish brown, transversely wrinkled.

CLASS II.
CIRRHIPEDES.
HAS BUT ONE FAMILY.

CIRRHIPEDES. Ten genera.

Lamarck divided the Lepas of Linnæus into the various genera which compose this family. The term lepas is derived from the Greek word λεπας, a rock, alluding to its custom of adhering to rocks and marine bodies. The shell often varies in shape, covering, and colouring; it is generally conical, but sometimes hemispherical; some of the valves are placed perpendicularly on a base, broad at the lower margin and tapering towards the summit, which is closed by small horizontal valves forming the operculum. The number of valves is indefinite, from four to twenty-four; but all are diversified with striæ, ridges, and grooves. The striæ are mostly transverse, and the ridges longitudinal.

The valves which compose the operculum or lid vary in shape, and are in number two, three, four, or more; they are generally attached to a ligament.

They are seldom, if ever, found detached, but adhere in groups to rocks, shells, anchors, marine animals, &c. Those that fix themselves to ships are generally called barnacles; they rapidly increase in size and number, do great damage, and greatly impede the progress of the vessel. Some of this family are affixed at the base of the shell to other substances, and are therefore called sessile; others are attached to a fleshy peduncle or stem, and are said to be pedunculated. The peduncle or stem, proceeding from the base of the shell to the substance which sustains it, is sometimes smooth, fine in texture, and tinged with bright red or orange; sometimes it is of a dark or brownish colour, with a texture much coarser and granulated.

1. Tubicinella. One species.

Has the form of a cylindrical tube, slightly curved, and open at both ends; one extremity closed by four trapezoidal valves attached to the inner margin, the other end closed by a membrane. The annular ribs which separate the compartments show its progressive growth. Found buried so deeply in the fat of marine animals, particularly whales, that only the operculum and the upper part of the tube are visible. Shell rather elevated, sub-cylindrical, the partitions rather small and indented; the spaces or compartments almost quadrilateral; the inferior much more narrow than the others; the apertures equal and circular; the membrane which closes the superior forming a tube between the four almost equal valves of the operculum.

_T. balænarum._ The Whale Tubicinella.

Tubular, with transverse ribs, and a ring-shaped margin; operculum bottle-shaped.

2. Coronula. Three species.

Found imbedded in the skin of whales and other marine animals, though not generally at so great a depth as the Tubicinella. Shell in form a little variable and without trace of support; the coronary part formed of six pieces, as in those properly called _Balanus_, but more regularly disposed in a manner to imitate a kind of crown or tube; spaces alternately hollowed and saliant; operculum not articulated, composed of two pairs of small, level, delicate valves, joined at the aperture of the tube by a considerable membranous part, leaving a passage for the cirrhous appendages of the animal.

Coronula testudinaria.
C. balænarum.
C. diadema.
C. quinquevalvis.

_C. testudinaria._ The Tortoise Coronula.

Very depressed, circular, as if radiated by the disposition of marked spaces, striated transversely, forming six rays diverging from the centre to the circumference; aperture oval and hexagonal.

_C. balænarum._ The Whale Coronula.

A little more elevated; the spaces prominent, equal between them, much larger than the excavated; the aperture subcircular; the operculum of four valves, almost equal, occupying but a small space of the membranous part which forms between them a sort of tube.

_C. diadema._ The Crown Coronula.

More elevated, sub-hexagonal; the spaces almost equal, the hollow parts larger than the saliant; the superior aperture very large and hexagonal; the inferior much smaller, of the same form, and communicating in a round excavation by radiated plates; the operculum bivalve.

_C. quinquevalvis._ The five-valved Coronula. Pl. 4, fig. 3.

Species irregular, having only five valves, of a purple hue.

3. Balanus. The Acorn Shell. Twenty-eight species.

So named from its resemblance to an acorn. Shell conical; the coronary part formed of six very distinct valves, one dorsal, one ventral, and two pairs of laterals, with or without a calcareous support; operculum of four articulated pieces, forming a sort of pyramid in the superior aperture of the tube.

Balanus angulosus.
B. sulcatus.
B. tintinnabulum.
B. nigrescens.
B. cylindraceus.
B. calycularis.
B. roseus.
B. palmatus.
B. stalactiferus.
B. plicatus.
B. duploconus.
B. patellaris.
B. semiplicatus.
B. galeatus.
B. ovularis.
B. miser.
B. amphimorphus.
B. perforatus.
B. lævis.
B. spinosus.
B. radiatus.
B. subimbricatus.
B. rugosus.
B. placianus.
B. crispatus.
B. punctatus.
B. fistulosus.
B. latus.

_B. sulcatus._ The furrowed Balanus.

White; valves nearly smooth; operculum strongly ridged transversely, with longitudinal, nearly obsolete striæ.

_B. tintinnabulum._ The little Bell Balanus. Pl. 4, fig. 1.

Shell conical; valves strongly and irregularly ribbed; interstices delicately striated transversely; colour purple.

_B. spinosus._ The spiny Balanus.

Either has no support or a membranous one; armed with spines exteriorly.

4. Acasta. Three species.

Found in sponge, from which, when detached, it cannot stand erect on account of the convexity of the base.

Shell oval, sub-conic, shaped like a Patella, with six lateral unequal valves slightly connected; operculum with four valves.

Acasta Montagui.
A. glans.
A. sulcata.

_A. Montagui._ Montague’s Acasta.

Valves erect, triangular, acute, with muricated ascending spines.

5. Creusia. Three species.

The shells of this genus are generally small; found in the seas of hot countries attached to madrepore and other marine substances.

Shell sessile, thin, Patella-shaped; aperture oval, rather large, closed by a large sub-pyramidal bivalve operculum; a considerable calcareous support, funnel-shaped, penetrating the bodies to which the animal is attached.

Creusia stromia.
C. spinulosa.
C. verruca.

_C. spinulosa._ The spiny Creusia.

Very depressed, striated, sometimes with marks of division into four pieces; operculum bivalve.

