504 



ANNELIDA. 



large (RJiyncJielmis). In the Terricolae the ovisacs, when present, are 



usually small and paired 

 (Fig. 413, etc.). They are 

 diverticula of the septum 

 at the hind end of the 

 ovarian segment, and in 

 some Liinicolae the 

 sperm-sac projects into 

 them. 



The generative ducts 

 correspond in number to 

 the generative glands. 

 They usually open into 

 the general body-cavity 



Tls 



ing the gonads, but in 

 some Terricolae (Lum- 

 bricus, etc.) the vasa 

 deferentia open into the 

 median part of the 

 sperm-sacs (sperm- 

 reservoir). In the Ter- 

 ricolae there are two 

 oviducts and two pairs 



of vasa deferentia. The oviducts, as in the Limicolae, are short, and 

 open externally on the segment behind that containing the ovaries, 

 usually on the 14th; and internally into the coelomic chamber of the 

 ovarian segment, usually the 13th. The two vasa deferentia of the 

 same side join behind to form a single duct, except in Phreoryctes, 

 where they open on two consecutive segments, and in Pelodrilus, in 

 which they open on the same segment. The opening of the vas 

 deferens is variable in position*; in Lumbricus it opens on segment 

 15. The internal openings of the vasa deferentia or sperm rosettes 

 as they are called are in the coelom of the segments of the testis 

 (generally 10 and 11), and if there is a sperm reservoir they open 

 into it. There is in many forms attached to and opening into the 

 vas deferens near its external opening a glandular appendage called 

 the prostate, or spermiducal gland (Fig. 414). In some genera the 

 spermiducal gland opens to the exterior independently of the sperm 

 ducts. 



* From segment 11 in Moniligaster to 22 in Diachaeta. 



FIG. 414. Diagram of the organisation of Megascolides 

 (from Perrier, after Benham). 1, generative apparatus ; 

 2, renal organs. Segments numbered in roman numerals. 

 In VIII and IX are the spermathecae ; in X and XI the 

 testes ; in XI to XIV the four sperm-sacs S ; in XIII 

 the ovaries and funnels of the oviducts ; in XVIII the 

 male generative opening and spermiducal glands pr. 

 ip the pepto-nephridia ; p dilatations of the intestine. 

 The nephridial network is shown in 2. 



