94 A 
a 
of the larve of Chironomus*—a small, gnat-like insect, —twelve per 
cent. of the larve of other small diptera, and the remaining seven 
per cent. of ephemerid larve (May flies). y 
Twelve specimens of the genus Alvordius were studied—seven of 
maculatus and five of phoxocephalus. These represented five different 
localities and dates. This is a larger species than the preceding, 
and to this fact is probably due the predominance (seventy-five per 
cent.) in its food of the larve and pupe of May flies (Hphemeride), 
These included four per cent. of the larve of Palingenia bilineata, 
Say, one of the largest ephemerids in our streams. The remaining 
kinds were larve of dragon flies (Agrionide), four per cent.; larve 
of Chironomus, seven per cent., Coriza tumida, Uhl., thirteen bey 
cent., and Cyclops, one per cent. 
The genus Boleosoma, regarded by Dr. Jordan as the typical 
darter, was represented by twelve specimens from eight localities — 
nine of maculatum, two of olmstedi and one of camurum.+ These 
specimens show but slight food differences from other darters of 
similar size; the only notable variation being the appearance of 
fifteen per cent. of case-worms (larve of Phryganeide). Sixty-five 
per cent. of the food was Chironomus larve, seven per cent. larvae 
of other minute diptera, and the remaining twelve per cent. was 
larve of small ephemerids, and a few Cyclops. A 
I studied the food of two specimens of Pecilichthys variatus, four 
of P. spectabilis and two of P.asprigenis—making eight of the genus, 
representing six localities. Fifty-eight per cent. of small larve of 
diptera (forty-nine per cent of Chironomus), thirty-two per cent. of 
larve and pup of small ephemerids, and ten per cent. of case 
worms made up the entire bill of fare. 
Percina caprodes, the largest of the group, departs from all the 
foregoing species by the prominence given to crustacean food—thirty. 
per cent of Entomostraca and three per cent. the smallest of our 
Amphipoda, Allorchestes dentata, (Smith) Faxon. Most of the En- 
tomostraca were Cladocera, including Daphnia, ' Kurycercus and 
Daphnella.? 
Here occurred the only instance of molluscan food in the ovoup. 
One specimen had taken a few individuals of Ancylus rivularis, Say. 
Keduced ratios of Chironomus and ephemerid larve, eu a | 
Corixa tumida complete the list. 
Of Nanostoma zonale, less common than the others, but two indi 
viduals were examined, and these had eaten nothing but larvee of 
small diptera, including sixty-five per cent. of Chironomus. " 
3 
— 
*The larve of Chironomus are among the most important elements of fish food in our 
waters, appearing in abundance in the stomachs of the young of a great variety of species. | 
They have been too little studied in this country tu allow specific determination. - 
t Boleosoma maculatum and B. olmstedi should undoubtedly be united. Specimens in 
the laboratory collection present the extremes of both forms, together with numerous in- 
termediate stages of each character used to distinguish them 
This whole group exhibits « surprising variability, perhaps due to its comparatively 
recent origin. 
t Daphnella was fonnd in a Pereina from the Calumet River, at South Chicago, but not 
in condition to permit the determination of the species. 
