44 Proceedings of the Royal Physical Society. 
narrow duct. with the wide pouch is marked by a hemi- 
spherical elevation, consisting of columnar cells increasing 
in height towards the centre. In transverse section this 
papilla appears perfectly circular and marked peripherally 
by a highly refracting band, which looks like a layer of 
chitin; in the centre it is perforated by the minute duct. 
The comparatively spacious pouch into which the duct 
opens communicates with seven radially disposed pouches ; 
possibly it might be considered more 
accurate to say four, since the appear- 
ance of a greater number is produced 
by a division of some of them, the 
line of division not coming so far 
down as the septa between the four 
primary pouches. These diverticula 
in no way differ in minute structure 
from the pouch whence they arise. 
The pouch itself communicates with 
the cesophagus. 
Behind the male pores in each of 
the three following segments is a 
single median structure, which seems 
to be of the nature of a sensory 
papilla. The first of the three is 
situated just at the end of the clitel- 
lum. Each gland (Fig. 3) consists of 
a cushion-like mass of cells of a 
flattened hemispherical contour; it 
lies immediately beneath the nerve 
cord, and seems, in fact, to be a 
dilatation of the nerve cord. The 
lower part of the sheath of the nerve | 
N' 
Fig. 3. 
A ventral sensory papilla in 
longitudinal section. A, 
epidermis of body wall at 
point where the processes 
of the cells of the organ 
reach the exterior; B 
body wall; NN’, two layers 
of nerve cord. 
cord is continuous_over the cells 
which form the organ referred to. 
The cells of which it is composed 
are large, pear-shaped, and granular; 
towards the periphery they are more coarsely granular than 
centrally. The cells-are ten or twelve times as large as those 
in other regions of the nerve cord. The processes of these 
