. 
404 REPORT OF THE COMMISSIONER OF FISHERIES. 
the complicated set of teeth in the stomach reduce it to a thin fluid 
mass before it is allowed to pass into the intestine. : 
Digestion in the crab seems to be a rapid process, for the food dis- 
appears so quickly from the stomach that this organ is usually found 
to be perfectly empty within a few minutes after having received a 
full meal. It is a common idea among the fishermen that food is not 
retained in the crab’s stomach at all, but this I have disproved by 
numerous dissections. 
REPRODUCTION. 
The sexes of the crab are separate, and reproduction is effected by 
means of eges, which are laid by the female after copulation. The male 
crab may instantly be recognized by its narrow 1-shaped abdomen, or 
apron, which is folded under the cephalo-thorax and lies over a rather 
deep groove inthe sternum between the second, third, and fourth pairs 
of legs. (Fig. 2, pl. 1.) Its base is broad and nearly fills the space 
between the fifth pair of legs. The verges, or intromittent organs, 
consisting of the much modified first pair of abdominal appendages, lie 
within the sternal groove and are ordinarily completely hidden by the 
abdomen, but are easily exposed by raising that portion of the animal’s 
body. The male is also usually distinguishable by its larger size and 
the greater amount of blue on its legs and the lower surface of the 
body. The soft-shelled male shows a good deal of blue on the back also, 
but as the shell hardens this gives way to the usual dull gray green. 
Among the female crabs two distinct forms are recognizable, which 
we may designate, respectively, as virgin and ovigerous forms. In 
both the body is more tumid and the abdomen is much broader than in the 
male. Inthe virgin form the abdomen has a triangular shape, the sides 
converging nearly uniformly from the base to the tip. (Fig. 3, pl. 1.) 
In the ovigerous form it is nearly semicircular ijn outline, except for 
the small terminal segment, which projects in front as a smail triangle 
on the middle line. (Fig. 4, pl. um.) In the virgin form the abdomen 
lies, as in the male, in a depression between the bases of the last four 
pairs of legs, but it is fastened in its place so strongly, by means of 
a pair of hooks which project from the body and fit into a pocket on 
ach side of the abdomen, that it can hardly be raised without being 
broken. Theswimmerets on such an abdomen are small—almost rudi- 
mentary—and would hardly be noticed in a cursory examination. In 
the ovigerous form, on the other hand, the abdomen covers nearly the 
whole lower surface of the shell, even overlapping the basal segments 
of the last four pairs of legs, and it is held in position only by a mus- 
cular effort on the part of the animal. When such an abdomen is 
lifted up, the observer is at once struck with the large size of the 
swimmerets, which, with their fringes of hairs, entirely fill the space 
between the abdomen and the shell of the body. It will further be 
