«5 FRESH WATER FTSH 



Description of a new Genus, and of several new spe- 

 cies of fresh water fish, indigenous to tJie United 

 States. By C. A. Le Sueur. — Read, December 

 i9th, 1S20. 



Messrs. Maclure, Ord, and Say, from tlieir voyage 

 to Florid"a, and Mr. Nuttall, in his last journey up 

 the river Arkansa, brought back with them se- 

 veral species of fish, which it is my desire to commu- 

 nicate to this society. Several of them are unde- 

 scribed, and one of them appears to constitute a new 

 genus, allied to Cyprinodon ; if we may admit for 

 distinctive character the form of the body, that of the 

 fins, their position, and particularly that of the anal 

 one placed exactly between the ventral fins ; the last 

 of which characters appears to me of peculiar im- 

 portance ; it has likewise four or five branchial rays, 

 and the remarkable teeth of Cyprinodon, whether or 

 not they exist in the pharynx, as in that genus, I 

 have not been able to ascertain. 



The other species of fish which form the subject 

 of this memoir appertain to the genus Poecilia, of 

 Schneider, and Lebia of Cuvier. 



I would here observe generally, that all these spe- 

 cies possess a form of body sufficiently similiar among 

 themselves; that tliey are all of saiall magnitude, with 

 the body and neck compressed and elevated anteri- 

 orly; the tail compressed, and wide in proportion, but 

 narrower than the anterior part of the body taken be- 

 tween the back and the ventral fin ; the hea i is flat- 

 tened and terminated by a cuneate snout, cleft cross- 

 ways by the mouth, of which the jaws are protractile. 



