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Show 702 MR. F. E. BEDDARD ON N E W [DeC 20, Separate calciferous glands like those of Pontoscolex do not exist in the present species, though it is very possible that three pairs of oesophageal caeca, the structure of which will be described presently, are the homologues of those glands. The calciferous glands are, however, functionally represented, as is so generally the case with Earthworms in which no separate caeca exist, by a tract of oesophagus with much folded walls; numerous crystals lying in the interstices of the folds appear to be the product of their epithelium, and are apparently similar to the crystals met with in true calciferous glands. This tract of oesophagus extends through about three segments, commencing with the tenth. It closely resembles the corresponding structure in the nearly allied form Onychocheeta \ In segments vii., viii., ix. are three pairs of very small oesophageal caeca; their calibre in transverse section is about the same as that of the dorsal vessel, but as they are very short and narrower at both extremities, they only possess even this small diameter for a limited distance. Each caecum is lined by a layer of low cubical epithelium which does not appear to be ciliated; between this epithelium and the peritoneum is a plexus of blood-vessels which are very large in proportion to the caecum itself, and protrude into the lumen, reducing it very greatly and causing it to assume here and there a star-shaped contour. It will be noticed that these caeca occupy the same segments as do the calciferous glands of Pontoscolex, and they may probably be safely regarded as the degenerate representatives of the latter. The gizzard is large and extends apparently through a considerable number of segments; defining its limits by the septum which bounds it posteriorly, it would seem to lie in the sixth segment, but the anterior septa are not sufficiently clear to permit of fixing its anterior limits. There are, as in some other Geoscolecidae, only a single pair of testes. These belong to the xith segment, and are attached to the front wall of that segment. They are, together with the funnel of the vas deferens, enclosed in a sac, which extends back for some segments (to about the xviith) and is the sperm-sac ; the sperm-sacs, however, although the worm was fully mature, contained no sperm, and were of a very narrow calibre as in Trichochceta hesperidum. The funnel of the sperm-duct is very large and folded ; the funnel extends below the testes and nearly reaches the septum to which the testis is attached ; the posterior limit of the funnel, still of course enclosed within the sperm-sacs, is in the septum bounding segments xiii./xiv.; but they lie close to the ovary. The sperm-duct itself opens on to the exterior on or beyond the xviith segment; I only traced it as far as the latter, but did not observe the actual opening. The ovaries are in xiii. and opposite to them are the funnels of the oviducts; the oviducal pores are just in the groove between the xivth and xvth segments. The spermatothecae are three pairs of simple sacs like those of Pontoscolex iuix., x., xi.; the last pair open on to the boundary line of segments xi./xii. 1 Q. J. M. S. vol. xxi. p. 159. |
