x URINOGENITAL ORGANS 467 



them and in their ducts (Wolffian ducts). In the 

 male, the anterior part of the kidney takes on a close 

 relation with the generative organs, and gives rise to a 

 glandular body the epididymis (A, k") with which the 

 long, convoluted Wolffian duct (Spd), serving mainly as a 

 spermiduct, is closely connected ventrally. The middle 

 part (k'} becomes vestigial : in the female this is the case 

 as regards both anterior and middle parts and the Wolffian 

 duct. The hinder part of the embryonic kidney in each 

 sex is retained in the adult as the renal organ (k\ which is 

 somewhat swollen posteriorly, and on the surface of which 

 nephrostomes open. The ureters (ur) are independently 

 developed tubes, about five in number on either side. In 

 the female they open separately into the swollen persistent 

 posterior ends of the Wolffian ducts, which unite together to 

 form a median urinary sinus (B, u.s), opening by a single 

 aperture into the cloaca ; while in the male (A, ur) most of 

 them unite to form a wide main ureter before communicat- 

 ing with a similar median sinus, which, as it receives the 

 products both of the spermaries and kidneys, is called the 

 urinogenital sinus (u.g.s). 



The spermaries are a pair of large, elongated, soft 

 organs united with one another posteriorly, and suspended 

 to the dorsal body- wall by a fold of peritoneum. From 

 the anterior end of each (A, ts) arise delicate efferent ducts 

 (ef. d\ which pass to the epididymis to become connected 

 with the convoluted spermiduct. The latter dilates pos- 

 teriorly, where it underlies the functional kidney, forming 

 an elongated, spindle-shaped seminal vesicle (s.v\ which opens 

 (s.v') into the base of a thin-walled blind reservoir of about 

 the same length, the sperm-sac (sp. s) ; just to the inner side 

 of its aperture are the openings of the ureters (ur). The 

 sperm-sac is continuous posteriorly with the urinogenital 



H H 2 



