i6 
SEA MONSTERS UNMASKED, 
Sepia and Loligo, are all free swimmers. For them it is 
necessary for accuracy of natation that their soft, and in 
the squids long bodies, should be supported by such a 
framework as they possess. In Sepia^ the mantle-sac is 
flattened horizontally all along its lateral edges so as to 
form a pair of fins, which nearly surround the trunk. These 
flns could never be used, as they are, to enable the animal 
to poise itself delicately in the water by means of their 
beautiful undulations, which I have often watched with 
delight, if their attached edges were not kept in a straight 
line on either side. Then, these ten-footed or ten-armed 
genera have not, because they need them not, eight long, 
FIG. I. — BEAK AND ARMS OF A DECAPOD CUTTLE. 
the eight shorter arms ; the tentacles ; the funnel, or locomotor tube. 
strong and highly mobile arms like those of the octopus, nor 
have they large suckers upon them. Whereas a great length 
of reach is an advantage to the octopus, animals which are 
purely swimmers, and which hunt and overtake their prey 
by speed, would be impeded by having to drag after them 
a bundle of stout, lengthy appendages trailing heavily 
astern. Their eight pedal arms are short and comparatively 
weak, though strong enough, in individuals such as are 
regarded on our own coasts as fullgrown, to seize and hold 
