24 PROCEEDINGS OF THE ACADEMY OF [Jan., 



very best of the laboratory equipment at my disposal, is largely 

 responsible for the existence of this paper. I gladly take this oppor- 

 tunity to acknowledge also the assistance of iVIr. J. Ashbrook in 

 collecting material. 



Genus CYCLOPS O. F. MuUer. 



Subgenus CYCLOPS Claus s. str. 



Cyclops bicuspidatus Claus. PI. II, figs. 1-5. 



Cyclops bicuspidatus Claus, '57, p. 209. 



Cyclops pulchellus Sars, '63, pp. 246, 247, pi. XI, figs. 6 and 7. 



Cyclops nai'us Herrick, '82a, p. 229, pi. V, figs. 6-13, 15-17. 



Cyclops thomasi Forbes, '82a, p. 649. 



Cyclops bicuspidatus Schmeil, '92, pp. 75-87, pi. II, figs. 1-3. 



Cyclops ininnilus Forbes, '93, p. 247. 



Cyclops serratus Forbes, '93, pp. 247, 248. 



Cyclops forbesi Herrick and Turner, '95, p. 104. 



Cyclops navus Brewer, '98, p. 133. 



Cyclops pulchellus Brewer, '98, pp. 133, 134. 



Cyclops bicuspidatus Lilljeborg, '01, pp. 11-14, pi. I, figs. 12-17, pi. II, fig. 1 



Cyclops pulchellus Byrnes, pp. 24, 25, pi. X. 



Cyclops bicuspidatus Byrnes, pp. 25, 26, pi. X. 



Synonymy and Distribution. — In his discussion of the synonymy 

 of this very variable and widely distributed species, Forbes has 

 cleared up the question of C. thomasi Forbes, C. navus Herrick, 

 C. minnilus Forbes, and C. serratus Forbes = C. forbesi Herrick. He 

 finds, after a careful comparative study, that they should all be 

 considered as slight variations of the type C. bicuspidatus, but the 

 differences are not sufficient to warrant the varietal names. Schmeil 

 has also discussed the question at great length. He does not consider 

 C. thomasi Forbes nor C. navus Herrick of specific value, since the 

 latter is only a variety of C. thomasi Forbes. Brewer has described, 

 as C. nanus Herrick and C. pulchellus Koch, two species of cyclops 

 from the vicinity of Lincoln, Nebraska. His descriptions of the 

 rudimentary and .swimming feet show that he wa* dealing with 

 slightly different specimens of C. bicuspidatus Claus. As C. pul- 

 chellus Herrick and C. bicuspidatus Forbes, Miss Byrnes has described 

 examples of C. bicuspidatus Claus from Long Island. Her descrip- 

 tions of the swimming feet and her drawings of the receptaculum 

 seminis show very conclusively that the two forms both belong under 

 this specific name. The variation of the single seta on the fifth 

 foot is frequently encountered in the species. The form of the fifth 

 foot in what she describes as C. bicuspidatus Forbes is very interesting, 

 for Forbes has found it but once and on that occasion from Woods 

 Hole, Mass. It corresponds exactly with the European forms and 

 with the representatives of this species from this locality. 



C. bicuspidatus Claus is very widely distributed over the L^nited 



