318 WILLIAM A. HASWELL. 



rencontrent pas dans toute I'etendue du corps de Histrio- 

 drilus. Je n'en ai pas vu la moindre trace dans la tete ; 

 aussi, sans en vouloir nier d'une fa9on absolue la presence, 

 je suis porte a croire qu'ils n'y existent pas."^ "Dans la 

 partie tont a fait posterieure du corps je n'ai jamais pu de- 

 couvrir d'organes excreteurs."^ 



Reproductive System. 



The male reproductive organs (figs. 1 and 14 — 16) consist, 

 in addition to the claspers, of two testes fused together in 

 part of their extent, two seminal vesicles (ves.), two lateral 

 vasa deferentia {v. def.), a median ejaculatory duct, a median 

 chitinous penis {f.), two sets of gi*anule glands {gr. gld.), and 

 a pair of accessory glands (ac). The claspers have been 

 already referred to. In the interior of the base of each is a 

 large unicellular gland (fig. 14, gl. cl.), the duct of which opens 

 at the extremity. The testes when fully developed fill the 

 greater part of the cavity of the third, fourth, and fifth seg- 

 ments. Anteriorly (in the third and partly in the fourth 

 segment) the right and left testes are separated from one 

 another by a distinct space ; posteriorly they are completely 

 fused. They consist of oval masses of spermatidia and 

 sperm, the fully developed sperms being in later stages of 

 formation, most abundant towards the posterior end. A 

 thin envelope invests the whole. 



The seminal vesicles {ves.) are a pair of oval sacs situated 

 laterally in the interior of the testes, just in front of the third 

 cirri. Each has on its dorsal aspect a wide, nearly longi- 

 tudinal slit, the edges of which are beset with vibratile cilia. 

 In the interior, in mature specimens, is always a large mass 

 of sperms. On the ventral surface are usually to be observed 

 several curved ridges, which are found when carefully traced 

 to be continuous with the ducts about to be described as 



1 L. c, p. 469. 



2 Ibid., p. 471. 



