THE ANATOMY OF PHORONIS AUSTRALIS. 11 
the pit is composed of elongated glandular cells, with nearly 
homogeneous, feebly-staining contents, and with a nucleus 
flattened against one side of the cell. The cells vary in 
length, so that we have apparently more than one layer ; 
ordinary epidermic cells are here absent, except quite at the 
bottom of the pit, where there is a combination of the glan- 
dular structure and the structure of the outer wall. At 
the bases of the glandular’ cells are seen rounded nuclei; 
it is these, perhaps, that have led the above-named ob- 
servers to attribute a sensory character to the gland, but 
I take them to be the nuclei of some of the longer gland- 
cells which are not pressed to the sides of the cells, and 
consequently retain a more circular outline. This glandular 
structure extends as a ridge (g/.) throughout the lophophore, 
lying along the base of the inner series of tentacles. I have 
therefore called it the “lophophoral gland,” or glandular 
ridge (fig. 15). 
The “ epistome”’ remains to be mentioned, although more 
properly belonging to the alimentary system. Allman (1) 
figured this as a somewhat finger-shaped process, arising 
between anus and mouth and overhanging the latter. In 
truth, this finger-shaped appearance is only to be seen in 
longitudinal sections, and then only to a very slight extent. 
Allman’s figure conveys quite a wrong idea of the organ. 
The epistome is attached along the outer base of the 
inner series of tentacles (fig. 15), and has only a small part of 
its upper edge free. It extends right across the oral side of 
the animal, from right to left (figs. 12, 7), and is readily seen 
on removing the outer series of tentacles (fig. 7). It may be 
conceived as a ridge along the oral side of the base of the 
inner row of tentacles at the bottom of the lophophoral groove 
on each side. As the latter deepens to become the mouth the 
line of origin of the ridge dips downwards, whilst its upper 
edge retains its former level. At the mouth, then, we have 
a vertical, transversely-placed flap, standing up between the 
mouth and the inner series of tentacles, and thus preventing 
any direct passage between mouth and anus which would other- 
