North American Fresh-water Cyclopidce. 37 



Cyclops viridis Jurine. (PI. X., Fig. 1-3.) 



Monoculus quadricornis var. viridis, Jurine. '20. p. 46, PI. III., Fig. 1. 

 Cylops viridis, Schmeil, "92, pp. 97-101, PI. VIII., Fig. 12-14. 



SYNONYMICAL DISCUSSION. 



Though the subdivision of the viridis group here proposed 

 is not entirely satisfactory and may not be final, still after 

 long study of more extensive collections than have heretofore 

 been brought into comparison in America, I have arrived at 

 some conclusions with regard to the subdivision of the group 

 which may be of service to any one following me in the study 

 of the American Cyclopidce. 



C. rifi dis occurs in America, so far as I now know, only in 

 the larger forms of that species. C. ingens (Herrick, '82a) 

 seems to me the only described form corresponding very 

 nearly to the European viridis, and 1 therefore regard it as 

 the American representative of that species. It is considered 

 by Marsh as equivalent to C. americanus (= ('. insectus), and 

 Herrick himself says that it is distinguished from this form 

 only by its greater size. From Fig. 3, PI. XXV., in Herrick 

 and Turner '95, I judge that C. ingens is synonymous with 

 ( '. viridis, thus representing in America the maximum devel- 

 opment of the species, as does ('. gigas in Europe. 



Dr. Forbes has for years recognized such a form as ('. 

 ingens, and it is to be found in the temporary ponds of central 

 Illinois. The species was in 1870 given the manuscript and 

 label name of ('. levis, but the description was never pub- 

 lished. This ('. ingens or levis differs from specimens of 

 viridis received from Sars and Schmeil only in its greater 

 size, and from specimens of ( '. gigas received from Sars only 

 in some of the more minute details in the outline of the two 

 segments of the fifth foot. The two forms gigas and ingens 

 are undoubtedly typical C. viridis. It is of interest to note 

 that in both of these large forms the small spine of the fifth 

 foot is not separate from the segment, but is a process of the 

 segment itself. Schmeil states that in C. viridis it may or 

 may not be separated from the segment by a suture. ( '. 

 ingens is the only form in America having the stylets ciliate 



