| OCR Text |
Show 1901.J FROM BRITISH E A S T AFRICA^ 357 In mauy earthworms, for example iu Sparganophiliis ', the oviducal funnel opens partly into the xiiith segment, but the greater part opens into the egg-sac behind. It might be held that the Eudrilidas present us with a simple exaggeration of this state of affairs. The separation between the two parts of the oviducal funnel is more emphasized, and at last results in its complete division into two funnels. O n the other hand, as Dr. Benham has pointed out, the actual change which seems to be more possible is that the funnel entirely loses its orifice into the xiiith segment, and comes to open entirely into the egg-sac; this at least is what occurs in Eudrilus. It must be borne in mind that in that genus, which is in some respects the most specialized of the Eudrilida?, the spermathecal system is constructed on lines rather different from those upon which the spermathecal system of other genera of the family are built. Now" it has been shown that a large part at least of the complicated series of sacs which constitute the spermathecal system originate from the septa of which they are outgrowths, like the egg-sacs or the sperm-sac. It seems therefore at least a possible view that the lateral sacs of Stuhlmannia which encircle the gut are to be compared to the egg-sacs of the xivth segment ; that, in fact, they are an anterior pair of egg-sacs belonging to the xiiith segment. To these the second pair of funnels belong. In Eudrilus, where there are no such lateral sacs, there are no oviducal funnels in the xiiith segment. Just as iu Stuhlmannia, where on one side of the body the egg-sacs of the xivth segment are wanting, there is a corresponding absence of the funnels of that segment. Before leaving this matter I would direct attention again to the remarkable asymmetry-which I found so frequently that I am disposed to regard it as normal-of the female reproductive apparatus in this species. I may compare with this an apparently similar, and also apparently quite normal, atrophy of one oviduct and the absence of its external orifice in Typhoeus nicholsoni, a species recently described by myself~, aud the asymmetry of the pores in Polytoreutus gregorianus. Asymmetry, of at all a constant character, is so rare in Annelids, that it is legitimate to emphasize these two cases. The sperm-ducts of the geuus Stuhlmannia show a peculiarity which has not been apparently mentioned. It was first pointed out by Rosa:' in the case of the genus Tdeudrilus that the funnels of the sperm-ducts, instead of opening in the normal way opposite to the testes in the xth and xith segments, bent round aud opened into the xith and xiith segments. I found subsequently the same arrangement in Hyperiodrilus. I had thought, however, that this peculiarity was confined to the Eudriline division of the Eudri- 1 Benham, " A new English Genus of Aquatic Oligochajta, &c," Quart. Journ. Micr. Sci. xxxiv. p. 155. 2 P.Z.S. 1901, vol. i. p. 195. •> "Lombrichi delle Scioa," Ann. Mus. Oiv. Genova (2), vi. p. 574. PROC. ZOOL. Soc-1901, VOL. I. No. XXIV. 24 |
