MICROPTERUS — BLACK BASS 263 



MICROPTERUS DOLOMIEU Lacepede 

 (small-mouthed black bass) 



LactSpede, 1802, Hist. Nat. Poiss., IV, .32 5. 



G., I, 258 (Centrarchus fasciatus and obscurus); J. & G , 485- M V 120- B I IS- 



J. & E., I, 1011; N., 37 (salmoides) ; J., 44 (salmoldes) ; F., 67; L., 25; F. F., I.' 



3, 41 (salmoides). 



Length 12 to 15 inches; body ovate-fusiform, moderately com- 

 pressed, becoming deeper with age; profile convex; depth 2.9 to 3.1; 

 greatest width about f greatest depth ; depth of caudal peduncle 1 . 5 to 1 . 9 

 in its length. Color of upper parts silvery to golden green, with faint 

 vermiculations of darker (olive-green) above lateral line and with 10 to 

 1-5 more or less indistinct olive-green bars below it; belly and breast 

 pale bluish gray to whitish ; cheeks with 5 olive-green bars radiating back- 

 ward from eye and one forward to end of snout ; iris rufous ; fins nearly 

 plain in adults, olive to grayish, the caudal dark about margin; young 

 plain, or with dark spots tending to form vertical bars, never with a 

 dark lateral stripe; caudal of young specimens yellowish at base, and 

 with free margin whitish, the region between dusky; color of adults 

 varying* with the range, the season, and the -mood of the fish. Head 

 2.9 to 3.7; width head 1.8 to 2.1; interorbital space convex, 3 . S to 

 3.9; eye 5 . 6 to 6 . 9 ; nose 3 to 3 . 3 ; mouth smaller than in the next species, 

 maxillary 2.1 to 2 . 3, considerably shortf of back of orbit; lower jaw pro- 

 jecting; gill-rakers long, X + 6 or 7, + rudiments. Dorsal X (or IX), 

 13 -15, the spinous dorsal long and low and separated by a deep notch 

 from soft dorsal, the fifth (longest) spine about 4 in head and the lowest 

 posterior spine about i height of fifth; caudal lunate; anal III (rarely 

 IV or II), 10-12; ventrals more than half to vent; pectorals short, little 

 past backward reach of ventrals, 1.9 to 2.1 in head. Scales 10-12, 

 66-78, 19-22; lateral line complete or nearly ;so; scales on cheeks in 

 about 1 7 rows. 



This is perhaps the most famous and familiar of our fresh-water 

 fishes, surpassing the brook trout in that respect because of its much 

 more general distribution, and the whitefish and the lake trout both 

 for that reason and because of its surpassing interest as a sports- 

 man's fish. It is far better known to many anglers than to our- 

 selves, and has been written upon so much from the angler's point of 

 view that we shall treat it briefly in this report. 



In Illinois it is mainly a northern fish, avoid ng the lower Illi- 

 noisan glaciation, within whose boundaries it has occurred but once 

 in our 101 collections of the species, owing largely no doubt to its 

 marked preference for clear, swift water. It is much the most abun- 

 dant n the northern section of the state, its frequency ratio there 



*See Reighard, Henshall, etc. 

 fOld examples sometimes have maxillary nearly to back of orbit, according to 

 Jordan and Evermann. 



