130 FISHES OF ILLINOIS 



state. It is an exception to the general rule in the fact that it enters 

 freely the lower Illinoisan glaciation, notwithstanding its evident 

 preference for clear water. 



Gravid females occur in our June collections, and in others 

 taken as early as the 21st of ^lay. Females are uniformly smaller 

 than males, and the latter are further distinguished in spring by 

 nine large tubercles on the snout, five of them in a row just above 

 the upper lip, two additional ones between the nostrils, and one on 

 each side between the nostril and the eve. 



Gexus NOTROPIS Rafixesque 



Body oblong or elongate, either more or less compressed; mouth 

 mosth' terminal and oblique, sometimes subinferior; premaxillaries 

 protractile; no barbels; teeth in 1 or 2 rows, the main row always 4-4; 

 peritoneum as a rule pale, though often dusky, and in some species black 

 (anogenus) ; dorsal rays usually 7 or 8; anal rays ordinarily 7 or 8 (or 9), 

 in a few species 11 or 12; scales usually rather large, as a rule less than 

 40 in lateral series; lateral line complete or imperfect. Size usually 

 small, most species not exceeding 3 or 4 inches. A verv' large group, 

 embracing about 100 species, all confined to the fresh waters of America 

 east of the Rocky Mountains; 17 species in Illinois. 



Key to the Species of NOTROPIS found in Illinois 



a. Anal rays typically 7 or 8 ; occasionally 9 in two compressed forms (see bb, 



below), in which, however, scales before dorsal are not over 17, and no 

 black spot is present at base of first dorsal ravs; teeth 4-4; 1, 4-4, 1; or 

 1 or 2, 4-4, 1 or 2. 



b. Eye moderate, 2^ to 2f in head, always less than 4; body not usually much 



compressed, the back gently and broadly rounded in front of dorsal fin; 

 scales not closely imbricated; teeth 4-4; 1, 4-4, 1 ; or 1 or 2, 4-4, 1 or 2. 



c. Small species, seldom over 2\ inches in length; with (1) a black lateral stripe 



along sides and through eye to end of snout, or (2) a conspicuous dark 

 spot above and below each pore of lateral line anteriorly, or (3) pale 

 species, with no vertebral streak and the spots above lateral pores incon- 

 spicuous; teeth 4-4 or 1, 4-4, 1 (except heterodon) . 



d. Eye 3 or more in head (sometimes under 3 in heterodon, in which dark 



lateral stripe extends through eye to end of snout, tipping chin) ; small, 

 usually less than 2 k inches. 



e. Scales before dorsal large, 12 to 15 in number; teeth 4-4 (except heterodon). 



f. A black stripe along sides through eye to end of snout. 



g. Chin white; mouth small, nearly horizontal, the upper lip below level of 



lower margin of pupil cayuga. 



gg. Chin black at tip; mouth moderate or very small, oblique, tip of upper lip at 

 level of upper margin of pupil. 



h. Maxillary reaching posterior nostril; mouth moderately oblique, making 40° 

 to 60° with vertical; teeth 0, or 1, or 2, 4-4, 0, or 1, or 2; peritoneum 

 silverv heterodon. 



