2 



they are capable of contraction and extension ; they can 

 stretch at full length, or roll themselves into a ball. The 

 scales, or valves, of which they are formed, are from 

 six to eight in number, and are so disposed, that they 

 move on each other like the joints on the tail of a 

 lobster. The valves which are very solid, vary in shape 

 and colour according to the species, but the smallest 

 is generally before and the largest behind: they are 

 connected together by a projecting cartilaginous border 

 which surrounds the shell, and which is sometimes 

 plain, sometimes spinous, and often covered with minute 

 scales. 



The name of petite nacelle, which has been occasionally 

 given to this shell, is by no means unapplicable, for 

 nothing can convey a better idea of a little boat than 

 the interior of a Chiton. In some species the colour 

 of this surface is bluish green, in some it is quite white ; 

 others are stained with violet, or purple, along the 

 middle, and some are very prettily variegated. 



Chitons fix themselves to rocks, to ships, and even 

 frequently to fish, and to other shells. They are capable 

 of locomotion, but seldom appear to use that faculty ; 

 they seem to be satisfied with their first attachment, and 

 never wish to change their place. When forced from 

 their hold they roll themselves into a ball, presenting 

 nothing to their enemy but an invulnerable shell, and a 

 portion of the lateral ligament defended by scales, or 

 spines. Bosc observed, on the coast of America, that 

 when the Chitons rolled themselves up in consequence 

 of being separated by violence from the bodies to which 

 they were fixed, it was a considerable time before they 

 recovered their natural position ; the most expeditious 

 required two days to compose themselves, and several, 



