304 FISHES OF ILLINOIS 



aa. Lateral line always more or less incomplete, the number of pores lacking 

 usually 10 to 30, rarely as low as 5. 



c. Spinous dorsal fin not exceptionally low, its height as a rule 75 to 90 per 



cent, of height of soft dorsal; no enlarged dark humeral scale. 



d. Cheeks and opercles scaled. 



e. Rays of second dorsal 9 or 10; scales 55-60; rust-red spots on sides, no bars. 



iowae. 



ee. Rays of second dorsal 12 to 13 ; scales 49-57 ; brown bars on sides. . . . jessiae. 

 dd. Cheeks naked; opercles scaled; spring males with alternating red and blue 



bars cceruleum. 



cc. Spinous dorsal fin as a rule less than 60 per cent, height of soft dorsal; an 



enlarged dark humeral scale more or less conspicuous. 



f. Gill-membranes little connected, distances from muzzle to angle and to 



back of orbit not far from equal. 



g. Cheeks, opercles, nape, and breast naked; chin, cheeks, and opercles sprin- 



kled with fine dark dots; a large black humeral scale, its depth § diameter 



of eye • obeyense. 



gg. Cheeks, opercles, nape, and breast covered with embedded scales, chin and 

 cheeks with pronounced dark mottlings and vermiculations ; humeral 



scale rather small and not very black squamiceps. 



ff. Gill-membranes broadly connected, distance from muzzle to their free mar- 

 gin If to H times that to back of orbit; dorsal spines each ending in a 

 fleshy knob in the male flabellare. 



Fig. 73 



ETHEOSTOMA ZONALE (Cope) 



(banded darter) 



Cope, 1868, Journ. Ac. Xat. Sci. Phila., 212 (Poecilichthys). 



J. &G., 510"(Nanostoma);M. V., 130; B., I, 83; J. & E., I, 1075; J. ,41 (Nanostoma) ; 

 F., 65; L., 28. 



Banded darters which have a superficial resemblance to females of 

 E. cceruleum, and mav even be confused (especially in preservative) with 

 E. jessicE. From the first this species is easily distinguished by its closely 

 and finely scaled cheeks, and from both, as well as also from all other Illi- 

 nois species of the genus Etheostoma except flabellare, it may be readily 

 separated bv the broad union of the gill-membranes. Length ordinarily 

 a little less than 2 inches; body moderately elongate, considerably com- 

 pressed, the depth 4.7 to 6 in length; greatest width of body about 

 § its greatest depth; depth of caudal peduncle 2 .4 to 3 . 1 in its length. 

 Colors in life "bright olivaceous above, golden below; 6 dark brown 

 quadrate dorsal spots, which connect by alternating spots with a broad, 



