266 FEANK E. BEDDARD. 



riodrilus there is a penis, which is a hollow process of the 

 body-wall. In both genera the vasa deferentia open in the 

 11th and 12th segments into the interior of the sperm-sacs ; 

 each vas deferens perforates the septum, from which the sperm- 

 sac depends, twice. 



(5) The ovaries are enclosed in special coelomic sacs which 

 communicate with the egg-sac, and are prolonged dorsally so 

 as to entirely (Hyperiodrilus) or partially (Heliodrilus) 

 enclose the single spermatheca which opens on the middle line 

 of the 13th (Hyperiodrilus) or 11th (Heliodrilus) seg- 

 ment ; in the latter case the spermatheca itself lies in the 13th 

 segment, and has a long duct. In Hyperiodrilus the peri- 

 gonadial sacs form a ring round the oesophagus, and are con- 

 nected with a dorsal unpaired sac. 



III. — Some Notes upon Nemertodrilus griseus, Mich. 



The principal points in the anatomy of this Eudrilid have 

 been already made out by Michaelsen;^there are, however, a 

 few facts of minor importance which I have been able to note 

 down from the examination of specimens which Dr. Michaelsen 

 was so good as to place at my disposal. With regard to the 

 female reproductive organs, I can only confirm the accurate 

 description given by Michaelsen; but the structure of these parts 

 suggests certain reflections concerning the homologies of the 

 various organs which constitute the female reproductive system 

 in the Eudrilidse. As Michaelsen has stated, the cavity of 

 Segment 13 is greatly reduced, so that the ovaries are enclosed 

 in a narrow chamber ; the receptaculum ovorum communicates 

 with this segment, and is also connected with a large pouch 

 extending on each side of the body through several segments. 



Michaelsen suggests that these large pouches may be possibly 

 the equivalents of the receptacula and the distal part of the 

 spermatheca. The proximal part of the spermatheca on this 

 supposition is represented by a pair of orifices, of which more 

 later, opening into the exterior of the body from the reduced 

 cavity of the 13th segment. Dr. Michaelsen decides, however, 



