442 MR. F. E. BEDDARD ON THE [Nov. 5, 
Perrier, loc, cit. pl. i. fig. 1) is not clearly defined. In the sexual 
individuals studied by myself the last segment was only furnished 
with the ventral bundles of sete. This character may possibly 
prove to be of specific value. 
It is of some importance to note that budding and sexual repro- 
duction do not take place concurrently in Dero, since d’Udekem has 
asserted that they do in some allied forms. 
Among the specimens of Dero which 1 examined were a few 
individuals which agreed in every particular with the others except 
for the entire absence of all traces of the branchial apparatus. There 
was, moreover, no appearance of any injury to this part of the body, 
and the segments ended off in a perfectly regular fashion. I do not 
believe that these individuals were a species of Nais or any other 
Fig. 2. 
to} 
e 
Ce 
Clitellar epithelium of Dero. 
a. Showing granules in cells of developing clitellum ; %. Fully mature cells, 
surface view ; ¢c. Fully mature cells showing crenated margin, surface view ; 
d, Section showing granular coagulum which accumulates between epi- 
thelium and cuticle. 
described allied genus, but I hope to be able to reinvestigate the 
point if I succeed in keeping the brood of Dero alive. 
I now pass to the description of the generative organs. 
Clitellum.—This modified region of the epidermis was very con- 
spicuous in fully mature individuals by its somewhat greater opacity. 
Its anterior limits are as nearly as possible bounded by the apertures 
of the spermathece (see fig. 1), posteriorly it extends beyond the 
5th seta-bundles ; the clitellum therefore occupies three segments, 
