ETHEOSTOMA 309 



and the fan-tailed darters, the other relatively abundant species 

 of its genus. These are .37 for the first of the above-named 

 species, .77 for the second, and 1.27 for the third, an average of 

 .8, to be compared with the general subfamily average of 2.02, 

 and with one of 5.54, which is the mutual associative coefficient 

 of the three other species of the group. It has, in short, been 

 found by us in company with the three other common species 

 only about one seventh as frequently as they have been found 

 with each other. 



The species has occurred nearly three times as frequently in 

 central, and nearl}^ twice as frequently in southern, as in north- 

 ern Illinois. Notwithstanding this indifferent distribution as 

 to the kinds of waters it inhabits, our data of situation indicate 

 a decided preference for a strong current and a bottom of rock 

 or sand. It is a very common species in the Illinois at Havana 

 and Meredosia, 88 of our collections haidng come from that 

 situation, usually conspicuous by the absence of other darters. 



It is reported outside Illinois from Devil Lake and Tiffin 

 River, Michigan, through Indiana and Iowa to Mississippi,, 

 Arkansas, Oklahoma, Texas, and the Rio Grande, and also from 

 the Etowah River in Georgia. 



Its food consists of larvae of May-flies and Chironomus 

 larvae, taken by the specimens studied in about equal quantity. 



Females with large eggs were caught in the middle of March, 

 but others captured May 12 had not yet spawned. Craig, 

 however, reports it spawning at Havana in April and May, 1898. 

 Males still retained their breeding colors in August, 1903. 



ETHEOSTOMA CCERULEUM Storer 



RAINBOW darter; SOLDIER-FISH 



(]\Iap XCV) 



Storer, 1845, Proc. Bost. Soc. Nat. Hist., 47. 



J. & G., 517 (Poecilichthys); M. V., 133; B., I, 71; J. & E., I, 1088; N., 34 (Pceci- 



lichthys coeruleus and spectabilis) ; J., 41 (Poecilichthys variatus and spectab- 



ilis); F., 64; L,., 29. 



Length 2 inches; robust, rather deep and compressed, and back, es- 

 pecially in males, more or less elevated; depth 4.7 to .5; greatest width about 

 % greatest depth; depth of caudal peduncle 2.1 to 2.5 in its length. Color 

 dark olive, overlaid with dusky to bluish (or brilliant indigo-blue) bars and 

 blotches; scales of sides each with a dark central spot, these forming more 

 or less longitudinal rows most distinct in females and in the so-called variety 

 spectahile*; back with 7 or 8 rather obscure quadrate blotches; sides of males 



* E. cceruleum speclabile (Agassiz), Jordan & Evermann, 1896, Bull. U. S Nat Mus ,No 

 47, Pt. I., p. 1089. 



