* WATERLIME GROUP. 
397 
The different species of this genus present some slight modifications in general 
form and in the appendages. The feet are all surrounding the mouth, and belong 
to the cephalic portion of the animal. The anterior feet are nine-jointed, including 
the terminal articulating spine : the first joint is narrow at its base and spreading 
above, and the second joint is longer than the others. In the three anterior pairs, 
the distal extremities of several of the articulations preceding the last one have 
a slender spine on each side ; but this character may perhaps be varied by ori¬ 
ginal conformation, or by accident. The dilated portion of the first joint is in¬ 
tended to aid in the process of manducation, and may have been serrate. 
The accompanying diagram is an enlarged figure of one of the third pairs of 
feet. 
Fig. 1. 
In the arrangement of these appendages, the part a of the second joint is covered 
by the next one behind it as far as the oblique line limiting what appears to be a 
flattened portion of the joint. A part of the first joint b was, in like manner, co¬ 
vered by the next posterior one. 
The fourth pair, which are more slender than the others, with longer joints, 
have shown no spines except on the penultimate, and the last joint is itself a 
slender spine. 
The fifth or swimming feet are eight-jointed, with a terminal palette*. 
Fig. 2. 
The figures refer to the number and relative position of the successive joints of 
the natatory feet. 
At t the margin is serrated, as mentioned in the description above. 
At the line s there is a soldered suture, connecting the fixed ramus of the chela 
with the penultimate joint. In some specimens the parts have been separated along 
this. line. 
* In indicating the number of joints, I have been governed by no theoretical views, but simply by the 
appearances of separation in the parts; and though the two extremities of the third joint, as marked, show 
no articulating processes, the limitation of the parts is distinct, and they may have been separated only by 
a thin extension of the chitine, and may not be properly articulating surfaces. 
