310 Proceedings of Boyal Society of Edinhurgh, [sess. 
Then the view of the ventral surface makes the sex equally 
plain : the female has a broad up-tucked abdomen or “ flap/'" 
margined with long hairs, and bearing on the side next the body 
four pairs of modified, biramous, hairy appendages ; the male 
exhibits a much narrower and more pointed flap, that bears twO' 
pairs of hard, channelled styliform appendages, which are adapted 
for the transmission of milt, just as those of the female are suitable 
for giving attachment to the spawn. Under the flap, too, opposite 
the third pair of walking-legs, the female has two large and very 
distinct apertures, through which the roe is extruded ; the male has 
its genital apertures at the ends of soft funnel-shaped processes 
from the basal joints of the fifth pair of walking-legs. 
But if the sex is easily determined, the same cannot be said of 
the periods of sexual activity. The females, after spawning, carry 
their ova under the flap for several months ; and so fishermen at 
certain places find the “ berried crab ” during a great part of the 
year, and conclude that the spawning occurs at any season. On 
the other hand, at some places it is a rare thing to find a crab in 
berry, and a chance occurrence leads to a generalisation as to the- 
spawning- time, with the result that, in such districts, almost any 
month in the year may be stated as the time of spawning. 
I have proceeded to settle the matter by examining the repro- 
ductive organs of large numbers of crabs, and by keeping crabs 
in “bullies,” or crab-stores, and in boxes. 
Following the first method, I ascertained that, towards the end 
of the year — in the last two or three months — and in January, the- 
female crabs that were caught might be sorted into two lots : those 
that had recently cast, and were not preparing to spawn soon, and 
those that had not recently cast, and had well-developed ovaries.. 
A third class exists at the time, namely, those that have recently 
spawned ; but these conceal themselves so well, that I only 
obtained specimens from my bullies. 
The soft crabs or recent casters have pale ovaries, that show 
no development of ova to the naked eye ; the hard crabs have 
brilliant orange or scarlet ovaries, with ova distinctly visible, and 
often, because of their softness, seeming larger under the microscope 
than the tenser extruded ova taken from under a crab’s flap. 
The catch, then, from October to February, so far as it consists 
