Anatomy and Histology of a Neiv Earthivorm. 57 



side towards the outlet in somite 19. They lie just outside the 

 outer seta of the inner pair, are perfectly cylindrical, a little 

 contorted, and gradually approach the exterior, so that at the 

 point at which the ducts of the first pair of prostate glands 

 pass to the exterior, the vasa are at the middle of the muscular 

 layer in which they are embedded. Just before turning out- 

 wards to their outlet in somite 19, they unite, and thus open 

 by a single duct in the copulatory fossa, as already noted. 

 From their position in the muscle layer, they cannot be traced 

 by the methods of ordinary dissection, and it was only by cut- 

 ting serial sections that they were finally traced to the external 

 outlets. 



Four peculiar glands, doubtless the homologues of what 

 have been named prostate glands in other genera of Oligo- 

 chaeta, still remain to be described as a part of the male repro- 

 ductive apparatus. In Diplocardia they have no direct con- 

 nection with the vasa deferentia, but the products of both are 

 discharged into the copulatory fossaa, and thus the same re- 

 sult is probably attained as would be by the passage of the vasa 

 into the glands. Each gland opens by a separate duct at one 

 end of a fossa. The glands are long, strap-shaped, orange- 

 yellow bodies, floating for the greater part of their length free 

 in the somatic fluid, so that they often pass by the apertures of 

 the dissepiments into somites other than those in which they 

 belong. They are abruptly bent where attached to the floor of 

 the somites in which they open, and a large muscular duct 

 arises near this end of the gland and penetrates the integu- 

 ment to the exterior. Each duct is accompanied by a pair of 

 long copulatory setee, occupying the place of the inner pairs in 

 somites 18 and 20. 



Excepting the form of the ovaries, the female genital 

 organs of this genus are not especially different from those of 

 Lumbricus. The ovaries are attached to the posterior face of 

 the septum, between somites 12 and 13, and thus lie in the 

 latter division of the body. They consist of rather large 

 fan-like sheets of tissue, narrowing to a thick pedicel by 

 which they are fastened to the septum, and under the micro- 

 scope are seen to be made up of numerous parallel series of 

 ova, growing more and more mature towards the free edges of 



