314 FISHES OF ILLINOIS 



maxillary past front of orbit; cleft 2.9 to 3.3 in head; lower jaw as long as 

 upper or slightly projecting; gill-membranes broadly connected, the distance 

 from muzzle to their free margin as a rule over 1^ times that to back of 

 orbit. Dorsal fin VII or VIII, 12-14; the two portions very closely approx- 

 imated or united at base; first dorsal very low, its height 42 to 68 per cent, of 

 height of second (height of first 3.2 to 5.1 in head, second 1.8 to 2.3); caudal 

 rounded; anal II, 7 or 8 (or 9); pectorals 1.2 to 1.3 in head; separation of 

 ventrals about half their width at base. Scales 8 or 9, 51-63, 8-10 [12-16]; 

 lateral line straight, 15 to 25 pores lacking; cheeks and opercles usually naked, 

 the latter with sometimes a trace of scales; nape naked or with very deeply 

 embedded scales; breast naked; belly covered with ordinary scales. 



The fan-tailed darter has a distribution in this state very 

 like that of the rainbow darter, although it is a less common 

 inhabitant of our streams. Of the thirty-five localities from 

 which we have taken it, but one falls within the lower Illinoisan 

 glaciation, while two are in Union county in extreme southern 

 Illinois, and the remainder are in the northern two thirds of the 

 state, mostly in northern Illinois proper, for which section the 

 frequency coefficient is 1.92. This is mainly a darter of the 

 smaller streams, usually inhabiting the swifter creeks and brooks, 

 although occasionally taken in rivers and lowland lakes. 



It is widely distributed, from Quebec and New England 

 down the Atlantic coast to the Catawba River in South Carolina, 

 westward by way of the Great Lakes and the Ohio basin to 

 Missouri and northeastern Iowa, and southward to northern 

 Alabama. 



It stands high on our list of typical darters, and Jordan and 

 Copeland say of it: ''The Darter of Darters is the fan-tail, 

 Etheo stoma flabellare. Hardiest, wiriest, wariest of them all, it 

 is the one which is most expert in catching other creatures, and 

 the one which most surely evades your clutch. * * * It is a 

 slim, narrow, black, pirate-rigged little fish, with a long pointed 

 head, and a projecting, prow-like lower jaw. It carries no 

 flag, but is colored like the rocks among which it lives. * * * 

 The Fan-tailed Darter chooses the coldest and swiftest waters, 

 and in these, as befits his form, he leads an active, predatory 

 life. He is the terror of water-snails and caddis-worms, and 

 the larvae of mosquitoes. " 



Six specimens were found by us to have made nearly two 

 thirds of their food from Chironomus larvse, about a fourth from 

 small May-fly larvse, and the rest from copepod crustaceans. 



Females apparently nearly ready to spawn are in our collec- 

 tions obtained the last of May. 



