118 



it will be seen that it is provided with an especiallj* effective strain- 

 ing apparatus. The intestine is unusually short, the entire alimen- 

 tary canal measuring consiuerably less than the length of the body 

 without the head. 



The following account of its food is derived from the dissection of 

 twenty- five specimens, obtained -from Crystal Lake, Fox River, and 

 Calumet Kiver in Northern Illinois, from Peoria and Mackinaw 

 Creek in the central part of the State, and from Little Fox Kiver 

 in the Wabash Valley. The food of these specimens was purely 

 animal, a little over half consisting of insects, and a little less than 

 half of crustaceans. The larva? of Chironomus were among the 

 most important elements of the food, standing at thirty per cent, of 

 the whole. The crustaceans were all Entomostraca, and represented 

 a great vaiiety of both Copepoda and Cladocera, although none of 

 the specimens examined happened to have eaten Ostracoda. Among 

 the Cladocera recognized were Ikiphnia pidex, refrocurva, and hyalina, 

 Simoccphalas americaniis, Bosmina, Chydorus, Pleuroxus, Alona, and 

 Eurycercus ; and among the Copepoda were Cifclops thomasi, Can- 

 thocamptus, Diaptomus, Limnocalanus, and Epischura lacustri.'i. 

 Spiders and terrestrial insects, accidently washed or fallen into the 

 water (the latter including Chalcididte, various Diptera, plant-lice, 

 Tettigonidie, Thrips, and Podura), amounted to twelve per cent, of 

 the food. The only peculiarities of food corresponding to differences 

 of locality were found among the group from the northern lakes, in 

 which the Chironomus larvae were present in diminished ratios, while 

 the Cladocera were more abundant. 



Family CYPEINODONTID.E. 



This family consists, in Illinois, of four species, one of Fundulus 

 and three of Zygonectes.* The family is divided into two sections, 

 carnivorous and herbivorous, by Dr. Giinther in his "Introduction to 

 the Study of Fishes." Although our genera both belong to the car- 

 nivorous section, it will be seen that they are not by any means 

 strictly confined to animal food, vegetation making about one fifth 

 of their usual nutriment. 



Fu^^DULUS DiAPHNUS, LcS. Barred K.llifish. 



This species is very abundant in the northern portion of the State, 

 especially in lakes or in clear and sandy streams, but we have not 

 taken it anywhere in ('entral or Southern Illinois. Most of our 

 collections were made in the lakes of Lake and McHenry counties. 



The intestine is shorter than the body, the gill-rakers are short, 

 obtuse, and few in number, the pharyngeal jaws are of the pave- 

 ment type, set with tine, sharp teeth, and the mouth is small, but 

 extraordniarily protractile. 



Eight specimen* were studied, from Crystal and Cedar Lakes. 

 About four tiftlis of tiie food consisted of animal substances, the re 

 maining fifth of vegetation. Except a few tilamentous Algie taken 



* 1 do not consider Finiduluf! menona. Jor. and Cope, as distinct. 



