202 



MOLLUSCA. 



a large head, flattened at the top into a sort of 

 disk, in the centre of which is a beak almost exactly 

 resembling in form, texture, and action, that of a 

 Parrot, save that the upper mandible shuts into 

 the lower. On each side of the head is a large and 

 complex eye, covered by the common skin, which 

 there becomes perfectly transparent, and, by a fold, 

 forms eyelids for its protection. Around the edge 

 of the disk, between the beak and the eyes, are 

 eight or more fleshy arms, usually of great length, 

 tapering to a point; they are very flexible, but of 

 great muscular power, and their under surface is 

 furnished with many suckers of curious construc- 

 tion. Each sucker may be compared to a most 

 perfect cupping-glass, consisting of a circular mus- 

 cular cup, whose concave surface has in its centre 

 an aperture leading into a cavity ; a piston accu- 

 rately fits the orifice, which may be withdrawn by 

 muscular force. The animal, then, in throwing out 

 its long flexible arms, brings one of them into con- 

 tact' with its prey ; the instant the concave surface 

 of but a single sucker is applied, the piston is with- 

 drawn, and a vacuum is created, and by the atmo- 

 spheric pressure without, the sucker adheres with 

 astonishing force. But, as the suckers are nume- 

 rous and close, many are made to adhere at one 

 moment ; the arm is swiftly twined round the object, 

 and the other arms being likewise applied to it, it is 

 easier to tear asunder the muscular fibres of the 

 limb than to loosen the fearful and often fatal 

 embrace. With all this adhesive pow r er, which is 



