HADROPTERUS BLACK-SIDED DARTERS 289 



Represented in our collections by a single specimen, taken from 

 Rock River in 1877, still identifiable but in poor condition for de- 

 scription. Outside of Illinois taken in the Wabash and Maumee 

 basins in Indiana, and west and southward to central Iowa, Arkan- 

 sas, Kentucky, and Tennessee, "in the larger clear streams." 



>^X/% 



Fig. 69 



HADROPTERUS SCIERUS vSwain 



Swain, 1883, Proc. U. S. Nat. Mus., 252. 



M. v., 127 (Etheostoma) ; B., I, 80 (Etheostoma) ; J. & E., I, 1037. 



Length of our specimens 2 to 2^ inches*; form and appearance of 

 H. aspro; depth 6 to 6.7; greatest width f of depth; depth caudal ped- 

 uncle 2 .9 to 3.1 in its length. Color essentially as in H. aspro; yellow- 

 ish olive, with back and upper part of sides vaguely blotched with black 

 in longitudinal pattern, and with a median lateral row of 8 or 9 large 

 and more or less confluent dark blotches; a faint central caudal spot 

 with a smaller one above it and a larger one below, the central spot 

 more or less merged with the lower one; under side of caudal peduncle 

 with small dark blotches ; suborbital bar wanting entirely in our speci- 

 mens; dorsals, caudal, and pectorals faintly barred. Differs from H. 

 aspro in the presence of 3 caudal spots, the lack of the suborbital bar, and 

 in the blotching of under side of caudal peduncle. Head pointed, 4 to 

 4.2; width of head 2.1 to 2.4 in its length; interorbital space 4.7 to 

 4.9; eye 3.5 to 4.1; preopercle not serrulate; nose 3.6 to 3.8, short; 

 mouth smaller than in H . aspro, the maxillar}^ scarcely reaching front of 

 orbit, the cleft 3.4 to 3.9 in head; lower jaw included; gill-membranes 

 broadly connected, the distance from muzzle to free posterior margin 

 of membranes about IJ times that from muzzle to back of orbit. Dorsal 

 fin X or XII, 13; spinous and soft portions separated by a distance 

 equal to width of eye; height of first dorsal 2 to 2.2 in head, second 

 1.7 (height of first 79 to 85 per cent, of second); caudal lunate; anal 

 II, 9; pectorals 1 . 1 in head; separation of ventrals equal to or a little 

 greater than their width at base. Scales 7, 64-67, 11 [15 or 16]; 1 to 

 13 pores lacking; cheeks and opercles fully scaled; nape scaled; breast 

 naked and belly closely scaled. 



*"5 inches" (Jordan and Evermann). 



