426 



PTEJIOPODA. 



tongue covered, as in many other Mollusca, with sharp horny 

 spines. 



One of the jaws removed from the body, and magnified twenty- 

 eight diameters, is represented in the subjoined figure (Jig. 

 199, A). It consists of a series of sharp horny teeth of unequal 

 length, fixed to the sides of a lateral pedicle in such a manner 

 that their points are all nearly at the same level. The teeth them- 

 selves have a golden metallic lustre, and, when examined in the 

 sunshine under water by means of a lens, are especially beautiful 

 objects. The basis to which they are fixed is apparently of a 

 fleshy character, and if smashed by being squeezed between two 

 plates of glass, and then placed under the microscope, it would 

 seem to be made up of a multitude of regularly disposed fibres that 

 cross each other in two principal directions. 



The jaws thus constructed are placed on each side of the mouth, 

 contained in two hollow curved cylinders, the walls of which are 

 muscular ; and, if one of these muscular capsules be snipped by 

 means of a pair of very fine scissors, the strangely-formed jaw, 

 with its teeth, is found lodged within it. 



The manner in which the Clio uses these dental organs is ob- 

 vious from their anatomical position. The curved muscular cylin- 

 ders, by the contraction of their walls, force out the teeth, so that 

 they then project from the mouth, and are ready to seize and drag 

 into the oral orifice whatever food presents itself. 



Once conveyed by the jaws into the interior of the mouth, the 

 prey seized is taken hold of by the tongue ; the free extremity and 



Fig. 199. 



