272 FISHES OF ILLINOIS 



on jaws and palatines; pseudobranchise well developed; pyloric caeca 3; 

 dorsal spines 12 to IS; anal spines 2, slender and closely appressed to 

 the soft rays; scales small, ctenoid. 



Large carnivorous fishes of the fresh waters of North America 

 north of Mexico ; 2 species known. Highly valued as food, and im- 

 portant as game fishes, but very costly of maintenance if one takes 

 into account the numbers and kinds of other fishes necessary to 

 bring one of these pike-perch to maturity and to keep it in good 

 condition until it is caught. 



Key to Species of STIZOSTEDION found in Illinois 



. Pyloric caeca 3, subequal, as long as stomach; rays of soft dorsal 19 to 22, 

 usually over 20; cheeks rather sparsely scaled; base of pectorals without 

 distinct black blotch; a black blotch at back of spinous dorsal; soft 

 dorsal obscurely reticulated vitreum. 



. Pyloric cseca 5 to 8, unequal, the 4 longest much shorter than stomach; rays 

 of soft dorsal 17 to 19; cheeks as a rule closely scaled; a distinct black 

 blotch at base of pectoral; last dorsal spines without black blotch; soft 

 dorsal with rows of dark spots canadense.* 



STIZOSTEDION VITREUM (Mitchill) 

 (wall-eyed pike; pike-perch ; jack-salmon) 



Mitchill, ISIS, Supp. Amer. Month. Mag., II, 247 (Perca). 



Q., I, 74 (Lucioperca americana) , J. & G , 525; M. V., 135; B., I, 54 (Lucioperca) ; 



J. & E., I, 1021; N., 36 (americanum and var. salmoneum) ; J., 44; F. F., I. 



3, 32 (Stizostethium) ; P., 63; L., 26. 



Length 3 feet; body slender, only moderately compressed; profile 

 long and straight ; depth 4.3 to 5.2; greatest width about § great- 

 est depth ; depth caudal peduncle 2.3 to 2.6 in its length. Color a 

 brassy olive-buff ground, shading to olive-yellow in spots, and every- 

 where mottled with black, mottlings on head, cheeks, and opercles in 

 vermiculate pattern, those on back and sides arranged more or less 

 definitely in five large irregularly-shaped cross -blotches with smaller 

 blotches between; belly whitish, tinged with green, iris chocolate with 

 gold margin next pupil; cornea milky, giving the eye its characteristic 

 muddy or "wall-eye" appearance; spinous dorsal with a narrow inky- 

 black margin and with a large black blotch behind, nearly or quite 

 including posterior two membranes; soft dorsal reticulate or indis- 

 tinctly barred; base of pectoral without a prominent black blotch, an 

 indistinct and diffused patch of dark color sometimes present; caudal 

 with indefinite bars; ventrals and anal whitish with tinge of green. 

 Head slender and tapered, less depressed than in next species, 3.2 to 

 3 . S in length; width head 2 to 2.2 in its length; interorbital flat, 5.2 



*Represented in Illinois by variety grisenm. 



