PREFACE. 



It is with the hope that the following paper may be of service to some who, 

 like myself, were interested in the many and varied forms found in every stag- 

 nant pool as well as in the lakes and ponds of our country, but who were unable 

 to find any connected account of them, that it is offered to such, as a contribution 

 toward a better understanding of a little known order of the natural kingdoms. 



The lakes within a radius of ten miles of Minneapolis have furnished all the 

 material examined, and the supply is not exhauated by any means. It is only 

 hoped to so outline the extent and limits of this division of animal life that it will 

 be less difficult to place the forms found from time to time, in approximately 

 their true position. 



With very few exceptions, as far as has been ascertained, no one has devoted 

 any attention to the fresh water Entomostraca oi' America, and it is necessary for 

 some one to act as a pioneer, to learn whether any of the forms described in 

 Europe appear here, and to discover, if possible, if there be a general similarity 

 between these widely separated faunae. This has been the ambition of the pres- 

 ent writer ; and if only an intelligent attention be durected to this field, he will 

 feel abundantly repaid for the attempt. 



The works consulted were Dana's ' ' Report of the Crustaceans collected during 

 the Wilkes Exploring Expedition to the Pacific Ocean", Dr. W. Baird's " Brit- 

 ish Entomostraca," " Report of U. S. Fish Commission," papers in " Hayden's 

 Survey of the Territories", and papers in the American Naturalist and other peri- 

 odicals. Many thanks are due to Prof. N. H. Winchell, director of the State 

 Geological Survey, for assistance and advice in many ways; to President W. W. 

 Folwell, and Dr. P. L. Hatch, for assistance and intelHgent sympathy, and to 

 fellow members of the " Naturalist's Club." 



That there will be found mistakes in the work is to be expected, but it is hoped 

 that the information will be reliable in the main. 



It is not without hesitation, that, as a novice in scientific investigation, names 

 are suggested for the new species found, but the purpose of this paper will be 

 best served by defining as well as possible these forms, and submitting them to 

 the test of further study; and if in the futare more experience and greater research 

 can be brought to bear upon this domain, these preliminary notes will periiaps 

 not be without their value. The drawings were all made by the writer, in most 

 cases from life, though some details have been introduced from the works con- 

 sulted, and the plate of Phyllopoda was collected from the government reports 

 and elsewhere. Clearness in outline and detail rather than beauty in execution 

 was the desideratum. 



C. L. HERRICK. 



