CHITON IDiE. 115 



until a knife, or something thin, is inserted under the rim, 

 and it is gradually prized up. When you have it in hand, 

 and turn it over, it appears filled with a living creature ; not, 

 indeed, remarkable for activity, but by no means powerless 

 or senseless. The greater part of the flat side is composed 

 of an oval, sucker-hke disc, which, exactly like the leather 

 " sucker " of the boys, has served to keep the creature in its 

 place. 



Varying very much in their natures, habits, and appear- 

 ance, and having convex but not spiral shells, the examples 

 of still life to which these remarks have introduced the reader 

 will be found to belong to some of the families named at the 

 head of the chapter. We must now study the characters of 

 each as far as we can without the microscope. 



CHITONID^. 



Chiton. — Among the sucker-footed molluscs stationary 

 on the surfaces of stones and shells, some will be found in 

 which the oval convex surface is composed of a series of 

 arched shelly plates, set in a rough softer border : the two 

 end-plates of the shell are semicircular, and the border is, 

 in some species, studded with star-like branches of bristles ; 

 in others, finely shagreened ; in others, apparently smooth. 



