SHIRAS EXPEDITIONS TO WHITEFISH POINT. 117 



Dragon-flies: Aeschna sp., Gomphus sp., Tetragoneura sp., Sotna- 

 tochlora sp., Leucorhinia intacla Hag., Sympetnim sp., Ladonia exusta 

 Say, Libellula pulchella Drury, Plathemis lydia Drury, and Enallagma 



sp. 



Aquatic Hemiptera: Xotonecta undidata Say, Corixa sp., Ardo- 

 corisa nitida Lieb., Arctocorisa interrupta Say, Lethocerus sp., Gerris 

 remiges Say, Gerris rufoscutellatus Latr., Gerris marginatus Say. 



Alder flies: Sialis sp. 



Aquatic Diptera: Chironomus sp., Ceratopodon sp. 



Aquatic Colcoptera: Dytiscus sp., Gyrinus ventralis Kirby, Gyrinus 

 canadensis Regim])art, Dineutes nigrior IXoh. 



Crustaceans were not found in noticeable numbers anywhere, yet en- 

 tomostracans formed a prominent part of the food of small whitefish, 

 herrings, suckers, sticklebacks, and j^erch that gathered in large numbers 

 during calms on the Lake Superior shoal. The compact masses of 

 entomostracans in the fish stomachs and intestines are of an orange 

 color and frequenth^ are evident through the body wall of an undis- 

 sected fish. Analyses of the material revealed three genera and three 

 species in the stomachs of the little fish examined; these are: Bosmina 

 longirostris, Diaptomus ashlandi, and Cyclops viridis hrevispinosus. 

 Droppings of the fish were numerous on the shore at the water's edge, 

 where thej- formed minute windrows, like orange-colored strings, 

 thrown up by the gentle waves. The distribution of these small crus- 

 taceans was not studied, but they appeared verj^ scarce in shallow 

 water; none could be seen in water dipped up in a pail or bottle. The 

 marginal shoal may not be the main feeding ground for the fish, which 

 may be there for other reasons such as higher water temperature, or 

 excess of oxygen. Entomostracans were also found in the stomachs 

 of fish taken in bodies of water other than Lake Superior. 



CraN'fish were occasionally caught in the marsh lakes and were 

 quite common in their outlet streams. Cambarus virilis was the only 

 species found here, but of the two specimens taken in Shelldrake River, 

 one was Camharus virilis and the other C. propinqiius. Amphipods 

 .could be picked from masses of aquatic plants draAvn in by a net. 

 Those taken were all Hyalella knickerbockeri (Bate) and Eucrongonyx 

 gracilis (Smith). The former appear the most common and more 

 generally distributed. Amphipods also were in Lake Sui:)erior for they 

 were taken from the stomachs of Menominee whitefish. A feAv isopods, 

 Mancasellus tanax (Smith), were found on i)lant debris from the marsh 

 lakes. 



Mollusks were found in numljers by the writer only in certain phices. 

 In a small, marsh-bordered bay of Beaver Lake (Station 55), many 

 small bivalves could be taken b\^ drawing the net through the thick 



