FISHES OF MINNESOTA 63 



KEY TO THE GENERA OF PERCIDJl. 



A. Branchlostegal rays 7; preopercle serrate; pseudobranchia (false 

 gills on under side of the opercle) well developed; mouth large. 

 B. Canine teeth (large conical teeth) present on the jaws and pal- 

 atine bones. ... ... Stizostediou, 64 



BB. No canine teeth present Perca, 65 



AA. Branchlostegal rays 6; preopercle very little if at all serrate; 



pseudobranchia very little developed; all small fisiies. 



B. Upper portion of the skull rather depressed, very little convex 



when seen in cross section. 



C. Space between the eyes wide, upper jaw not protractile; 



snout sharp and conical, projecting beyond the mouth. 



Percina, 65 

 CC. Space between the eyes not wide, snout not projedting 

 much beyond the mouth. 

 D. Body not semi transparent in life; not greatly elon- 

 gate; well covered with scales. 

 E. Upper jaw not protractile, no groove separating' 

 the skin which covers the premaxillaries from 

 the skin of the forehead; anal fin large; scales 

 of the middle line of the belly often dropping 

 off, leaving a naked space. . Hadropterus, 66 



EE. Upper jaw protractile, a groove separating the 

 skin 'which covers the premaxillaries from the 

 skin of the forehead; anal spine one, this very 

 small; anal fin shorter than the soft dorsal. 



Boleosoma, 67 

 DD. Body semitransparent in life; very long and slender; 

 belly naked; upper jaw protractile; a row of black 

 dots along the lateral line. . . Ammocrypta, 68 

 BB. Upper portion of the skull not depressed, convex in cross 

 section; upper jaw not protractile. 

 C. Lateral line developed, at least on the anterior portion of 

 the body; dorsal spines 8 to 14. 

 D. Lateral line straight; body rather heavy. Etheostoma, 69 

 DD. Lateral line slightly curved, running high ante- 

 riorly; dorsal fins well separated ; body slender. 



Boleiclithys, .71 

 CC. Lateral line not at all developed; dorsal spines 6. Microperca, 72 



