181 



Six of this species had eaten only insectB, and these made ninety 

 per cent, of the food of two otliers. One had filled itself with the 

 larvae of Bihio aUnpcun'i^, a terrestrial gnih ahnndant in early spring. 

 Three from Peofia Lake, ciptiired in Octoher, had eaten Cladocera 

 only, nearly all a single species, Bosvihia hnui'iroHtrU. 



PnoTOOKMS ANALOSTANUS, Grd. Silver Fin. 



Excessively abundant in streams of all sizes. 



The gill-raker-s 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 nisects, seven per (^eut. tishes. taken by three indi- 

 viduals, and one f)er 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- neuropterous larvae 

 being the most important, aquatic forms. The vegetable food 

 (twenty-nine per cent.) was nearly all of terrestrial origin, about 

 oae third consisting of Aigae, both filamentous and unicellular, in- 

 cluding Spirogyra and Gkeocystis. Seeds, anthers, and pollen of 

 plants, and fragments of grass-like vegetation were noticed. 



Eight of the specimens had taken only msects, and in two others 

 these amounted to ninety-five per cent. Two had fed upon terres- 

 trial 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. 



Phenacobius scopjfekus, Cope. 



This species occurs not very abundantly throughout the State, 

 from Galena to extreme Southern Illinois. It has been taken by us 

 almost invariably in swift and shallow streams. 



The mouth is small and inferior, provided with fleshy lips some- 

 what resembling a sucker's in form. The gill-rakers and pharyngeal 

 teeth are as usual in this group, and the intestine is contained once 

 and a half in the length of the head and body. 



The nine specimens studied were from five localities, distributed 

 from Galena to Union county. The food was almost purely insects, 

 only two per cent, being unrecognized vegetation. Seventy-six per 

 cent, consisted solely of Chironomns larv.e. and six per cent, of 

 case-worms. Adult chironomids, taken by two of the specimens, 

 amounteil to two per cent. A few Cyclops found in a single speci- 

 men were the only Crustacea eaten b'y these fishes. 



The peculiar character of this food, almost precisely that of a 

 darter, is evidently related to the habitat of the fish.* 



*Fnr M flisoiission of tlii^ m;itt<'r. sf^ft Bnltetin 3 of this ^crif s. p. 25. 



