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A REVISION OF THE NORTH AMERICAN SPECIES 

 OF CYCLOPS. 



C. DWIGHT MAKSH. 



As collections are made more and more widely from all 

 parts of the world and as these collections are studied more 

 thoroughly, it becomes increasingly evident not only that the 

 genus of Cyclops is distributed over the whole world, but that 

 individual species have an exceedingly wide distribution. 

 Many of the species which have been described as peculiar to 

 America have been clearly shown either to be identical with 

 species in Europe or merely varieties of those species. Little 

 by little it has been necessary to reduce to synonyms the 

 names which have been proposed for American species. It 

 can not yet be said that all American species are identical 

 with those in Europe, but it is very evident that most of 

 them are. Most of the species of Cyclops have wide limits of 

 variation, and it is these variations which, at a time when the 

 knowledge of the entomostraca was imperfect, lead to the intro- 

 duction of many new names for species which we now know 

 are only varieties. 



This leads to a great deal of confusion when students of 

 anatomy or plankton, who may have no particular interest in 

 a systematic knowledge of Entomostraca, attempt to name 

 the species which they are studying. So great is this con- 

 fusion that many students of plankton do not attempt to use 

 specific names, but simply describe the distribution of 

 "Cyclops." This is extremely unfortunate, for the species of 

 Cyclops have very different habits and a discussion of plank- 



