Part 5

2. The _Mactridae_ are somewhat triangular in shape, and may be at once recognised by the pit for the hinge-ligament, which also assumes that form, as seen in the accompanying figure of _Lutraria elliptica_ (Fig. 21).

3. The _Tellinidae_ comprise some of the most delicately tinted, both externally and internally, of all shells. In some, coloured bands radiate from the umbones, and well bear out the fanciful name of "Sunset shells" bestowed upon them. Their valves are generally much compressed.

4. The _Solenidae_, or "Razor-shells," rank next, and are readily recognised by the extreme length of the valves in proportion to their width, and also by their gaping at both ends.

5. The _Myacidae_ or "Gapers," have the siphonal ends wide apart (in the genus _Mya_ both ends gape), and are further characterized by the triangular process for the cartilage, which projects into the interior of the shell. One valve (the left) is generally smaller than the other.

6. The _Anatinidae_ have thin, often inequivalve pearly shells. The genus _Pandora_ is the form most frequently met with in collections.

7. The _Gastrochaenidae_ embraces two genera (_Gastrochaena_ and _Saxicava_) of boring mollusca, which perforate shells and rocks, and also, the remarkable tube-like "Watering-pot-shell" (_Aspergillum_) which is hardly recognisable as a bivalve at all.

8. The _Pholadidae_ concludes the list of bivalves, and comprises the common rock-boring Pholas (Fig. 22) of our coasts and the wood-boring shipworm "Teredo" (Fig. 23).

* * * * *

Although the _Brachiopoda_, or "Lamp-shells," are not true mollusca, they are not very far removed from them, and are so often to be found in cabinets that it will not do to pass them over, especially since in past times they were very abundant, an enormous number occurring in the fossil state. Only eight genera are now living. Shells belonging to this class are readily recognised by the fact of one valve being larger than the other, and possessing a distinct peak, the apex of which is perforated. The _Terebratulidae_ are the most extensive family of this class.

HOW TO ARRANGE THE SHELLS IN THE CABINET.

When you have arranged your specimens in the order above indicated, proceed to place them in your boxes, arranging and labelling them after the manner shown in the accompanying diagram.

+----------+----------+----------+----------+----------+ | Class. | | | | | +----------+ Species. | Species. | Species. | Species. | | Order. | | | | | +----------+----------+----------+----------+----------+ | Family | | | | | | Name. | | | | | +----------+ Species. | Species. | Species. | Species. | | Generic | | | | | | Name. | | +----------+ | +----------+----------+----------+ Family +----------+ | | | | Name. | | | Species. | Species. | Species. +----------+ Species. | | | | | Generic | | +----------+----------+----------+ Name. +----------+ | | | +----------+ | | | Generic | | | | | Species. | Name. | Species. | Species. | Species. | | | | | | | +----------+----------+----------+----------+----------+ | | | | | Generic | | Species. | Species. | Species. | Species. | Name. | | | | | | | +----------+----------+----------+----------+----------+ | | | Generic | | | | Species. | Species. | Name. | Species. | Species. | | | | | | | +----------+----------+----------+----------+----------+ | | | | | | | Species. | Species. | Species. | Species. | Species. | | | | | | | +----------+----------+----------+----------+----------+

On the lid, or on a slip of paper or card placed at the head of your columns of trays, write the class and order, with its proper number (I., II., etc., as the case may be); then at the top of your left-hand column place the family and its number, and under it the name of the first genus. The species (one in each tray) come next, then the name of the next genus following it, succeeded by its species, and so on.

The object of the young collector should be to obtain examples of as many _genera_ as possible, since a collection in which a great number of genera are represented is far more useful and instructive than one composed of a great many species referable to but few genera. He will also find it very convenient to separate the British Shells from his general collection, sub-dividing them for convenience into "Land and Fresh-water," and "Marine." Of these he should endeavour to get every species, and even variety, making the thing as complete as possible. Or a separate collection may be made of all those kinds which he can find within a certain distance of his own home. A collection of this sort possesses, in addition to its scientific worth, an interest of its own, owing to the local associations that invariably connect themselves with it.

TABLE OF SOME OF THE MORE IMPORTANT GENERA, SHOWING THE APPROXIMATE NUMBER OF SPECIES BELONGING TO EACH GENUS AND THEIR DISTRIBUTION.

CLASS I.--CEPHALOPODA.

ORDER I.--Dibranchiata.

Section A.--_Octopoda._

Family. Genus. No. of Species. Distribution.

