The Food of the Smaller Fresh - Wafer FMes, 77 



ami Cvniatdpleura 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 A'i((//etta vt'ridis, and a 

 few specimens of EiKjlena acus^ represented the animal kingdom. 

 Full half tlie 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, J-Ju- 

 [jlena viridiK was the most abundant object, making about six- 

 tenths of the food; and Eufflena acim and a species of Phacus 

 also occurred. Various filamentous Alg;v, specimens of Closter- 

 ium and Cosmarium, and numbers of diatoms were the remaining 

 elements. In another specimen, taken at the same tini(^ 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 Euglota mridis 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 Cyprinida^ 

 draw almost indiscriminately, for their food supply, upon Protozoa, 

 Alg:e, and Entomostraca, differing in this respect from the young 

 of all the other families which I have studied, witli the exception 

 of the Catostomid;!?. 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 larv;« as their earli- 

 est food, were all possessed of raptatorial teeth on the jaws when 

 very young; whereas in young suckers and Cyprinid.e, the mouth 

 is unarmed at all ages. 



Group I. 



Intestine long. Pharyngeal teeth not hooked, with grinding surface. 



Campostoma axoialu.m, Raf. Stone LuGtiKit. 



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 liave not 

 yet encountered it in Lake Michigan or in stagnant pools. It is 

 commonest, however, in swift creeks of medium size. 



