8 Mr. C. Chilton on a new Species of 
is produced forwards and downwards to form the groove, so 
that when the end of the limb is bent back upon the ischios 
it is protected and held in its place both on the inside and the 
outside. ‘The meros is flat or hollow above and expands a 
little distally, its articulation with the ischios is concealed in 
a view from the outer side by the prolongation of the outer 
portion of the ischios. The carpus is nearly as wide at the 
base as the preceding joint, but expands distally and has the 
end shaped something like a mallet, being produced both 
above and below, the lower portion finely crenate—the exact 
form will be learnt from the figure more easily than from any 
verbal description. The propodos is attached to the upper 
distal corner of the carpus; it is nearly circular in shape, and 
bears a small dactylos which ends in two claws as in the other 
legs. The whole limb is, in fully developed males, quite free 
from sete; the ischios and meros are rather thick through 
from side to side, but the carpus and propodos are thinner and 
plate-like. 
The whole leg is most striking in appearance and quite 
unlike anything else that I have seen among the Isopoda. 
It most probably forms a grasping-organ of some kind, though 
it is not easy to see exactly how it is used, and while grasping- 
organs are usually formed by means of the terminal joints 
(propodos and dactylos) in other species, in this case these are 
small and more or less rudimentary. 
In young males the first pair of limbs is much more like 
those of the female and quite different from those of the fully 
developed male. One stage in the development is shown in 
figure 86 of Plate If. The basos is of fair size, though not 
so long in proportion to the other joints as in the female; the 
ischios is much larger and already shows signs of its future 
great expansion; the remainder of the limb is practically 
the same as in the female, except that there are fewer spini- 
form sete on the carpus. A more advanced stage is shown 
in figure 8¢ of Plate [I]. The ischios is more enlarged, the 
meros more elongated and more like that of the adult male, 
the carpus has begun to take its peculiar mallet shape, the 
propodos is becoming more rounded, and the sete: have almost 
disappeared from the whole limb. 
It will thus be seen that in this species, as in many other 
cases, the young male resembles the female, and that the 
peculiar characters of the adult male are acquired by a gradual 
development *. 
* See Darwin's ‘ Descent of Man,’ p. 252 (second edition), 
