Doe ALFRED GIBBS BOURNE. 
following segment. There is, however, so far as I can see, no 
anastomosis between the branches of one ventro-tegumentary 
vessel and those of another. 
In Segments vi, vii, and vir each ventro-tegumentary 
vessel, very soon after its origin from the bulbous enlargement 
at the base of the heart, gives off a small branch which supplies 
the wall of the heart itself and the wall of the dorsal vessel ; 
the next branch runs along the anterior surface of the septum 
which bounds posteriorly the segment to which it belongs, 
gives off some small branches, and then passes up towards the 
dorsal region of the posterior portion of the body-wall of the 
segment, giving off numerous branches, some of which run 
backwards and some forwards, while all supply the various 
layers of the body-wall. The ventro-tegumentary vessel itself 
runs forward in the segment and gives off a branch to the 
nephridium, and, lastly, supplies the posterior side of the 
septum which bounds the segment anteriorly, and, passing 
towards the dorsal region, supplies the body-wall of the ante- 
rior portion of the segment. 
The ventro-tegumentary vessel, which originates in Segment 
vim but passes backwards to supply Segments 1x, x, and, to 
a certain extent, x1, is the largest of the whole series. It 
penetrates the Septum vui1-1x close alongside the latero- 
longitudinal vessel and runs backwards with this. It gives 
off a branch to the posterior side of Septum viit-1x and the 
anterior region of the body-wall of 1x, one of the subdivi- 
sions of which branch forms the afferent vessel of the ne- 
phridium of Segment 1x, then a branch to the posterior portion 
of the body-wall of Segment 1x, which will be seen from 
fig. 27 to pass just in front of the external aperture of the 
nephridium of Segment x, and close to this last branch 
another, which, after giving off a small branch to the wall of 
the heart of Segment 1x, passes to the seminal capsule ; its next 
branch supplies the nephridium of Segment x; its next branch, 
after giving off a vessel to the prostate, supplies the ventral 
region of the body-wall in the anterior portion of Segment x, 
and then, after giving off a branch which goes to the nephridium 
