STEUCTURE OE TWO NEW GENERA OF EARTH-WORMS. 247 



deferens is lined by a tall columnar epithelium, and the cilia 

 are very long. The narrow portion lying behind the septum 

 is composed of an epithelial layer of low quadrangular cells 

 comparatively few in number ; the two vasa deferentia of 

 each side pass down the body just covered by the peritoneum, 

 and on a level with seta No. 3 ; they are accompanied by a 

 blood-vessel which supplies them with capillary branches. 



In the 17th segment is situated the terminal apparatus of 

 the male reproductive organs, which consist of two large 

 '^ prostate ^^ glands or atria, opening on to the exterior by 

 means of the protrusible penis. 



Each atrium is furnished with a muscular duct which leads 

 to the exterior. 



The entire gland is sausage-shaped, and recalls the corre- 

 sponding structure in Acanthodrilus ; it has the same form 

 as in that genus, and the same opaque white appearance. 

 We do not find the nacreous appearance of these organs in 

 Eudrilus; the reason for this difference is to be found in 

 the absence from Hyperiodrilus of the thick muscular coats 

 composed of longitudinal and circular fibres which are charac- 

 teristic of Eudrilus. In Hyperiodrilus the muscular 

 layer is indeed present, but it is reduced, as shown in fig. 38, 

 to a very thin layer. This figure may be compared with 

 that illustrating a transverse section through the atrium of 

 Eudrilus (Beddard, 1, pi. xxx, figs. 8 — 10). 



The interior of the distal part of the prostate is formed of a 

 compact mass of cells loaded with darkly staining granules. 

 I could not distinguish (see fig. 42) two layers of cells, such as 

 appear to be met with in the prostates of all other earthworms 

 in which those glands have the tubular form which they 

 exhibit in the present genus ; that this, however, is due to the 

 obliteration of the distinction into two layers by the immense 

 quantity of secretion present is shown by another specimen 

 (fig. 38), in which the inner layer of columnar cells was quite 

 plainly visible. 



The vasa deferentia, which retain their distinctness up to 

 the very point of opening, open into the glandular part of the 



