No. 462.] CRABS OF GAY HEAD MIOCENE. 385 
In drying, this specimen has cracked considerably. As a whole 
the sternum is nearly a plane surface except where it is hollowed 
in the center to receive the abdomen. The anterior portion, 
triangular in shape, is usually well separated from the rest. It 
varies considerably in size and shape. The main part of the 
large anterior plate is divided into three parts by a Y-shaped 
combination of sutures as seen in the figure. This is an incom- 
plete division but the sutures are nearly always in evidence. 
As noted by Dr. Stimpson the “male genital tubercles are 
found on the posterior margin of the second segment. These 
are situated just within the edge of the abdomen so that they 
are covered by it. 
Dr. Stimpson found the abdomen of the male only, but in the 
collections of the past two years there are a few specimens of 
the abdomen of the female. The males appear to have been 
much more common. The male abdomen is approximately as 
figured by Dr. Stimpson, none of the segments being fused. 
A figure of the female abdomen is given (Pl. 2, Fig. 10). The 
third joint from the end is the widest, and there is an abrupt 
tapering from it toward either end. Of the abdominal append- 
ages but one specimen, and that very incomplete, has appeared 
(Pl.2, Fig. 11). This specimen indicates at least two pairs of 
these appendages. 
One specimen (Pl. 2, Fig. 12) shows a cast of the outer max- 
illiped from which a fairly complete idea of these appendages 
may be obtained. Several other specimens show the basal 
joints in place and the minutely tuberculated surface (Pl. 2, 
Fig. 9). 
The front legs are shown in a number of specimens, the basal 
and outer joints being those most frequently preserved. The 
teeth on two of the joints as figured by Dr. Stimpson, were not 
made out. The chele have a series of alternating teeth alike 
in both the left and the right sides. The various joints were 
more or less ornamented with a color pattern, portions of which 
are well preserved in a number of specimens. The teeth and 
the tips of the chelz are much lighter colored than the other 
portions. The portion of the shell about the base of the anterior 
pair of legs has a raised beaded edge. This portion is often 
broken away and variously placed in some of the specimens. 
