STEUOTUEE OF TWO NEW GENEEA OF EAETHWOEMS, 259 



spermatheca of any other Eudrilid, or in fact any other earth- 

 worm at present known. 



It is a large oval sac lined by columnar cells ; a portion of 

 one of the walls is represented highly magnified in fig. 37 : 

 below the layer of columnar cells are some smaller cells, the 

 contours of which are not very clear, though their nuclei are; 

 outside these are a few muscular fibres, which make up a layer 

 of no great thickness. The interior of the spermatheca con- 

 tains a granular substance which appears to be formed by the 

 columnar cells. The calibre of the spermatheca (fig. 41) 

 gradually diminishes towards the apex and towards the ventral 

 side of the body ; here the cells lose their glandular character, 

 and become at the same time considerably shorter, so that the 

 muscular coat appears to acquire an additional thickness. 

 The narrow duct of the spermatheca does not open upon the 

 13th segment as in Hyperiodrilus, but bends under the 

 nerve-cord and runs forwards, always lying beneath the nerve- 

 cord, as far as the 11th segment; throughout the whole of its 

 course beneath the nerve-cord it is a narrow tube with thick 

 muscular walls, and a lining of short columnar cells, which, it 

 is perhaps unnecessary to remark, show no traces anywhere of 

 cilia. The diameter of the spermathecal tube in these seg- 

 ments is about equal to that of the nerve-cord. In the 11th 

 segment the spermathecal tube perforates the body-wall, and 

 opens on to the exterior by an inconspicuous orifice which is 

 situated on the median ventral line. The ventral sucker-like 

 organ of this segment is pushed to one side, as shown in fig. 

 21, and does not therefore interfere with the accurately median 

 position of the spermathecal pore. 



The number of segments occupied by the spermatheca is 

 thus considerably in excess of that which is found in any other 

 earthworm. 



If the spermatheca is developed in the Eudrilidae as in the 

 Lumbricidae by an inpushing of the epidermis, the point of 

 opening will fix the morphological position of the organ ; hence 

 Heliodrilus serves in this respect to connect the Eudrilidae 

 with other earthworms, for the spermatheca opens in front of 



