THE OLIGOCH.'ETA TERRICOL-fE. PART I. 187 



browner as conti'asted with the whiter color of the rest of the 

 sperm sac. This pecuhar differentiation of the sperm sacs is 

 not unknown in other species of the genus Pheretima. Each 

 sperm sac is connected with a sperm reservoir as it has been 

 termed, but for which the term testicular sac seems much more 

 suitable since the testes lie within it. 



Ude ° has lately called renewed attention to these sacs which 

 present differences in different species. In the species of Phe- 

 retima now under consideration there is no median fusion 

 between the pairs of testicular sacs. On the other hand, the 2 

 sacs of each side in those belonging to segments XI and XII 

 are apparently hardly in communication, and unquestionably in 

 contact. When the sacs in question are opened and their con- 

 tents revealed, the complete separation between all four of them 

 becomes very obvious. When the walls are cut away dorsally 

 the cavity of each sac is seen to be circular in contour. The 

 anterior wall of the anterior pair presumably represents the 

 otherwise entirely missing septum between segments IX/X. 



In view of the certain amount of variation met with in the 

 internal structure of Pheretima decipiens, it is important to 

 notice that there is practically none in P. bengiietensis, although 

 this statement must be qualified by the further consideration that 

 I am in a position to report upon only 2 fully mature individuals. 

 In the second of these, I found a precise agreement with the 

 example described above. The appendicular lobe of the sperm 

 sacs, however, originated rather farther down than in the first 

 named individual where each caps its corresponding sac, but in 

 their relative smallness these appendices contrast with those of 

 Pheretima decipiens. 



The spermiducal glands and the terminal male apparatus lie 

 entirely within the XVIIIth segment, whose septa, however, 

 bulge somewhat laterally to accommodate these male organs. 

 The spermiducal gland is divided into 3 inequisized, principal 

 lobes, of which the anterior is the largest, and the middle one 

 the smallest and again subdivided into two. A division of these 

 lobes into equal-sized lobules is also quite plain. The duct of the 

 gland is short and rather swollen, and either straight (running 

 at right angles to the long axis of the body) or slightly bent 

 posteriorly; it opens into a well developed bursa copulatrix 

 of circular area. The vasa deferentia can be traced to their 

 opening at the commencement of the muscular duct of the 

 spermiducal gland, a point which is hidden by the glandular 



' Ztschr. f. wiss. Zool. (1905), 83, 405. 



