Marsh — North American Species of Cyclops. 1069 



It will be noticed, doubtless, that the sub-generic names that 

 nave been adopted by some authors have not been recognized. 

 The species of Cyclops certainly fall into certain groups, but it 

 is the feeling of the author that our knowledge of the relation- 

 ships of the species in these groups is not yet sufficiently wide to 

 warrant the formality of fixed sub-generic names. I must con- 

 fess to a dislike of multiplying names in systematic work, and 

 do not enjoy sub-generic names under any circumstances, pre- 

 ferring to avoid them when practicable. The number of species 

 in the genus Cyclops is not very large, and the addition of sub- 

 divisions in our present state of knowledge is distasteful to me. 



A considerable number of figures has been used to illustrate 

 the paper, enough, it is hoped, to make clear the diagnoses. 

 The synopsis is not published as a final production. No one 

 appreciates better than the author how much work re- 

 mains to be done on these forms. On the other hand the 

 paper is the result of accumulations of material covering many 

 years. A large number of slides have been made from these 

 collections, and while the work is confessedly incomplete, it is 

 perhaps due to others who are interested in these animals to 

 make some of the results available for use. The systematic 

 study of entomostraca is, at best, a very laborious process, and 

 it is hoped that this brief paper may help in lightening the 

 labors of others who may wish to use specific names for the 

 Cyclopidae. 



The key is based on the characteristics of mature females 

 and includes only those species which are recognized members 

 of the American fauna. 



6— S. & A.— 3 



