72 On the Food of Young Fishes. 
The full-grown black bass, for example, feeds princi- 
pally on fishes and crawfishes, the sheepshead on mol- 
lusks, the gizzard-shad on mud and Algae, while the cat- 
fishes are nearly omnivorous; yet these are all found to 
agree so closely in food when very small that one could 
not possibly tell from the contents of the stomachs which 
group he was dealing with. 
It is my purpose in this paper to give what facts I have 
relating to the food of our fresh-water species during 
this first period of the fish’s life. These facts were de- 
rived from the examination of one hundred and twenty- 
six specimens, ranging from three-eighths of an inch in 
length up to an inch and a half, and in a few cases to two 
and three inches. These specimens belong to twenty-four 
genera and represent eleven families. In two or three 
genera none were obtained small enough to be regarded 
as belonging strictly to this first food-period, but the 
earliest food is nevertheless plainly inferable; and the 
general distribution and variety of the species studied is 
such that I think the main conclusions will be found to 
stand the test of full investigation. As the first period is 
evidently much shorter with some species than with 
others, and doubtless varies in the same species accord- 
ing to situation and circumstances generally, of course 
no common limit of size could be set up, but the smallest 
specimens of each species were selected until a size was 
reached where a marked difference of food appeared. 
Acanthopteri. 
Although the young Acanthopteri have already been 
discussed in the preceding paper on the food of that 
group, it will be convenient to review the facts concern- 
ing these young fishes for the purpose of comparing 
their food with that of the other orders. 
The food of six common perch (Perea americana ), 
from an inch to an inch and a quarter long, consisted 
wholly of Entomostraca and larvae of Chironomus — eight 
per cent. Chironomus, fifty-two per cent. Cladocera and 
forty per cent. Copepoda. 