1. Argonauta 4 Tropical seas. 2. Octopus 46 Rocky coasts in temperate and tropical regions. Section B.--_Decapoda_.

3. Loligo 19 Cosmopolitan. 4. Sepia 30 On all coasts. 5. Spirula 3 All the warmer seas.

ORDER II.--_Tetrabranchiata_.

6. Nautilus 3 or 4 Chinese Seas, Indian Ocean, Persian Gulf.

CLASS II.--GASTEROPODA.

ORDER I.--Prosobranchiata.

Division _a_.--_Siphonostomata._

No. of Family. Genus. Species. Distribution.

1. Strombus 60 W. Indies, Mediterranean, Red Sea, Indian Ocean, Pacific--low water to 10 fathoms. Pteroceras 12 India, China. 2. Murex 180 On all coasts. Columbella 200 Sub-tropical regions, in shallow water on stones. Mitra 350 Tropical regions, from low water to 80 fathoms. Fusus 100 On all coasts. 3. Buccinum 20 Northern seas, from low water to 140 fathoms. Eburna 9 Red Sea, India, Australia, China, Cape of Good Hope. Nassa 210 World-wide--low water to 50 fathoms. Purpura 140 World-wide--low water to 25 fathoms. Harpa 9 Tropical--deep water, sand, muddy bottoms. Oliva 117 Sub-tropical--low water to 25 fathoms. 4. Cassis 34 Tropical regions, in shallow water. Dolium 15 Mediterranean, India, China, W. Indies, Brazil, New Guinea, Pacific. Triton 100 Temperate and sub-tropical regions, from low water to 50 fathoms. Ranella 50 Tropical regions, on rocks and coral-reefs. Pyrula 40 Sub-tropical regions, in 17 to 35 fathoms. 5. Conus 300 Equatorial seas--shallow water to 50 fathoms. Pleurotoma 500 Almost world-wide--low water to 100 fathoms. 6. Voluta 100 On tropical coasts, from the shore to 100 fathoms. Cymba 10 West Coast of Africa, Lisbon, Straits of Gibraltar. Marginella 90 Mostly tropical. 7. Cypraea 150 Warmer seas of the globe, on rocks and coral-reefs. Ovulum 36 Britain, Mediterranean, W. Indies, China, W. America.

Division _b_.--_Holostomata._

8. Natica 90 Arctic to tropical regions, on sandy and gravelly bottoms, from low water to 90 feet. Sigaretus 26 E. and W. Indies, China, Peru. 9. Cancellaria 70 W. Indies, China, S. America, E. Archipelago--low water to 40 fathoms. 10. Pyramidella 11 W. Indies, Mauritius, Australia, in sandy bays and on shallow mud-banks. Odostomia 35 Britain, Mediterranean, and Madeira--low water to 50 fathoms. Chemnitzia 70 World-wide--low water to 100 fathoms. Eulima 26 Cuba, Norway, Britain, India, Mediterranean, Australia--5 to 90 fathoms. 11. Solarium 25 Sub-tropical and tropical--widely distributed. 12. Scalaria 100 World-wide--low water to 100 fathoms. 13. Cerithium 100 World-wide. Potamides 41 Africa and India, in mud of large rivers. Aporrhais 3 Labrador, Norway, Britain, Mediterranean--20 to 100 fathoms. 14. Turritella 50 World-wide--low water to 100 fathoms. Vermetus 31 Portugal, Mediterranean, Africa, India. 15. Melania 160 S. Europe, India, Philippines and Pacific Islands--in rivers. Melanopsis 20 Spain, Australia, Asia Minor, New Zealand--in rivers. 16. Paludina 60 Northern Hemispheres, Africa, India, China, etc.--in lakes and rivers. Ampullaria 50 S. America, W. Indies, Africa, India--in lakes and rivers. 17. Litorina 40 On all shores. Rissoa 70 World-wide--in shallow water on sea-weed to 100 fathoms. 18. Calyptrea 50 World-wide--adherent to rocks, etc. Crepidula 40 West Indies, Mediterranean, Cape of Good Hope, Australia. Pileopsis 7 Britain, Norway, Mediterranean, E. and W. Indies, Australia. Hipponyx 70 W. Indies, Galapagos, Philippines, Australia. Phorus 9 W. Indies, India, Javan and Chinese Seas--in deep water. 19. Turbo 60 On the shores of Tropical seas. Phasinella 30 Australia, Pacific, W. Indies, Mediterranean. Imperator 20 S. Africa, India, etc. Trochus 150 World-wide--from low water to 100 fathoms. Rotella 18 India, Philippines, China, New Zealand. Stomatella 20 Cape, India, Australia, etc. 20. Haliotis 75 Britain, Canaries, India, Australia, California--on rocks at low water. Stomatia 12 Java, Philippines, Pacific, etc.-- under stones at low water. 21. Ianthina 6 Gregarious in the open seas of the Atlantic and Pacific. 22. Fissurella 120 World-wide--on rocks from low water to 5 fathoms. Emarginula 26 Britain, Norway, Philippines, Australia--from low water to 90 fathoms. 23. Nerita 116 On the shores of all warm seas. Neritina 110 In fresh waters of all warm countries, and in Britain. Navicella 24 India, Mauritius, Moluccas, Australia, Pacific--in fresh water, attached to stones. 24. Patella 100 On all coasts--adhering to stones and rocks. 25. Dentalium 30 World-wide--buried in mud. 26. Chiton 200 World-wide--low water to 100 fathoms.

