OCR Text |
Show 1903.J NEW SPECIES OP EARTHWORMS. 219 the spermatheca of Ileliodrilus. For this reason I cannot agree to Michaelsen's placing of my genus Alvania within the genus Hyperiodrilus. The former has a true spermatheca, homologous with that of other non-Eudrilid earthworms, while the latter has not. This also is the case with the genus or genera with which we are dealing now. Pareudrilus stagnalis has a spermathecal sac which communicates with the coclomic sacs envolving the ovary; " Pareudrilus " papillata has not. It is possible, therefore, that we should revive Michaelsen's Unyoria for the latter species. The stalk of the egg-sac, as might be expected, lodges the funnel of the oviduct, or, to speak more accurately, the greater part of the funnel. The exact conditions obtaining are the following. In a series of sections it may be seen that the narrow tube communicating with the coelomic sac surrounding the proximal end of the spermatheca runs forwards and opens into the cavity of the xiiith segment by a wide orifice; its walls are therefore continuous with, and no doubt developed from, the septum bounding segment xiii. posteriorly. The upper " lip " of the ostium is covered by the cubical cells of the oviduct, which here opens freely into the cavity of the xiiith segment. Further on in the series of sections, the mouth of the sac surrounding the spermatheca is closed, and the tube opens into the egg-sac through a wide tube which is entirely lined by the cells of the oviducal funnel; these are, of course, perfectly continuous with those cells which lie in the xiiith segment. The part of the oviducal funnel which lies in the xivth segment appears to be divided into two, and to open by as many mouths into the huge egg-sac, which is so kidney-shaped as to be nearly divided into two sacs ; I cannot pretend to an accurate description of the funnel and its various foldings. It is clear, however, that the conditions which obtain are those of the more typical Earthworms, where the funnel opens partly freely into the xiiith segment and is partly reflected so as to open within the egg-sac. Now, the simpler forms of Eudrilidse, such as the genus Eudriloides, are distinguished by the fact that the ovary is unenclosed in any sac, and that the funnel of the oviduct opens precisely as has been just described in Pareudrilus papillata. On the other hand, in the more complicated forms, such as Stuhlmannia, the sacs containing the ovaries envelop also the oviduct-funnel and communicate with the spermathecal sac. The species which forms the subject of the present remarks is plainly intermediate between these two extremes; and for that reason, as I think, deserves generic separation from Pareudrilus. § On the Spermatophore. The spermatophores of the Eudrilidse have not been much studied, and, so far as I am aware, are known only in the genera Stuhlmannia and Polytoreutus, in which I have myself described them. Many, if not most, of the individuals of the present species which I examined had a single spermatophore in both the spermathecse. |