On the Food of Young Fishes. 
79 
of unicellular Algae ( sixty- tliree per cent.), of which only 
Protococcus and Closterium were recognized. Specimens 
of Anuraea were reckoned at twenty-seven per cent., and 
the remainder of the food consisted of Copepoda and 
Cladocera. These specimens were taken from the Illinois 
E., in early June. 
Four carp-slickers (Carpiodes), seven-eighths inch -to 
two inches long, taken from the Illinois and from Clear 
L., in Kentucky, had fed like the preceding genus, except 
that the Entomostraca were in larger quantity (forty- 
eight per cent.), and included a number of Ostracoda, 
while the rotifers were comparatively few. The Daph- 
niidae of the Illinois E. specimens were nearly all Scaph- 
oleheris mucronata. Canthocamptus in trivial numbers 
was also found in a single specimen. 
Keviewing the food of these thirty young suckers, we 
see that they differ from the other families studied in the 
larger foocl-resonrces open to them; for, while the struc- 
ture of their mouths does not prohibit their taking Ento- 
mostraca, it enables them to draw upon the multitudes of 
minute organisms found upon the bottom. Evidently 
they have no means of selecting such microscopic struc- 
tures from the mud in which these most frequently rest, 
and considerable quantities of dirt are consequently 
often found in the intestines; but from the “richness” of 
the contents I infer that they doubtless have the power 
of distinguishing mud containing a large percentage of 
organic matter from relatively barren portions. 
SlLURIDiE. 
Numerous specimens of the young of this family show 
that, notwithstanding its many peculiarities of structure 
and habit, it is no exception to the general rule respect- 
ing the food of the young. The smallest of these speci- 
mens were from a little school of minute fry, taken in 
June from the friendly protection of an old oyster-can in 
the Illinois E. These little creatures were colorless and 
seemingly almost helpless, and only three-eighths of an 
inch in length. They had already begun to eat, however, 
and their stomachs were well filled with Cyclops and a 
