110 



S. HATAI. 



dorsal lateral vessels are gradually enlarged from segment TV backwards, and 

 the number of constrictions also increases. 



The dorsal vessel divides into two also in the anal segment, in which it 

 ramifies greatly. 



The ventral vessel, like the dorsal vessel, sends out a pair of lateral vessels 

 in each segment, which are continued into the corresponding vessels from the 

 dorsal trunk, not directly as in most other oligochretes, but by the intermediation 

 of smaller vessels. 



The ventral vessel divides into two in segment III ; these two branches pro- 

 ceed forwards and curving towards the dorsum in the first segment become 

 continuous with the single dorsal vessel. A little in front of the point of 

 separation of the two vessels just mentioned, these are united by a transverse 

 vessel, from which is given off in the median line a branch which itself divides 

 into two in segment I. These two vessels break up into smaller branches, which 

 become continuous with the corresponding vessels of the dorsal side. Besides 

 the lateral vessels corresponding to those of the dorsal vessel, the ventral vessel 

 sends out another set of lateral vessels, which always alternate with the former. 



The branching of the lateral vessels of the dorsal and ventral vessels is dis- 

 similar. The dorsal lateral vessels divide successively, while in the ventral 

 lateral we can recognize one main trunk, from which a number of smaller 

 branches are given off symmetrically on either side. 



In only a few among the many specimens that I have observed have I been 

 able to demonstrate valvular cells in the ventral vessel ; but their position is 

 very variable, and they are mostly confined to the anterior part of the body. 



Comparison op the two species. 



V. pilosus Goodrich. V. liraosus, n. sp. 



Clitellum X— XIII. Wanting. 



Sperm-duct Of uniform calibre throughout ; only Gradually increases in calibre 



the m : ddle portion appear swollen, backwards ; opens into a dis- 



owing to tho tall peritoneal cells tinct atrium, 

 surrounding it ; no atrium. 



Nephridium Begins in segment VI. Begins in segment VII. 



Oviduct Rudimentary. Absent. 



Sperm-sac Anterior sperm-sac in segment IX ; A single sperm-sac extending 



none in X ; posterior sperm-sac through segments IX — XIII. 



extending through segments XI — 



XII. 



Ovisac Formed by the posterior septum of Formed by the posterior s°p- 



segment XI. tum of segment XII. 



Cilia-like process... Uniformly present. Absent in the anterior portion, 



thickly eet in the posterior 

 portion. 



