PERCOPSID^. 



207 



Fam. 8. PERCOPSID^. 



Percopsides, Agass. Lake Superior, p. 286, 



Body covered with ctenoid scales. Margin of the 

 upper jaw formed by the intermaxillary; opercular 

 apparatus complete. Barbels none. Gill-opening 

 wide ; pseudobranchise? Adipose fin present. Ovaries'? 

 (probably as in Salmonidae). Pyloric appendages'? 



Freshwater fishes of North America. 



The characters of this family are but incompletely known ; as far 

 as our present knowledge reaches, it would appear that it has some 

 affinity to the Haplochitonidce, from which it diff'ers in having 

 ctenoid scales. 



Only one genus is known. 



1. PERCOPSIS. 



Percopsis, Agassiz, I. c. p. 284. 



This genus reminds us in its general habit of Acerina. Scales ot 

 moderate size ; head naked. The dorsal fin occupies nearly the 

 middle of the length of the fish ; and the ventrals, which are eight- 

 rayed, correspond to its anterior rays. Adipose fin small ; caudal 

 forked; anal short. Nostrils close together, before the eye, which is 

 of moderate size and without adipose eyelid. Minute, villiforra teeth 

 in the jaws, none on the palate. Mouth small. 



Lake Superior. 



1. Percopsis guttatus. 



Percopsis guttatus, Agass. I. c. p. 286, pi. 1. figs. 1-2. 

 Percopsis (Salmoperca) pellucida, Thompson, Proc. Bosf. Sac. Nat. 

 Hist. iii. 1851, pp. 164, 306. 



B. 6. D. 12. A. 8. P. 12. V. 8. 



The height of the body is contained four times and a half in the 

 total length (without caudal), the length of the head thrice and two- 

 thirds. The eye is somewhat nearer to the gill-opening than to the 

 end of the snout. Pectorals shorter than the head, extending be- 

 yond the root of the ventral. Body with a silvery band along its 

 middle, and with longitudinal series of round dark spots above the 

 band. 



Sault St. Mary, Michipicotin, Fort William. 



Percopsis hammondii (Gill, Proc. Acad. Nat. Sc. Philad. 1864, 

 p. 151) is said to be distinguished by a longer head, its length being 

 two-sevenths of the total (without caudal). 



From Kansas. 



