196 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. V. 



Family XVII. Percidse. 

 THE PERCHES. 



Body more or less elongate, terete, or moderately compressed; 

 mouth terminal or inferior, small or large; the premaxillaries pro- 

 tractile; teeth usually villi^orm, on jaws, vomer and palatines (occa- 

 sionally they are absent on vomer and palatines) ; scales usually small, 

 ctenoid ; opercle usually ending in a flat spine ; branchiostegals 6 or 7 ; 

 gill membranes free or connected; lateral line usually present, never 

 extending on the caudal fin ; dorsal fins 2 , the first composed of 6 to 15 

 spines; ventral fins thoracic, each with one spine and 5 soft rays; 

 caudal fin truncate, lunate, or rounded. 



Subfamily Ethostomatinae. 

 77. Etheostoma Rafmesque. 



Etheostoma Rafinesque, Journ. de Phys. etc., Paris, 1819, 419. 



(Type restricted by Cope & Jordan to Etheostoma flabellare P_af.) 



Oligocephalus Girard, Proc. Acad. Nat. Sci. Phila., 1859, 67. 



(Type, Boleosoma lepida Baird & Girard.) 

 Torrentaria Jordan & Evermann, Bull. 47, U. S. Fish Comm., 1896, 



1080. (Type, Etheostoma australe Jordan.) 

 Rafinesquiellus Jordan & Evermann, Bull. 47, U. S. Fish Comm., 



1896, 1082. (Type, Aplesion pottsii Girard.) 



Body robust or rather elongate, somewhat compressed; mouth 

 terminal or subinferior; premaxillaries not protractile; teeth rather 

 strong, usually present on vomer and palatines; gill membranes 

 separate, or more or less broadly connected; scales moderate or small, 

 ctenoid; no scales on top of head; scales on belly persistent, of the 

 ordinary sort ; dorsal spines 7 to 15; anal spines i or 2 ; vertebrae us- 

 ually 33 to 39. 



The darters comprise a large group of small, highly colored fishes 

 inhabiting the streams of North America east of the Rocky Moun- 

 tains; one species, Etheostoma pottsii, occurs in a Pacific coast stream. 



KEY TO THE SPECIES OF ETHEOSTOMA. 

 a. Anal spine single; gill membranes connected; PAGE 



scales in the lateral series 58 to 66 australe 197 



aa. Anal fin with two spines; gill membranes not 



connected, 

 b. Head rather large, 3^ to 3% in the body; 



scales in the lateral series 44 to 50 pottsii 197 



bb. Head smaller, 4% in the body; scales in the 



lateral series 48 to 54 lepidum 198 