ORDER II.--Pulmonifera.

Division _a_.--_Inoperculata._

No. of Family. Genus. Species. Distribution.

27. Helix 1,600 } Succinea 68 } World-wide--on land in moist places. Bulimus 650 } Achatina 120 World-wide--burrowing at roots and bulbs. Pupa 236 World-wide--amongst wet moss. Clausilia 400 Europe and Asia--in moist spots. 28. Limax 22 Europe and Canaries--on land in damp localities. Testacella 3 S. Europe, Canaries, and Britain-- burrowing in gardens. 29. Oncidium 16 Britain, Red Sea, Mediterranean--on rocks on the seashore. 30. Limnaea 50 Europe, Madeira, India, China, N. America--in ponds, rivers, lakes, etc. Physa 20 America, Europe, S. Africa, India, Philippines--in ponds, rivers, lakes, etc. Ancylus 14 Europe, N. and S. America--in ponds, rivers, lakes, etc. Planorbis 145 Europe, N. America, India, China--in ponds, rivers, lakes, etc. 31. Auricula 50 Tropical--in salt marshes. Siphonaria 30 World-wide--between high and low water.

Division _b_.--_Operculata._

32. Cyclostoma 80 S. Europe, Africa } Cyclophorus 100 India, Philippines }--on land. Pupina 80 Philippines, New Guinea } 33. Helicina 150 W. Indies, Philippines, Central America, Islands in Pacific--on land. 34. Acicula 5 Britain, Europe, Vanicoro--on leaves and at roots of grass. Geomelania 21 Jamaica--on land.

ORDER III.--Opisthobranchiata.

Division _a_.--_Tectibranchiata._

No. of Family. Genus. Species. Distribution.

35. Tornatella 16 Red Sea, Philippines, Japan--in deep water. 36. Bulla 50 Widely distributed--low water to 30 fathoms. 37. Aplysia 40 Britain, Norway, W. Indies--low water to 15 fathoms on sea-weed. 38. Pleurobranchus 20 Britain, Norway, Mediterranean.

Division _b_.--_Nudibranchiata._

39-44. All shell-less.

ORDER IV.--Nucleobranchiata.

No. of Family. Genus. Species. Distribution.

45. Firola 8 Atlantic, Mediterranean. Carinaria 5 Atlantic and Indian Oceans. 46. Atlanta 15 Warmer parts of the Atlantic.

CLASS III.--PTEROPODA.

Division _a_.--_Thecosomata._

No. of Family. Genus. Species. Distribution.

1. Hyalea 19 } Cleodora 12 } Atlantic, Mediterranean, Indian Ocean. 2. Limacina 2 Arctic and Antarctic Seas.

Division _b_.--_Gymnosomata._

3. Clio, etc. Shell-less.

CLASS IV.--LAMELLIBRANCHIATA.

No. of Family. Genus. Species. Distribution.

