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Show 218 MR. F. E. BEDDARD ON [Mar. 3, therefore to be possible that, after all, in spite of undoubted resemblances, Michaelsen and I have examined different species and indeed different genera. The female organs of the species which I have examined show a number of not uninteresting features. The two most salient parts of that system, which are visible on a dissection, are the two spermathecse and the egg-sacs. The spermathecae are sausageshaped, and distinctly divisible into two regions. The proximal part, i. e. that nearest to the external orifice, is strongly muscular, and indeed is enveloped with stronger muscular bands than is the bursa propulsoria of the spermiducal gland. Its epithelium is perfectly continuous with the general epidermis of the body-wall, and it has every appearance of being formed as an ingrowth from the exterior. The distal region of the spermatheca has very thin muscular walls, much thinner than the walls of the glandular part of the spermiducal gland. The interior has an epithelium which is raised into folds. I cannot speak of the histological characters of the cells, as the material was not sufficiently good. There is a very close resemblance, on a superficial view, between this spermatheca and the spermiducal glands. Indeed, on a cursory inspection, they might be taken for consecutive pairs of either spermathecae or spermiducal glands. The next most obvious part of the female reproductive system is a very large mushroom-shaped body closely adherent to the septum dividing segments xiii./xiv. This body is stalked, and appeared, on dissection, too large to be identified with a receptaculum ovorum (or egg-sac). Nevertheless it is the egg-sac, and by virtue of its large size it appears to be precisely like the egg-sac of P. papillata described by Michaelsen. On a closer inspection, a fine tube, apparently leading from the stalk of the egg-sac to the muscular part of the spermatheca, was apparent; this seems to correspond to the narrow tube (sg.) figured by Michaelsen. A series of longitudinal sections through the body showed more accurately the relations of these diverse organs to each other. I find that the spermatheca is entirely independent of the rest of the female apparatus, and that its cavity does not communicate with the narrow tube arising from the egg-sac. That narrow tube exists, as I have already mentioned; but on reaching the base of the spermatheca, i. e. the muscular end portion, it dilates into a sac which entirely surrounds the muscular part of the spermatheca, but does not, so far as I could ascertain, open into it anywhere. The conditions, therefore, are those of such a genus as Hyperio-drilus or Heliodrilus, where a true spermatheca is invested by a ccelomic sac. Now, though the difference may appear to be slight, I am disposed to think that it is important, and that a spermatheca which has no communication with the egg-conducting apparatus is essentially different from a spermatheca which has such a communication. It seems to me, for example, to be wrong to compare the spermatliecal sac of Lybiodrilus or Stuhlmannia with |