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to their size. Some of them, closing these fingers with force 
and rapidity, produce a considerable noise. 
The Crustacea in general, as we have already remarked, 
live on animal matters, especially on such as are in a state of 
decomposition. The crabs, craw-fish, and prawns, come 
from all quarters to the dead bodies which float upon the 
water, or which are cast out by the sea upon the shore ; and 
there is every reason to suspect that they are brought thither 
by the sense of smell. 
It also appears that certain isopods live on the substance of 
the gelatinous animals, which compose the sponges ; at least 
it is always on these marine bodies that some oi them are to 
be found in very large numbers. Some others, such as the 
aselli, &c. are accused of destroying the nets of the fishermen, 
by gnawing the ligneous fibi'es of the cordages with which 
they are formed. The onisci, or wood-lice, live, as is well 
known, on rotten vegetable substances. 
Finally, there is no doubt that the smallest entomostraca 
eat, along with the little animalcule which abound in fresh 
waters, the remains of vegetables equally microscopic, for 
their alimentary canal, visible at the middle of their body in 
consequence of its transparence, is often of a fine green 
colour. 
Among the carnivorous Crustacea, there are some which 
seek a living prey, and fight to procure it. In these combats 
they often lose their forceps, but they shoot out again after a 
little time. 
Those of the Crustacea whose sexes are separate, never 
exhibit unions by pairs, which are observed in animals of the 
first two classes, namely, the mammifera and birds, and which 
are also to be found again among the insects. In general 
there is no relation between the sexes but at the period of 
reproduction. 
The females, as we have said, preserve their eggs, aftei 
