PROCESS OF FERTILIZATION IN THE CRAB 161 
3. COPULATION 
We now come to the question of the transfer of the sperma- 
tophores from the body of the male to that of the female; from. 
the deferent duct to the seminal receptacle. We therefore turn 
our attention from the sperm itself to some of the habits of these 
crabs. Menippe mercenaria lives in crevices under or between 
the rocks, or in burrows which it digs in the mud along the shore 
a little below low water line. Usually one crab is found in each 
burrow, but occasionally, and even frequently in the month of: 
August, a male crab will be found guarding a hole in which there 
is a female. Sometimes the female thus found has a soft shell. 
If its shell be hard it molts within a few days after being brought 
into captivity. On August 17, a female with a soft shell and 
male crab which had been taken from the same hole about noon, 
were placed together in a compartment of a floating cage. At 
5:45 p.m. they were observed to be copulating. On being dis- 
turbed they separated. Their behavior was then observed while 
copulation was resumed. The most significant point with regard 
to this behavior was the apparent care with which the male 
acted in order to inflict no injury upon the soft, delicate shell 
of the female. 
During copulation the spermatophores are transferred from the 
deferent duct to the portion of the seminal receptacle which is 
lined with chitin, where they are deposited in a very compact 
mass. Here they remain until the next spawning of eggs. Only 
a portion of the spermatozoa are used for the fertilization of any 
one batch of eggs. One crab, kept by itself in a compartment 
of a floating cage for sixty-nine days during the summer of 1911, 
spawned six times and apparently all of the eggs in the six dif- 
ferent batches of 500,000 to 1,000,000 eggs each, were fertilized 
and developed normally. 
4. SPAWNING HABITS 
The spawning habits and the development of this crab will 
be discussed in a later paper. Here we will present only such 
points as are necessary in order to make it clear how the stages 
in the entrance of the sperm and fertilization are obtained. 
