29 
nera Polybius, Portunus, Podophthalmus, &c. These 
animals’ have the posterior leg terminated by very flat 
joints, of an oval or orbicular form, and calculated to 
act as fins in swimming. The last pair of legs in all 
the Swimming Crabs, is constantly furnished with 
these flattened joints, and in some species the preced¬ 
ing pairs have them also, but never so broad as those 
of the hind legs. The eyes of the Telescope Crab 
(Podophthalmus spinosus), are supported on very long 
slender pedicles, reaching from the middle of the an¬ 
terior margin of the shell to the lateral angles, and 
lodged, when at rest, in a groove on the edge. This is 
the only known recent species belonging to this genus. 
Here are also specimens of the Freshwater Crabs 
( ThelphusceJ, which live in the rivers and streams of 
Italy, and the south of Europe, and are likewise found 
in Asia and America; they are capable of existing a 
considerable time out of the water. One species, peculiar 
to the south of Europe and the Levant, (Le Cancre de 
riviere of Rondeletius,) enjoyed great celebrity amongst 
the Greeks, for its supposed medicinal virtues, and is fre¬ 
quently represented on the coins of Agrigentum, with 
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 cylindri¬ 
cal 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 (Gelasimus) is in 
its hole, it closes the entrance with its claw, one of 
which, sometimes the right, sometimes the left, is com¬ 
monly 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 beckoning to some 
one at a distance, whence they have acquired the name 
of Calling Crabs (Cancer vocans } Linn). What has 
been 
ROOM JX, 
Nat. Hist. 
