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Show 304 MR. F. E. BEDDARD ON NEW OR [May 18, In all the species described by Perrier there appears to be but a single vasa deferens on either side of the body, which opens directly into the bursa copulatrix and not, as in m y species, into the prostatic glands. The single vas deferens of either side is figured by Perrier (loc. cit. pi. ii. fig. 26). In all the specimens of Eudrilus boyeri dissected by me there were unmistakably two vasa deferentia on each -side of the body, which after came to be separated by a considerable interval, owing perhaps to the contraction of the body-walls, though more usually lying side by side and in close juxtaposition. The only other genus in which there are two vasa deferentia on each side of the body is Acanthodrilus, and this is in correspondence with the two generative orifices of each side ; where there is only a single pair of male generative pores, the vasa deferentia become fused directly behind the posterior funnel and pass down the body as a single tube. In Microchaita, however, Benham l has described the two vasa deferentia of each side continuing separate for several segments, though they ultimately become fused some way in front of the male generative pore. The condition of the vasa deferentia in Eudrilus boyeri forms another intermediate term in the series which connects Acanthodrilus with Lumbricus; in Acanthodrilus the two vasa deferentia are separate throughout their whole extent and their external apertures are each furnished with a prostate gland2. In Eudrilus boyeri there is only a single generative opening, but the vasa deferentia remain distinct. In Microchceta, where there is also a single male generative pore, the vasa deferentia of each side are partially fused. Finally, in Lumbricus and other genera the vasa deferentia unite immediately behind the posterior internal funnel. The nephridia of this species are well developed, and open in every case in front of the dorsal setae. The organs themselves are remarkable for the very large muscular duct. The alimentary tract presents certain features of interest. The oesophagus is furnished with three pairs of thick-walled whitish-coloured glands disposed in pairs in consecutive segments, viz. 11, 12, and 13; the posterior pair was smaller than the two anterior pairs. These glands appeared to have a lamellar structure, and the interior was filled with irregularly-shaped calcareous masses: there seems to me to be no doubt that these structures correspond to the calcigerous glands of Lumbricus. Along the intestine are another series of glands, about 40-50 pairs, commencing in the 90th segment. There is a single pair of these glands to each segment, which become larger towards the middle of the series, and 1 Quart. Journ. Micr. Sci. vol. xxvi. 2 In a species of Perichceta recently described by myself (Ann. & Mag. Nat. Hist. 188(5, xvii. p. 89) there are two prostates on either side, whose apertures are, however, situated in the same segment, and not in different segments as in Acanthodrilus. The condition of the specimen was such that I could not detect the connection of these with the vasa deferentia. It seems very possible that each prostate may correspond to a single vas deferens, in which case the male generative organs of this w o r m will be in certain respects intermediate between those of Acanthodrilus and Eudrilus boyeri. |
