Earth Worm. 215 



posterior and larg-er portion ; and posteriorly to each of 

 these infundibula there exists also in each of these segments 

 the funnel-shaped opening* of the segmental organ of the 

 segment next behind it. The coexistence therefore of the 

 vasa deferentia with the very similarly constructed seg- 

 mental organs would appear to be inconsistent with a view 

 which should regard them as modihcations of those glands. 

 Still the great development and increase of mass observable 

 in other organs in these segments may, as suggested by 

 Mr. Lankester, induce us to hold that the typical number 

 of segmental organs in any one segment is four, and that 

 this number is attained to in those generative segments only 

 on account of their superabundant nutrition. Upon this 

 view the vasa deferentia, as also the oviducts n, would be 

 serially homologous with the seg^mental organs. 



j I. Vas deferens from anterior spermatic infundibulum of left 

 side. 



j 2. Vas deferens from posterior spermatic infundibulum of left 

 side. The junction of the two vasa deferentia to form one 

 common canal is well seen in the twelfth segment on the 

 right side, and the ending of the common canal there 

 formed is well shown on both sides in the fifteenth seg- 

 ment. The external opening of the common vas deferens 

 has the shape of an oval slit, with its long axis transverse 

 to that of the animaFs body, guarded at the breeding season 

 by prominent tumid lips. 



k I . Anterior testis of right side. 



k 1. Posterior testis of right side. 



I. The single ovary of the right side, occupying the same posi- 

 tion relatively to the nerve-cord and the inner row of setae 

 as the testes. 



m. Infundibular ciliated mouth of oviduct, holding a similar 

 position to that held by the infundibulum of the segmental 

 organ c 5, which opens both internally and externally in the 

 same segments. 



n. Oviduct in the posterior of the two segments in which its 

 various parts are found. After passing through the dissepi- 

 ment separating the thirteenth from the fourteenth segment, 

 the oviduct has a saccular dilatation, ordinarily found to 



