272 THE INHABITANTS OF TIlt SEA. 
orders, Octopods and Decapods, the former having only eight 
Poulp (Octopus). 
composed of a circular 
Calamary. 
In many of the decapods, who, generally seeking their prey in 
sessile feet, while the latter possess 
an additional pair of elongated ten- 
tacles, which serve to seize a prey 
that may be beyond the reach of 
the ordinary feet, and also to act as 
anchors to moor them in safety during 
the agitations of a stormy sea. 
Both the arms and tentacles are 
furnished with suckers disposed along 
the whole extent of the inner surface 
of the former, but generally confined 
to the widened extremities of the 
latter, where they are closely aggre- 
gated on the inner aspect. 
In all the octopods the suckers are 
soft and unarmed. Every sucker is 
adhesive disk, which has a thick fleshy 
circumference and bundles of mus- 
cular fibres radiating towards the 
circular orifice of an inner cavity. 
This widens as it descends, and 
contains a cone of soft substance, 
rising from the bottom of the cavity, 
like the piston of a syringe. When 
the sucker is applied to a surface 
for the purpose of adhesion, the 
piston, having previously been raised 
so as to fill the cavity, is retracted, 
and a vacuum produced, which may 
be still further increased by the 
retraction of the plicated central 
portion of the disk. So admirably 
are these air-pumps constructed, and 
so tenacious is their grasp, that, 
when they have once seized or fixed 
upon a prey, it cannot possibly dis- 
engage itself from their murderous 
embrace. 
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