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Transactions of the Society. 
rigid, some movable ; and these mandibles form the best specific 
distinctions. It seemed probable that this strong sexual dimor- 
phism had some cause; but was it primary or secondary, did it 
subserve actual coition, or was it like the mane of the lion ? After 
obtaining all the anatomical information I could by dissection and 
sections, I endeavoured to watch the actual coition in specimens re- 
tained in confinement. It was a long time before I could find species 
which would copulate in confinement, but at last 1 found three or 
four species. Watching for occasions was wearisome work and when 
they occurred the position of the creatures was such that only partial 
knowledge could be obtained ; I therefore tried killing the creatures 
instantaneously during the coitus by either boiling water or chloro- 
form ; in this way, by getting a series at various stages of the coitus, 
I was at last able to trace a process which seems to me little, if at all, 
less curious than that in spiders. The spermatozoa, when they leave 
the testis, are not free, but a number are enclosed within a sperm- 
mother-cell or spermatophore : immense accessory glands greatly in- 
crease the volume of the secretion. At the moment of coition a 
hollow flask-like sack is blown from the genital aperture just as a 
glass-blower blows a flask or a boy blows a soap-bubble ; this partially 
sets but remains elastic ; it is filled as it forms by the rush of sperm- 
mother-cells and mucous secretion, which sets in the end of the flask 
next the genital aperture, closing the flask as with a stopper. If the 
creatures be killed at this time the flask is in the genital aperture of the 
male. The male now, in most species, applies its mandibles one on 
each side of the flask. Just behind the chela on each mandible there 
is a small brush of hairs, and to these the still sticky flask adheres 
firmly ; it is removed by the mandibles from the genital aperture of 
the male. If the creatures be killed at this stage, the flask will be 
found adhering to the two mandibles of the male ; it is now applied 
by the mandibles to the copulatorv orifice of the female ; the elasticity 
of the flask and the pressure of the mandibles drive out the stopper, 
and if the creatures be killed now the empty flask will be found still 
adhering to the mandibles of the male, but the contents have passed 
into the female. The male if not killed may be seen cleaning the 
empty flask off its mandibles. I found an even more curious variation 
of this process in the case of Gamasus crassus ; this species has an 
oval hole in the movable arm of the chela of each mandible, and 
instead of the two mandibles being applied to the already formed 
flask one mandible is applied by the male to its genital aperture, and 
the flask is blown right through the hole ; the flask swells out at both 
ends so that it cannot come out of the hole, and in this condition the 
single mandible, bearing the flask threaded through the hole, is 
plunged right into the vulva of the female. The drawing before you 
was made from a mandible which I cut out of the vulva in a case 
where I had killed the creatures during coitus. I have mounted it as 
a microscopical preparation and it is still in my possession. 