_C. verruca._ The warted Creusia. Pl. 4, fig. 2.

Whitish, slightly depressed, with interwoven obliquely striated valves; the margin at the base irregularly serrated.

6. Pyrgoma. One species.

The principal difference between this genus and the Creusia is in form.

Shell sessile, rather globular appearance on account of the valves being more closely united, ventricose, convex above, apex perforated, aperture small and elliptical; operculum bivalve.

_P. cancellata._ The cancellated Pyrgoma.

Thick, conical, Patella-shaped, ribs radiating from the summit to the base; aperture very small, closed by an operculum of which the two pieces are long and narrow on each side; pale violet colour.

7. Anatifera. Five species.

The shells of this genus and the three following genera are affixed to marine bodies by a tough membranous peduncle, varying in length.

Shell flat, with five valves imbricating more or less on the edges, united by a thin membrane.

Anatifera lævis.
A. villosa.
A. dentata.
A. striata.
A. vitrea.

_A. lævis._ The smooth Anatifera. Pl. 4, fig. 5.

Five smooth valves; the dorsal one rounded at the sides, and slightly carinated; peduncle long, naked, of a scarlet colour.

8. Pollicipes. Three species.

Easily distinguished by the numerous small valves situated at the base.

Pollicipes cornucopia.
P. mitella.
P. scalpellum.

_P. cornucopia._ The Cornucopia Pollicipes. Pl. 4, fig. 6.

Peduncle covered with imbricated scales, the lower ones rounded and turned upward.

_P. mitella._ The Mitre Pollicipes. Pl. 4, fig. 4.

Valves indefinite in number, from six to twenty-four; almost equal, and open like tulips; colour bluish, purplish, brownish, or reddish cast.

9. Cineras. One species.

Shell composed of five testaceous oblong valves, separate, not covering the whole of the body; two at the sides of the aperture, the others on the back; peduncle of a greenish colour, with six longitudinal stripes.

_C. vittata._ The filleted Cineras.

Answers to the above description.

10. Otion. Two species.

Shell composed of two testaceous valves, enclosed in a mantle or membranous bag, which is prolonged and terminated in two fleshy tubes formed like ears, one of the two having a lateral opening.

Otion Cuvierii.
Otion Blainvillii.

_O. Cuvierii._ Cuvier’s Otion.

Answers to the above.

_O. Blainvilli._ Blainville’s Otion.

Ash coloured; the body and ears spotted with black.

CLASS III.
CONCHIFERA.

CONTAINS TWENTY FAMILIES.

FAMILY I.
TUBICOLA. Six genera.

1. Aspergillum. The Watering-pot Shell. Four species.

A well-known but rare shell; the larger end closed by a convex disk, with numerous small perforations, and encircled by a dilated margin of elegant papyraceous tubes, resembling a beautifully plaited ruff; the smaller end open. Found in sandy places at low water.

Shell oval, slightly elongated, striated longitudinally, sub-equilateral; adhering, more or less confounded with the coats of a rather thick calcareous tube, conic, club-shaped, open at its attenuated extremity, and terminated at the other by a convex disk pierced by a great number of sub-tubular, rounded holes, and by a fissure in the centre.

Aspergillum Javanum.
A. vaginiferum.
A. Novæ Zeylandiæ.
A. agglutinans.

_A. Javanum._ The Java Aspergillum. Pl. 33, fig. 3.

Species smooth, in which the circumference of the disk is bordered with a waved testaceous fringe.

_A. Novæ Zeylandiæ._ The New-Zealand Aspergillum.

Species in which the circumference of the disk is without a fringe.

2. Clavagella. One species.

An irregular tube, with branches or projecting tubes at the closed end; within it is one free or moveable valve, united by a ligament to another, which is blended with the tube; this distinguishes it from the Aspergillum. Found in sand and coral.

Shell oval, very slightly elongated, striated longitudinally, slightly irregular; equivalve, inequilateral; hinge a little variable; ligament exterior; two well-marked distant muscular impressions; a calcareous sub-cylindrical tube, more or less completely surrounding the shell, and terminated before by a single orifice.

_C. aperta._ The open Clavagella.

Tube erect, adhering; aperture waved, entire, expanding, funnel-shaped, leaving the two valves open or uncovered in all their anterior part; with an ovate face valve.

3. Fistulana. Four species.

Lamarck asserts that the tube and shell of this genus are quite distinct. It so greatly resembles the Teredo that it is with difficulty distinguished. It is found in sand, wood, stone, and sometimes shells.

Shell annular or very short, not sharp nor angular anteriorly, but in other respects much like that of the Teredo.

Tube generally shorter, thicker, more solid, more club-shaped than that of the Teredo, always closed at its anterior extremity in such a manner as to contain and entirely hide the shell; the posterior extremity open, and divided interiorly into two syphons by a partition.

Fistulana clava.
F. corniformis.
F. gregata.
F. lagenula.

_F. corniformis._ The horn-shaped Fistulana.

Answers to the above description.

_F. gregata._ The gregarious Fistulana.

Sheath or tube doubly club-shaped, congregating; shell angularly arcuated, with double angulated serrated wings.

_F. Clava._ The Club Fistulana. Pl. 33, fig. 5.

Species with one end clavate, the other incurved, narrower, obtuse, and perforated in the middle; shell generally flexuous, of a brownish colour; exterior rough, interior smooth.

4. Septaria. One species.

The tube of this genus unquestionably contains a bivalve shell; but, as no perfect specimen has yet been found, nothing decisive is known respecting it.

Tube calcareous, thick, conically elongated, more or less flexuous, as if composed of pieces placed on the ends of each other, or as if articulated, with a ring or projection more or less marked at the place of the joints, but without traces of partitions; terminated on one side by an inflation, oftentimes with some interior partitions, and on the other by two tubes, distinct and sub-articulated.

_S. arenaria._ The Sand Septaria.

The type of this genus.

5. Teredina. Two fossil species.

A genus without a living species, given here to preserve the family entire, having a shell thick, oval, short, very gaping posteriorly, equivalve, inequilateral; summits well marked; a spoonlike cavity in each valve.

