26o CALIFORNIA ACADEMY OF SCIENCES. 



but in shape it is entirely and characteristically different 

 from the one in that species. It is about one-third as 

 thick and three-fourths as long as the diverticulum of the 

 oesophagus. The spermatheca of O. agricola is about 

 one and one-half times thicker than the diverticulum, 

 and almost globular in outline. 



The ciliated rosettes are in this species smaller, as com- 

 pared to those of other species. 



The -prostate glands are very slender and twist consid- 

 erably, extending behind the clitellum, or as far as the 

 end of somite xx. In width they are about the size of the 

 widest part of the ventral ganglion. The prostate con- 

 sists of two distinct parts; the more distant one, which is 

 glandular, and the one nearest the male pore, which is 

 muscular. The glandular part is by far the longest, as 

 well as the widest. In form it is cylindrical, of the same 

 width throughout its length, and not tapering as in some 

 other species. This glandular part consists of a single 

 layer of epithelial cells, just as in all other species. 



The muscular part is in this species very long, occupy- 

 ing about the length of one and two-thirds somite, and 

 about one-third or one-half longer than the enlarged part 

 of the sperm duct. In width the muscular part of the 

 prostate is slightly narrower than the glandular part. It is 

 also more transparent. The transverse muscles are very 

 conspicuous (fig. 24), enclosing a large, regular and well 

 defined lumen. The prostate and the sperm duct are en- 

 tirely independent of each other until they reach the male 

 pore, in which they both open apparently separately. 



The muscular part of the prostate is a little less than 

 one-half as long as the glandular part, and somewhat 

 narrower. It is narrowest close to the glandular part, 

 and then becomes wider towards the male pore. The 

 greater part, however, is of even thickness. In the 



