MOLLUSCA CEPHALOPODA. 



187 



they twine with ease round an object of any shape, and grasp 

 it with prodigious force. In addition to these properties 

 they derive a remarkable power of adhesion to the surfaces 



of bodies from their being furnished with numerous suckers 

 all along their inner sides. Each of these suckers, as shown 

 separately in Fig. 122, is usually supported on a narrow 

 neck, or pedicle, and strengthened at its circumference by 

 a ring of cartilage. Their internal mechanism is more ar- 

 tificial than the simple construction already described, (p. 



106;) for when the surface of the disk is fully expanded, as 

 shown in Fig. 123* b, we find that it is formed of a great 

 number of long slender pieces, resenibling teeth closely set 

 together, and extending from the inner margin of the cartila- 

 ^^, ginous ring in the form of converging radii, to within a short 

 'distance of the centre, where they leave a circular aperture. 

 In the flattened state of the sucker, this aperture is filled by 

 the projecting part of a softer substance, which forms an in- 

 terior portion, capable of being detached from the flat cir- 

 cle of teeth, when the sucker is in action, and of leaving an 



