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SUPPLEMENT 
where these Crustacea are very common, that they were 
derived. 
It is more especially to the decapods that the name of Crus- 
tacea has been given. Of all the animals of this class, the 
decapods are the most remarkable for their size, the complica- 
tion of their organs, the solidity of their teguments, and their 
longevity. They all possess a very carnivorous instinct. Some 
travellers do, nevertheless, inform us, that certain species feed 
on fruits; but this appears to be doubtful. Some pass a very 
considerable portion of their lives out of the water, and repair 
thither only at the period of their amours, and for the purpose 
of laying their eggs. They go in very numerous bands, always 
pursuing the shortest and straiglitest direction, without em- 
barrassing themselves with any obstacles in the way, and they 
return in the same manner, after having fulfilled the decrees 
of nature. The others scarcely ever, or at all events, but for 
a very short time, abandon the element in which they were 
born. Some among them live in the fresh waters ; but the 
majority inhabit those which are salt or brackish, most fre- 
quently near the shore, at depths and localities which vary 
according to their means of subsistence, and the resources 
with which nature has provided them, to escape from the 
dangers by which they may be menaced. Thus the pin- 
notheres withdraw themselves into bivalve shells. The 
dromise form with alcyones a sort of mantle, which completely 
covers them. Many apply, upon their back, the valve of a 
shell, and on that account, these Crustacea, like dorippus, have 
their four posterior feet recurved upwards, and adapted for re- 
taining, with the strong hook that terminates them, and which 
in some species, is even accompanied by another, but a smaller 
one, the bodies which they think proper to appropriate. 
Many, such as the matuti, portuni, orithyias, and the 
macrouri in general, swim with facility. But the other 
