ON TWO NEW GENERA OF AQUATIC OLIGOCH^TA. 299 



whether Lumbriculus does or does not agree with other Lumbriculidse in the relations of 

 the vasa deferentia. 



Sutroa is a somewhat aberrant Lumbriculid, quite recently described by Eisen 

 [4]. Each atrium is furnished with two vasa deferentia, the funnels of which both open 

 into the Xlth segment (? Xllth). 



Phreoryctes shows no affinities with the Lumbriculidse, except in possessing two pairs of 

 vasa deferentia. The atrium is entirely absent, and the vasa deferentia open separately on 

 to the Xlth and Xllth segments [see No. 12]. In Pelodrilus the conditions differ from both 

 the Phreoryctidse and the Lumbriculidse, and approach to a certain extent the Lumbricidse. 



There are two pairs of funnels which open into segments X. and XL The funnels 

 are of large size, and the arrangement of the septa is such (see fig. 39) that they face 

 upwards. In both cases the funnels are completely enclosed by the sperm sacs, which 

 almost completely fill the segments in which they lie. The cilia are very long, as is 

 usually the case with the Lumbriculidse [cf. Claparede, 1, pi. iii. fig. 1, Vejdovsky, 7]. 

 The position of the funnels agrees with that of the Phreoryctidse and most Earthworms. 

 They are both a segment farther back than in most of the Lumbriculidse. 



The vasa deferentia are remarkably long and greatly coiled. Fig. 38 illustrates the 

 coils of one of the second pair of vasa deferentia, which are, like those of the first pair, 

 almost entirely included within the sperm sac. The vas deferens is for the most part 

 extremely thin, though it widens out just before joining the funnel, and also for some 

 little distance in front of the external orifice. 



In the extremely thin and much coiled vasa deferentia, Pelodrilus differs from all the 

 Oligochseta, to which it presents other points of affinity. In both the Lumbriculidse and 

 Phreoryctidse the vasa deferentia are almost straight, or at most slightly sinuous. The 

 Enchytrseidse are more like Pelodrilus in this particular than any other family. The 

 structure of the vasa deferentia is not in any way peculiar ; they are, as is always the 

 case, composed of a single layer of ciliated cubical cells, and are covered by a delicate 

 layer of peritoneum. 



The communication of the vasa deferentia with the exterior is effected in a way 

 which is unique among the Oligochseta. 



There is, in the first place, no trace of an atrium — a structure which is present in all 

 the Lumbriculidse. The vasa deferentia open directly on to the exterior, as in Phreoryctes 

 and the Lumbricidse. 



The male apertures are situated within the clitellum, and are conspicuous when this 

 region of the body is examined in a specimen mounted entire. The cells of the clitellar 

 epidermis are seen to have an arrangement which is illustrated in fig. 35. They radiate 

 outwards from a conspicuous orifice placed upon the Xllth segment. In such preparations 

 I have been able to recognise two pairs of orifices upon the Xllth segment corresponding 

 in position to the orifices of the spermathecse upon the VHIth segment. In longitudinal 

 sections (fig. 28), two distinct male apertures are to be found upon each side of the body, 

 placed one in front of the other and on a line with the oviducal pores, as well as with the 



