CHROSOMUS 113 



(faint in females), the upper and narrower one extending from upper 

 corner of gill-cleft nearly straight backward to base of caudal, sometimes 

 breaking up into spots or oblique bars on caudal peduncle; the lower 

 stripe broader, extending from snout through eye and along lower portion 

 of sides to end of caudal peduncle, followed by a black spot at base of 

 caudal rays; the interspace between lateral bands a bright silvery or 

 satiny cream, tinged with brassy to crimson in males; belly white, over- 

 laid with silvery; females much more obscurely marked than males 

 which in spring coloration have the belly, breast, and chin bright scarlet, 

 and the fins a bright lemon-yellow, the dorsal with a large blotch of bright 

 scarlet at its base and the body everywhere minutely tuberculate. Head 

 rather pointed, 4 to 4.2 in length, its width 1.8 to 2; interorbital space 

 nearly flat, 2.6 to 3 in head; eye 3.3 to 3.8; nose 2.9 to'3.5, short, pointed, 

 longer than the small eye ; mouth moderate, terminal, oblique, the tip of 

 upper lip nearly at level of middle of pupil; maxillary 3.2 to 4 in head 

 (usually greater than 3 .4) , reaching but slightly past anterior nostril-open- 

 ing; jaws about equal; isthmus less than width of eye. Teeth 4-4, 4-5, or 

 5-5, long, slender, and compressed, with a long and narrow masticatory 

 groove, and with tips slightly hooked; intestine 2.4 to 3.5 times length of 

 head and body; peritoneum black. Dorsal fin with rays usually 7, in 

 occasional instances 6, placed behind ventrals and about equidistant be- 

 tween snout and base of caudal; longest dorsal ray 1.1 to 1.3 in head; 

 anal rays 7 or 8, usually 8; pectorals 1.2 to 1.5 in head; ventrals reaching 

 yent. Scales very small, 17-20, 77-91, 9-12 (not usually over 85 in Illi- 

 nois specimens), of uniform size everywhere, the exposed surfaces scarcely 

 deeper than long; lateral line incomplete, there being usually no pores 

 present on posterior half of bodv ; scales before dorsal 35 or 40. 



This beautiful species, one of the most showy in our waters, 

 occurs rarely in our collections from the northern half of the state 

 and from extreme southern Illinois. None of our twenty-two 

 localities of its occurrence falls within the lower glaciation, and all 

 but three of them are in northern Illinois. We have not taken the 

 species from Lake Michigan or from any part of the lake drainage. 

 Outside the state it has been reported from Maine and New Bruns- 

 wick to North Carolina, from Michigan, and from the Ohio Valley 

 generally to the streams of Kansas tributary to the Missouri, and to 

 northern Alabama. It is commonly found only in small clear streams, 

 and has not once been taken by us from any of the larger rivers. 



Its food is evidently obtained by nibbling or sucking the surface 

 slime from stones and other objects on the bottom. It consists, in 

 all the cases examined by us, mainly of mud containing algas with 

 an occasional trace of Entomostraca. 



The breeding season falls in May and June, at which time the 

 colors of the male reach their most gorgeous development. While 

 not especially hardy, this species lives well in the aquarium, where 

 it is indeed a most beautiful object. 



