MICUOPTERUS — BLACK BASS 263 



MICROPTERUS DOLOMIEU Lacepede 



SMALL-MOUTHED BLACK BASS 

 (Map LXXX) 



Lacepede, 1802, Hist. Nat. Poiss., IV, 325. 



G., I, 258 (Centrarchus fasciatus and obscurus); J. & G., 485: M. V.. 120; B., I, 15; 



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



3, 41 (salmoides). 



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

 becoming deeper with age; profile convex; depth 2.9 to 3.1; greatest width 

 about % 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 15 more or less indistinct 

 olive-green bars below it; belly and breast pale bluish gray to whitish; cheeks 

 with 5 olive-green bars radiating backward 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 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, 3.5 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 projecting; 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 x /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 17 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 sportsman's fish. It is far better known to many 

 anglers than to ourselves, 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, avoiding the lower 

 Illinoisan 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 abundant in the northern section of the state, its 

 frequency ratio there being 2.35 as compared with .32 for each 



* See Reighard, Henshall, et al. 



f Old examples sometimes have maxillary nearly to back of orbit, according to Jordan 

 and Evermann. 



