CHITON. 415 



— Gould, Invert. Massachus. p. 148, f. 23. (probably). — 

 Dekay, New York Fauna, Moll. p. 165, pi. 10, f. 99 (pro- 

 bably). 

 Chiton pictus, Bean, Brit. Marine Conch, p. 264, f. 56. 



Otlio Fabricius, who appears to have been the first who 

 directed his attention to the insertional teeth in the valves 

 of Chiton, has described this Chiton in his Fauna of 

 Greenland, a work which, considering- the carefulness and 

 sufficiency of his descriptions, contrasting strongly with 

 the loose, curt, and indefinite language of most of the 

 subsequent writers upon Conchology, has been singularly 

 neglected by our writers upon shells. 



The shape of this Chiton, our largest British species, is 

 ovato-elliptic, the form being rather broader in front than 

 behind, where also the shell, which is moderately elevated, 

 becomes rather more depressed, and the dorsal angulation, 

 which even anteriorly is more or less obtuse, becomes 

 almost or wholly obsolete in the larger examples. The 

 plates or valves are rather glossy, and apparently smooth, 

 but when magnified exhibit an extremely minute shagreen- 

 ing, wherein the granules, which, although remarkably 

 numerous, cannot be termed crowded considering their 

 size, seem all of the same dimensions, and are not disposed 

 in any peculiar arrangement upon the several areas ; the 

 lines of increase are tolerably distinct. The lateral tri- 

 angles are indicated by their slight superior elevation 

 either wholly or anteriorly ; in the latter case there is 

 occasionally an indistinct radiating approximate sulcus, or 

 the central portion is hollowed out, so that the hinder edge 

 seems slightly raised likewise. The posterior dorsal edge 

 is a little incurved laterally, and rather abruptly beaked in 

 the centre ; the mucro is short, and not distinguished from 

 the rest of the surface by either colour, substance, sculp- 



