MR FRANK E. BEDDARD ON THE ANATOMY OF OCNERODRILUS. 577 



occupy in the vast majority of Earthworms ; that is to say, they are attached to the front 

 wall of the XHIth segment near to the ventral body wall. In this species, however, the 

 Xllth segment has a very restricted lumen, and it appears to me quite possible that the 

 delicate septum which separates this segment from the XHIth may have been overlooked 

 by Eisen, who studied only the living worm as a transparent object. This suggestion is 

 perhaps hardly borne out by the figure which he gives of the entire reproductive system 

 of the Annelid. I feel convinced, however, that there must be some error in Eisen's 

 description and figure, as it would be difficult from his statements to understand how the 

 ova could reach the exterior. I am not aware that there is any case known in which the 

 ovary lies in a different segment from that which contains the oviducal funnels, except 

 Sutroa [see Eisen, 2]. I am of opinion that these apparent exceptions require reinves- 

 tigating before they can be regarded as certain. Contrary to Eisen's statement, I did 

 find ova detached from the ovary and floating freely in the perivisceral cavity of the 

 Xlllth segment. In one specimen there were two such ova on one side of the body, and 

 six on the other. As my sections formed a continuous series, cut by the Cambridge 

 Rocking Microtome, I am confident of this fact. I imagine, from the absence of any 

 mention of the clitellum in Eisen's description, that this organ was not yet developed in 

 his specimens, and that the worms were therefore not fully mature. This may account 

 for the fact that he did not see any ripe ova floating freely in the body cavity. 



The point may be in reality one of some little importance in relation to the question 

 of the affinities of Ocnerodrilus. A large number of Earthworms have been shown to 

 develop special sacs for the reception of the ripe ova ; probably the majority are thus 

 provided. Similar structures occur in a considerable number of genera belonging to the 

 "Limicolse"; but there are several, particularly among the Enchytrseidse, where these 

 receptacles do not occur. 



§ Summary. 



Ocnerodrilus Eiseni presents the following structural characters : — 



The setw are strictly paired, and are of the usual Lumbricid pattern. They are not 

 modified upon the clitellum ; the ventral pair are wanting upon the XVIIth segment, 

 which bears the apertures of the vasa deferentia and atria. 



The clitellum occupies segments XIII-XIX. It has the same structure as in Earth- 

 worms. 



The nephridiopores open in front of the ventral pair of setae. 



The oviducts open upon the XI Vth segment. 



The atrial pores are upon the XVIIth segment. 



The spermathecal pores are in the IXth segment, on the border line between this and 

 the VTIIth segment, in front of the ventral setae. 



There are no dorsal pores. 



The alimentary tract consists of (1) a buccal cavity occupying the first three segments ; 



