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Show 362 MR. F. E. BEDDARD ON EARTHWORMS [A pi'. 16, by myself, is distinguished from Gordiodrilus by the fact that the sperm-ducts open by a single orifice on each side of the body into a terminal muscular sac; into this also opens one of the two or three pairs of spermiducal glands. In the first described species of Nannodrilus the spermiducal glands are but two pairs, of which the posterior opens into tbe muscular bulbus on the xviiith segment. In Dr. Michaelsen's subsequently described species N. staudei' there is in addition a third pair of spermiducal glands which open behind the muscular bulbus; so N. africanus can be derived from that species by a suppression of the last pair of spermiducal glands. In Gordiodrilus, on the other hand, the sperm-ducts open directly on to the exterior, and not through any terminal muscular bulbus; that at least is the structure of those species which have been investigated up to the present time. The new form described in the present communication is, however, different. There are as usual two pairs of spermiducal glands which open, the one pair behind the other, on to segments xix. and xx. On to segment xix./xx., just at the boundary-line and between the two pairs of spermiducal glands, open tbe sperm-ducts. These ducts, instead of simply burrowing their way through the integument, open first of all into a largish spherical muscular bulbus like that of Nannodrilus, which is not provided with an appended spermiducal gland. This species is thus intermediate between Nannodrilus staudei and the genus Gordiodrilus as hitherto defined. The middle pair of spermiducal glands may be supposed to have disappeared. Pygmaodrilns is a still further reduction of the same structural plan. There is but one pair of spermiducal glands, and the end of the vas deferens is involved in a muscular sheath, which may be looked upon-as Michaelsen has suggested-as the last remnant of such a muscular terminal sac as is possessed by Nannodrilus or Gordiodrilus papillatus.. Coming now to the details of structure of these various glands, the spermiducal glands themselves are long and extend through four or five segments in front of their point of opening. It does not seem to be important in which direction the glands lie, but in the present species they are coiled and lie in front of the pores. The glands themselves are, as iu other species of the genus, lined with a single glandular layer of cells. The terminal part which perforates the body-wall is short and of less calibre than the glandular part. It is lined by smaller and non-glandular cells : the muscular layer enveloping it is thin. At the actual orifice one of the two ventral seta? has disappeared ; one, however, is clearly present, so that in this matter Gordiodrilus papillatus seems to differ from at any rate some of the other species of the genus, in which the ventral pair of seta?, and not merely one of the two seta?, has disappeared. Female Organs of Generation.-The ovaries and oviducts furnish 1 " Neue und wenig bekannte afrikanische Terricolen," JB. Hamb, wiss, Anst. xiv. |
