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choose another more spacious. For this purpose it enters 
successively, and backwards, into almost all the empty shells 
with which it meets. It endeavours to discover that in which 
the hinder part of its body will be most at ease; and unless it 
be favoured by chance, it is frequently unable to lodge itself 
until after many trials and examinations. 
In their youth, these Crustacea sink down almost entirely in 
their shells, and scarcely can the extremity of their feet be 
perceived ; but when more advanced in age, and increased in 
bulk, their claws and the two or four following feet always 
show themselves, in a great measure, outside. When their 
pincers are of a very unequal size, the largest often closes the 
entrance of the shell, in the manner of a lid. The same spe- 
cies of pagurus lodges in univalve shells of different species, 
and even of different genera. “ But,” says Olivier, “ what 
appears to us not to have been sufficiently observed, though 
well worthy of observation, is, whether the same individual, 
on quitting its shell now become too small for it, proceeds 
constantly to lodge in a shell similar to the first ; whether 
it confines itself to certain species of the same genus; or 
takes indifferently all which present themselves, no matter to 
what species they may appertain. Might it not be possible 
that the individual which at first inhabits a buccinum, and 
in which its body is in some sort modelled, could not after- 
wards lodge conveniently but in another buccinum, and that 
it would find itself incommoded or constrained if it wished to 
fix itself in a murex or a tonna?” It does not, however, 
appear, according to the opinion of this skilful naturalist, that 
the form of the body of the pagurus is intimately adapted to 
that of the cavity of its dwelling ; for, were it so, the indivi- 
duals of the same species of pagurus, inhabiting shells of 
divers species, would also present notable differences, which 
has not been remarked, and which even cannot take place, 
since the trunk, although of a consistence less solid than that 
