334 ALFRED GIBBS BOURNE. 
fig. 27. One branch—the “ branche tegumentaire” of Jaquet! 
—runs on to the body, comes into the neighbourhood of the 
distal portion of the ventro-tegumentary vessel of the segment, 
and runs along parallel to this towards the dorsal median line ; 
its branches run parallel to those of the ventro-tegumentary 
vessel, and their capillaries communicate. It is evident that, 
as the ventro-tegumentary vessel is the afferent vessel for these 
capillaries, this branch of the dorso-tegumentary vessel is the 
efferent vessel. The other branch (the “ branche dorso-sous- 
nervien”’? of Jaquet) loops round and becomes directly con- 
tinuous with the branch of the subneural vessel belonging to 
the segment; from about the outer seta line inwards it runs 
parallel to and close alongside of the proximal portion of the 
ventro-tegumentary vessel, and there are branches of this dorso- 
subneural vessel corresponding to each of the branches of this 
portion of the ventro-tegumentary vessel; there are, again, 
efferent vessels of the capillary networks in the body-wall and 
nephridia, supplied by the ventro-tegumentary vessel. 
There is thus a loop or commissural vessel which is connected 
on the one hand with the dorsal vessel, and on the other with 
the subneural vessel, all the branches of which bring blood 
back from capillaries. Does this blood pass into the dorsal 
vessel or into the subneural vessel, or into both? I believe 
that the blood passes into the subneural vessel only, and that 
no blood enters the dorsal vessel by means of the dorso- 
tegumentary vessel. I have already discussed this question 
when speaking of Megascolex, and although we are now dealing 
with a very different genus, it is not, I think, on a priori 
grounds, likely that the dorso-tegumentary vessel would carry 
blood out of the dorsal vessel in the one case and into it in the 
other ; moreover, in Moniligaster as in Megascolex, while there 
are valves which would mechanically prevent blood flowing 
into the dorso-intestinal vessels from the dorsal vessel, there 
are no such valves where the dorso-tegumentary vessels join 
the dorsal vessel. I have, however, observed in Moniligaster 
and some other worms a sphincter muscle in the wall of the 
1 «Mitth. Zool. Stat. Neap.,’ Bd. vi, 1885-6. 
