DESCRIPTIONS OF GENERA AND SPECIES 597 



Genus PLATYDRILTTS, MICHAELSEN. 



DEFINITION. Setae paired, the setae wider apart at the two ends of the body 

 and larger than at the middle. Clitellum saddle-shaped, XIV-XVII. Male 

 pore on XVII. Ovaries unenclosed by a sac. Single median spermathecal 

 sac, opening on XIII, communicates by a tube on each side with the oviduct. 

 Fenial setae. 



This genus helps to bridge over the gap between the Eudrilidae and other 

 earthworms. It possesses, like the remaining genera of Eudrilidae a single median 

 spermatheeal sac probably of mesoblastic origin opening on to the exterior on the 

 thirteenth segment ; but the ovaries are quite free, and hang from the septum dividing 

 segments xii/xiii, entirely unenclosed by any sac. Nevertheless, the median sperma- 

 thecal sac gives off on either side a much coiled narrow tube, which appears, though 

 MICHAELSEN is not able to be quite certain upon the point, to open into the oviduct. 

 The spermathecal sac lies, at any rate, in Platydrilus lewaenais, beneath the nerve- 

 cord. The oviducal funnel opens freely into the thirteenth segment. The usual 

 two pairs of testes are present; these lie in segments x and xi. The spermiducal 

 glands open by a common pore upon segment xvii, just in front of the groove which 

 separates this segment from the one behind. There is no information forthcoming 

 as to the relation of the sperm-ducts to the glands. There are a pair of sacs containing 

 penial setae, which are ornamented. The sperm-sacs are in segments xi and xii. The 

 gizzard is in segment v. There appear to be no calciferous glands of any kind ; nor 

 are there any ventral pouches. The nephridia open, as they do in Nemertodrilus, 

 in front of the ventral setae. 



The genus contains three species ; all of these are East African. 



(i) Platydrilus callichaetus, MICHAELSEN. 

 P. callichaetus, MICHAELSEN, JB. Hamb. wiss. Anst., ix, 1891, p. 15. 



Definition. Penial setae with sculpturing, with three points on each side at extremity 



connected by a wing-like membrane. Hob. Mbitsini, E. Africa. 



This species is only doubtfully included in this genus by MICHAELSEN. The 

 description which MICHAELSEN is able to give is perhaps not quite sufficient to 

 determine the generic position of the worm with certainty. The clitellum is rather 

 longer than that of the only other species (P. lewaensis) in which it has been observed. 

 It extends from segment xiv to segment xviii, or possibly xix. The shape of the 



