The Food of Fishes. 
25 
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 (larvae of Phryganeidae). Sixty-six 
per cent, of the food was Chironomus larvae, seven per 
cent, larvae of other minute Diptera, and the remaining 
twelve per cent, was larvae of small ephemerids, and a 
few Cyclops. 
I studied the food of two specimens of Pa’dlichthys 
variatus, four of P. spectabilis, and two of P. asprigenis 
— making eight of the genus, representing six localities. 
Fifty-eight per cent, of small larvae of Diptera (forty- 
nine per cent, of Chironomus), thirty- two per cent, of 
larvae and pupae of small ephemerids, and ten per cent, of 
case-worms made up the entire bill of fare. 
Pereina 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, of the smallest of our Amphipoda, Allor- 
chestes dentata (Smith), Faxon. Most of the Entomos- 
traca were Cladocera, including Daphnia, Eurycercus, 
and Daphnella.f 
Here occurred the only instance of molluscan food in 
the group. One specimen had taken a few individuals of 
Ancylus rivularis, Say. Reduced ratios of Chironomus 
and ephemerid larvae, and a few Corixa tumida complete 
the list. 
Of Ncmostoma zonale, less common than the others, but 
two individuals were examined, and these had eaten 
nothing but larvae of small Diptera, including sixty-five 
per cent, of Chironomus. 
* Boleosoma maculatum and B. olmstedi should undoubtedly be united. 
Specimens in the laboratory collection present the extremes of both forms, 
together with numerous intermediate stages of each character used to 
distinguish them. 
This whole group exhibits a surprising variability, perhaps due to its 
comparatively recent origin. 
t Daphnella was found in a Pereina from the Calumet River, at South 
Chicago, but not in condition to permit the determination of the species. 
