442 



MR. F. E. BEDDARD ON THE 



[Nov. 5, 



Perrier, loc. cit. pi. 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 setae. 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 concmrently in Dero, since d'Udekem has 

 asserted that they do in some allied forms. 



Among the specimens of Dero which I examined were a few 

 individuals which agreed in every particular with the others exce})t 

 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. 



• €■ ?:> ''''* ''''' 



^ d 



Clitollar epithelium of Dero. 

 a. Showing granules in cells of developing clilellum ; h. Fully mature cells, 

 surface view ; c. Fully mature cells showing crenatccl margin, surface view ; 

 d. Section showing granular coaguluni which accumulates between epi- 

 thelium and cuticle. 



described allied genus, but I hope to be aljle to reinvestigate the 

 point if I succeed in keeping the brood of Dero alive. 



I now pass to the description of the generative organs. 



CAitellum. — This modified region of the epidermis was very con- 

 spicuous in fully mature individuals by its somewhat greater oj)acity. 

 Its anterior limits are as nearly as possible bounded by the apertures 

 of the spermathecae (see fig. 1), posteriorly it extends beyond the 

 .5th seta-bundles ; the clitellum therefore occupies three segments, 



