1893-94.] Mr Gregg Wilson on Reproditction of Edible Crab. 309 
The Reproduction of the Edible Crab {Cancer pagurus). By 
Gregg Wilson, M.A., B.Sc., IN'atural History Laboratory, 
University of Edinburgh. Communicated by Professor J. C. 
Ewart, M.D., F.R.S. 
(Read March 19, 1894.) 
During the last two winters I have had considerable opportunity 
of making observations on the reproduction of the edible crabs of 
the Northumberland coast ; and though my results are still incom- 
plete, and some of them, as, for instance, those relating to the 
size of sexually mature crabs, are chiefly of local importance, I 
think the meagreness of past work on the subject, and its practical 
importance in connection with fishery legislation, justify me in 
publishing some account of what I have seen. I reserve for a 
subsequent paper many details, the full significance of which it is 
impossible to understand without further observation. 
Male and female crabs can very readily be distinguished from 
one another. As they lie back upwards, the well-arched or 
“rounded” shell of the females is enough to enable fishermen 
to separate them from the flatter males ; and even the size of the 
great claws in relation to the length of the shell is, I have observed, 
a sufficient characteristic : in the male the circumference of the 
claws is greater than the length of the cephalo-thorax, while in the 
female it is considerably less.* 
* In a few crabs taken at random the measurements were as follows : — 
Breadth. 
Length. 
Right Claw. 
Left Claw. 
Male . 
6 in. 
3f in. 
4J in. 
4f in. 
5 | „ 
3| „ 
44 „ 
44 „ 
n * • 
s. 
3| „ 
4 „ 
3| „ 
Female 
8 „ 
4 „ 
44 „ 
>} 
71 „ 
H „ 
4 (almost) 
4 jj 
6| „ 
^2 >> 
3§ in. 
3| „ 
3 J • • 
„ 
2f » 
34 „ 
