SUCKERS OF A POULP. 273 
the deeper waters, have to contend with the agile, slippery, aud 
mucus-clad fishes, more powerful organs of prehension have 
been superadded to the suckers. 
Thus, in the Calamary the base of 
the piston is enclosed by a horny 
hoop, the margin of which is de- ® 
veloped into a series of sharp-pointed 
eurved teeth; and in the still more 
formidable Onychoteuthis each hoop 
is produced into the form of a long, 
curved, and sharp-pointed claw (/), 
which the predacious mollusc presses 
firmly into the flesh of its struggling 
victim, and then withdraws by mus- es 
cular contraction. Qua rin a 
Besides the hooked acetabula, a \ 
cluster of small simple unarmed 
suckers may be observed at the base Secton of an gm and suckers of a 
of the expanded part. These add _ «. Soft and tumid margin of the disk, 
; 5 g- Circular aperture. 
greatly to the animal’s prehensile 
powers, for when they are applied to one another (e), the 
tentacles are firmly locked together at that point, and the 
united strength of both the elongated peduncles can be applied 
to drag towards the mouth any resisting object which has been 
grappled by the terminal hooks. There is no mechanical 
contrivance which surpasses the admirable structure of this 
natural forceps. 
The size of the arms and the arrangement of the suckers differ 
considerably in the various species. In the octopods or poulps, 
which generally lead amore sedentary creeping life, and, hidden 
in the crevices of rocks, await the passing prey, the arms, in 
accordance with their wants, are with rare exceptions longer, 
more muscular, and stronger, than in the actively swimming 
decapods, where the two elongated tentacles or peduncles are the 
chief organs of prehension. In some species we find the arms 
distinct—in others they are united by a membrane. Some 
have a double row of suckers on each arm, others four rows, 
others again but one. So wonderful are the variations which 
nature, that consummate artist, plays upon a single theme— 
so inexhaustible are the modifications she introduces into the 
