ZooL.— Vol. II.] RISEN— OLIGOCHMTA. l8l 



muscular strands. The diverticle of the spermathecae in 

 VIII is so large that it projects through the septum VII/VIII 

 into VII. It does not seem to contain any trabeculse. 



Reproductive Organs. — Testes are large, in X, XI. 

 Ovaries are strongly digitate, longitudinal sections showing 

 six or eight narrow lobes starting from the septum. 



S-perm-sacs. — There are three pairs of sperm-sacs sur- 

 rounded by a peritoneal membrane. The pair in IX is 

 slightly racemose and preseptal. The pair in X is not 

 racemose, but still traversed by trabeculae starting out from 

 septum IX/X. They are thus postseptal. In XI there is 

 a large sperm-mass like the pair in X, but there are no 

 trabeculae and there is no peritoneal membrane. The sacs 

 in XII are strongly racemose and postseptal. 



Prostates. — The prostates are large and thick, each one 

 folded once. The outline is rough, wavy and warty. The 

 muscular duct is well marked and folded two or three times. 

 Each prostate occupies about two somites. They open as 

 usual near sacs with penial setae, but I am unable to say 

 whether these are sculptured or smooth. The structure of 

 the glandular part of the prostate is peculiar. The lumen is 

 not wider than the lumen of the muscular part. This lumen 

 is along its entire length ramified with tapering branches 

 into which open the glandular cells. The lumen appears, 

 both in the main canal as well as in the branches, to be 

 lined by a thin membrane only, which probably must be 

 considered as a reduction of the regular columnar epithelial 

 cells which characterize the prostates of all higher Oli- 

 gochseta except the Ocnerodrilini. This membrane con- 

 tains, so far as I can see, no nuclei. The glandular part of 

 the prostates is thus only one layer thick, all the cells being 

 of the same quality. Around each branch of the lumen 

 the glandular cells are arranged as around the lumen of a 

 common prostate. They also open in the main lumen. 

 Compared to the prostate of D. Udei, the parts of the 

 present species are yet more reduced as regards the inner 

 epithelium. In D. Udei I could now and then find a nucle- 

 ated cell in the lining epithelium, while in D. Michaelseni 



