The Food of the Smaller Fresh - Water Fishes. 
79 
The alimentary canal is two or three times the length of the 
body, and the gill-rakers are fifteen in number and somewhat 
more prominent than usual, those on the posterior part of the first 
arch being about one-third the length of the corresponding fila- 
ments. 
Only four specimens were studied, one from the Pecatonica 
River at Freeport, and three from Otter Creek in Jersey County. 
With this fish as with the preceding, about three-fourths of the 
contents of the intestine consisted of mud, the remainder beinxr 
almost wholly insfects. These were partly terrestrial species, oc- 
curring accidentally in the water, and partly aquatic larvae of Dip- 
tera. The vegetable food of these specimens amounted only to 
about one per cent., chiefly various unicellular Algae. 
Hyborhynchus notatus, Raf. Blunt-nosed Minnow. 
This extremely abundant minnow occurs in streams and rivers 
throughout the State, but has not been found by us in ponds. 
Specimens were taken, however, in the small lakes of Northern 
Illinois. 
The intestine is about two and one-half times the length of 
O 
the head and body. The gill-rakers are few, short* and thick, 
being about one-fifth of the length of the corresponding filaments. 
Nine specimens were studied from all parts of the State, when 
their food proved to be so uniform in character that further obser- 
vations were deemed unnecessary. Mud made about eighty per 
cent, of the contents of the alimentary canal, the remainder con- 
sisting of unrecognizable vegetable debris, with a few filaments 
of Alga?. Undeterminable insects occurred in- one, and a single 
specimen of Cypris in another. 
Hybognathus nuchalis, Ag. Blunt-jawed Minnow. 
This species is likewise generally distributed in rivers, creeks 
and ponds, occurring in our collections from Galena to Cairo, and 
at a great number of points intermediate. 
The alimentary canal in this genus is elongate, being about lour 
times the length of the body. The gill-rakers are few and rather 
short, triangular in form, and about one-fourth to one-fifth the 
length of their corresponding filaments. 
Eight specimens of this species were dissected, with results in 
