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Show 172 MR. F. E. BEDDARD ON A LARGE EARTHWORM. [Mar. 16, Generative System.-In the 12th segment are a pair of glands attached firmly to the mesentery which separates this segment from the one anterior to it; in two specimens these glands were paired, while in a third only the left-hand one of the two was present; in one specimen these glands have a racemose structure, and although a microscopic examination did not reveal any structure, I have little doubt that these glands are testes. Out of the seven examples at m y disposal one specimen possessed a similar pair of glands in the 11th segment in addition to those found in the 12th segment; in all the remaining specimens save one, which was small and immature, the 10th segment (that which follows the segment containing the posterior pair of spermathecee) has a pair of glandular-looking bodies which are very similar in general appearance to the structures which I have regarded as the testes ; they are attached, however, to the posterior wall of their segment, which, as in other Earthworms, is not separated by a mesentery from the 9th segment; these two segments, which are thus fused, contain the gizzard. The fact that these glands are attached to the posterior and not to the anterior wall of their segment is perhaps against the view that they represent an anterior pair of testes ; at the same time it happens that the segment in which they occur has no anterior wall, being fused with the preceding 9th segment; these glands were not present in the only specimen that had two pairs of testes. In Acanthodrilus capensis 1 there are three pairs of testes situated in segments 10, 11, and 12; but out of a number of examples that I dissected only one had the three pairs developed. There is therefore nothing unusual in supposing that the present species, like^4. capensis, has three pairs of testes, although all the other species that are known appear to have only two pairs. On the other hand, the gland in segment 10 is very similar to a curious structure which exists in A. capensis in a similar position, i. e. attached to the posterior wall of the segment. In this species, however, the gizzard happens to be placed in front of the copulatory pouches, and not in the segment which contains them ; so that the two pairs of pouches are separated from each other and from the following segments by fully developed mesenteries, which, as already stated, is not the case with the species that forms the subject of the present communication ; in this species the gizzard lies in the 9th and 10th segments. If, however, these structures correspond to those recorded by m e in A. capensis, it is no explanation of their nature ; in neither case is their function at all evident. The vasa deferentia were not visible. Each of the four male genital apertures are furnished with a long sac containing a number of penial setae which open on to the exterior in common with the duct of a long coiled prostate gland, which appears to be similar in structure to the prostates of A. obtusus2; on the other hand, the characters 1 Proc. Koy. Phys. Soc. loc. cit. p. 375. I have written 11, 12, and 13 in error; the ovaries, as I have been able to assure myself by a subsequent examination, are in segment 13, and so presumably the testes are in the three segments anterior to that which contains the ovaries, viz. in segments 10, 11, 12. 2 Perrier, loc. cit. p. 88. |