STRUCTURE OF SUCKING DISCS. 97 



fisli. The body is much smaller in comparison, and almost 

 globular, while the anus arc much longer, only eight in number, 

 all uniform, and united at the base by a thick membrane or web, 

 which greatly aids our friend in his natatory operations. 



And now turn to the inner face of the arms, and look at- 

 tentively at the discs. Observe that they each consist of a 

 muscular membrane with a thick fleshy circumference, pre- 

 senting when expanded a number of radii converging around the 

 circular orifice of an inner cavity. In this cavity is a movable 

 muscular piston, which, when not in action, is on a level with 

 the circular aperture ; but which, when the disc is closely ap- 

 plied to any object, is drawn strongly back, and the cavity it 

 filled converted into a vacuum ; each separate disc being, in fact, 

 an admirably contrived pneumatic apparatus, which firmly ad- 

 heres, wherever it is applied, on the same principle as a surgeon's 

 cupping-glass or a school-boy's sucker. The purpose of these 

 " suckers " is to act of course as agents in seizing prey ; and of 

 so terrible a character are they, says Professor Jones, that, 

 " armed with these formidable organs, the Poulpe becomes one of 

 the most destructive inhabitants of the sea ; for neither superior 

 strength nor activity, nor even defensive armour, is sufficient to 

 save its victims from the ruthless ferocity of such a foe. A 

 hundred and twenty pair of suckers, more perfect and efficacious 

 than the cupping-glasses of human contrivance, crowd the lower 

 surface of every one of the eight flexible arms. If the Poulpe 

 but touch its prey, it is enough ; once a few of these tenacious 

 suckers get firm hold, the swiftness of the fish is unavailing, as 

 it is soon trammelled on all sides by the firmly-holding ten- 

 tacula, and dragged to the mouth of its destroyer. The shell of 

 the lobster or of the crab is a vain protection for the hard and 

 crooked beak of the Cephalopod easily breaks to pieces the frail 

 armour, and even man himself, while bathing has been entwined 

 by the strong arms of gigantic species, and struggled in vain 

 against a grasp so pertinacious." 



It is stated by Dr. Roget, that so long as the muscular fibre of 

 the piston is contracted, it is easier to tear away the substance of 

 the animal's arms than to release the suckers from their attach- 

 ment, and that even after the animal is dead, these organs still 

 retain a considerable power of adhesion. 



We have hitherto spoken of the tentacula of the Cephalophods 