Tube or sheath testaceous, cylindrical; anterior end open; posterior end closed, but exhibiting the two valves of the shell.

6. Teredo. The Ship Worm. Three species.

This genus derived its name from the faculty it possesses of boring wood. The T. navalis can penetrate the stoutest oaken planks of a ship’s sides by means of two valves affixed to the head of the animal. The effects produced would be much more destructive but from the fact of their generally perforating the wood in the direction of the grain. Sir E. Home wrote a very scientific and interesting description of a species not mentioned by Lamarck, called the T. gigantea, found imbedded in indurated mud in the Island of Sumatra. It is the largest species known, some having been seen four or five feet long.

Shell thick, solid, very short or annular, open at both extremities; equivalve, equilateral, angular and sharp anteriorly, only slightly touching by the opposite edges; hinge obsolete; a considerable internal spoonlike cavity; one slightly sensible muscular impression.

Tube more or less distinct from the substance in which the animal lives, cylindrical, straight or flexuous, closed with age at the oral extremity so as to envelop the animal and its shell; always open at the other end, and divided interiorly into two syphons by a middle partition.

Teredo navalis.
T. palmulata.
T. gigantea.

_T. navalis._ The common Ship Worm.

Species very thin, cylindrical, and smooth; slightly twisted, white, finely striated longitudinally.

FAMILY II.
PHOLADARIA. Two genera.

1. Pholas. The Stone Piercer. Nine species.

This genus is without any tubular sheath; it derives its name from the Greek word φωλεω, to hide, alluding to the custom of its inhabitant in forming cells in rocks, wood, &c.

In form the Pholas is generally oblong, having two large valves opposite to each other, with a number of smaller ones attached to the back as a substitute for a hinge. The two large valves never shut close; they are open at one end, and sometimes at both.

The exterior of the shell is usually of a pure or dusky white, but sometimes of a brownish cast. In some species the shell is adorned with beautiful delicate reticulations, like the finest lace; in others the texture is coarser, like small basket-work. They are found in the American, Indian, and European seas, each shell in a separate habitation formed in limestone, sandstone, wood, coral, &c.; often discovered completely imbedded in the oak planks of ships traversing those seas; as they advance in growth they enlarge the space within, and leave the aperture by which they entered of its primitive size.

Shell thin, sub-transparent, finely striated, elongated oval, bivalve, equivalve, inequilateral; the valves only touching in the middle of their edges; the summits but little marked, and concealed by a callosity produced by the expansion of the dorsal lobes of the mantle; near the hinge are often developed one or more accessory calcareous pieces; an incurved tooth interior beneath the hinge.

Pholas dactylus.
P. orientalis.
P. candida.
P. dactyloides.
P. silicula.
P. costata.
P. crispata.
P. callosa.
P. clavata.

_P. dactylus._ The prickly Pholas. Pl. 3, fig. 3.

Answers to the general description, but is beset with small calcareous spiny nodules on the ribs, which run widening and enlarging from the summit to the margin; colour white or very light brown.

_P. striata._ The striated Pholas. Pl. 3, fig. 5.

Oval, the dorsal callosity leaving the summit free, and extending towards the anterior and inferior extremity in such a manner that each valve seems to be formed of three parts, because of an oblique furrow from the summit to the margin; a tooth running down in the inside from the summit; one pair of accessory pieces at the posterior extremity of the shell.

_P. candida._ The white Pholas. Pl. 3, fig. 2.

Elongated, wedge-shaped; muscular impression almost medial; a kind of oblique tooth parting from the summit; no accessory pieces.

_P. costata._ The ribbed Pholas. Pl. 3, fig. 4.

Elongated, wedge-shaped, covered with regular elevated jagged or scalloped ribs, elegantly disposed; three dorsal accessory pieces; muscular impression almost medial.

_P. crispata._ The curled Pholas.

Somewhat oval, truncated behind, and as if divided into two parts by an oblique furrow from the summit to the base; anterior part reticulated, the other parts plain; muscular impression marginal.

_P. clavata._ The clubbed Pholas.

Short, wedge-form, little gaping, with many accessory pieces.

2. Gastrochæna. Three species.

Always without accessory pieces, and, therefore, easily distinguished from the Pholas.

Shell equivalve, somewhat wedge-shaped, with a very large, oval, oblique, anterior opening between the valves; the posterior extremity nearly close; hinge linear, marginal, without teeth; two distant muscular impressions; sometimes with a kind of tube or calcareous general envelope.

Gastrochæna cuneiformis.
G. mytiloides.
G. modiolina.

_G. modiolina._ The Modioliform Gastrochæna.

Oval, thin, brittle, gaping at the side; light reddish brown, with a bluish white interior.

_G. cuneiformis._ The wedgelike Gastrochæna. Pl. 3, fig. 1.

Species with a smooth shell, and without distinct tube. (Represented as imbedded in wood.)

FAMILY III.
SOLENIDES. Four genera.

1. Solen. Eighteen species.

There are many species belonging to this genus differing considerably in form and appearance. Its name is derived from a Greek word signifying a pipe or tube. It is a bivalve whose breadth sometimes exceeds its length; some species have a resemblance to the sheath of a razor or a knife handle; others are curved like the scabbard of a cimeter.

The Solen is found in the sand of the seashore, which it sometimes penetrates to the depth of one or two feet. Most of the species are covered with an epidermis, which renders their colours more or less obscure. In general they present but little beauty, though some are of a bright pink colour, and some are beautifully and delicately radiated with purple and white.

The principal characteristic of this genus is the hinge, which generally has one subulate tooth, though sometimes two or three.

Shell equivalve, extremely inequilateral, transversely elongated, open at both ends; the apices very small, and entirely at the commencement of the dorsal line; one or two teeth in the hinge; ligament external; two distant muscular impressions; the anterior one very long and narrow, the posterior one sub-angular.

