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the inner surface, which is flattish, while the outer is rounded, is a row of circular sucking' discs, amounting" in number to upwards of one hundred in each foot; once let these suckers get a firm hold of anything that is worth retaining, and farewell to all hope or chance of its ever getting free, so long as their owner pleases to operate on his prey with these perfect cupping glasses. Examine any one of them, says Rymer Jones,[1] "It is an admirably arranged pneumatic apparatus—an air-pump. The adhesive disc is composed of a muscular membrane, its circumference being" thick and fleshy, and in many species (the Decapods, or ten-armed) supported by a cartilaginous circlet, so that it can be applied most accurately to any foreign body. In the centre of the fleshy membrane is an aperture leading into a deep cavity, at the bottom of which is placed a prominent piston that may be retracted by muscular fibres provided for the purpose. No sooner therefore is the circumference of the disc placed in close and air-tight contact with the surface of an object, than the muscular piston is strongly drawn inwards, and a vacuum being thus produced, the adhesion of the sucker is rendered as firm as mechanism could make it."
The ten footed Cephalopoda or Decapods have a pair of fins by which they swim in all directions, but the broad web connecting the feet of the Octopods enables them to swim in a retrograde direction, a peculiarity we but recently noticed in a specimen kept for our observation by the Keeper of the bathing houses at Geelong (Mr. Rigney), and in our investi-
- ↑ Structure of the Animal Kingdom, p. 558.
