APHODODERID^E. XCin. 249 



The two species known inhabit lowland waters, and 

 are remarkable for their voracity and for their nocturnal 

 habits. The unusual position of the vent (as in Ambly- 

 opsidcB) distinguishes them widely from the Percoid 

 fishes. 



The relations of this group are obscure. It much re- 

 sembles the Haplomi, and is perhaps as near to Umbridce 

 as to Centrarchidce. Although the vent is normally 

 jugular, specimens occur with the vent variously poster- 

 ior. On specimens with the vent between the ventral 

 fins, the genus Asternotremia, Nelson was based. Others 

 have the vent even farther back. From the observations 

 of Prof. S. A. Forbes, it appears that in this group the 

 position of the vent is not a generic character not even 

 specific, and that the four nominal species, Aphododerus 

 sayanus and A. cookianus, and Asternotremia isolepis and 

 A. mesotrema, are to be reduced to one species of one 

 genus. 



/. APHODODERUS, LeSueur. PIRATE PERCHES. 



1. A. sayanus, ( Gilliams ) DeK. PIRATE PERCH. 

 Head 3^ in length; depth 3f; greenish olive; a sub- 

 orbital bar, and dark bars at base of caudal; caudal 

 rounded; lower jaw longest; D. IV, 11; A. II, 7; lat. 1. 

 50 to 55; length 5 inches. N. Y. to La., in brooks near 

 the coast; also throughout Mississippi Valley in sloughs 

 and bayous. 



NOTE. The position of the vent in this family varies with age; 

 the young having the vent behind the ventrals, the adult in front 

 the difference being due to the prolongation of the rectum. 



