334 FRANK E. BEDDARD. 
of this Oligochzete is the presence of an extensive integumental 
network of capillaries. These consist of a large number of 
longitudinal trunks united by transverse vessels so as to con- 
stitute a network. A portion of this network is illustrated in 
fig. 7, which figure also shows the branchial loops: the 
branchial loops are not connected with the network shown in 
the figure. 
The aquatic Oligocheta are, as a rule, not provided with an 
integumental blood-plexus ; indeed, until recently the absence 
of such would be considered to distinguish the earthworms 
from the limicolous Oligocheta. Nevertheless Ilyodrilus 
appears, from the figures given by Stole,’ to possess an integu- 
mental vascular plexus which seems to be as fully developed as 
in Branchiura. In the small tract of body-wall illustrated 
in fig. 7 I observed at least three longitudinal trunks. 
In the anterior part of the body, at any rate, the vascular 
network arises from paired trunks, which take origin from the 
supra-intestinal blood-vessel (see fig. 9). 
The existence of an integumental network is, as has been 
already mentioned, a rare occurrence among the aquatic Oligo- 
cheeta ; the interest.attaching to its existence in Branchiura 
is increased by the fact that the worm possesses special branchial 
organs. In about seven or eight of the anterior segments two 
of the longitudinal trunks of the integumental network are 
particularly enlarged, and in one specimen, at any rate, were 
very conspicuous; they run, as shown in the figure (fig. 9, 
L. V.), on either side of the nerve-cord, but below the ventral 
blood-vessel. I have not attempted to represent their branch- 
ing, which is, I believe, connected with the system of vessels 
derived from the supra-intestinal blood-trunk. 
I regard these vessels as the homologues of the “ intestino- 
tegumentary” trunks of earthworms; their presence in 
Branchiura removes another structural barrier between the 
“ Terricole” and “ Limicole” of Claparéde. 
Finally, with regard to the circulatory system, I have to 
mention the existence of a pair of intestinal hearts; they lie in 
1 « Monografie Geskych Tubificidu,” ‘ Abh. Bohm, Ges.,’ 1888, pl. ii, fig. 3, 
