376 Proceedings of the Royal Physical Society. 
much larger than the first ; they consist each of four joints, 
the two terminal joints being provided with a few bristles. 
Eyes are wanting in the female. 
The segments of the dorsal surface of the body are sym- 
metrical, with the exception of the sixth, the unsymmetri- 
cal character of which is due to the animal being slightly 
curved, the convexity of the curve being towards the right 
side, and involving this segment. The segments gradually 
increase in size from the third to the sixth ; the latter is very 
much expanded on the right side of the mesial line, corre- 
sponding to the convexity of the curve of the body. The 
seventh segment is symmetrical, but very much smaller 
than the preceding one. All these segments bear feet, which 
are very much distorted. From the different relative pro- 
portions of the segments, the feet are placed at various dis- 
tances from each other. The first pair closely surround the 
head, and have the second pair intimately applied to their 
external margins. The third pair are placed very near the 
second, but slightly posterior to them ; and the fourth pair 
are removed at some distance from the former, and also from 
the fifth pair, which lie behind them. A considerable in- 
terval exists between the fifth and sixth pair of feet, which 
is especially marked upon the right side of the animal. The 
sixth and seventh pair lie contiguous to one another. 
Projecting beyond the posterior margin of the body 
(seventh segment) are the five branchial segments, all of 
which, with the exception of the terminal one, carry a pair 
of oval pedunculated branchiae. The segments are rounded, 
and diminish in size as they approach the extremity. The 
terminal one ends in an oval-shaped process, which probably 
performs the same function as the branchiae. 
The six ventral membranes of the breeding cavity in- 
crease in size as they approach the posterior extremity. 
The first or head pair differ in their form from the other 
five, from which they are also distinguished by their edges 
not being overlapped. 
They appear to be supported upon very short jointed 
stalks, and they consist of two portions, an anterior and pos- 
terior. The anterior portion is oblong in form, and bears 