Division _a_.--_Asiphonida._

1. Ostrea 100 World-wide--in estuaries, attached. 2. Anomia 20 India, Australia, China, Ceylon-- attached to shells from low water to 100 fathoms. Placuna 4 Scinde, North Australia, China--in brackish water. 3. Pecten 176 World-wide--from 3 to 40 fathoms. Lima 20 Norway, Britain, India, Australia-- from 1 to 150 fathoms. Spondylus 70 Tropical seas--attached to coral-reefs. 4. Avicula 25 Britain, Mediterranean, India-- 25 fathoms. Perna 18 In tropical seas--attached. Pinna 30 United States, Britain, Mediterranean, Australia, Pacific--low water to 60 fathoms. 5. Mytilus 70 World-wide--between high and low water mark. Modiola 70 British and tropical seas--low water to 100 fathoms. 6. Arca 400 In warm seas--from low water to 200 fathoms. Pectunculus 58 West Indies, Britain, New Zealand-- from 8 to 60 fathoms. Nucula 70 Norway, Japan--from 5 to 100 fathoms. 7. Trigonia 3 Off the coast of Australia. 8. Unio 420 World-wide--in fresh waters. Anodon 100 North America, Europe, Siberia--in fresh waters.

Division _b_.--_Siphonida._

9. Chama 50 In tropical seas on coral reefs. 10. Tridacna 7 Indian and Pacific Oceans, Chinese Seas. 11. Cardium 200 World-wide--from the shore line to 140 fathoms. 12. Lucina 70 Tropical and temperate seas--sandy and muddy bottoms--from low water to 200 fathoms. Kellia 20 Norway, New Zealand, California--low water to 200 fathoms. 13. Cyclas 60 Temperate regions--in all fresh waters. Cyrena 130 From the Nile and other rivers to China--and in mangrove swamps. 14. Astarte 20 Mostly Arctic--from 30 to 112 fathoms. Crassatella 34 Australia, Philippines, Africa, etc. 15. Cyprina 1 From Britain to the most northerly point yet reached--from 5 to 80 fathoms. Circe 40 Britain, Australia, India, Red Sea-- 8 to 50 fathoms. Isocardia 5 Mediterranean, China, Japan--burrowing in sand. Cardita 54 Tropical seas--from shallow water to 150 fathoms. 16. Venus 176 } World-wide--buried in sand, from low Cytherea 113 } water to 100 fathoms. Artemis 100 Northern to tropical seas--from low water to 100 fathoms. Tapes 80 Widely distributed--burrowing in sand, from low water to 100 fathoms. Venerupis 20 Britain, Canaries, India, Peru--in crevices of rocks. 17. Mactra 125 World-wide--burrowing in sand. Lutraria 18 Widely distributed--burrowing in sand. 18. Tellina 300 In all seas--from the shore line to 15 fathoms. Psammobia 50 Britain, Pacific and Indian Oceans-- from the littoral zone to 100 fathoms. Sanguinolaria 20 W. Indies, Australia, Peru. Semele 60 Brazil, India, China, etc. Donax 68 Norway, Baltic, Britain--in sand near low water mark. 19. Solen 33 World-wide--burrowing in sand. Solecurtus 25 Britain, Africa, Madeira, Mediterranean--burrowing in sand. 20. Mya 10 North Seas, W. Africa, Philippines, etc.--river mouths from low water to 25 fathoms. Corbula 60 United States, Britain, Norway, Mediterranean, W. Africa, China-- from 15 to 80 fathoms. 21. Anatina 50 India, W. Africa, Philippines, New Zealand. Thracia 17 Greenland to Canaries and China--from 4 to 120 fathoms. Pandora 18 Spitzbergen, Panama, India--from 4 to 110 fathoms, burrowing in sand and mud. 22. Gastrochaena 10 W. Indies, Britain, Red Sea, Pacific Islands--from shore line to 30 fathoms. Saxicava Arctic Seas, Britain, Mediterranean, Canaries and the Cape--in crevices and boring into limestone and rocks. Aspergillum 21 Red Sea, Java, New Zealand--in sand. 23. Pholas 32 Almost universal--from low water to 25 fathoms. Xylophaga 2 Norway, Britain, S. America--boring into floating wood. Teredo 14 In tropical seas--from low water to 100 fathoms.

SOME WORKS OF REFERENCE.

MOLLUSCA IN GENERAL.

"A Manual of Mollusca." By Dr. S. P. Woodward.

"Tabular View of the Orders and Families of the Mollusca." Published by the Society for Promoting Christian Knowledge.

"Cassell's Natural History," latest edition, article on the Mollusca. By Dr. Henry Woodward.

BRITISH MOLLUSCA.

"A History of British Mollusca and their Shells." By Professor E. Forbes and S. Hanley.

"British Conchology." By J. G. Jeffreys.

"Common Shells of the Sea-shore." By Rev. J. G. Wood.

BRITISH LAND AND FRESH-WATER MOLLUSCA.