ON CRUSTACEA. 
307 
of the other Crustacea, is nevertheless capable of a certain 
degree of resistance, and that a change in its external form 
would induce others in the principal organs of life. The em- 
barrassment of these Crustacea in choosing their retreats would 
be still greater, and they would be too much exposed to 
perish if they were obliged to lodge in shells analogous to 
those which they had abandoned. All the conditions which 
nature seems to require are, that the shells shall be univalve, 
of a capacity proportioned to that of the bulk of the body of 
the pagurus ; that they should be turbinated at their extre- 
mity ; and that their mouth or aperture should be accommo- 
dated to the form, to the thickness, and to the action of the 
claws, and of the anterior feet of the parasite animal. It 
moves and walks at the bottom of the sea, or on the shore, by 
means of its organs of locomotion, and by the pincers of its 
claws it seizes the little marine animals on which it feeds. 
When menaced with any danger, it retires, as far as is pos- 
sible, into the interior of its dwelling, and does not show itself 
until long after the peril has ceased. When seized, it is said 
to utter a little cry ; but it resists all efforts which can be 
made to draw it out of its shell, and this cannot be done until 
after its death. The moments devoted by the paguri to the 
catching of their prey, those of their amours, and the periods 
of their change of domicile, are to them times of crisis and 
danger : they have then to dread a crowd of enemies which 
devour them, and particularly the fish, which are very eager 
in their pursuit. These Crustacea, according to the testi- 
mony of Belon, furnish even an excellent bait to take the 
fish which frequent the rocks, or which approach the shore. 
But all the paguri do not live in the sea. Le Pere Nichol- 
son, in his Essay on the Natural History of St. Domingo, 
describes a species which inhabits the dry places of the sea- 
shores, and of the hills ; which, when plunged into the water, 
and even into the fresh water, uses every effort to get out, 
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