On the Food of Young Fishes. 
75 
well filled with mud with only a slight sprinkling of uni- 
cellular Algae. 
Mucli as these young resemble young Cyprinidse, they 
can be easily distinguished from them by the very long 
anal fin; and from the brook silversides (Labidesthes), 
to which they bear some superficial resemblance, by the 
absence of a spinous dorsal. 
These twelve fishes, all under two inches in length, had 
eaten about ninety per cent, of Entomostraca, two per 
cent, of Chironomus larvae, and for the remainder, Algae. 
The Crustacea were about equally Cladocera and Copep- 
oda. Among the former were Daphnia pulex , - Simo- 
cephalus americanus , Ceriodaphnia dentatci, Bosmina, 
Cliydorus and Alona. In a specimen three-quarters of an 
inch long which I took from the stomach of a M or one 
interrupta, I found a few specimens of Leptodorci hya- 
lina (?) Lillj. The Copepoda were all Cyclops, so far as 
recognizable. 
Cyprinid^:. 
A single minute minnow, three-eighths of an inch long, 
which I could not determine specifically, had eaten Daph- 
nids (twenty-five per cent.) and Chironomus larvae.. 
The specimens of the common chub minnow ( Semotilus 
corporalis), ranging from five-eighths inch to one inch, 
indicate somewhat doubtfully an exception to the general 
rule respecting the early food of fishes. Only seven per 
cent, of their food was Entomostraca, and the whole re- 
mainder consisted of filamentous Algae. It should be 
noted, however, that twenty per cent, of the food of the 
smallest specimen, w r hich was five-eighths of an inch 
long, was Cyclops, and it may be that Semotilus lives 
wholly on Entomostraca at first, merely changing its 
habit earlier than most of its allies. 
Two specimens of Notropis, an inch and a half in 
length had eaten nothing but Daphnids. 
Catostomidje. 
Thirty specimens, representing five genera of this pe- 
culiar family, were studied. A very curious feature of the 
food of the young is the frequent dependence of suckers 
