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Show Ib87.] ANATOMY OF EARTHWORMS. 385 leading from the internal lumen of the penis to the exterior of the organ. These points are illustrated in the diagrammatic drawing of these parts (fig. 15). Next to the extraordinary complicated structure of the terminal section of the male generative ducts, the most remarkable fact about these organs in Eudrilus is the muscular coat of the vas deferens. In so far as I am aware, there is no Earthworm in which the*e tubes consist of more than a ciliated cubical epithelium surrounded by a delicate peritoneal investment ; the muscular coat of the vas deferens is another point of resemblance to the Leech. Besides the " prostate " gland, the eopulatory apparatus is furnished with another structure-the Y-shaped appendage of Perrier. This body has been correctly stated by Perrier to open into the bursa copulatrix, although his dissections did not enable him to demonstrate its precise relations. In m y paper on the anatomy of Eudrilus boyeri I stated that the duct of the Y-shaped gland opened into a cushion-like outgrowth of the bursa copulatrix, which Perrier has figured (I. c. pl. ii. fig. 27). I find that in the pre-ent species the structure is the same. The body in question in E. sylvicola appears to be invariably Y-shaped (fig. 15); the two arms of the Y never join at their extremities to form a horseshoe-shaped tube, as is stated by Perrier to occur in his species and by myself in E. boyeri. The two arms of the Y remain separate for only a short distance, when they become united into a single tube, which passes through the padlike outgrowth of the walls of the bursa, and opens at its extre nity into the interior of the bursa. The structure of the Y-shaped body is illustrated in Plate XXXIII. fig. 15 ; its walls are very thick and muscular, and the narrow lumen is lined by a somewhat flattened epithelium ; the extreme development of the muscular layers as compared with the epithelial lining rather suggests that its function is not that of a gland. Although the duct of the Y-shaped appendage opens freely into the interior of the bursa, it is really practically continuous with the lumen of the penis; tbe pad which bears the terminal orifice of the Y-shaped appendage projects so far into the interior of the bursa as nearly to occlude its lumen; only a narrow space is left between the pad and the penis, and this communicates directly with the lumen of the penis by the orifice already referred to above under the description of the penis. The pad itself is very muscular, and it is easy to imagine that by appropriate contraction of its walls the duct of the Y-shaped appendage might be brought into actual continuity with the interior of the penis. I have no facts at m y disposal which enable me to state positively what is the function of the Y-shaped appendage, but I am rather disposed to think from its structure and relations that it serves as a seminal reservoir. _ There is no doubt that Eudrilus differs very widely from other Lumbricidae in the structure of the female generative apparatus, and in the terminal apparatus of the male generative organs. In spite, however, of this great divergence, it agrees very closely in other particulars with the ordinary type of structure which characterizes the |