Percoidea, or Perch-like Fishes 311 
First among the darters because largest in size, most perch- 
like in structure, and least degenerate, we place the king darter, 
Percina rex of the Roanoke River in Virginia. This species 
reaches a length of six inches, is handsomely colored, and looks 
like a young wall-eye. 
The log-perch, Percina caprodes, is near to this, but a little 
smaller, with the body surrounded by black rings alternately 
Fic. 244.—Log-perch, Percina caprodes (Rafinesque). Ticking Co., Ohio. 
large and small. In this widely distributed species, large 
enough to take the hook, the air-bladder is present although 
small. In the smaller species it vanishes by degrees, and in 
proportion as in their habits they cling to the bottom of the 
stream. 
The genus Hadropterus includes many handsome species, 
most of them with a black lateral band widened at intervals. 
Fic. 245.—Black-sided Darter, Hadropterus aspro (Cope & Jordan). 
Chickamauga River. 
The black-sided darter, Hadropterus aspro, is the best-known 
species and one of the most elegant of all fishes, abounding in 
the clear gravelly streams of the Ohio basin and northwestward. 
Hadropterus evides of the Ohio region is still more brilliant, 
