56 C H I T K. 



for it. It is capable, in the same inaiiner, of rolling 

 itself into a perfect ball. 



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 composecTof 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. squa- 

 mosus possessing only 7 valves, with a perfect 

 margin ; but these must be considered as lusus 

 naturce^ 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 Patella, it is generally found 

 parasitical, but possesses the power, which they do 

 not, of removing from its station. The name of 

 the Genus, Chiton, is derived from the Greek 

 word x«Tc«v, signifying a coat of mail ; and aptly 

 expresses the loricated appearance of the shell, 

 arising from the position of the valves. 



