The Food of the Smallei- Fresh- Water Fishes. 87 



made two-thirds of the food, nearly two-tliirds of them being ter- 

 restrial. Neuropterous larv;i; were tlie principal a([uatic forms, 

 chiefly case-worms and huva' of ephenuM-ids. The Crustacea 

 ( twenty-two per cent. ) were all Entomostraca, about two-thirds 

 of them Cladocera, the remainder Copepoda. Amoiiir 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 larvje of Jiiblo alhi^yeu/iis, 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- 

 yirostris. 



Photogenis analostanus, Grd. Silver Fin. 



Excessively abundant in streams of all siz(>s. 



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, fislies, taken by 

 tln'Pe individuals, and one per cent, spiders, l)ringing the ratio of 

 animal food up to seventy-one per cent. Besides tliese, a Limniea 

 was eaten by one, and traces of Cladocera and Copepoda occur in 

 three. Nearly half the insects were terrestrial, Corixa and neu- 

 ropterous larva' being the most important aquatic forms. The 

 vegetable food (twenty-nine per cent.) was nearly all of terrestrial 

 origin, about one-third consisting of Alga.', both filamentous and 

 unicellular, including Spirogyra and Glceocystis. Seeds, anthers 

 and pollen of plants, and fragments of grass-like vegetation were 

 noticed. 



Eight of the specimens had taken oidy 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 Alg<e, and 

 ninety per cent, or more of the food of three others consisted of 

 vegetable structures in general. 



