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Show 1892.] SPECIES OF EARTHWORMS. 691 inary Notice of Earthworms from the Nilgiris and Shevaroys." P. Z. S. 1886, p. 670. (7) R. H O R S T . - " Descriptions of Earthworms.-I. Moniligaster houtenii, n. sp., a gigantic Earthworm from Sumatra." Notes Leyd. Mus. vol. ix. p. 97. (8) E. P E R R I E R . - " Recherches pour servir a, l'histoire des Lombri-ciens terrestres." Nouv. Arch. Mus. vol. viii. p. 130. (9) D. R O S A . - " Viaggio di Leonardo Fea in Birmania e Regioni vicine: xxv. Moniligastridi, Geoscolecidi ed Eudrilidi." Ann. Mus. Civ. Genova, ser. 2 a, vol. ix. p. 368. (10) W . M I C H A E L S E N . - " Terricolen der Berliner Zoologischen Sammlung." Arch. f. Nat. 1892, p. 209. In this list, it should be mentioned, I have only included papers containing new facts with reference to the genus ; other papers which refer to it will be quoted in their place in the course of the following pages. External Characters. In the present species, which I name Moniligaster bahamensis, the clitellum was fortunately developed ; it was not, however, visible until the worm was examined by means of sections, and was then found to occupy four segments, viz. x.-xiii. It will be remembered that Perrier created a special group, the Aclitelliens, for Moniligaster, since it appeared to possess no clitellum ; the anterior segments were, however, described as resembling in certain particulars the clitellum of other worms and as probably representing that organ ; but it is not necessary to remark that frequently the anterior segments of Earthworms, especially of the smaller species, are considerably thicker, and also appear more opaque owing to the enclosed viscera. The first to describe the clitellum was Prof. Bourne ; he wrote that it occupied segments x.-xiii.; but there are no details given as to whether the clitellum was visible without first having recourse to section-cutting; it certainly is not in the present species. The clitellum begins and ends sharp at the margins of the segments which it occupies. The resemblance which the forward position of the clitellum in Moniligaster gives this genus to the Lumbriculidee need not be again emphasized ; I have already sufficiently dwelt upon the matter. I have, however, now to refer to an interesting point with regard to the clitellum which has not yet been described : the minute structure of the clitellum differs from that of all other Earthworms and agrees with that of all " Water-worms " in being composed of a single layer of cells only. This appears to me to be a point of great importance; coupled with the position of the clitellum it gets even greater importance than it would otherwise have. Rosa has sought to minimize the significance of the anterior position of the clitellum ; but I do not think that anyone will deny that the resemblance in structure which it shows to the lower Oligochaeta cannot be explained away; there is, moreover, no resemblance in |