1887.] 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 thc^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. 



Be.-ides the " prostate " gland, the copulatory apparatus is fur- 

 nished with another structure — the Y-shaped appendage of Perrier. 

 This body has been correctly stated by Perrier to open into the bursa 

 copulatiix, although his dissections did not enable him to demon- 

 strate its precise relations. In my paper on the anatomy of Eudrilus 

 boyeri I stated that the duct of the Y-shaped gland opened into a 

 cushion-like outgiowth of the bursa copulatrix, which Perrier has 

 figured {I. c. pi. 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 pad- 

 like outgrowth of the walls of the bursa, and opens at its extrenity 

 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 com- 

 pared 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 ; the 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 appen- 

 dage might be brought into actual continuity with the interior of the 

 penis. 1 have no facts at my 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 orgaus. In spite, 

 however, of this great divergence, it agrees very closely in otlier par- 

 ticulars with the ordinary type of structure which characterizes the 



