MONILIGASTER GRANDIS, A. G. B. 331 
bounds posteriorly the segment to which they belong, so that 
they lie in the posterior portion of their segment. 
These ventro-tegumentary vessels supply not only the body- 
wall, but all the viscera excepting only the walls of the 
alimentary canal, and they and their branches almost always 
run strictly side by side with vessels belonging to the latero- 
longitudinal and subneural system; their finest branches 
(capillaries) are in every case continuous with the finest 
branches of this system—they are, in fact, the afferent vessels 
while the branches of the latero-longitudinal and subneural 
system are the efferent vessels of the tissues. So closely are 
these afferent and efferent vessels associated throughout the 
greater part of their course that I have again and again ima- 
gined that I was dealing with a single vessel, but when I 
knew what to expect, more careful examination always re- 
vealed two vessels lying side by side and branching at the 
same spots. 
As atype of what occurs with regard to the majority of 
these ventro-tegumentary vessels we may take that of Segment 
x11. The vessel lies on the mesentery and runs towards the 
dorsal region : it sends outwards towards the body-wall a series 
of branches; the first of these supplies the region of the body- 
wall which lies ventrad of the inner row of setz following this ; 
then there are three branches going to the region of the body- 
wall which lies between the two rows of set, and near the first 
of these a branch to the nephridium of the next following seg- 
ment (tothe nephridium, that is to say, all of which except the 
funnel lies in the next following segment). Up to the point 
where the last of these branches is given off, the vessel is closely 
accompanied by a branch of the subneural vessel, but at this 
point the ventro-tegumentary vessel leaves for a short time 
the subneural-tegumentary branch and runs more closely 
along the body-wall, giving off a series of five or six small 
vessels in its course towards the dorsal region. The subdivi- 
sions of all these branches to the body-wall run backwards as 
well as forwards, so that the vessel is not distributed to its 
own segment only, but to the anterior portion of the next 
