42 CHITON. 



By far the greater number of species consist of 

 8 valves ; and the specimens of 6 or 7 are so rare, 

 that they may, not unreasonably, be suspected of 

 having sometimes been either carelessly or fraudu- 

 lently composed of disconnected valves. The mar- 

 ginal membrane being entire, will always afford an 

 obvious security against such sort of imposition. 

 There are, however, instances of the C. squamosus 

 possessing only 7 valves with a perfect margin ; 

 but these must be considered as lusus naturcc. 



The animal adheres, usually, to rocks, or other 

 shells, by means of a gelatinous fluid which exudes 

 from the papillary under-surface of its body. Like 

 the Patellae, it is generally found parasitical, but 

 possesses the power, of removing from its station. 



The name of the Genus, Chiton, is derived from 

 the Greek word -/jtuv, signifying a coat of mail; 

 and aptly expresses the loricated appearance of 

 the shell, arising from the position of the valves. 



