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Show 1892.] SPECIES OF EARTHWORMS. 697 integumental pigment and to the consequent visibility of the bloodvessels through the skin. The setae are strictly paired. The clitellum is not developed ventrally, it extends dorsally over four segments, viz. xiv.-xvii; the male pore is single and median upon segment xvii. near to the posterior end of that segment; the spermatothecal orifice is also single and upon the xiiith segment. There are a few papillae present; on the eleventh segment are a pair on each side of the median ventral line; on the fifteenth segment are another pair occupying a corresponding position ; finally there are two pairs on segment xiii., one pair in front of and one behind the spermatothecal orifice ; in sections these papillae are seen to be slight depressions of the integument, and the epithelium is deeper than that which covers the body generally ; it is also composed of large clear cells which have a glandular appearance. It is possible that the papillae are adhesive disks, and not, as they seem frequently to be in some other Oligochaeta, sense-organs. A very marked peculiarity of the family Eudrilidae is the presence in the skin of those peculiar sense-bodies which were first described by myself in Eudrilus, and have since been found in a few other genera of the family ; they are, however, by no means universal, but have never been met with in any worm not belonging to the family Eudrilidae: they occur in the species under consideration. I only observed them in the clitellar region; this was perhaps due to the fact that elsewhere they were not so readily visible owing to the thinness of the epidermic layer ; they lie in the clitellum beneath the epidermis, and are placed longitudinally with reference to the long axis of the body. The muscular layers are not very thick; but there are no noteworthy points to comment upon. With regard to the internal anatomy, the alimentary tract shows a peculiarity not hitherto described in any Eudrilid: in many genera of this family there are calciferous glands of two kinds- paired organs in segment xiii., and ventral unpaired pouches in segments ix., x., xi. The present species has neither of these two kinds of appendages ; but it is not, as are many forms (e. g. Libyodrilus), entirely without glands appended to the oesophagus. In segments vi.-x. there are pairs of whitish-coloured glands which have a remarkable structure, quite unusual and unparalleled in the group Oligochaeta (see, however, the following description of Tricho-cheeta barbadensis). One of these glands is illustrated in fig. 11 of Plate XLVI.; the gland is of an oval or sometimes a more irregular shape; it is bounded externally by a thin layer which stains darkly with borax carmine, and which is perhaps to be regarded as the peritoneal layer investing the gland externally ; within this there is a mass of tissue consisting of innumerable spherules like the yolk-spherules of an ovum, and, like them, not stained by the reagent. Here and there among the mass of spherules are scattered nuclei, evident on account of their staining very deeply with the reagent that produces no effect upon the surrounding granules ; there were |
