STRUCTURE OF UROCHiETA AND DICHOGASTER. 255 
much evidence of being a paired structure in the adult worm ; 
the two halves of the vesicle are almost completely fused in 
the ventral median line where they enclose the nerve-cord. The 
ventral blood-vessel is not enclosed within the vesiculae, but is 
suspended by a vertical mesentery some little way down between 
the two vesiculae, which here become distinctly separate ; a 
portion, however, of the transverse vessel of this segment, as 
well as (necessarily) a branch on each side, which runs to the 
testis, are enclosed by the vesiculae. The vesiculae send off a 
narrow lateral band, which seems to become fused with its 
fellow of the opposite side in the dorsal median line (see 
fig. 15). 
In the eleventh segment is another pair of vesiculae, for a 
description of which the foregoing remarks will nearly suffice. 
The same segment also contains (see fig. 15) the racemose 
structures already referred to. These are composed of a large 
number of small spherical acini, which contain bundles of de- 
veloping spermatopliora. The whole structure is firmly attached 
to the mesentery, which divides its segment from the one in 
front. I have not been able to make out any connection 
between this portion of the vesiculae and the undivided median 
sac. 
Finally, segment 12 contains another pair of these racemose 
organs, which have apparently no connection with the vesiculae 
of the preceding segment. 
Yasa Deferentia. — There are two pairs of vasa deferentia 
funnels situated in segments 10 and 11 ; they open into the 
middle of the vesiculae seminales of these segments, on each 
side of the nerve-cord and near to it. Their structure calls for 
no special remark, neither does that of the vasa deferentia, 
which open, in common with the glandular body, upon the 
seventeenth segment of the body. 
When the worm was opened in dissection the seventeenth, 
eighteenth, and nineteenth segments were seen to be largely 
occupied by three pairs of glands, a pair to each segment, of a 
whitish colour, and meeting above the intestine. The anterior 
pair of these is very much larger than those which follow, and 