Solen vagina
S. corneus.
S. ensis.
S. pygmæus.
S. ambiguus.
S. Dombeii.
S. Javanicus.
S. Caribæus.
S. antiquatus.
S. vaginoides.
S. siliqua.
S. cultellus.
S. planus.
S. minutus.
S. constrictus.
S. coarctatus.
S. rostratus.
S. violaceus.

_S. vagina._ The Razor Sheath. Pl. 31, fig. 5.

Valves equal, truncated at both ends; straight or slightly curved; summit terminal.

_S. cultellus._ The kidney-shaped Solen.

Species a little curved lengthwise; summit not terminal.

_S. rostratus._ The violet-beaked Solen.

Species with longer and narrower valves, flatter at the extremities; callosity at the hinge very visible; cardinal teeth or hinge nearer the middle than the anterior side.

_S. ensis._ The Sabre Solen.

Species linear, sabre-shaped; a single compressed tooth in each valve; olive brown at the base, and of a purple hue near the apex.

_S. siliqua._ The podlike Solen.

Species linear, straight; two teeth in one valve and one in the other; covered with a glossy brown epidermis; striated transversely.

_S. antiquatus._ The Antiquated Solen.

Species thin, white, and almost transparent; striated concentrically; ends rounded; hinge near the centre; a tooth in one valve locking into two in the other; the teeth erect and projecting beyond the margin; covered with a dark-coloured epidermis.

2. Panopæa. One species.

Distinguished from the Mya by the prominency of the apex and the situation of the ligament.

Shell regular, elongated oval, gaping at the two extremities, equivalve, inequilateral; summit but little marked, and anterodorsal; hinge very complete, similar, formed by a conical primary tooth before a short, compressed, ascending callosity; ligament exterior, attached to the callosity; two muscular impressions.

_P. Aldrovandi._ The Panopæa of Aldrovandus. Pl. 5, fig. 2.

The type of this genus, transversely elongated, undulated; concentrically wrinkled; of dark green colour, almost black.

3. Solecurtus. Three species.

Shell oval, elongated, equivalve, sub-equilateral, edges almost straight and parallel; the extremities equally rounded, and as if truncated; summits but little marked; hinge toothless, or formed by some rudimentary primary teeth; ligament projecting, affixed to the thick nymphal callosities; two distant, rounded muscular impressions.

Solecurtus radiatus.
S. strigilatus.
S. legumen.

_S. radiatus._ The radiated Solecurtus.

Species flat, small, with an interior ridge running down obliquely from the summit to the abdominal margin.

_S. strigilatus._ The strigilated Solecurtus.

Species more cylindrical, without interior ridge.

_S. legumen._ The Pease-pod Solecurtus. Pl. 31, fig. 6.

Species still more elongated and sub-cylindrical.

4. Glycimeris. Two species.

Distinguished from the Solen by being without teeth at the hinge.

Shell covered with epidermis, slightly irregular, elongated, gaping at the two extremities, equivalve, inequilateral; the summits but little marked; hinge toothless; a longitudinal callosity; ligament exterior, affixed to very projecting callosities on the shortest side of the shell; two distinct muscular impressions.

Glycimeris margaritacea.
Glycimeris siliqua.

_G. siliqua._ The podlike Glycimeris.

Transversely oblong, covered with a black epidermis; umbones decorticated; internal disc of the valves white, thick, and callous.

FAMILY IV.
MYARIA. Two genera.

1. Mya. The Trough Shell, or Gaper. Four species.

This term is derived from the Greek word μυω, to close, alluding to the animal’s custom of closing the valves. The principal characteristic of the Mya is its gaping at one end; it is likewise distinguished by having a large spoonlike tooth proceeding from beneath the beak. Its form is greatly varied, but generally covered with a greenish epidermis, which may be removed; and the shell, when polished, will display beautiful prismatic colours. The Mya is found on the seashore or on the banks of large rivers, partially concealed in the sand and mud.

Shell transverse, inequilateral, surrounded with a thick epidermis; rather solid; edges thin and sharp; summits but little marked; hinge dissimilar; one or two large, compressed, spoon-shaped teeth rising perpendicularly from the plane of the left valve, and fitting into the entrance of a primary cavity in the right valve; ligament interior, attaching the tooth and cavity; two distant muscular impressions; the anterior long and narrow, the posterior rounded; the mantle impression narrow, with a large sinus or hollow.

Mya truncata.
M. arenaria.
M. erodona.
M. solenimyalis.

_M. arenaria._ The Sand Mya. Pl. 5, fig. 1.

Regular species.

_M. erodona._ The Erodona Mya.

Irregular species, in which the cavity of the right valve is bordered by strong projections.

_M. truncata._ The truncated Mya. Pl. 5, fig. 3.

Sub-oval, truncated; small end gaping; large end rounded; covered with a dark yellowish epidermis; inside white; wrinkled transversely.

2. Anatina. The Duck’s Bill. Ten species.

Shell elongated oval, very thin, fragile, semipellucid; much inflated at one end like a duck’s bill, whence it derives its common name; equivalve, very inequilateral; hinge toothless; the anterior side rounded and much longer than the posterior; ligament interior affixed to a bony spoonlike process in each valve, and sustained by a lateral plate running obliquely into the interior of the shell.

Anatina laterna.
A. truncata.
A. subrostrata.
A. longirostris.
A. globulosa.
A. trapezoides.
A. rugosa.
A. imperfecta.
A. myalis.
A. rupicola.

_A. subrostrata._ The beaklike Anatina.

Species equivalve and regular.

_A. myalis._ The Mya-like Anatina.

Species inequivalve.

_A. trapezoides._ The trapezium-shaped Anatina. Pl. 12, fig. 5.

Species with a moveable tooth or calcareous piece upon the right valve, lodged in the angle formed by the spoonlike process.

FAMILY V.
MACTRACEA. Seven genera.

1. Lutraria. Eleven species.

This genus was taken from the Mactra, and is perfectly distinct, as it wants the lateral teeth. It is called Lutricola by De Blainville, from its lurking in sand or mud at the mouths of large rivers.

