316 FISHES OF ILLINOIS 



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

 times 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 71 to 86 per cent, of second) ; 

 caudal faintly lunate; anal II (or I), 6 or 7; pectorals 1 to 1.3 in head; sepa- 

 ration 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 between here and middle of back 

 about J4 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 

 characteristic feature of the highly differentiated darters, 

 departs most widely from the rest in ecological situation also. It 

 has consequently the smallest coefficient of subfamily associa- 

 tion (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 (Hadropterus 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 counties 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 sluggish or 

 stagnant water and for a mud bottom 78 per cent, of our collec- 

 tions 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 every- 

 where 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 larvae 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. 



