ON VERMICULUS LIMOSUS.^ 



105 



IX 



the larger portion of which lies on the dorsal side of the alimentary canal. In 

 segment IX the posterior septum forms on the left ventral side an evagination 

 towards the anterior, and this evagination is directly continued into the sperm- 

 sac, which is very voluminous and is situated on the dorsal side of the intestine, 

 in the median line. Of V. 2*losns Goodrich says (2, p. 261), "The sperma- 

 tozoa are shed at an early stage of development into segment 10, and the 



anterior septum of this 

 segment soon bulges out, 

 forming a sac — the anterior 

 sperm-sac. Later on this 

 sperm-sac pushes its way 

 across segment 9, through 

 its anterior septum into seg- 

 ment 8. The hinder wall 

 of segment 10 also bulges 

 out, forming the posterior 

 sperm-sac." In the new 

 species before us these two 

 sacs have become one and 

 continuous. The walls of 

 the sperm-sac are exactly 

 like those of the ovisac to 

 be presently described, and 

 arc covered with peritoneal 

 cells on A both surfaces. The 

 hinder end of the sperm- 

 sac projects into the cavity 

 of the ovisac. 



8. Ovary. — One pair 

 attached to the anterior 

 septum of segments X and 



almost reaching the pos- 

 J). V. Doisal Vessel, int. intesi ine, Cvs. Ovisac, + • , i e n 



Sep. Septum, 5«. Sperm-sac, V.O. Ventral Cord, terIor septum when fully 



V.Y. Ventral Vessel. developed, in which case 



the peritoneal covering is also very indistinct. 



XI 



XII 



XIII 



xiv 



