376 Proceedings of the Royal Physical Society. 



segment in front of that which contains the testes are a pair 

 of rosette- like structure ; these are the hmbriated orifices of 

 the vasct deferentia. They are placed below, and a little to 

 one side of the alimentary canal, on the posterior wall of the 

 segment, and closely approximated to each other, being in 

 actual contact for a short space. I failed to find the posterior 

 pair of vasa deferentia funnels. 



The vasa deferentia pass as two extremely minute slender 

 tubes to their openings on the 17th segment, in common wdth 

 the prostate gland and the sac containing the two penial setae. 



The prostate glands, as in other Acanthodrihis, have the 

 form of a simple coiled glandular tube opening by a narrow 

 muscular duct. There are four of these two in the 17th, 

 and two in the 19th sej^ment. 



The penial seta? are developed in a sac-like diverticulum, 

 which opens in common with the prostate of its own side 

 and segment. The structure of the penial setae, of which 

 there are a single pair to each of the four generative aper- 

 tures, is characteristic of the species. The seta is covered 

 upon its lowermost one-third with numerous short pointed 

 processes, the points of which are directed towards the 

 extremity of the seta. 



There are two pairs of spermathecas in segments 8 and 9 ; 

 each consists of a piriform sac, opening by a narrow passage 

 on to the exterior. A small supplementary sac of the same 

 form as the principal sac, but narrower and bent downwards, 

 is present as a diverticulum of the spermathecse. In the 

 segment which contains the posterior pair of spermatbecic 

 are a pair of largish, rounded, and somewhat flattened bodies 

 attached generally to the septum, which divides this from 

 the succeeding segment, but occasionally to the anterior 

 septum also. The walls of these sacs are comparatively 

 stout, and the contents do not present an organised appear- 

 ance, but appear to be entirely granular. Interspersed among 

 the granules are a number of gregarious cysts. I am quite 

 unable to suggest what may be the possible function of these 

 structures. 



The position of the ovaries and their ducts in the genus 

 Acanthodrilus has not yet been ascertained with certainty. 



