ERICYMBA 157 



to 5.2 in length; caudal peduncle as a rule about $ length of head, 

 slender, its depth contained 2.2 to 2.9 in its length. Color pale olive 

 above, the scales rather narrowly aiid indistinctly dark-edged; sides pale 

 silvery with bluish reflections ; a dark dorsal "streak and an indistinct 

 plumbeous lateral band developed 

 posteriorly; no caudal spot; fins all 

 plain; cheeks and opercles bright 

 silvery ; iris silvery below, with some 

 dusky above; spring males without 

 bright colors. Head long for its j£ , 

 depth, depressed above, with prom- 

 inently decurved muzzle ; chin broad 

 and flat ; length of head 3.5 to 3.7 

 in body and head, its width 1 . 9 to 



2.4 in its length; interorbital space FlG 3g 



nearly flat and quite narrow, 3 . 5 to 



3 . 9 in head; eye 3 . 3 to 3 . 6 in head; suborbitals, interopercles, and lower 

 jaw-bones with greatly developed mucus channels, appearing externally as 

 vitreous streaks; nose 2 . 6 to 3 in head, always distinctly longer than eye; 

 mouth small, horizontal, subinferior, tip of upper lip below level of lower 

 margin of orbit; maxillary 3.5 to 4 in head, not reaching past anterior 

 nostril-opening; lower jaw much shorter than upper; isthmus less than 

 pupil. Teeth 4-4, or 1, 4-4, 1, rather strongly hooked, the grinding 

 surface somewhat weakly developed as a narrow groove whose edges are 

 smooth ; intestine .9 to 1.0 times length of head and body ; peritoneum 

 bright silvery, with a very few scattered dark specks. Dorsal fin with 8 

 rays, set nearly directly over ventrals, but distinctly nearer tip of snout 

 than base of caudal; longest dorsal ray 1.1 to 1.2 in head; anal rays 8, 

 sometimes 7; pectorals long, reaching nearly to ventrals; ventrals past 

 vent but not quite to front of anal. Scales 5, 32-35, 3; 13 to 15 rows 

 before dorsal; breast without scales; lateral line nearly straight. 



This interesting little fish is especially peculiar because of the 

 tubular cavities, the so-called mucus canals, in the bones of the side 

 of the head and the lower jaw. It has, on the whole, an easterly 

 distribution, ranging, according to Jordan and Evermann, from 

 Michigan and western Pennsylvania to Kansas and southward 

 to western Florida. In our collections it has been limited almost 

 wholly to the central eastern part of the state, occurring chiefly in 

 the headwaters of the minor tributaries of the Wabash and in the 

 upper course of the Kaskaskia River, and in the tributaries of the 

 Iroquois and of the Sangamon. The distribution map of the state 

 for this species suggests a relation to an eastern center, and an ex- 

 tension past the watersheds from the tributaries of the Wabash to 

 the headwaters of adjacent streams. Our 74 collections came in so 

 large a proportion from the smaller streams that the coefficient of 

 frequency for creeks is 4.85, and that for the smaller rivers is 1.06. 



