316 DESCRIPTION OF THE PLATES. 



e i, e 2, e 3, e 4, e 5. * Capsulogenous glands ' of D'Udekem. These bodies 

 are stated to be specially modified and greatly developed setiparous 

 glands, which attain this prominence in the somites connected with 

 the essential, and with the accessory organs of generation ; amongst 

 the latter of which the long inner setae of many somites may be 

 reckoned, besides those here lettered e i to e 5. At e 2 we see a 

 slip of muscle passing across the glandular mass, and connecting the 

 inner with the outer row of setae. 



f i. Outer row of setae. Each seta is formed by a separate sac, and 

 has a separate insertion. The setae of the aquatic Oligochaeta are, 

 on the contrary, ' fasciculate ' in their insertion. In the clitellum the 

 outer row of setae may be enlarged to serve as copulatory organs. 



/2, Inner row of setae. The spines are solitary in their insertion as 

 in the outer row, but they are enlarged so as to serve as organs of 

 adhesion in many somites, as, for example, in the tenth and fifteenth, 

 as well as in the somites constituting the clitellum. 



gi. Anterior receptaculum seminis of the left side, opening in the interval 

 between the ninth and tenth somites, in the line of the outer row of 

 setae. 



g 2. Posterior receptaculum seminis, opening in the interval between the 

 tenth and eleventh somites. These organs are very variable in 

 size, according as they are full or empty. 



h i. Anterior vesicula seminalis of the left side. See p. 206, ante. 



h 2. Middle vesicula seminalis of left side. 



h 3. Posterior and largest vesicula seminalis. 



i i. Internal funnel-shaped orifice of vas deferens anterior of right side. 



i 2. Similar orifice of vas deferens posterior of right side. Nephridia are 

 present in these somites, and are disposed in the ordinary manner. 

 Diagrammatic : see pp. 206-8, ante, and Q. J. M. xx. p. 80-82, with 

 woodcut, p. 79. 



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 somite on the right side, and the ending of the 

 common canal there formed is well showri on both sides in the fifteenth 

 somite. The external opening of the common vas deferens has 

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

 the animal's body, guarded at the breeding season by prominent 

 tumid lips. 



k i. Anterior testis of right side. 

 k 2. Posterior testis of right side. 



/. The single ovary of the right side, occupying the same position rela- 

 tively to the nerve-cord and the inner row of setae as the testes. 



