38 
PROCEEDINGS OE SOCIETIES. 
current around and through, the ova, seemingly by means of the pedi- 
palps, at the same time keeping the mass in constant vibration by rhyth¬ 
mical up-and-down motions of the abdominal false feet, to which the 
ova were attached. She also sought the sunny side of the tank more 
than her wont now is. On the evening of the 12th the zoes could he 
distinguished coiled up in the ova, fully formed, and the motions for 
aeration were very vigorously carried on; and on examining the tank 
on the morning of the 13th I found it completely filled with many thou¬ 
sands of zoes, which kept together in one continuous swarm at the side 
nearest the light. These gradually increased in size, and also altered 
in their form, seeming so active and healthy that I was in hopes I 
might have been able to trace their complete changes; hut unfortunately 
the second specimen of JE. aspera died on the evening of the 17th, poi¬ 
soning the tank, so that on the morning of the 20th I found my poor 
zoes dead, putting a stop to experiments as far as they were concerned. 
The parent crab, however, still continues in health and vigour, al¬ 
though the water has not been changed till to-day for the last six weeks, 
and does not now consist of more than two pints in a circular tank, six 
inches in diameter, and although two green crabs, C. mcenas, during the 
time died from the poisonous effects of impure water. Its habits are inte¬ 
resting ; it is but a sedentary animal; it seeks the light occasionally, 
generally, however, keeping to the shadiest part of the tank. At night it 
is most active, running over the sides and bottom of the tank after the 
lights are extinguished, the noise it makes being considerable as it 
rattles over tKe glass. Its mode of feeding is sometimes most amusing. 
On its hack, completely concealing it, is a large mass of sponge, which 
of course the crab carries about with it everywhere ; it, however, causes 
these strange passengers to pay toll occasionally, as frequently I have 
seen the JE. aspera stretching its long anterior limbs backwards over its 
carapace, and, deliberately tearing off a portion of the sponge, coolly 
proceed to tuck it in between its jaws; sometimes holding the piece of 
sponge in one of the chelae, it daintily tears off small pieces from the 
mass, which it then quietly devours. I detected it once feasting on a 
little varying Hippolyte, II. varians , which was in the same tank; but 
generally speaking, its food must consist of the Entomostraca and other 
minute animals, &c., which abound in the water, and possibly also the 
Ulva. [It is a most sluggish animal, slow and deliberate in its move¬ 
ments, and during the day remains with its back to the light in -a lair 
it has formed under a projecting piece of Ulva lactuca, its long and 
beautifully carved arms kept semiflexed at some distance from each side of 
its body; and the whole animal perfectly motionless, except an occasional 
vibration of the foot-jaws, looking like some monster in his den. The 
species is not uncommon in moderately deep water on the banks around 
the coast, and I would recommend it as a good species to those who keep 
tanks, as it is generally tenacious of life, and bears travelling well, living 
for a long time, even in a small quantity of water. 
My tanks, in which I have succeeded in keeping many of the rarer 
Crustacea, are so convenient, and their arrangement so simple, that I am 
