April, 1910. Fishes of Chicago — Meek and Hildebraxd. 261 



ing surface; alimentary canal twice length of the body; peritoneum 

 black. 



Chrosomus erythrogaster Rafinesque. Red-bellied Dace. 



Head 4.0 to 4.2; depth 4.4 to 4.9; D. 7 ; A. 7 or 8; Scales 77 to 91. 



Body rather robust, not much compressed; head rather pointed; 

 mouth terminal, margin of upper lip on level with middle of pupil; 

 maxillary 3.2 to 4.0 in head; its tip reaching slightly past anterior 

 nostril; diameter of eye ^.^ to 3.8 in head; snout pointed, 2.9 to 3.5; 

 teeth 4-4 or 4-5 or 5-5, with tips slightly hooded and with flat or 

 grooved surfaces; alimentary canal 2.4 to 3.5 times length of the body; 

 peritoneum black; scales very small, 35 to 40 scales in series before 

 dorsal fin; lateral line incomplete. 



Color brownish olive, a dark vertebral streak; dark spots on upper 

 part of sides; sides with two black stripes; a dark caudal spot; 

 spaces between dark lateral stripes cream colored to red; males in 

 spring with sides and belly with much scarlet. 



Length 2 to 3 inches. 



This species inhabits clear water from the Dakotas to Maine, 

 Alabama, and Kansas. It is nowhere especially abundant except in 

 the streams of the Ozark mountains, where it occurs in large numbers. 



Bull Creek, Zion City, Illinois; Pettibone Creek, North Chicago, 

 Illinois; Hickory Creek, Alpine, Illinois; Hickory Creek, Marley. 

 Illinois; Lagoon, Pine. Indiana. 



Genus Hybo8:uathu.s Agassiz. 



Body elongate,, somewhat compressed; mouth small, the jaws 

 sharp edged; premaxillary protractile; no barbel; teeth 4-4 with 

 oblique grinding surface, little if any hook; alimentary canal 3 to 10 

 times length of the body; peritoneum black. 



Hybognathus nuchalis Agassiz. Silvery Minnow. 



Head 4.0 to 4.6; depth 3.9 to 4.5; D. 8; A. 8; scales 37 to 39. 



Body elongate, somewhat compressed; head small, subcorneal; 

 mouth small, terminal, oblique, margin of upper jaw slightly below 

 middle of pupil, maxillary 3.6 to 4.3; diameter of eye 3.8 to 4.5 in 

 head ; snout 2.9 to 3.5 ; lower jaw slightly the shorter, with sharp hard 

 edge; teeth 4-4, with narrow grinding surface, tips slightly if at all 

 hooked; alimentary canal 3.7 to 8.0 times length of the body; peri- 

 toneum dusky; scales large, 13 to 16 in a series before dorsal ; lateral 

 line complete. 



