MONILIGASTER GRANDIS, A. G. B. 323 
of longitudinal muscle, and below that an equally thin layer of 
circular muscle; in both cases there are scattered fibres rather 
than a regular layer. In the intestinal wall there are fairly 
strong longitudinal bands in the median dorsal and ventral 
walls. Further, in this region, to an extent which increases 
from before backwards, the muscle fibres of the septa spread 
out circularly round the outside of the intestinal wall. These 
fibres lie outside the ccelomic epithelium, and in the rectal 
region the circular muscular bands so formed become so broad 
as to be almost continuous (figs. 25). 
The coelomic epithelium of the intestinal region presents the 
usual characters. 
VASCULAR SYSTEM. 
Having had a practically unlimited supply of fresh speci- 
mens, I have been able to work out this system in considerable 
detail. There is no doubt but that the system has become 
very fully developed ; in dissections, in sections, and in other 
microscopic preparations I have again and again seen most ex- 
quisite “capillary” networks. I have also procured admirable 
injections for dissecting purposes by injecting a mixture of any 
very soluble oil paint dissolved in turpentine. This mixture is 
very excellent in one way, viz. that when the injected speci- 
men is plunged into spirit loose drops of injection at once 
separate, leaving the specimen quite clean. 
Dorsal Vessel.—The dorsal vessel extends from the an- 
terior portion of the pharynx to the last segment of the body. 
It lies above the alimentary canal, and is adherent along its 
whole length to the wall of this organ. For the greater part 
of its length it appears to be actually attached to the intes- 
tinal wall, but anteriorly (in the region of the gizzards and in 
front of them) the nature of the attachment becomes clear, 
and the latter is seen to be due to the presence of a longi- 
tudinal double fold of mesentery (fig. 41), so that it is nowhere 
possible to put a needle under the dorsal vessel without 
piercing this mesentery. There is no mesentery connecting it 
with the dorsal region of the body-wall. 
VOL. 36, PART 3.—NEW SER. Z 
