MICROPERCA 



317 



Genus MICROPERCA Putnam 



Body short and stout; mouth small, slightly oblique; premaxillaries 

 not protractile; vertebrae (M. punctulata) 30 (16+20); differing from 

 Etheostoma only in the almost or complete absence of the lateral line; 

 the vertebrae and fin rays fewer than in other darters, and the scales 

 larger than in most species. Size extremely small, the smallest of the 

 darters; coloration plain; species few, or perhaps not more than one. 



Fig. 76 



MICROPERCA PUNCTULATA Putnam 

 (least darter) 



Putnam, 1863, Bull. Mus. Comp, Zool., I, 4. 



J. & G., 523; M. V., 134 (Etheostoma microperca) ; B., I, 87 (Etheostoma micro- 

 perca); J. & E., I, 1104; N., 34; J., 43; F., 64; F. F., I. 3, 24; L.. 29. 



Length 1 to H inches; body not much elongate, compressed, the 

 back moderately arched; depth 4.6 to 5.2; greatest width about f of 

 greatest depth; depth caudal peduncle 2.6 to 3.1. "Coloration oliva- 

 ceous, the sides closely speckled and with vague bars and zigzag mark- 

 ings ; second dorsal and caudal barred ; dark streaks radiating from eye ; 

 a dark humeral spot" (Jordan and Evermann). Head blunth' rounded, 

 3 . 6 to 4 ; width of head 1 . 9 to 2 . 2 in its length ; interorbital space 6.7; 

 eye 3.7 to 4.1; nose 4.8 to 5.5; mouth terminal, oblique, maxillary to 

 middle of orbit, cleft 3 . 5 to 4 in head ; jaws equal ; gill-membranes scarcely 

 connected. Dorsal VI, 9; spinous and soft dorsals separated by a space 

 about equal to pupil; anal II, 5 or 6; separation of ventrals less than 

 half width of base; pectorals equaling head. Scales large and strongly 

 ctenoid; 33-36, oblique series 9 or 10; lateral line absent; cheeks naked; 

 opercles with a few scales; breast and neck naked. 



This, the smallest of the darters and the smallest, indeed, of our 

 spiny-finned fishes, is very rare in our collections outside those from 

 the upland lakes of northeastern Illinois. We have taken it, in 

 fact, but twice south of Joliet, in Will county, the exceptional in- 

 stances coming from Skillet fork in Wayne county, and from Drury 

 creek in Union county, in the southern part of the state. It has 

 been wanting, it will be seen, in all our central Illinois collections. 



