99 



70. Seviotilus amhlops, Raf. — Silver Chub. 



(Bal. II, 62; Ceratichthys amhlops: Synop., 214; do.) 



This fish has been obtained by us not rarely in IlHnois, chiefly 

 from the Ohio and the Wabash and the larger tributaries of the 

 latter. 



71. Semotiliis biguttatus, Kirt. — Horny Head; River Chub; Jerker. 

 (Bui. II, 62; Ceratichthys biguttatus: Synop., 212; do.) 



This species seems limited, in Illinois, to creeks and rivers, and 

 has not occurred in our collections south of the center of the State. 



72. Semotilus corporaUs, Mitch. — Chub ; Horned Dace. 



Almost wholly confined to small streams, in which it is, in Illi- 

 nois, the most abundant minnow, commonest in those with muddy 

 bottom ; but a few have been obtained in the Illinois River, from 

 lakes in the Illinois bottoms, and from the Little Wabash. It 

 ranges throughout the State. 



Genus 42. Playtigobio, Gill. 

 Flat-headed Chubs. 



73. Platygobio palUdus, Forbes. "'-^'^ ' - 



A single specimen of this very rare species, obtained in the Ohio 

 River at Cairo, is the only one hitherto taken. 



Genus 43. Couesius, Jordan. 



74. Couesius prosthemius, Cope. -^^ ■ "^ " -•--/ y 



Not in our collection. Specimens from near Evanston, taken in 

 Lake Michigan, are said by Dr. Jordan to be in the National 

 Museum. 



Genus 44. Rhinichthys, Agassiz. 



75. Rhinichthys atronasus, Mitch. — Black-nosed Dace. 



(Bui. II, 62 and 63; Rhinichthys cataractce, Rhinichthys ohtusus, 

 Rkiiilchthi/'i mdenrfris: Synop., 207, 208; Rhinickthys cata- 

 ract(e, Rhinichthys atronasus, Rlilnichthys ohtusus.) 



This is essentially a brook species, delighting especially in swift 

 and rocky streams. We have not found it in Southern Illinois, its 

 localities being confined, in our expei'ince, to the northern half of 

 the State. Its relative rarity here is doubtless due to the infre- 

 quent occurrence of suitable streams. 



