310 FISHES. 



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

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

 from the Yangtsekiang. 



/. POLYODON, Lacepede. DUCK-BILLED CATS. 



= Spatularia, Shaw. 



= Planirostra, LeSueur. 



1. P. folium, Lacepede. DUCK - BILLED CAT. SPOON- 

 BILLED STURGEON. Snout nearly ^ of length ; opercular 

 flap reaching much beyond pectorals; fins all more or less 

 falcate; color gray; D. 55 to 60; A. 56; length 5 feet or 

 more. Mississippi and its larger tributaries, abundant. 

 A singular fish, bearing considerable resemblance to a 

 Shark. 



OEDEE FF. - CHOKDOESTEI. 



(The Cartilaginous Ganoids.) 

 This order is equivalent to the family Acipenseridce. 



FAMILY CXV. ACIPENSERID^E. 



(TJie Sturgeons.) 



Body elongate, sub-cylindrical, with five longitudinal 

 rows of bony shields, the lower sometimes deciduous; 

 snout produced; mouth entirely inferior, transverse, 

 protractile, toothless; four barbels in a row under snout 

 in front of mouth; vertical fins with fulcra; caudal hete- 

 rocercal; dorsal and anal far back. No branchiostegals ; 

 air bladder large, not cellular; stomach not ccecal, with 

 pyloric appendages; intestines with spiral valve; distri- 

 bution same as that of Salmo. Fresh waters of northern 

 regions, some species marine and entering rivers. 

 Genera two; species twenty (Giinther\ eighty or more 



