696 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



seminal receptacles in the female. They are much larger than the 

 receptacles, however, and as a result the abdomen of the male is com- 

 paratively larger and longer than that of the female of the same species. 

 The testes {t.) are ovoid or ellipsoidal in shape, and in neaily every 

 species are covered on the dorsal surface with dark pigment spots cor- 

 responding to those on the dorsal surface of the ovary. From the 



Fig. 23.— Male sexu.\l organs of Argulus americant^s. 



duct; .<. v., SEMEN vesicle: f., TESTIS; V. d., YAH 



b. C, BLIND capsule; f. (I., EJACULATORY 



deferens; v. c, vas efferens. 



anterior end of each testis there runs a duct, the vas efferens (/'. e.), 

 which leads forward to the unpaired seminal receptacle or vesicle (.v. v.) 

 lying in the posterior thorax on the midline, above the intestine. 



The vasa efferentia enter the vesicle at its posterior end. From the 

 anterior end there is given off on either side another duct, the vas 

 deferens (r.d.), which turns l)ackward alongside the vas efferens until 



