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Show 1887.] ANATOMY OF E A R T H W O R M S. 373 The genus Eudrilus was first described by M. Perrier1, who, however, had only ill-preserved material to work at, consequently his account of the structure of the worm is imperfect; it is very evident, nevertheless, from what he has written upon the subject, that Eudrilus is one of the most remarkable genera of Lumhricidse, and I was particularly glad to have the opportunity of studying its structure in really well-preserved specimens. The most important facts which I have to bring forward in the present paper concern the structure of the female generative apparatus. In a note communicated to the ' Zoologischer Anzeiger' a, I pointed out that Perrier's description of these organs was inaccurate- that it did not, at least, apply to the species (a native of New Caledonia) studied by myself. Perrier was right in stating that the ovary was connected with the spermatheca, aud that its contents were set free by passing down the duct of the spermatheca : but he overlooked the fact that the ovary, although apparently sessile upon the duct of the spermatheca, was in reality connected with it by its own duct, a long coiled tuhe. This latter structure did not indeed escape the attention of Perrier; but he erroneously regarded it as a mere diverticulum of the spermatheca, and failed to make out its connection with the ovary. I was inclined to regard the species of Eudrilus3, upon which my own investigations were made, as distinct from any of those which Perrier has described. On this account I held it possible, though not probable, that Perrier and myself were both right, and that the discrepancies between our observations might be explained by supposing a real difference, as regards the points at issue, between the two species. Now that I have been able to study a second species of Eudrilus, I am disposed to think that Perrier was entirely wrong in his description. § External Characters. The Eudrilus which forms the subject of the present paper is a small worm, not measuring more than 32 millim. in length. It is remarkable for the fact that the body is built up of very few segments ; I counted 44, 45, and 46 respectively in each of the three specimens at m y disposal. The colour of the worm is a dark bluish purple upon the dorsal surface, fading into a dull yellow upon the ventral surface. The seta are disposed in pairs, as in Lumbricus. I did not notice any tendency to an increased number in any of the pairs which Perrier has referred to. The clitellum occupies segments 14-18 inclusive. The nephridiopores are placed in front of the ventral pair of setae ; in all other species of this genus the nephridial apertures are related to the dorsal pair of setae. The female generative pores are a pair of conspicuous orifices situated upon the 14th segment, and in front of the dorsal pair of ' "I Nouv. Arcb. d. Mus. t. viii. (1872) p. 71. 2 No. 224 (1886). s Proc. Zool. Soc. May 18th, 1886, p. 302. |
