406 
EDWIN S. GOODRICH. 
septum passing behind the pharynx. The septa separating 
the next three segments are very incomplete in both sexes, 
so that their cavities communicate freely with each other. 
In the male complete septa occur between segments 4 
and 5, 5 and 6, 6 and 7, and 7 and 8 ; in the female 
only the first three of these septa appear to be com- 
plete. In sections coelomic epithelium can be seen to cover 
the alimentary canal, and, of course, the two faces of the 
septa. It is less distinct, though still traceable, on the 
nephridia (figs. 13, 36). On the other hand, it is very 
difficult to make out on the body-wall, and I am not sure 
that a distinct epithelium exists here separate from the 
muscles. The coelomic cavity extends up the hollow tenta- 
cles, palps, and cirri (figs. 4, 35) ; it reaches the tentacles as 
a median channel over the brain, which divides into three 
canals at their base (fig*. 35). 
A nearly complete ventral mesentery extends along the 
greater length of the alimentary canal below the longitudinal 
ventral blood-vessel (figs. 22, 23). The dorsal longitudinal 
mesentery is much less complete, remaining only here and 
there as narrow strips. 
Very few coelomic corpuscles are to be seen floating in 
th e coelomic fluid. A few cells with small granules occur 
separate or in strings in the first segment. Spreading in all 
directions through the coelom is found a peculiar mesenchy- 
matous network, which is of considerable morphological 
interest, and may possibly take the place of the floating* 
corpuscles more usually found in Annelids. This network 
has exceedingly delicate branches, and is best studied in the 
living worm, where it is seen to consist of branching cells 
forming slender strands, chiefly longitudinal, with the finest 
threads of protoplasm extending to all the surrounding sur- 
faces. A portion of the network is shown in fig. 8, stretching* 
from the body-wall to the stomach. Similar strands pass up 
the cavity of the tentacles and cirri, or join the nephridia to 
the neighbouring parts (fig. 15). 
The significance of this mesenchymatous network will be 
