1891.] EARTHWORM FROM WEST AFRICA. 175 



its deficiency in blood-capillaries — perhaps both ; the extreme vascu- 

 larity and the thinness of the walls of the buccal cavity in Libyo- 

 drilus perhaps account for the fact that it is not usually (? ever) 

 protruded during locomotion. 



The setcB are strictly paired. 



There are no dorsal pores. 



The clitellum occupies segments 15 and 16 (in some specimens a 

 part of segment 14 also), and is complete, that is it entirely encircles 

 the body. 



The 7)iale reproductive pore is single and median, upon the border 

 line between segments 17 and 18. The orifice is situated upon the 

 summit of a conspicuous elevation of a yellowish colour. 



The spermathecal pore is also median and unpaired ; it lies on 

 segment 13 between the ventral pairs of setae. 



The oviducal pores occupy what is at present a unique position 

 among Earthworms, viz, on segment 15. Thus another of the 

 characters supposed to distinguish the group Terricolse no longer 

 holds universally. 



The chief characteristic of the family Eudrilidse is the remarkable 

 development of ccelomic sacs which enclose the different parts of the 

 female reproductive organs. 



Libyodrilus, though in some respects approaching Hyperiodrilus, 

 offers a new type. A large sac occupies the dorsal region of 

 segments 14-18; it is closely adherent to the dorsal vessel and 

 oesophagus ; this sac gives off three pairs of approximately corre- 

 sponding diverticula ; anteriorly it divides into two, and embraces 

 the oesophagus as in Hyperiodrilus ; the two parts are reunited 

 immediately below the oesophagus and run forwards and downwards 

 until they reach the nerve-cord ; here they again divide and reunite 

 upon the ventral side of the nerve-cord, to open by a single median 

 orifice upon segment xiii. 



The oviduct passes from this sac on each side straight to its ex- 

 ternal orifice. In transverse section it may be seen that the oviducal 

 funnel opens into the interior of an egg-sac ( = receptaculum ovorum, 

 auctorum) which is quite independent of the large spermathecal sac, 

 though lodged within it. 



The ovaries are only visible in immature worms ; they occupy the 

 usual position in segment xiii. 



The sperm-ducts, which open by ciliated funnels into segments x. 

 and XI., opposite to the testes, retain their distinctness until the point 

 of opening into the atria. 



The atria have a very thick muscular coat ; they open by a common 

 orifice on to the boundary line between segments xvii. and xviii. ; 

 each is provided with a sac containing a single short penial seta, not 

 ornamented, and ending in a blunt rounded free extremity. 



The nephridia are paired, but are connected with an integumental 

 network of tubules opening on to the exterior by numerous pores. 



The alimentary tract consists of the usual divisions ; the oesoph- 

 agus has no calciferous glands nor ventral pouches ("Chylustaschen " 

 of Michaelsen), which are so characteristic of the Eudrilidse. There 



