272 fISHES OF ILLINOIS 



Large carnivorous fishes of the fresh waters of North Amer- 

 ica north of Mexico; 2 species known. Highly valued as food, 

 and important 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 THE SPECIES OF STIZOSTEDION FOUND IN ILLINOIS 



a. 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. 



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 eanadense.* 



STIZOSTEDION VITREUM (MITCHILL) 



WALL-EYED PIKE; PIKE-PERCH; JACK-SALMON 

 (MAP LXXXII) 



Mitchill, 1818, Supp. Amer. Month. Mag., II, 247 (Perca). 



G., 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); 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 % greatest 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 everywhere mottled with black, mot- 

 tlings 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 in- 

 distinct 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 flat, 5.2 to 5.9; eye 4.6 to 6; nose 3.3 

 to 3.8; mouth large, terminal, little oblique, maxillary past back of pupil, 

 2.2 to 2.4 in head; lower jaw slightly shorter than upper; gill-rakers slender; 

 pyloric caeca 3, subequal, as long as stomach. Dorsal XIII or XIV, 19 to 22; 

 longest dorsal spine about 2^- in head; caudal lunate; anal II, 12-14; ventrals 



* Represented in Illinois by variety griseum. 



