A ustratian Earthiuorms. 2 1 5 



receiving a small vessel from the dorsal in 13, and ends on the 

 ventral body wall in 16. 



The ventral vessel is not very well developed anteriorly to 13. 

 It receives a commissural in each segment, and breaks up into 

 very fine branches in 1, some of which pass to the dorsal surface 

 and appear to form very fine connections with branches of the 

 lateral. Behind 14 the ventral is small, and sends branches to 

 the body wall in each segment. In section it appears to be 

 connecting with a sinus around the alimentary canal by ex- 

 tremely small vessels. This sinus is supplied by well-marked 

 vessels from the dorsal. 



Both dorsal and ventral vessels are unusually thick-walled and 

 muscular in the hinder region of the body. 



4.— Cpyptodpilus manlfestus, Fletcher. Proc. Linn. Soc. 



N.S.W., 1888. 



Plate XLT., Fig. 4 ; Plate XLtl., Fig. 7. 



Dissection. — Dorsal vessel single, slightly swollen in seg- 

 ments 13, 14 and 15, and running forward to apparently break 

 up in 1. 



From 15 backwards it gives oft' two vessels in each segment 

 closely applied to the alimentary canal. In 14 there is appar- 

 ently only one of these, while in 13 none arises from the dorsal 

 at all. 



In 10, 11 and 12, a pair of hearts arise from a double origin 

 at the posterior part of each segment, and pass to the ventral 

 vessel. From the hinder end of segments 9-5 a pair of commis- 

 surals arise, running parallel to, if not joining with, the lateral 

 or one of its branches for some distance in each segment, and 

 sending vessels to the posterior septum and ventral body wall 

 before joining the ventral. The mesenteries anterior to 7 are 

 very thin, which makes the segmental arrangement difficult to 

 distinguish, but in 5 the commissural gives branches to the 

 alimentary canal as well as those already described for each 

 segment. Anterior to 4, the vessels are small and indelinite, 

 but the dorsal appears to give branches to the alimentary canal 

 and break up in 1. 



