540 CLASSIFICATION OF ANIMALS. 



nary bladder. Two ovaries. Heart consisting of a single auricle 

 and ventricle. They may be distributed into two leading divisions; 

 the cartilaginous, whose skeleton consists of cartilage ; the bony, 

 where it is formed of a more firm substance. 



(A) Cartilaginous Fishes. 



Order I. Chondropterygii ~ having no gill-cover; an uterus, with 

 two oviducts. 



1 Petromyzon, lamprey 4 Squalus, shark, saw-fish 



2 Gastrobranchus 5 Lophius, sea-devil, frog, fish 



3 Raia, skate, torpedo, stin- 6 Balistes, file -fish 



gray 7 Chimaera 



II. Branchiostegi ; having a gill cover. 



1 Accipenster, sturgeon, beluga 5 Cyclopterus, lumpsuckei 



2 Ostracion, trunk-fish 6 Centriscus 



3 Tetrodon 7 Syngathus, pipe-fish 



4 Diodon, porcupine- fish 8 Pegasus 



(B) Bony Fishes, divided according to the situation of their fins* 



Order I. Apodes; no ventral fins. 



1 Muraena, eel kind 5 Ammodites, launce 



2 Gymnotus, electrical eel 6 Ophidium 



3 Anarrhichas, sea-wolf J Stromateus 



4 Xiphias, sword fish 8 Trichiurus 



II. Thoracici ; ventral fins directly under the thoracic. 



1 Echeneis, sucking fish 6 Sparus 



2 Coryphama, dorado 7 Perca, perch 



3 Zeus, dory 8 Scomber, mackarel, bonito, 



4 Pleuronectes, flounder, plaice, tunny 



dab, holibut, sole, turbot 9 Mullus, mullet, 



5 Chaeladon &c. &c. 



III. Abdominales ; ventral fins behind the thoracic ; chiefly in- 

 habit fresh water. 



1 Cobitis, loach 5 Clupea, herring, sprat, shad 



2 Silurus 6 Cyprinus, carp, tench, gold fish, 



3 Sal mo, salmon, trout, smelt miuow, &c. &c. 



4 Esox, pike 



