20 The Ganoids 
in the pound nets. A similar species, Acipenser mtikadot, is 
abundant and valuable in the streams of northern Japan. 
‘Ss ——_——— 
Fic. 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* fedtschenkot, rossikowt, 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 (céAayos, 
shark; oroya, mouth). This group consists of a single family, 
Polyodontide, 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. 
