564 FRANK E. BEDDARD. 



from the body-wall ; their course is straight without any 

 windings; the two sperm ducts of one side appear to unite 

 just behind the intersegmental septum 12 — 13 ; as a matter of 

 fact they do not unite here or anywhere else until at their 

 actual orifice j they lie, however, in close contact. In trans- 

 verse sections the sperm ducts are seen to have quite the 

 ordinary structure; there is no development of muscular fibres 

 round them such as occurs in Eudrilus. The funnels are 

 large and their walls are much folded. 



The atria have the tubular form which is characteristic of 

 the family ; but they are short, and usually contained entirely 

 within the 18th segment. Towards the external aperture they 

 become narrower. These organs have the " nacreous" appear- 

 ance of the corresponding organs in Eudrilus, which is due 

 in both cases to the great development of the muscular coat. 

 This reaches an extraordinary thickness in Libyodrilus, 

 which is thus remarkable even among the Eudrilidae. 



The external orifice is single, and is situated upon the summit 

 of a rounded elevation occupying the middle of the ventral 

 surface of the body and extending over a portion of Segments 

 17 and 18. The epithelium which covers this elevation is fur- 

 nished with numerous glandular cells, conspicuous on account 

 of their dark staining. With each atrium is connected a sac 

 in which lies a single short penial seta. The sac communicates 

 with the distal part of the atrium that is embedded in the 

 thickness of the body-wall. 



The penial seta is illustrated in fig. 8 ; it is remarkable 

 on account of its shortness and its blunt rounded free extremity, 

 which is not ornamented. 



The atrium is lined throughout with epithelium, which is 

 separable into two strata. 



The cells, however, had not in any case (I examined the 

 atria of three individuals) the extremely glandular appearance 

 of the corresponding epithelium in Eudrilus. This may, no 

 doubt, be owing simply to a cessation in the secretory activity 

 in the cells. 



In nearly all the Eudrilidse the vasa deferentia open into the 



