Ai'llJtEDODERUS — I'lEATE-PERCHES 329 



what oblique; premaxillary not protractile; maxillary without evident sup- 

 plemental bone; teeth in villiform bands on jaws, vomer, palatines, and 

 pterygoids; pyloric caeca about 12; intestinal canal ending at throat in the 

 adult, the vent more posterior in the young, migrating forward, with growth, 

 from just behind the ventral fins; air-bladder simple, large, adherent, the 

 duct probably obsolete. 



Fresh waters of the United States; a single hving genus and 

 species ; several fossil genera While the structure of the skeleton 

 is essentially that of percoid fishes, the character of the forward 

 position of the vent leaves the Aphredoderidce singularh^ isolated, 

 without close relationships with the true perch-like forms. 



Genus APHREDODERUS Le Sueur 



pirate-perches 

 Characters of the genus included above. 



Fig. 55 



APHREDODERUS SAYANUS (Gilliams) 



PIRATE-PERCH 



(Map LXIX) 



Gilliams, 1824, J. Ac. Nat. Sci. Phila., IV, 81 (Scolopsis). 



J. & G., 460; M. V., 113; J. & E:., I, 786; N., 39 (A. sayanus and Sternotremia 

 isolepis); J., 48; (Aphododerus isolepis); F., 70; L., 22. 



Length 2 to 4 inches; body robust, rather deep and considerably com- 

 pressed, the caudal peduncle" stout; depth 3.1 to 3.5; greatest width scarcely 

 more than }/2 greatest depth; depth caudal peduncle 1.6 to 1.9 in its length. 

 Color dark olivaceous over transparent pinkish to lavender, the head and 

 body everywhere profusely specked with black, appearing bluish over the 

 ground-color; under side of head and sometimes fore part of breast and belly 

 yellowish; two blackish bars at base of caudal; fins, except ventrals, dusky 

 with a more deeply pigmented band around bases; ventrals yellowish ; median 

 fins with a narrow marginal fringe of white. Breeding males and females show 

 much iridescent color, the predominating lusters being violet and purple; 



