344 Prof. M‘Intosh on Cephalodiscus, a new Type 
and forms a transverse margin anteriorly. The edges of the 
mouth are slightly raised laterally and posteriorly, the latter 
often being spout-shaped; anteriorly it is devoid of any 
well-defined boundary, and leads directly upward into the 
alimentary canal. 
There are no special organs in connexion with the mouth, 
which leads by a canal with frilled walls into the stomach, 
situated on the ventral surface of the body. At the posterior 
end of the latter the intestine turns upward and advances 
along the dorsum, to open by a large anus on the anterior 
projection of the body behind the plumes. No part of the 
alimentary canal enters the pedicle. In minute structure the 
canal resembles that in the Nemerteans, the first or pharyngeal 
region, however, being perhaps less firm than the gastric. 
The folds of the latter show numerous and somewhat regular 
vertical streaks and granules from the arrangement of the 
eland-cells ; indeed the smooth, firm, gastric ridges have a 
characteristic granular striated appearance. ‘The canal 
throughout has proportionally thick walls. Externally is a 
firm investment, probably containing muscular fibres. Inter- 
nally the surface seems to be covered by a fine limiting mem- 
brane, through which the contents of the glands have in many 
cases escaped. In the interior of the stomach are cellulo- 
granular matter, grains of sand, minute spicules, and bodies 
resembling minute Thalassicollide. The canal agrees with 
that in Rhabdopleura in having no differentiation into regions 
as in the Polyzoa proper. It 1s probably ciliated during life, 
after the manner of canals of similar structure. 
The body-wall is composed externally of a thin hypodermic 
layer (for no distinct cuticular coat can be demonstrated in 
the preparations), within which is the elastic coat, bounded 
internally by the longitudinal muscular layer. The wall is 
much attenuated over the distended ovigerous region anteriorly. 
There is no other investment of the alimentary canal than the 
foregoing wall, which is probably homologous with the “ thin 
glassy skin” of Sars, surrounding the digestive canal in 
Lhabdopleura. As with the latter, the preparations give no 
evidence of perigastric fluid. 
As previously mentioned, the short ventral surface of the 
body is continued into the cylindrical pedicle, whereas the 
dorsal outline rises abruptly above the pedicle. The 
stomach and the dorsal curve of the intestine would alone 
require considerable space. ‘The hypoderm on the ventral 
surface of the body appears to be somewhat thicker than on 
the dorsal, and in the preparations is generally thrown into 
bold transverse wrinkles, evidently from the strong muscular 
