42 
room ix, the utmost accuracy. In this Case are likewise 
some Crabs peculiar to hot countries, which are 
remarkable for the rapidity of their motions, and 
other peculiarities. They live in holes, usually 
near the sea-shore or in the neighbourhood of 
water; these holes are of a cylindrical form, 
oblique, and very deep, and several of them are 
generally found near together, but each hole con¬ 
tains only one inhabitant. When the animal of 
one of the genera belonging to this family (Gela- 
simus) is in his hole, he closes the entrance 
with his claw, one of which, sometimes the 
right, sometimes the left, is commonly much 
larger than the other. These Crustacea have 
also a singular habit of holding up the large 
claw in front of the body, as if they were beck¬ 
oning to some one at a distance, whence they 
have acquired the name of Calling Crabs (Cancer 
means , Linn.). What has been said of the ra¬ 
pidity of the motions of these Crustacea, is par¬ 
ticularly applicable to those of the genus Ocy- 
pode, which hide in holes in the sand on the 
sea-shore during the day, and leave them at 
sumset. This Case also contains specimens of 
the genus Pinnotheres, a very small race of 
Crustacea, which inhabit bivalve shells, and were 
supposed “ by some of the ancients to be con¬ 
sentaneous inmates with the animal, bound by 
mutual interest; the fable is beautifully told by 
Oppian, 
