312 CLASSIFICATION OF FISHES, ETC. 



Order III. CARTlLAGINES. Cartilaginous Fishes. 



Bones cartilaginous ; branchia or gills concealed beneath 

 the skin, upon which, however, there are as many small 

 apertures as there are internal rays ; fins in general 

 perfect ; body either pisciform*, or suborbicular and 

 greatly compressed. 



FA3IILY. 1. SQUALID^. Sharks. 



Body pisciform ; all the fins free and distinct ; snout 

 or fore part of the head more or less broad and pro- 

 truded beyond the mouth, which is placed beneath ; 

 teeth acute.t 



1. SuBFAM. SQUALIN^. Typical Sharks. 



Spiracles or air-holes behind the eyes either entirely 

 wanting, or exceedingly minute, so as to become obso- 

 lete ; dorsal fins two, without spines. 



Squalus Linn. Spiracles entirely wanting ; snout 

 broad, depressed ; teeth compressed, cutting, and 

 pointed, generally toothed or serrated on their sides ; 

 first dorsal fin before the pectoral, the second nearly 

 opposite to the anal ; nostrils placed under the mid- 

 dle of the snout ; the posterior branchial apertures 

 extending above the pectoral fins. 



S. Carcharias. Linn. Belon. glaucus. Bloch, pi. 86. Yarr. 

 . pi. 60. ii. 381. 



* By this term is meant that form seen in the generality of fishes. 

 + Except in such types as form the passage to the rays, as Pristis and 

 Mustelus, 



