F 105 
It will be seen that this species apparently agrees closely with 
the preceding in its food. The large amount of crustacean food in 
he smallest specimen shows that we should probably find: still 
smaller Labracide depending upon these as strictly as the Percide. 
Family CENTRARCHIDA. The Sun-fishes. 
This interesting group, known, in some of its members, to every 
gne who has ever seen a dozen fishes, is represented, in [llinois, by 
sixteen species, as the species of this family are now understood. 
[he two black bass, included in this family for technical reasons, 
are, of course, the most important species. ‘The rock bass, the 
3roppie and the common sun-fish (Lepiopomus pallidus), although 
aot fishes of the first class, would be seriously missed if we were to 
lose them; and boyhood in the country would be quite another 
thing if it were not for the ‘‘pumpkin seed” in the mill-pond, whose 
barbaric splendor thrills the heart of the youthful fisherman as the 
pore delicate beauties of the trout or salmon do. those of tougher 
re. 
J have studied the food of thirteen species of this group, as indi- - 
cated by two hundred and thirty-seven specimens, well distributed 
in time and area. ee 
Decided differences in food made out in the various genera, have 
been found to coincide with differences in a few structures about 
the mouth in such a way that one may predict, from an examina- 
tion of these structures, what the leading peculiarities of the aver- 
age food of any genus will be. 
Microprerus pautipus, Raf. Larce-mourHeD Buack Bass. 
This famous species is too well known to require extended com- 
ment. The ordinary fishermen rarely distinguish it from the fol- 
lowing; and, indeed, sportsmen do not always recognize the differ- 
ence. 
I have examined the food of thirty-one specimens of this species, 
fourteen of which were adults, and the remainder young, of differ- 
ent ages. 
Food of the Young. 
The first group, consisting of five specimens under one. inch in 
length (ranging from % to 2 in.), represent three localities,—Crystal 
Lake, in McHenry county, the Dllinois River at Pekin, Tazewell 
county, and the same stream at Starved Rock, in LaSalle county. 
They were taken in June, July and August of. three different years. 
It is evident, therefore, that the common features of their food can 
not well be attributed to any other fact than their similar size. 
The entire food of these fishes consisted of small Crustacea,—all 
Entomostraca except seven per cent., eaten by a single fish, which 
consisted of the very young of some undetermined amphipod,— 
probabiy Allorchestes. Highty-seven per cent. of the food was 
Cladocera, principally Bosmina longirostris, Mull.  Stmpcephalus 