Shell inequilateral, orbicular, sub-triangular or transversely oval, gaping at the extremities; hinge with one cardinal tooth folded in two, or two teeth, one of which is plain, with an opposite hollow to receive it; no lateral teeth; ligament interior and fixed in the hollow cavity of the primary tooth.

Lutraria solenoides.
L. rugosa.
L. compressa.
L. piperata.
L. tellinoides.
L. elliptica.
L. papyracea.
L. plicatella.
L. crassiplica.
L. complanata.
L. candida.

_L. solenoides._ The Solen-like Lutraria.

Species oblong, sub-cylindrical, very gaping, two very strong cardinal teeth; the spoonlike cavity of the ligament vertical.

_L. compressa._ The compressed Lutraria.

Species oval or orbicular, almost equilateral, very compressed, little gaping; hinge similar; internal ligament inserted in the pit of a vertical spoonlike cavity; two distinct tubes, without longitudinal striæ.

_L. rugosa._ The rugged Lutraria.

Species ovate, closed at both ends; striæ from the summit to the base.

_L. elliptica._ The oval Lutraria.

Oblong oval, nearly smooth, having a few concentric striæ, and some diagonal striæ at the ends of the valves; colour yellow or greenish brown; inside white.

2. Mactra. The Kneading-trough. Thirty-three species.

The name given to this genus was derived from the Greek word μακτρα, from its resemblance to a trough used for kneading bread.

In all species of this genus a similarity of colouring and form pervades the whole. In shape they are sub-triangular or oblong, with a smooth, striated, or transversely-ribbed exterior. In some species the valves gape at both ends, and in others at the anterior only. The most general colour is lilac, or white tinged with blue or yellow; some have purple rays on a brown ground.

A singularity in the form of the hinge of the Mactra distinguishes it from all other genera. It is of a triangular form, has a bent or angular compressed tooth on each valve, with a small oblique cavity on each side to which the ligament is attached. There are also two lateral teeth, one near the ligament and the other near the primary tooth. These teeth are thin and fragile; the primary tooth is sometimes indistinct, but the lateral teeth always exist.

The Mactra is found buried in the sand at a little distance from the seashore. Shell generally thin and brittle, covered with epidermis, of a triangular form, transverse, equivalve, inequilateral; beaks prominent; one compressed, folded, cardinal tooth, with an adjoining pit in each valve, projecting inward; lateral teeth thin, lamellous, entering, placed near the hinge; exterior ligament small; an interior ligament inserted in the cardinal pits; two muscular impressions, united by a narrow marginal tongue.

Mactra gigantea.
M. Spengleri.
M. striatella.
M. carinata.
M. straminea.
M. Australis.
M. violacea.
M. fasciata.
M. turgida.
M. plicataria.
M. rufescens.
M. maculata.
M. subplicata.
M. triangularis.
M. lactea.
M. abbreviata.
M. Helvacea.
M. grandis.
M. stultorum.
M. maculosa.
M. ovalina.
M. alba.
M. solida.
M. castanea.
M. rufa.
M. squalida.
M. Brasiliana.
M. donacina.
M. depressa.
M. lilacea.
M. trigonella.
M. deltoides.
M. crassatella.

_M. gigantea._ The gigantic Mactra.

Species in which the cardinal teeth are almost obsolete, in consequence of the enlargement of the pit of the ligament.

_M. stultorum._ The fool’s Mactra. Pl. 9, fig. 6.

Species in which all the teeth are very large, lamellous, striated longitudinally; colour reddish brown.

_M. solida._ The solid Mactra.

Species thick, solid, without epidermis; lateral teeth finely striated.

_M. trigonella._ The three-cornered Mactra.

Species in which the lateral teeth are almost obsolete; exterior surface smooth.

_M. triangularis._ The triangular Mactra.

Species very small, strong, opaque, white; inside white; margin strongly crenated.

_M. crassa._ The thick Mactra.

Species very thick, solid, striated longitudinally; the cardinal teeth obsolete, or almost so; the lateral very thick, very close, and reflected; an external ligament as well as an internal one.

3. Crassatella. Eleven species.

May be easily known from the Mactra and Lutraria, as the valves, when closed, fit exactly, and do not gape. It is remarkable that all the living species contained in this genus only exist in the seas of Australasia, while at least seven species in a fossil state are found in France.

Shell inequilateral, sub-orbicular, close, equivalve, sometimes attenuated at one end; two divergent primary teeth, with a cavity at the side; lateral teeth obsolete; ligament internal, inserted in the cavity of the hinge.

Crassatella Kingicola.
C. donacina.
C. sulcata.
C. subradiata.
C. contraria.
C. cuneata.
C. rostrata.
C. glabrata.
C. erycinæa.
C. cycladea.
C. striata.

_C. sulcata._ The furrowed Crassatella. Pl. 6, fig 4.

Shell ordinarily thick, striated transversely, denticulated, sub-triangular, equivalve, inequilateral, summits well marked and evidently turned forward; hinge very large, subsimilar, formed by two diverging cardinal teeth, separated by a large pit; ligament almost entirely interior, and inserted in the pit.

_C. Kingicola._ The King’s Island Crassatella.

Ovate, orbicular; yellowish white, with obsolete rays; very minutely striated transversely; the umbones somewhat plicated.

4. Erycina. One species.

The only living species of this genus is found on the sand in New-Holland, but there are many fossils in France. It is so equivocal in character that it is difficult to judge of their hinge.

_E. cardioides._ The cardium-shaped Erycina. Pl. 6, fig. 5.

Shell rather longer than high, sub-triangular, regular, equivalve, inequilateral, rarely gaping; the summits well marked and a little anteriorly inclined; hinge subsimilar; two unequal cardinal teeth, converging at the summit, and leaving a pit between them; two lateral teeth, not distant, lamellous, inserted; ligament interior, fixed in the cavity between the primary teeth.

5. Ungulina. Two species.

This genus is very remarkable for having the pit or cavity divided into two parts, the one at the end of the other; the ligament is partially seen from the outside.

