12 G. O. Sars. 



plumous setæ. The lower appendage, which constitutes the 

 palp and is turned obliquely backwards, is of very different 

 structure in the two sexes. In the female it has the form 

 of a simple conical lash tipped with 3 setæ, the median of 

 which is by far the longest. In the male this appendage 

 (see figs 4, 12) is much more powerfully developed, form- 

 ing a strong grasping organ, by the aid of which the 

 female is grasped during copulation. In shape it con- 

 siderably differs from that found in other male Cyprididæ, 

 being pronouncedly cheliform, with the proximal joint very 

 much expanded and produced below to a greatly projecting 

 thumb-like process tipped with a simple bristle. The ter- 

 minal joint has the form of a slender claw abruptly bent 

 at the base, and able v.o be impinged against the above- 

 named thumb-like process. There is but little difference in 

 the shape of this palp on the left and right maxillæ, where- 

 as in other male Cyprididæ the difference is very pro- 

 nounced. On a closer comparison, however, the left palp 

 (fig. 13) is found to be a little less expanded than the right 

 (see fig. 12), with the palmar edge more deeply concaved; 

 and the terminal claw tapers gradually to a very fine 

 setiform point, whereas in the right palp it is of more uni- 

 form breadth throughout. 



Of legs, as in other Cypridids, there are only 2 pairs 

 present, the anterior ones being rather strong, and able 

 to be stretched out from the shell below, whereas the 

 posterior ones are always kept within the shell-cavity, 

 being extended backwards and upwards across the sides of 

 the abdominal part of the body (see fig. 4). 



The anterior legs (fig. 14), which originate immediately 

 behind the posterior maxillæ, exhibit each a short and 

 thick, indistinctly biarticulate basal part strengthened by 



