New and Foreign llotifera. By V. Gunson Thorpe. 303 
situated, the ventral plate leaves the dorsal plate, aud suddenly 
narrows towards the orifice of the foot, which is bounded by two 
small spines; the floor of the body-cavity, except for this opening, 
is formed by a triangular basal plate, which meets the dorsal 
plate on a line joining the orifices of the lateral antennae (fig. 3, b, e). 
Thus there is for the lower two-fifths of the lorica a space left between 
the basal plate and the lower part of the dorsal plate, and it is in 
this space that parasitic infusoria, such as species of Golacium and 
Carchesium, take up their abode. The pectoral edge is almost 
straight, with a central notch, and two deep lateral notches, and 
ends at each extremity in the appearance of a sharp curved spine, 
about one -third the length of the antler, but not separated from it, 
forming in fact a strengthening buttress to its base. This pseudo- 
spine is evidently a transitionary form of the eighth occipital spine, 
as seen in B. polycerus. The animal is able to close the superior 
orifice of the lorica by bringing the dorsal and ventral edges into 
mutual contact. The foot can be protruded to a great length, equal 
to that of the body and antlers together. 
The digestive system needs no description, as it follows the 
usual type. There is a large contractile vesicle into which the 
lateral canals can be distinctly traced. There appear to be four 
vibratile tags on each side. In regard to the nervous system there 
is a large ganglion, in which is imbedded a crimson prism-shaped 
eye. In one specimen which I examined closely, I found that 
from the lower edge of the ganglion proceeded three fine nerve- 
fibres, each of which, whilst crossing the surface of the mastax, 
expanded into a small nucleated ganglion-cell; then diminishing 
to their former calibre, they lost themselves on the surface of the 
stomach and intestinal tract (fig. 3 a). Nerve-fibres also supply 
the dorsal antenna as well as the lateral antennae, which make their 
exit, as mentioned before, just above the junction of the dorsal and 
basal plates. The ovary is of a reddish tinge, especially marked 
when the young ova are in process of formation. The infant female, 
when in the egg, has the long anterior antlers as well as the posterior 
spines bent over inwards in such a way that they overlap each other 
close against the body, so that the whole animal is oval in shape and 
accurately fits the shell. Immediately after birth these spines are 
very soft and flexible. 
The male, many specimens of which I examined, is 1/167 in. 
in length, and is invested with a distinct lorica. The dorsal surface 
of this lorica is convex, and down its centre runs a high ridge. The 
occipital edge presents a deep central notch for the protrusion of the 
dorsal antenna (fig. 3 d). The ventral surface is deeply concave, 
and presents at its lower portion a large circular opening, through 
which a long flexible foot protrudes, as well as a large penis (fig. 3 e). 
There is a large red eye. The male rotifer is extremely active, 
swimming in a frantic sort of manner through the water, clambering 
y 2 
