272 FISHES OF ILLINOIS 



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

 dorsal spines 12 to 15; 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 



a. Pyloric cseca 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. 



aa. Pyloric caeca 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, 1818, Supp. Amer. Month. Mag., II, 247 (Perca). 



G., I, 74 (Lucioperca americana) ; J. & G., 525; M. V., I.i5; B., I, 54 (Lucioperca) ; 

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

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



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

 long and straight ; depth 4.3 to 5.2; greatest width about f 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 

 muddv 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- 

 tinctlv 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 . 5 in length; width head 2 to 2.2 in its length; interorbital fiat, 5.2 



*Represented in Illinois by variety griseum. 



