20 The Ganoids 



in the pound nets. A similar species, Acipenser mikadoi, is 

 abundant and valuable in the streams of northern Japan. 



FIG 7. Lake Sturgeon, Acipenser rubicundus Le Sueur. Ecorse, Mich. 



In the genus Acipenser the snout is sharp and conical, and 

 the shark-like spiracle is still retained. 



The shovel-nosed sturgeon (Scaphirhynchus platyrhynchus} 

 has lost the spiracles, the tail is more slender, its surface wholly 

 bony, and the snout is broad and shaped like a shovel. The 

 single species of Scaphirhynchus abounds in the Mississippi 



FIG. 8. Shovel-nosed Sturgeon. Scaphirhynchus platyrhynchus (Rafinesque). 



Ohio River. 



Valley, a fish more interesting to the naturalist than to the 

 fisherman. It is the smallest of our sturgeons, often taken in 

 the nets in large numbers. 



In Scaphyrhynchus the tail is covered by a continuous coat 

 of mail. In Kessleria * fedtschenkoi, rossikowi, and other 

 Asiatic species the tail is not mailed. 



Order Selachostomi : the Paddle-fishes. - - Another type of 

 Ganoids, allied to the sturgeons, perhaps still further degenerate, 

 is that of the paddle-fishes, called by Cope Selachostomi (<reAor^os, 

 shark ; Gropa, mouth) . This group consists of a single family, 

 Polyodontidce, having apparently little in common with the 

 other Ganoids, and in appearance still more suggestive of the 

 sharks. The common name of paddle-fishes is derived from 

 the long flat blade in which the snout terminates. This ex- 

 tends far beyond the mouth, is more or less sensitive, and is 



* These species have also been named Pseudoscaphirhynchus. Kessleria 

 is the earlier name, left undefined by its describer, although the type was 

 indicated. 



