NOTROPIS 151 



This is a small and insignificant species, without marked 

 specific characters, obviously limited by preference to the larger 

 rivers (coefficient, 1.63) and apparently avoiding the lower 

 Illinoisan glaciation. It occurs also in considerable numbers in 

 the smaller rivers (1.12), but is usually scarce, in creeks and only 

 moderately abundant in the lowland lakes. In Illinois it has 

 occurred in 51 collections, rather sparingly distributed along 

 the main streams and in their neighborhood, from the northern 

 boundary to Cairo and from the Wabash and Ohio to the Missis- 

 sippi. It is reported from the northern Mississippi Valley at 

 large, and from the Ohio basin, ranging from Kansas and western 

 Pennsylvania to Wyoming and Winnipeg. In Pennsylvania 

 it occurs only in the Ohio basin. 



The species is too small to be of any importance except as 

 food for larger fishes. 



Its breeding season is apparently late, no females with 

 swollen ovaries occurring in our collections until the last of June, 

 and specimens loaded with eggs being found by us as late as 

 August 27. The sexual differences are not noticeable. 



NOTROPIS ATHERINOIDES EAFINESQUE 



SHINER 

 (PL., P. 158; MAP XLIII) 



Rafinesque, 1818, Am. Month. Mag., 204. 



G., VII, 254 (Leuciscus rubellus), 255 (L. copii); J. & ''.., 202 (Minnilus rubellus 

 and M. dinemus); M. V., 61; J. & E., I, 293; N., 47 (Minnilus dilectus and 

 amabilis), 48 (M. rubellus and M. dinemus); J., 60; F. F., I. 6, 86 (Minnilus); 

 P., 76 (dinemus, part); L., 18 (also arge and dilectus). 



A common slender silvery minnow of the larger rivers, known especially 

 by its bright silvery color and by the posterior insertion of the dorsal fin. 

 Length 2^ to 4^ inches; general form slender, moderately compressed, 

 both back and belly about equally and very little arched, the body deepest 

 in front of dorsal fin; profile from dorsal to muzzle a gentle convex curve; 

 depth in length in typical specimens 4.9 to 5.5*. Color translucent green 

 above (olivaceous) ; sides bright silvery, the iridescent emerald, lavender, and 

 cerulean, common in other silvery minnows, being scarcely noticeable in 

 this species; scales above faintly specked, but not blotched or prominently 

 dark-edged; a narrow and rather faint dark vertebral line, and a faint plum- 

 beous lateral band from opercle to caudal; no caudal spot; cheeks and opercles 



* Specimens in some collections from Illinois have the depth as low as 4 to 4.25 in length, 

 these shorter and deeper forms seeming to grade insensibly into the typical slender atherinoides . 



