1893 - 94 .] Mr Gregg Wilson on Reproduction of Edible Crab. 311 
of mature female crabs, — and they form a very large proportion at 
that time, — is made up of caster crabs, which are worthless for 
trade purposes, and spawning crabs, which, of course, are specially 
valuable for the up-keep of the species, and might well be protected 
by law wherever there is evidence of a decline in the fishery. 
What, from a scientific point of view, is equally worthy of note, 
is that it seems as if the spawning took place only every second year 
of the crab’s life. As the casters have undeveloped roes in the 
autumn, it is not likely that they are prepared to spawn till late 
in the following year ; and, on the other hand, the crabs that are 
hard and prepared to spawn in autumn probably carry their ova 
through a considerable part of the next year, and appear as casters 
with undeveloped roes in the following autumn. 
At no time have I found ova undergoing segmentation within a 
crab ; and the old idea, that fertilisation is internal, must be 
abandoned. F. Buckland and Spencer Walpole say in their 
“Report on the Crab and Lobster Fisheries” (1877): “The 
crab carries its ova during the early period of pregnancy inside 
its shell.” Milt undoubtedly is passed by the male crabs into 
the body of the females ; but it does not affect the roe before 
extrusion. It is received in flask-shaped receptacula seminis, that 
open off the oviducts quite near the genital apertures. They 
are well-valved, and seem to retain the motionless spermatozoa for 
long periods. 
The ripe male is found in all the months in which I have 
examined crabs. There is a popular belief that milting takes 
place when the females have newly cast; and the idea is 
founded on the well-established fact that, when the females are 
casting in the rock-holes along our coasts, they are commonly 
watched over by hard males. But it is noteworthy that the 
sentry is sometimes an unripe male ; and sometimes a female is 
found guarding a soft male. These instances, taken together with 
the fact that males are found fully ripe long after casting is over, 
lead me to doubt the accepted view. I have noticed, too, that 
while I have carried a male and female shorewards from one of 
their rocky holes, the hard claws of the male have very readily 
passed through the soft casing of the caster ; and it has occurred 
to me that such damage would almost necessarily result to the 