Ungulina oblonga.
Ungulina transversa.

_U. transversa._ The transverse Ungulina.

Shell vertical or longitudinal, rather irregular, not gaping, equivalve, inequilateral, with summits little marked and decorticated; hinge dorsal, formed by one short, primary cleft tooth, before an oblong pit, divided by a small ligament, in which is inserted a sub-interior ligament; colour yellowish brown.

6. Solenimya. Two species.

This genus, which at first sight is confounded with the Solens, differs from them particularly by the singular disposition of the ligament placed at the short side of the shell.

Solenimya Australis.
Solenimya Mediterranea.

_S. Australis._ The Australian Solenimya. Pl. 6, fig. 2.

Shell covered with a thick brownish epidermis, regular, thick, elongated oval, edges straight and parallel, equally rounded at both extremities; valves equal, very inequilateral.

_S. Mediterranea._ The Mediterranean Solenimya.

Transversely oblong; dark brown, ribbed longitudinally, with imbricated projecting foliations; inside white.

7. Amphidesma. Sixteen species.

This genus was constituted by Lamarck on account of the peculiar characters which distinguished it from those genera which it most resembles; particularly in having the valves connected by two ligaments.

Shell generally small, transverse, sub-oval or rounded, occasionally a little gaping at the sides; hinge with one or two cardinal teeth, and a narrow cavity for the interior ligament; exterior ligament short.

Amphidesma variegata.
A. donacilla.
A. lactea.
A. cornea.
A. albella.
A. flexuosa.
A. prismatica.
A. phaseolina.
A. corbuloides.
A. glabrella.
A. lucinalis.
A. Boysii.
A. tenuis.
A. purpurascens.
A. nucleola.
A. physioides.

_A. glabrella._ The smooth Amphidesma. Pl. 6, fig. 9.

Species lenticular or oval, with or without a lunated depression.

_A. lactea._ The milky Amphidesma.

Sub-orbicular, sub-pellucid, compressed, reticulated; yellowish white.

FAMILY VI.
CORBULACEA. Two genera.

1. Corbula. Nine species.

This genus approximates the Crassatella and Ungulina, but is distinguished from them by the inequality of the valves and the strong primary tooth.

Shell rather solid, a little irregular and triangular, inequivalve, more or less inequilateral, rounded and enlarged before, attenuated and prolonged behind; summits well marked, one projecting behind the other; hinge anomalous, formed by a large, conical, recurved cardinal tooth, with a cavity at its base for the reception of the tooth of the other valve; ligament very small; two muscular impressions little distant.

Corbula Australis.
C. sulcata.
C. erythrodon.
C. ovalina.
C. Taitensis.
C. nucleus.
C. impressa.
C. porcina.
C. semen.

_C. nucleus._ The kernel Corbula.

Strong, sub-triangular, under valve larger than the upper one; transversely striated; covered with a thick brownish epidermis.

_C. ovalina._ The ovate Corbula. Pl. 6, fig. 6.

Regular species.

_C. Australis._ The Australian Corbula.

Irregular species, living in stone.

2. Pandora. Two species.

Closely allied to the Corbula.

Pandora rostrata.
Pandora obtusa.

_P. rostrata._ The beaked Pandora. Pl. 6, fig. 3.

Shell white, regular, elongated, inequivalve, inequilateral; right or upper valve entirely flat, with a plait or fold; much produced towards the beak; hinge anomalous, formed by a transverse cardinal tooth on the right valve, entering into a corresponding cavity on the left; ligament internal, oblique, triangular, inserted in a pit rather deep, with edges a little projecting on each valve; two rounded muscular impressions.

FAMILY VII.
LITHOPHAGI. Three genera.

1. Saxicava. Five species.

This genus is taken from the Mytilus, and, like the Pholas, possesses the faculty of penetrating calcareous rocks, from which it cannot be extracted without breaking the substance in which it is imbedded.

Shell bivalve, thick, covered with epidermis, rather irregular, elongated, sub-cylindrical, obtuse at the two extremities; summits little marked; hinge toothless, or with a very small rudimentary tooth; ligament external, a little inflated.

Saxicava rugosa.
S. Gallicana.
S. pholadis.
S. Australis.
S. veneriformis.

_S. Australis._ The Australian Saxicava. Pl. 7, fig. 6.

Answers to the above description.

_S. Gallicana._ The Gallic Saxicava.

Oblong, wrinkled, truncated at the posterior extremity, one valve larger than the other; pale horn colour.

2. Petricola. Thirteen species.

This genus possesses the same faculty of boring rocks as the Saxicava; it is distinguished from the latter genus by the hinge having one or two teeth in each valve.

Shell sub-trigonal, transverse, inequilateral; upper side narrowed and a little gaping; lower side rounded.

Petricola lamellosa.
P. ochroleuca.
P. semilamellata.
P. lucinalis
P. striata.
P. costellata.
P. rocelaria.
P. exilis.
P. ruperella.
P. chamoides.
P. pholadiformis.
P. labagella.
P. linguatula.

_P. lamellosa._ The lamellous Petricola. Pl. 7, fig. 3.

Species oval, trigonal, radiated; two teeth on one valve, and one on the other.

_P. pholadiformis._ The Pholas-shaped Petricola.

Species transversely elongated.

3. Venerirupis. Seven species.

Another lithophagous shell, taken from the genus Venus, from which it is distinguished by the different disposition of the teeth, having three primary in one of the valves at least.

Shell more or less irregular, sub-trigonal, striated or radiated, equivalve, inequilateral, the anterior side shorter and rounded, the posterior sub-truncated; summits well marked; hinge sub-regular, more or less dissimilar, formed by slender, narrow, cardinal teeth, variable in number on each valve, sometimes two on the right and three on the left, and sometimes three on both; these teeth are small, contiguous, parallel, and but little, if at all, divergent exterior; very weak.

Venerirupis perforans.
V. nucleus.
V. irus.
V. exotica.
V. distans.
V. crenata.
V. carditoides.

