394 cniTONiD.E. 



last valve is very short and narrow, and tlie fall from its 

 mucro rather abrupt. There are no distinct defined lateral 

 and central areas, but the entire exterior of the several 

 plates is adorned, except upon the dorsal ridge, which is 

 usually marked with coarse wavy longitudinal strise, or 

 (often interrupted) raised sulci, with rather large flat- 

 topped more or less tear- shaped separate granules, that 

 either do not preserve any regular arrangement, or else, 

 keeping their pointed ends towards the beaks, seem conse- 

 quently to radiate in some little degree from them. The 

 margiu which is tolerably broad, yet not so dilated as in 

 the succeeding species, is somewhat spinosely hairy, and is, 

 besides, armed with eighteen tufts or fascicles of crowded 

 bristles, that are extremely numerous, of but moderate 

 length, and of a pink or yellowish white tint. Four of 

 these fascicles precede the first valve, the rest are situated 

 at the junction of the several plates of which the Chiton is 

 composed. The general colour of the shell is of a greenish 

 or olivaceous ash, occasionally mottled with liver-brown, 

 sometimes pure white or flesh-colour, sometimes mixed 

 white and chocolate brown upon the dorsal ridge ; and 

 more rarely of a dull crimson, or variegated with crimson 

 and white. 



This is a much smaller species than the one next de- 

 scribed, and very rarely exceeds three quarters of an inch 

 in total length. 



Mr. Clark has communicated a detailed account of the 

 animal. " The foot is suboval, very little angular in fi-ont, 

 and slightly but obtusely tapering behind. The under part 

 of the mantle is of a red brown colour. Between the foot 

 and the mantle is the branchial cordon, consisting of fifteen 

 oblique cord-like, short, close-set, pale brown filaments on 

 each side, commencing close to the posterior extremity, 



