1882.] and Adjacent Waters. 539 



is not impossible that the food supply of young fishes is some- 

 times thereby materially diminished. 



In short, it would be difficult to mention a single group of 

 aquatic or semi-aquatic animals or plants, whose interests are not 

 affected, immediately or remotely, by these little animals. 



But they have other claims upon our attention besides their 

 importance in the general system of aquatic life. To the student 

 of classification, they offer a fresh and inviting field of original 

 work ; the physiologist and the histologist may examine here the 

 animal organs and tissues reduced almost to their lowest and 

 simplest terms, and yet easily studied in detail, while they still 

 form living parts of living organisms ; and those attracted by 

 natural beauty (as who is not ?) will find few lovelier objects for 

 the microscope, or more admirable illustrations of the play of life 

 than these exquisite, crystalline specks, each comprising within 

 its minute anatomy a system of organs and structures which for 

 complexity and for perfection of detail, would scarcely discredit 

 a butterfly or a fish. 



I know of but one contribution to an exact knowledge of the 

 Entomostraca of Lake Michigan— a brief paper by Professor E. 

 A. Birge, containing a list of nine species of Cladocera found in 

 the Chicago water supply/ with a description of Latona setifera 

 O. F. M.; and I have seen nothing upon those of any other of 

 the great lakes, except the notes on a few Cladocera published by 

 Professor S. I. Smith in his paper on the invertebrate animals of 

 Lake Superior. 2 



On the smaller Crustacea of the region adjacent to the lakes, 

 we have the valuable " Notes on Cladocera," 3 by Professor Birge, 

 and a paper by the writer on the Crustacea of Illinois. 4 



The Jake material upon which the present paper is based, was 

 obtained chiefly by the towing-net and dredge in Grand Traverse 



1 Notes on Crustacea in Chicago Water Supply, with remarks on the Formation of 

 the Carapace. By E. A. Birge, Professor of Zoology, University of Wisconsin, 



Dec., 1881, pp. 584-590, Pi! 1 and n. 



Sketch of the Invertebrate Fauna of Lake Superior. By Sidney I. Smith, 

 United States Commissioner of Fish and Fisheries. Part II. Report of the Com- 



s Transactions of the Wisconsin Academy of Sciences, Arts and Letters, Vol. IV, 



: -on,Wis., lS 79 ,pp. 77-110,' and PI. I ami IT. 

 'Bulletin of the Illinois - : >ry, No. 1, December, 1876, 



PP- 3-25. and PI. 1. 



