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PISCES. 



ORDER I. STURIONES. 



Branchiae free at their external edge ; a single orifice very 

 open in each operculum ; no rays to the membrane. One 

 remarkable genus. 



Genus Acipenser, Lin. Sturgeon. 



Body elongated and more or less covered with bony plates 

 implanted upon the skin in longitudinal rows ; the exterior 

 portion of the head also well mailed ; mouth placed under the 

 snout, small and without teeth ; eyes and nostrils in the sides 

 of the head ; cirri under the snout ; dorsal behind the ven- 

 trals and beneath it ; caudal surrounding the extremity of the 

 spine, and having a salient lobe beneath shorter than its 

 principal point. These enormous Fishes are not only inha- 

 bitants of the ocean but likewise nearly all the northern rivers 

 of the old and new world. Norway produces some of a 

 thousand pounds weight. In old Rome a respect approach- 

 ing to worship was paid them, and they were borne in tri- 

 umph through the streets. 



ORDER II. SELACHII. 



Branchia3 fixed on both edges, and letting the water escape 

 by as many holes pierced in the skin as there are intervals 

 between them ; the ordinary bones of the jaw reduced to mere 

 vestiges ; the bones which succeed, the palatines above and 

 postmandibularies below, alone armed with teeth ; branchi- 

 ostegal rays not apparent externally ; no operculum ; pecto- 

 rals and ventrals; the latter placed behind the abdomen. 

 Three remarkable genera. 



Genus I. Squalus, Lin. Shark. 



Body elongated ; tail thick and fleshy ; pectorals of mode- 

 rate size; form approaching that of ordinary Fishes; branchial 

 openings ; eyes upon the sides of the head and neck ; snout 

 sustained by three cartilaginous branches connected with 



