80 SGIUALIDES. 



ORDER il. — SELACHII. 



SQ.UALIDES. 



Sharks have no bones like those of the second 

 class of fishes ; they are elastic, cartilaginous por- 

 tions, embraced by numerous muscles. The bran- 

 chiae are pectinated, — the openings quite numer- 

 ous, without gill covers, and the palate and post- 

 mandibulary bones are studded with teeth. They 

 have pectoral and ventral fins, — but the last is 

 placed backwards, on the abdomen. While some 

 are viviparous, others are oviparous, — and all the 

 males may be identified by appendages at the in- 

 ternal margin of the ventral fins. Though these 

 are the indications of the sex, their use is totally 

 unknown. 



GEN. SCYLLIUM. 



Sea-Dog, — Scyllium Canicula, — le chein de 

 mer, of which we have a well preserved specimen, 

 four feet in length. It follows the perch, when they 

 first make their appearance in the spring, in the 

 margin of deep water. It has a remarkable metal- 

 lic color, like crude antimony. The teeth are ve- 

 ry small, giving the sensation to the finger of a 

 coarse rasp ; its body is slender, the head flat, — 

 the nose long and pointed : — the eyes much re- 



