CHITON. 401 



proportion of that on each side of the shell is unitedly, at 

 the fifth plate, as one to four ; it is delicately farinaceous, 

 and articulately painted with hrick-red and ashy-white, 

 so arranged, for the most part, that the latter tint is 

 chiefly aj^parent (and usually in narrow strips) in a hue 

 with the sutures of the valves. 



Mr. LowQ remarks that the insertional teeth are nine on 

 the first valve, ten on the last, and two on the intermediate 

 ones. 



The soft parts of the animal are of a flesh-red colour. 

 The branchial leaflets on each side extend very nearly to 

 half its length, and are about twelve in number. The 

 under-margin of the mantle is rather broad in proportion 

 to the foot, and the space between the mantle and foot 

 very narrow. Each series of branchial leaflets is also very 

 narrow. The hood of the head is narrow and slightly 

 extended at the angles. Loven has described and figured 

 the lingual teeth. The axile denticle is oblong quadrate, 

 the large hooked laterals bear incurved tridentate summits, 

 which, however, are not very broad and have nearly equal 

 denticulations. 



This species is generally distributed through the British 

 seas, but seldom taken in great plenty. It is occasionally 

 and not uncommonly found at low water, but its true resi- 

 dence is in the laminarian zone, where it is frequent, mostly 

 on the under surface of stones, and about the roots of 

 LanimarifE, in from three to fifteen fathoms water. We 

 have observed it in similar localities on both northernmost 

 and southernmost coasts. 



It is probably of northern origin, and ranges through 

 the seas of Scandinavia, Greenland, and Boreal America, 

 extending northwards on the American coast as far as 

 the New York province. Middendorft' includes it in 



VOL. II. 3 F 



