298 , FISHES OF ILLINOIS 



It was also impossible to distinguish any correlation, even 

 approximately constant, between robustness of form and 

 scaliness of cheeks and breasts, both stout and slender forms 

 having these parts sometimes naked and sometimes more or less 

 covered with scales. The larger percentage of specimens with 

 scaly breasts and cheeks came from the Rock River basin, from 

 the northwest district, and from the Lake Michigan drainage; 

 but in all these districts scaly and naked specimens were inter- 

 mingled, the latter preponderating. In collections from the 

 Kaskaskia, the Saline, the Cache, and the lower Wabash Valley, 

 on the other hand, both cheeks and breasts were almost in- 

 variably naked, while in the upper Wabash streams and in the 

 Illinois basin the two forms were indiscriminately commingled. 

 The larger number of the stouter specimens came from the Rock 

 River system and the northwest area, while those from the Kas- 

 kaskia, the Cache, and the Saline were of more slender propor- 

 tions, with the depth usually nearer six times than five times 

 the length. Similar study of specimens from a wider range 

 would probably show that Illinois is in a region of transition 

 between two varieties of this species — the typical nigrum, 

 with slender body and naked breast and cheeks, and some 

 scaly-cheeked variety, probably near olmstedi, or perhaps 

 identical with it. 



BOLEOSOMA CAMURUM Forbes 



(Map XCI) 



Forbes, 1878, Bull. ni. State Lab. Nat. Hist., XL 2, 40. 



J. & G., 494 (Vaillantia camura and V. chlorosoma); M. V., 130 (Etheostoma); B., 

 I, 96; J. & E., I, 1060; F., 66; L., 27. 



A small species, not reaching more than 1^ inches in length in our col- 

 lections; superficially resembling B. nigrum, but differing' distinctly from it 

 in its less angular head and less pointed snout, less protruding eyes, and 

 widely separated dorsals. The small size, the finely and fully scaled cheeks 

 and breast, and the peculiar ring-like light areas on the back between the 

 quadrate dark blotches will usually serve for its recognization. Length 1% 



