ANATOMY AND METAMORPHOSIS OF CYCLOPS. 229 



a. The ovary is in the middle line of the dorsal surface 

 of the carapace. Its appearance varies somewhat at 

 different times, and when nearly empty of eggs it is trans- 

 parent and almost invisible. 



b. On each side of it is a long, branched oviduct (Fig. 

 11.8, c) which is very dark and granular at its anterior end 

 when distended with eggs, while the posterior portion is 

 more transparent and difficult to detect. The eggs are 

 small and transparent when they leave the ovary, but they 

 become larger and opaque in the oviducts. 



The oviducts pass backwards to open on the sides of the 

 first abdominal segment, at the point a of Fig. 122, and the 

 opening is covered by a little lid which is fringed with 

 hairs, and serves for the attachment of the ovisacs. 



FIG. 122. Highly magnified diagrammatic view 

 of the ventral surface of the first abdominal 

 somite of a mature female specimen of Cyclops 

 brevicaudatus. (From Graber. Taf. xxvi. 

 Fig. 11.) 



a. Setose plate of integument which covers the 



external opening of the oviduct, b. Spermatic \ \ |j^/ "/ e 



duct, through which the semen (e) passes from 



the spermatheca (d) to the oviduct, r. Vulva, or 



orifice to which the spermatophore is attached, 



and through which the spermatozoa pass into the FIG. 122. 



the spermatheca. d. Spermatheca. e. Spermatic fluid.. 



c. Under the integument of the ventral surface of the 

 first abdominal segment, notice a transparent oval sac, 

 the spermafheca (Fig. 122, d). It opens to the exterior 

 by a median ventral aperture, the vulva (Fig. 122, c), 

 through which the seminal fluid of the male passes into the 

 sac. 



On each side of its anterior cud a small tube, the sper- 

 matic duct (Fig. 122, b) runs outwards and upwards to 



