The Food of the Smaller Fresh - Water Fishes. 
77 
and Cymatopleura and other diatoms, and spores of Ustilago, were 
the vegetable elements, while the head of a Chironomus larva and 
great numbers of the ciliate infusorian Euglena viridis , and a 
few specimens of Euglena acus , represented the animal kingdom. 
Full half the contents of these intestines consisted of the Proto- 
zoa mentioned. A third specimen of the same length, taken from 
the Illinois River in June, had derived about eight-tenths of its 
food from Bosmina, the remainder consisting of a small Chirono- 
mus larva and a minute larval hydrachnid. In a specimen seven- 
tenths of an inch long, taken in Mackinaw Creek in August, Eu- 
glena viridis was the most abundant object, making about six- 
tenths of the food; and Euglena acus and a species of Phacus 
also occurred. Various filamentous Algae, specimens of Closter- 
ium and Cosmarium, and numbers of diatoms were the remaining 
elements. In another specimen, taken at the same time and 
place, about three-fourths of an inch in length, fungi and fungus 
spores amounted to more than half the food, although the same 
forms of Algae occurred as before, together with a few examples 
of Euglena viridis and Difflugia. A Chironomus larva, a plant- 
louse, and some other insect not determined, had also been eaten. 
From the above we may conclude that the young Cyprinidae 
draw almost indiscriminately, for their food supply, upon Protozoa, 
Algas, and Entomostraca, differing in this respect from the young 
of all the other families which I have studied, with the exception 
of the Catostomidm. It is worthy of note, as a suggestive coin- 
cidence at least, that the other families just mentioned which were 
found to take Entomostraca and Chironomus larvm as their earli- 
est food, were all possessed of raptatorial teeth on the jaws when 
very young; whereas in young suckers and Cyprinidas, the mouth 
is unarmed at all ages. 
Group I. 
Intestine long. Pharyngeal teeth not hooked, with grinding surface. 
Campostoma anomalum, Raf. Stone Lugger. 
This very peculiar fish is exceedingly abundant everywhere ex- 
cept in the great lakes. I have taken it in streams of all magni- 
tudes, from the Illinois River to the smallest creeks, but have not 
yet encountered it in Lake Michigan or in stagnant pools. It is 
commonest, however, in swift creeks of medium size. 
