STRUCTURE OP EARTHWORM ALLIED TO NEMERTODRILUS. 563 



an excretory system which is at least of interest in being 

 formed on quite a novel plan. 



§ Male Reproductive System. 



The testes are paired structures lying in Segments 10 and 

 11 ; they are not enclosed in any sacs, and are quite indepen- 

 dent of the sperm-sacs. The gonads are remarkable on account 

 of their great length and thinness ; the extremities are frayed 

 out, as is usually the case among earthworms, into a number of 

 jagged processes. 



Sperm-sacs. — There are two pairs of sperm-sacs attached 

 to the anterior walls of Segments 11 and 12; each sac of each 

 pair is quite independent of its fellow. In the living worm 

 the sperm-sacs have a whitish appearance with the exception 

 of the basal part, which is greyish brown. In this part of the 

 sac the Gregarines, which appear to be parasitic in all earth- 

 worms, are chiefly lodged, and the colour is due to brown pig- 

 ment deposited round their cysts. As to the histological 

 structure of these sacs, they agree with those of other earth- 

 worms in having their cavity greatly broken up ; the sperm- 

 sacs on their first appearance are solid, except for a very small 

 cavity which communicates with the interior of the segment in 

 front of that in which they lie. There are no seminal reser- 

 voirs, and thus the testes, and funnels of the vasa deferentia, 

 depend freely into the coelom. 



Sperm Ducts and Funnels. — In all the members of the 

 family Eudrilidee (excluding from this family Eudriloides 

 and Pygmseodrilus) with the exception of Nemertodrilus 

 griseus, and perhaps Preussia siphonochseta, the sperm 

 ducts are dilated before their connection with the funnel. 

 In Liby odrilus there is no such widening of the sperm ducts 

 either in the neighbourhood of the funnels or anywhere else. 

 The funnels themselves occupy the usual position in Segments 

 10 and 11 ; those of Segment 11 are more nearly opposite to 

 the sperm-sacs than to the testes ; the sperm ducts are narrow 

 tubes of the usual appearance, but are unusual in passing 

 through the segments which they traverse at some distance 



