Marsh—North American Species of Cyclops. 1069 
It will be noticed, doubtless, that the sub-generic names that 
have 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. Ho 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 