_V. perforans._ The perforating Venerirupis.

Sub-rhombic, transversely striated, wrinkled on the anterior side; exterior brown, interior white, sometimes tinged with purple.

_V. irus._ The foliated Venerirupis. Pl. 7, fig. 2.

Species longitudinally striated; cardinal teeth two, sometimes three on the right and three on the left.

FAMILY VIII.
NYMPHACEA. Ten genera.

This family is divided into N. Solenaria and N. Tellinaria, from their resemblance to the Solen and the Tellina.

N. SOLENARIA. Three genera.

1. Sanguinolaria. Four species.

This genus may be distinguished from the Solen by never having the transverse oblong shape, or the edge of the valves parallel to the base.

Sanguinolaria occidens.
S. rosea.
S. livida.
S. rugosa.

_S. rosea._ The rosy Sanguinolaria.

Semi-orbicular, smooth, shining and convex; near the umbones of a beautiful rose colour, which becomes paler as it descends; acute transverse striæ.

_S. occidens._ The setting-sun Sanguinolaria. Pl. 7, fig. 4.

Oval, a little elongated, very compressed, slightly gaping, valves elliptical, equally rounded at the two extremities, without mark of posterior keel; summits slightly indicated; hinge formed by one or two contiguous cardinal teeth on each valve; ligament projecting, convex; margins not parallel.

2. Psammobia. Eighteen species.

Taken from the Tellina, which it much resembles in form, but from which it differs by not having the irregular plait on the anterior part.

Shell ovate, transverse, slightly gaping; summits projecting; hinge formed by two teeth on one valve, and only one inserted on the other.

Psammobia virgata.
P. Ferroensis.
P. vespertina.
P. florida.
P. muculosa.
P. cærulescens.
P. elongata.
P. flavicans.
P. squamosa.
P. alba.
P. Cayennensis.
P. lævigata.
P. tellinella.
P. pulchella.
P. aurantia.
P. fragilis.
P. livida.
P. Galathea.

_P. virgata._ The striped Psammobia. Pl. 7, fig. 1.

Species rather gaping, striated longitudinally, the teeth of the hinge considerably effaced.

_P. Ferroensis._ The Ferro Psammobia.

Oblong oval; white, radiated with crimson; finely striated transversely; valves obliquely truncated.

3. Psammotæa. Seven species.

Of the same form as the Psammobia, but differing in the number of teeth, as the left valve of the Psammotæa has only one tooth; sometimes one valve is toothless, while the other has two teeth.

Shell transverse oval or oblong; gaping a little at the sides; one primary tooth on each valve, though sometimes on only one of them; ligament exterior, attached to callosities at the hinge, and without an irregular plait.

Psammotæa violacea.
P. zonalis.
P. pellucida.
P. serotina.
P. candida.
P. Tarentina.
P. donacina.

_P. violacea._ The violet Psammotæa. Pl. 7, fig. 5.

Transversely ovate-oblong, sub-ventricose; transversely striated; purple radiations.

TELLINARIA. Seven genera.

The first five of these genera have one or two lateral teeth, the remaining two have none.

4. Tellina. The Tellen. Fifty-four species.

This genus differs but little from the Donax; its species are numerous, especially in the seas of hot countries; they are found sunk deep in the sand.

There are but few genera that can vie with the Tellina in beauty, variety, or number; some are smooth and polished, some are remarkable for their beautiful radiations, and others are covered with minute striæ and undulations; occasionally the whole surface is covered with imbrications or scales.

They are produced abundantly in almost every sea and in many rivers, but the finest species are found in the pearl-fisheries of Ceylon.

The usual form of the Tellina is broad at one end and gradually tapering towards the other. It derives its name from the Greek word τελειω, to bring to a termination.

Shell of variable form, generally striated longitudinally and very compressed; equivalve, more or less inequilateral; anterior side longer and more rounded than the posterior; offers a flexuous plait or twist at the inferior margin; summits little marked; hinge similar; one or two cardinal teeth; two distant lateral teeth, with a pit at their base in each valve; ligament external.

Tellina radiata.
T. unimaculata.
T. semizonalis.
T. maculosa.
T. virgata.
T. staurella.
T. crucigera.
T. Spengleri.
T. rostrata.
T. lutirostra.
T. elliptica.
T. albinella.
T. margaritina.
T. strigosa.
T. planata.
T. punicea.
T. depressa.
T. pulchella.
T. fabula.
T. tenuis.
T. sulphurea.
T. foliacea.
T. operculata.
T. rosea.
T. chloroleuca.
T. remies.
T. sulcata.
T. crassa.
T. lævigata.
T. linguafelis.
T. rugosa.
T. lacunosa.
T. gargadia.
T. pristis.
T. multangula.
T. polygona.
T. capsoides.
T. exilis.
T. donacina.
T. nitida.
T. scalaris.
T. psammotella.
T. striatula.
T. scobinata.
T. decussata.
T. Brasiliana.
T. obliqua.
T. umbonella.
T. deltoidalis.
T. nymphalis.
T. solidula.
T. bimaculata.
T. sexradiata.
T. ostracea.

_T. radiata._ The radiated Tellen. Pl. 8, fig. 5.

Shell elongated; posterior side shorter and more narrow than the anterior.

_T. foliacea._ The foliaceous Tellen.

Species transversely oblong; upon the edge of the front side of either valve are rows of serrated teeth, running from the apex to the margin.

_T. bimaculata._ The double-spotted Tellen.

Species orbicular, easily known by answering to its common name.

_T. fabula._ The false Tellen.

Shell very thin, pellucid, and oval; yellowish colour, darker towards the umbo, which is nearly central, pointed and turned a little to one side; anterior side slopes to an obtuse point; posterior side large and rounded; hinge with three teeth in one valve and two in the other.

_T. scobinata._ The rasp Tellen.

Species oval or sub-orbicular, sub-equilateral.

_T. donacina._ The Donax-like Tellen. Pl. 9, fig. 5.

