494 MR. F. E. BEDDARD ON THE 
their arrangement is as follows :—The dorsal vessel gives off on either side in 
each segment three vessels, of which one is very small, and supplies the 
mesentery (the mesentery receives its chief blood supply from the supra-nervian 
vessel). The other two vessels are large and very conspicuous; one runs over 
the kidney-shaped gland, sending off branches which run along its furrows ; 
after leaving the gland it is distributed to the walls of the intestine : the other, 
which is somewhat larger, runs between the glands, being attached to the 
intestinal wall by a series of short branches, which appear to end abruptly (in 
blood spaces ?), and give this vessel a very characteristic appearance (see 
Plate XXV. figs. 11, 12). Throughout a considerable extent of the intestine, 
both anterior and posterior to the kidney-shaped glands, the blood-vessels were 
turgid, and appeared to be rather larger than the same vessels in the other 
parts of the intestine. Anterior to these glands, the vessels of one segment 
are represented in Plate X XV. fig. 10, where it will be seen that the vessel a, 
which is the homologue of the vessels which supply the glands, resembles the 
interglandular trunk, in being attached to the surface of the intestine by a 
series of short branches, ending, as far as could be made out, abruptly. These 
vessels just described appear, like the same vessels in other parts of the 
intestine, to end in a plexus (in two instances this was perfectly clear), and not 
to be connected with any sub-intestinal vessel, nor with the supra-nervian 
trunk. Whether a supra-intestinal trunk exists for the whole length of the 
intestinal tube or not I cannot say ; it was traced as far back as the 20th 
segment, being in this region single instead of double, but having a trace of the 
other trunk running beside it. All the details of the intestinal circulation can 
only be made out by a series of careful injections; the facts given here are 
based upon a partial natural injection of the capillaries, which may of course be 
misleading. The general features of the circulation in this part of the body 
appear to be as follows :—The wall of the intestine itself is supplied with a rich 
network of vessels derived from the branches of the dorsal trunk (two in 
each segment). The supra-nervian trunk supplies the integument and the 
mesenteries, the latter receiving also a small twig from the dorsal vessel, 
which no doubt serves to put the dorsal and ventral systems into communi- 
cation. . 
The kidney-shaped glands in transverse section (Plate XX VI. fig. 19; Plate 
XXVII. fig. 9) show an outer layer of granular cells, which belong, as already 
mentioned, to the perivisceral cavity, and not to the coat of the glands; below 
this is a fibrous layer, which sends off trabeculz into the substance of the gland, 
larger ones dividing the gland into lobules or smaller ones lying simply between 
two adjacent columns of cells. The gland itself presents the appearance of a 
compound tubular gland, or perhaps rather of a folded membrane ; the duct 
opens on to the transverse fold in the intestine. The cells which compose the 
