SYSTEMATIC POSITION OF A GIGANTIC EAETHWOEBI. 75 



into which the terminal portion of the vas deferens has been thrown ; in the segment 

 in front, which contains the anterior pair of testes, there is a similar body, which is 

 attached to the testes of its own side, and also continuous with the terminal portion 

 of the vas deferens lying in segment eleven ; the ventral blood-vessel, which elsewhere 

 lies upon the nerve-cord, comes to be some way removed from it in these two segments, 

 in order to make room for the dilated extremities of the vasa deferentia which partly 

 cover the nerve-cord. These structures and their relations to each other are exhibited 

 in fig. 4 of PI. XV. The arrangement of the terminal apertures of the vasa deferentia, 

 their continuity with the testes, is evidently very favourable for conveying the seminal 

 fluid to the exterior ; in many Earthworms the fimbriated openings have no such direct 

 connection with the testes, but lie on the posterior wall, while the testes themselves 

 are attached to the anterior wall of the segment which contains them ; in most cases, 

 indeed, the apertures of the vasa deferentia are still further removed from the testes. 

 In Ponfodrilus the anterior pair of apertures are actually not in the same segment 

 with the testes corresponding to them, but in the one in front. 



(4) The ovaries (PI. XV. fig. 4, o) are two small bodies attached to the mesentery 

 which forms the anterior wall of segment thirteen ; they are supplied with abundant 

 blood-capillaries, which are frequently dilated in their course. Many observers have 

 noticed a similar condition of the blood-capillaries in Earthworms, especially in those 

 supplying the segmental organs; these dilations were visible with a hand-lens as 

 reddish specks in the ovary, and, indeed, enabled me first to find the organ, which is 

 sufficiently small — hardly, indeed, larger than in many small Earthworms. 



(5) The position of the oviduct (PI. XV. fig. 4, od), with reference to the ovary, is 

 rather anomalous ; the terminal aperture, which is very much folded, lies on the ante- 

 rior side of the same mesentery which bears the ovaries, and consequently in segment 

 twelve ; it appears, however, that a portion of the terminal funnel, connected with the 

 rest through the mesentery, opens into the same segment (segment twelve) that contains 

 the ovary, and is bound to it by a membranous sheet ; the two oviducts appear to open 

 separately on to the exterior in the immediate neighbourhood of the inner pair 

 of setae. 



(6) Copidatory Pouches. — There is no doubt that the small oval sacs (PI. XV. 

 figs. 4, 6, C.J)), already described in connection with the segmental organs, represent 

 functionally the copulatory pouches of other Earthworms; but it is rather surprising to 

 find that copulatory pouches of the ordinary size, and arranged in pairs, are absent. 

 Perrier remarks upon the absence of copulatory pouches in another Intraclitellian 

 genus Titanus. I have already pointed out that the series of small pouches in segments 

 13-16 correspond in all probability to quite similar structures in PerichcBta asjjergillum. 



In conclusion I may briefly abstract from the foregoing description the generic 

 definition of Microchwta. 



VOL. XII. — PART III. No. 3. — August, 1886. w 