Sub-oval, flattish, semi-striated and semipellucid; hinge with two teeth in one valve and one in the other; pale yellow, radiated longitudinally with pink.

_T. depressa._ The depressed Tellen.

Oval, flat, pointed at the smaller end and slightly reflected; pale yellowish colour, faintly striated concentrically; covered with a pale brown epidermis.

5. Tellinides. One species.

Though this genus bears a great affinity to many others, it cannot be united with any; having lateral teeth, it differs from the Psammobia; by not having the valves twisted, it differs from the Tellina; the valves closing, and having muscular impressions in the interior, render it distinct from the Lucina.

Shell equilateral, rather elongated, almost without the flexuous plait; two cardinal teeth diverging, and two remote lateral teeth, of which the anterior is but little distant from the summit.

_T. Timorensis._ The Tellinides of Timor. Pl. 8, fig. 3.

The only type and species of this genus.

6. Corbis. One species.

This genus was at first classed by Lamarck with the Lucina; but Cuvier, having discovered that the organization of the animals differed, made this a distinct genus, which was adopted by Lamarck.

Shell transverse, equivalve, no flexuosity; apices curved inward, opposed to each other; two primary and two lateral teeth, the posterior one nearest to the hinge; muscular impression simple, valves sometimes convex, strongly ribbed transversely, striated longitudinally, margins serrated and closely interlocking.

_C. fimbriata._ The fringed Corbis. Pl. 8, fig. 1.

Species white, rather thick, oval, a little elongated, almost equilateral; the cardinal and the lateral teeth well marked; the muscular impression anterior, rounded.

7. Lucina. Twenty species.

In the hinge and lateral teeth it much resembles the Tellina, but differs from it in never being flexuous. This genus is more easily characterized by the orbicular, compressed, general form of the shell, than by the dental system, which is sometimes entirely effaced.

Shell compressed, regular, orbicular, sub-equilateral; summits small and pointed, inclined anteriorly; hinge similar, but variable; two divergent cardinal teeth, little marked, and sometimes entirely effaced; two remote lateral teeth, with a pit at the base, sometimes obsolete; posterior ligament more or less sunk; two widely-separated muscular impressions, of which the anterior is narrow and long.

Lucina Jamaicensis.
L. Pennsylvanica.
L. edentula.
L. mutabilis.
L. radula.
L. squamosa.
L. lactea.
L. undata.
L. circinaria.
L. columbella.
L. concentrica.
L. divaricata.
L. carnaria.
L. scabra.
L. reticulata.
L. sinuata.
L. pecten.
L. lutea.
L. digitalis.
L. globularis.

_L. Jamaicensis._ The Jamaica Lucina. Pl. 8, fig. 8.

Species lenticular, striated concentrically; the teeth of the hinge variable, and sometimes obsolete.

_L. undata._ The waved Lucina.

Orbicular, thin, convex, undulated with fine irregular striæ; exterior pale yellow, interior white; margin glossy and plain.

8. Donax. The Wedge Shell. Twenty-seven species.

The singularity of form that gave rise to its common name renders it easily distinguished. It very much resembles a wedge, being very broad and thick at one extremity, and gradually tapering towards the other. They vary in colour, but the most general is purple radiated on a white ground, diverging from the beak to the margin; many have an orange tinge, and others a pink hue; the interior generally partakes of the colour of the exterior. There are not, perhaps, two species that have absolutely the same hinge.

The Donax is found buried deep in the sand of the seashore, with the short side uppermost.

Shell sub-trigonal, greater in length than in height, equivalve, very inequilateral; posterior side much shorter than the anterior; summits almost vertical; hinge complex, similar; two cardinal teeth in one or both valves; one or two remote lateral teeth on each valve; ligament posterior, short, and inflated; two rounded muscular impressions.

Donax scortum.
D. pubescens.
D. compressa.
D. cuneata.
D. deltoides.
D. radians.
D. abbreviata.
D. triquetra.
D. ringens.
D. rugosa.
D. Cayennensis.
D. elongata.
D. denticulata.
D. granosa.
D. columbella.
D. veneriformis.
D. Australis.
D. epidermia.
D. bicolor.
D. vittata.
D. meroe.
D. scripta.
D. trunculus.
D. flabagella.
D. cinatinum.
D. Martinicensis.
D. cardioides.

_D. scortum._ The beaked Donax. Pl. 8, fig. 4.

Species oval, of which the posterior side is sub-truncated; with decussated and muricated striæ.

_D. trunculus._ The common Donax.

Oblong, glossy, finely striated longitudinally, transversely banded and radiated with purple; white, clouded with purple within; internal margin of the valves distinctly dentated or crenulated.

_D. denticulata._ The denticulated Donax.

Species of which the posterior side is truncated; furrowed from the summit to the base.

9. Capsa. Two species.

This genus was separated by Lamarck from the Donax on account of the peculiarity of the hinge.

Capsa lævigata.
Capsa Braziliensis.

_C. lævigata._ The smooth Capsa.

Triangular, sub-equilateral, obsoletely striated transversely; covered with a greenish yellow epidermis; inside violet towards the umbones.

_C. Braziliensis._ The Brazilian Capsa. Pl. 8, fig. 7.

Shell elongated, covered with epidermis; equivalve, close; the cardinal teeth reduced to one large sub-bifid tooth on the right valve, placing itself between two very thin ones on the left; ligament external, on the short side.

10. Crassina. One species.

Distinguished from the Crassatella by the position of the ligament, and from the Venus by having only two teeth on each valve; one of them on the left valve projects very slightly.

_C. Danmoniensis._ The Devonshire Crassina. Pl. 6, fig. 1.

Solid, thick, sub-orbicular, sub-equilateral; two very large divergent teeth on one valve, and two very unequal ones on the other; regular parallel grooves and ribs; covered with a yellowish epidermis; inside white; margin broad and plain.

FAMILY IX.
CONCHACEA. Seven genera.

This family is divided into Conchæ fluviatiles, fresh-water shells, and Conchæ marinæ, sea shells.