92 FISHES OF ILLINOIS 



caudal light reddish outward, olive near base; lower fins salmon with paler, 

 greenish margins. Head extremely short, subconical, tapering both above 

 and below to the tip of the pointed snout; length of head 4.6 to 5.4 in body, 

 usually more than 5 in adults, width 6.6 to 7.6, depth 5.7 to 6.7; interorbital 

 space 1.9 to 2.4 in head, noticeably convex; chin convex; cheeks shallow, not 



vertically continuous to a flat chin as in aureolum 



and anisurum, a cross-section of the head in the 



orbital region not being squarish as in those species; 



snout 2.3 to 2.9 in head, not at all decurved; mouth 



small, upper lip rather coarsely plicate, the folds 



shallow and not continued back to the inside of the 



lip; lower lip truncate behind, the two halves scarcely 



separated at the shallow incision, the coarse but 



shallow plicse evident in front, but breaking up into 



FlG 23 irregular papillae posteriorly; eye small in comparison 



Lips of Moxostona with len S th of bod y> but contained 4 to 5 times in 



brevir.eps * ne ver y short head. Dorsal rays 12 or 13, the fin 



notably higher in front than behind, the last ray 



being less than half the length of the longest anterior ray, which is usually 



considerably longer than the base of the fin; free margin of dorsal concave; 



pectorals longer than the short head, but relatively shorter than in the two 



preceding species, scarcely reaching % of the distance from pectoral to ventral 



basis; upper lobe of caudal falcate, usually, though not always, longer than 



lower. Scales 6, 43-45,5 or 6; lateral line complete, nearly straight. 



This species occurs in the Ohio Valley and the Great Lake 

 region, being especially abundant in Lake Erie. In the Mis- 

 sissippi Valley it ranges up the Missouri to Cheyenne Falls. 

 It is especially a northern Illinois fish, only one of our collec- 

 tions made in the southern part of the state containing it, and 

 this falling outside the area of the lower Illinoisan glaciation. 

 It is about equally common in central and northern Illinois, 

 and has been more uniformly distributed, according to our 

 observations, than the other species of its genus, occurring in 

 about equal frequency, relatively to the number of collections 

 made, in the larger rivers and in creeks and lakes, but about 

 twice as abundantly in the smaller rivers. It shows also con- 

 siderably less marked preference than the preceding species for 

 clear and swiftly flowing waters. 



Genus PLACOPHARYNX Cope 



PAVEMENT-TOOTHED RED-HORSE 



Suckers like Moxostoma in all respects, except that the pharyngeal 

 bones are much more developed and the teeth reduced in number, those on 

 the lower half of the bone very large, 6 to 10 in number, nearly cylindrical 

 in form, but little compressed and with a broad and more or less flattened 



