(A) CARTILAGINOUS FISHES.
Chondropterygii ; having no gill-cover ; an uterus, with two oviducts.
1. Petromyzon, lamprey.
2. Gastrobrarichus.
3. Rant skate, torpedo, stingray.
4. Squanfs, shark, saw-fish.
5. Lophius, sea-devil, frog-fish.
6. Batistes, file-fish.
7. Chimera.
Branchiostegr ; having a gill-cover.
1. Accipenser, sturgeon; beluga.
2. Ostracion, trunk-fish.
3. Tetrodon.
4. Diodon, porcupine-fish.
5. Cyclopterus, lumpsucker. ' 6. Centriscus. • 7. Syfignathus, pipe-fish.
8. Pegasus.
(s) HONY FISHES, DIVIDED ACCORDING TC THE SITUATION OF THEIR FINS.
Order I. .2podeo ; no ventral fins.
1. Mitrmna, eel-kind.
2. Gymnotus, electrical eel, 3. Anarrhichas, sea-wolf.
4. Xiphias, swordfish.
5. Ammodites, launce.
6. Ophidinm.
7. Strom:dens.
8. Trichiurus.
II. Thoiacici ; ventral fins directly un ler the thoracic.
1. Echeneis, sticking-fish.
2. Coryphzna, dorado.
3. Zeus, dory.
4. PI eu ronectes, flounder, plaice, dab, holibut, sole, turbot.
5. Cliztodon.
6. Sparus.
7. Perca, perch.
8 Scomber, mackarel, bonito, tunny.
9. Mullus, mullet, &c. &c.
III. ../lbdominales ; ventral fins behind the thoracic ; chiefly inhabit fresh water.
1. Cobitis, loath.
2. Silurus.
3. Salmo, salmon, trout, smelt.
4. Esox, pike.
5. Clupea, herring, sprat, shad: 6. Cyprinus, carp, tench, gold-fish, minow, Sce..8cc.
IV. Jusrulares ; ventral fins in front of the thoracic.
I. Gadus, haddock, cod, whiting, 2. Uranoscoptts, star-gazer.
3. Blennius, bluffly.
4. Callionyrnus, dragonet.
5. 'I'rachinus, weaver.
The animals, which have no vertebral column, do not possess so many common characters as the vertebral classes ; their hard parts, when they have any, are ge nerally placed on the surface of the body ; the centre of the nervous system, instead of being inclosed in a bony case, lies in the same cavity with the viscera ; the wso phagus is generally surrounded by a ner vous chord coming from the brain ; their respiration is not carried on by lungs, and they have no voice ; their jaws move in. cartons directions ; they have no urinary secretion.
The invertebral animals were distribut ed by Linnmus into two classes; insects and worms (vermes.) The anatomical
structure of these animals was very im- perfectly known, when the Swedish na turalist first promulgated his arrange ment. But the labours of subsequent zoo logists, and particularly those of Cuvier, have succeeded in establishing such strik ing and important differences in their for mation, that a subdivision of the Linnwan classes became indispensably necessary. The insects of Linnxus are divided into crustacea and insecta : and the vermes of the same author form three classes : viz. Mollusca, Vermes, and Zoophyta.
The Mollusca derive their name from the soft fleshy nature of their body. This class includes those pulpy animals, which may either be destitute of an external covering, when they are called mollusca nuda, as the slug ; or may be inclosed in one or more shells, as the snail, oyster, &c. when they are termed testacea.
The animals of this class have no arti culated members : they have blood-ves sels, and a true circulation ; they respire by means of gills ; they have a distinct brain, giving origin to nerves ; and a spi nal marrow.
1. Sepia, cuttlefish.
2. Argonauts.
3, Nautilus.
4. Limax, slug.
5. Aplysia.
6. Doris.
7. Clio.
8. Patella, limpet.
9. Helix, snail.
10. Haliotis, Venus's ear.
11. Murex, caltrop, or rockshell.
12. Strombus, screw.
13. Buccinum, whelk.
14. Ascidia.
15. Thalia.
16. Ostrea, oyster.
17. Solen, razorshell.
18. Cardium, cockle.
19. Mytilus, muscle, &c. &c.
Cuvier classes the numerous genera of this order under the three following di visions : 1. Cephalopoda, (from zeecteeAv the head, and 7rfs; the foot) which have their organs of motion placed round the head; 2. Gasteropoda, (from Vsci', the belly, and such as crawl on the belly ; and 3. Acephala, (from et, priva tive, and selNe20:,) which have no head. The three first genera belong to the first division ; the ten succeeding ones come under the second ; and the remainder ex amplify the Est order.