16 ON THE ANATOMY OF MEGASCOLIDES AUSTRALIS, 
vessel becomes muscular and swollen out, and gives off the same three branches 
already described. From the ventral vessel arises a single one, as in the posterior 
sections, which supplies the septum and body wall. (This has inadvertently been 
omitted in the diagram Fig. 9, but should have been drawn as in Fig. 8, immediately 
above.) In addition to these there is also a lateral vessel present on either side of 
the alimentary canal, to which, as well as the septum, it gives branches. It is 
connected with the lateral’ vessels of the anterior segments, but appears to have no 
connection with any vessels in the 14th segment. (c) In the segments 13-6 inclusive, 
the blood-vessels are very differently developed. These are first the usual dorsal and 
ventral trunks, both somewhat muscular, and the former swollen out in each somite. 
From the dorsal arises on each side posteriorly a single large muscular vessel, the 
“heart,” (h.) passing down to join the ventral vessel. Hach transverse vessel, or 
heart, gives off a branch from its antero-internal surface. Hach of these again divides 
into two, of which one runs to join its fellow of the other side, and these two uniting 
form a small median vessel lying immediately upon the dorsal surface of the 
alimentary canal (al.* bv.) ‘The second branch runs downward, and this again divides, 
one branch running to join the lateral vessel (lat. bv.), the other, and larger, passing 
on to the face of the septum, and giving off one important branch ventrally to the 
body wall and nephridia. The lateral vessel on either side gives off branches to the 
alimentary canal. 
In front of the sixth segment, the dorsal, ventral, and lateral branches all break 
up into smail divisions, which supply the body wall and the alimentary canal and 
salivary glands. 
There are no blood-vessels in connection with the nerve cord—neither sub. nor 
lateral-neural vessels. 
The Blood itself has the usual red colour, due to the presence of hemoglobin in 
the fluid, and contains (1) very numerous nucleated corpuscles of definite outline, 
which may be either oval or round in shape, and measure about 0016 mm. in 
diameter (Plate 3, fig. 17, a.), (2) fewer more irregularly shaped nucleated corpuscles, 
from which few or many stiff pseudopodia-like processes may be extended (Fig. 17, b.) 
These are somewhat larger than the former, the body of the cell, exclusive of process, 
measuring about ‘0025 mm. in diameter. 
The Celonuc Fluid, on the other hand, is of a milky-white colour, and opaque. 
Its numerous corpuscles are all of more or less irregular shape, and precisely similar 
in size and appearance to the second kind described im connection with the blood. 
(Fig. 17, b.) Possibly, as suggested above, the masses of cells present in the 
diverticula of the tube surrounding the dorsal blood-vessel posteriorly are merely 
special developments of the peritoneal layer lining the ecelom which serve as supplies 
of these corpuscles. The latter, passing into the ccelom, lose their regular shape, and 
put out processes—becoming, in fact, ameceboid cells. 
