POLYODONTIDvE. CXIV. 343 



DIAMOND FISH. Snout broad, depressed, the length of 

 the cleft of the mouth being about half the length of the 

 head; color olivaceous; head 3 in length; D. 8; A. 8; 

 lat. 1. 60; very large, reaching a length of 8 feet or more. 

 Mississippi Valley, N. to Illinois and Ohio, abund- 

 ant southward. (A. ferox, Ka* L. adamantinus 

 Raf.) 



ORDER EE.-SELACHOSTOMI. 



(The Spoon -Bills.) 

 This order contains but the single family Polyo do ntidaz 



FAMILY CXIV. POLYODONTID^E. 



(The Spoon-Billed Cats.) 



Body elongated; skin naked, with minute stellated 

 roughnesses, and some bony plates about head and tail; 

 mouth very wide, not inferior, but overhung by the long 

 snout; minute teeth 011 lower jaw, maxillaries and palate, 

 teeth sometimes deciduous with age ; snout produced into 

 a very long and spatula-like process, thin and flexible at 

 its edges; no barbels; caudal with fulcra, as in Lepidos- 

 teus, heterocercal, the lower lobe well developed; opercle 

 with a long flap reaching to pectorals or beyond, and 

 sometimes to ventrals; spiracles present; no tongue; one 

 broad branchiostegal; air bladder large, communicating 

 with the oesophagus; intestine with a well - developed 

 spiral valve; stomach ccecal, with a broad divided pyloric 

 appendage. Fresh waters of U. S. and China. Species 

 two; P. folium from the Mississippi, and P. gladiits 

 from the Yangtsekiang. 



