314 FISHES OF ILLINOIS 



space flat, 6.2 to 8.3; eye round, 3 . 8 to 5 ; mouth rather large, terminal, 

 oblique, tip of upper lip almost on level with upper margin of pupil; max- 

 illary 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 dis- 

 tance 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 twoportions 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 witli 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 re- 

 mainder are in the northern two thirds of the state, mostly in north- 

 ern Illinois proper, for which section the frequency coefficient is. 

 1.92. This is mainly a darter of the smaller streams, usually in- 

 habiting 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 w^ay of the Great Lakes and the Ohio basin to Missouri and north- 

 eastern 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, Etheos- 

 ioma 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 pro- 

 jecting, prow-like lower jaw. It carries no flag, but is colored like 

 the rocks among which it lives. * * * xhe 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 larvas, about a fourth from small 

 May-fly larvae, and the rest from copepod crustaceans. 



Females apparently nearly ready to spawn are in our collections, 

 obtained the last of May. 



