316 FISHES OF ILLINOIS 



Dorsal fin IX or X, 10-12; the two portions as a rule hardly separated, 

 Sometimes apart a distance almost equal to width of orbit; height of first 

 dorsal 1.6 to 2.6 in head, second 1 . 3 to 1.9 (height of first 7 1 to 86 per 

 cent, of second); caudal faintly lunate; anal II (or I), 6 or 7 ; pectorals 



1 to 1 .3 in head; separation of ventrals about half their width at base. 

 Scales 3 or 4, 48-54, 7-8 [10-12]; lateral line with a marked upward curve 

 anteriorly, where it is parallel with line of back, the least distance be- 

 tween here and middle of back about j depth of body at same point; 25 

 to 35 lateral pores usually lacking; cheeks and opercles fully scaled; nape 

 usually scaled ; breast naked in most of our specimens ; belly covered with 

 ordinary scales. 



This rather insignificant little fish, with but few of the more char- 

 acteristic features of the highly differentiated darters, departs most 

 widely from the rest in ecological situation also. It has consequently 

 the smallest coefficient of subfamily association (1.22) among all our 

 darters — the general average coefficient for the subfamily being 



2 . 02, and the highest general coefficient of any species 2 . 69 (Hadrop- 

 terus phoxocephalus) . It has been obtained by us sixty times, most 

 of our collections coming from the southeastern part of the state, 

 but a few coming from the upland lakes of Lake and McHenry coun- 

 ties and from the upper branches of the Illinois. Several of our 

 localities are on the middle course of the Kaskaskia, and one is on a 

 branch of the Sangamon in Christian county. This is one of the 

 very few species of the subfamily which shows a preference for slug- 

 gish or stagnant water and for a mud buttqm — 78 per cent, of our 

 collections with data coming from the former and 66 per cent, from 

 the latter situation. Next to the glacial lakes we have found it 

 most abundant in creeks, and then in the smaller rivers. It seems 

 to be rare in the larger rivers and in lowland lakes and sloughs. 



In general distribution, it is reported from Massachusetts and 

 thence through Lakes Erie and Ontario to Minnesota and Montana, 

 southward to Indian River in Florida, and through the Ohio basin 

 to Mississippi and the Rio Grande. It is everywhere commonest in 

 ponds and lowland streams. Dr. C. C. Abbott, of New Jersey, found 

 it in shallow weedy streams, in water scarcely two inches deep, 

 and caught examples with a baited hook, which, in spite of their 

 small size, they seized with the quickness and voracity of a pike. 



Three specimens of this species from southern Illinois had fed, 

 like the darters generally, on larva; of gnats and May-flies, about 

 two thirds of the latter to one third of the former. 



Females containing full-sized eggs were taken by us April 28. 



