ON THE DEVELOPMENT OF PARASITIC COPEPODS. 4! 



In the male the same general arrangement of reproductive 

 organs exists, save that the seminal receptacles are absent and 

 the distal ends of the vasa deferentia are enlarged and become 

 the spermatophore receptacles. The cement glands secrete the 

 material for the walls of the spermatophores. 



In the dichelestid (Fie. 3) the genital segment is very much 

 elongated and the oviducts are not convoluted. The ovaries have 

 been carried backward until they lie in the anterior end of the genital 



e.g. 



FIG. 2. Semen receptacles and vagina of a female Lepeophtheirus. (Partly 

 after Claus. ) c. g. , cement glands; d. , cement gland duct; e. c., egg cases; s. , 

 spermatophores; s. r., spermaries ; v., vulva; va. , vagina; 5, fifth legs. (From 

 Wilson's CaligidtE.) 



segment and the oviducts pass forward to the anterior end of the 

 thorax, then backward to the attachment of the egg strings. In 

 other respects the description given for Caligus will hold for this 

 species. The older brood of oocytes occupies the posterior two- 

 thirds of the oviduct. When one brood passes into the egg 

 string the distal eggs of the remaining brood have nothing to 

 press against and tend to round up and become distorted. The 

 thickness of the oviduct at its posterior end varies somewhat, 

 depending on the number of eggs produced in one brood, and 

 the size of the eggs. When fewer, the eggs are thicker, and 

 when more numerous, thinner. The egg string is more slender 

 than the posterior portion of the oviduct, and the contained eggs 

 are, therefore, thicker. 



