The Food of the Smaller Fresh- Water Fishes. 
87 
made two-thirds of the food, nearly two-thirds of them being ter- 
restrial. Neuropterous larvae were the principal aquatic forms, 
chiefly case-worms and larvae of epheinerids. The Crustacea 
( twenty-two per cent. ) were all Entomostraca, about two-thirds 
of them Cladocera, the remainder Copepoda. Among the former 
Bosmina and Chydorus were recognized, and Diaptomus among 
the latter. 
Six of this species had eaten only insects, and these made 
ninety per cent, of the food of two others. One had filled itself 
with the larvae of Bibio albipennis , a terrestrial grub abundant in 
early spring. Three from Peoria Lake, captured in October, had 
eaten Cladocera only, nearly all a single species, Bosmina lon- 
girostris. 
Photogenis analostanus, Grd. Silver Fin. 
Excessively abundant in streams of all sizes. 
The gill-rakers are short, triangular, about one-fourth of the 
length of the filaments. The intestine is shorter than the head 
and body. 
Thirty-three specimens of this species were examined. Two- 
thirds of the food was insects, seven per cent, fishes, taken by 
three individuals, and one per cent, spiders, bringing the ratio of 
animal food up to seventy-one per cent. Besides these, a Limnaea 
was eaten by one, and traces of Cladocera and Copepoda occur in 
three. Nearly half the insects were terrestrial, Corixa and neu- 
ropterous larvae being the most important aquatic forms. # The 
vegetable food (twenty-nine per cent.) was nearly all of terrestrial 
origin, about one-third consisting of Algae, both filamentous and 
unicellular, including Spirogyra and Gloeocystis. Seeds, anthers 
and pollen of plants, and fragments of grass-like vegetation were 
noticed. 
Eight of the specimens had taken only insects, and in two others 
these amounted to ninety-five per cent. Two had fed upon 
terrestrial species only. Corixa made ninety-five per cent, of the 
food of one. One had fed solely upon filamentous Algae, and 
ninety per cent, or more of the food of three others consisted of 
vegetable structures in general. 
