LIFE HISTORY OF THE BLUE CRAB. 405 
observed with regard to these two forms among the females, that the 
first, or virgin form includes all the smaller individuals, while the 
second, or ovigerous form includes only those of larger size. That the 
condition is not an evidence of age, however, will be shown further on. 
Crabs may be found pairing at almost any time during warm weather, 
but there seem to be five or six periods between early June and the 
beginning of cold weather when the act is at its height. During these 
times mated crabs, ‘* doublers,” as they are called by the fishermen, are 
found in considerable numbers, either lying on the bottom in shallow 
water or swimming at the surface. It appears that the male crab is 
able to distinguish the female which is about to shed her shell, and 
having found such a one seizes her and carries her about with him, 
sometimes for a day or two, until the shedding of her shell is immi- 
nent. He then places her in some sheltered place and stands guard 
over her ready to repel the advances of any other male. At this time 
the female invariably is of the virgin form, and copulation has not 
taken place. When she sheds her shell, however, she has passed into 
the ovigerous form, the broad semicircular abdomen of her new con- 
dition having been withdrawn from the shell of the narrow triangular 
abdomen of the virgin form. She is now ready for copulation, and is 
immediately approached again by her mate. She turns back her 
abdomen, thus exposing the openings of her oviducts, the verges of 
the male are inserted, and she is grasped by the tips of his second, 
third, and fourth pairs of legs, and cee away. In the mated crabs 
the female, before she has cast her shell, is carried by the male with 
her back against his ventral surface; nage copulation her position is 
reversed. Copulation lasts for a day or two, coming to an end as 
soon as the new shell of the female has hardened. The pair then sepa- 
-rate, and so far as is known pay no further attention to each other.“ 
The female is now ready to produce her eggs, and for this act it 
seems that she seeks the ocean or the mouth of some large bay. In 
Chesapeake Bay mating crabs are abundant at least as far north as 
Annapolis, but a crab with eges is very seldom found there. On the 
other hand, at Cape Charles City, Va., at Hampton, Va., and neigh- 
boring points, egg-bearing females are far more abundant than either 
males or virgin females during the latter part of summer, but appar- 
ently do not often come into shallow water. All the individuals seen 
at the two Vi irginia localities had been caught on trot lines. An exactly 
@ Although the facts Ae in the last ea Pre are matters of common 
knowledge among the crab fishermen, I am not aware that their relation has been 
recorded in any of the printed accounts of this animal. The fact that copulation is 
possible only while the female is in the soft-shelled condition has been noted by 
several observers, and that about the time of copulation she changes from the narrow 
abdomened to the broad abdomened form is mentioned on page 369 of Miss Rath- 
bun’s paper. 
