436 DESCRIPTION OF THE MUSEUM. 



our rivers and ponds, and the last, which has 

 not been described, was sent us from North Ame- 

 rica by M. Milbert. 



The genus anableps is very distinct from the 

 loches, to which it has been united : the eyes 

 are very projecting ; the cornea and iris are di- 

 vided into two parts by transverse bands, thus 

 forming two pupils, although there is but one 

 crystalline humour and one retina; this con- 

 formation is the only example amongst verle- 

 brated animals. These species inhabit the rivers 

 of the warmer regions of America, and are said 

 to be viviparous. 



The genera poecilia, cyprinodon, and lebia com- 

 plete the family of the cyprini. We have six spe- 

 cies of the first, small fish which are found in the 

 rivers of North and South America ; only one of 

 the second, and two of the third, lately described 

 by M. Valenciennes. 



Next to the cyprini are the siluro'idcce : their 

 skin, destitute of scales, is bare or covered with 

 large bony plates: they almost all inhabit the 

 rivers of hot climates. We have fifty-seven spe- 

 cie's of them. The siluri, which are the first genus 

 of this family, have the first ray of the dorsal 

 and pectoral fins large, strong, and serrated ; they 

 erect it at pleasure, and it is a dangerous wea- 

 pon: their mouth is furnished with numerous 



