CHITON. 219 



zones ; occasionally between tide-marks at liigli springs ; 

 off Mull of Galloway^ 145 f. (Beechey). Macgillivray 

 says he found it at Aberdeen on a starfish ! The 

 variety is from the west of Scotland in deep water. 

 ^^ Glacial ''bed at Fort WHliam (J. G. J.); Coralline 

 Crag, Sutton (S. Wood). Greenland (Fabricius and 

 Eschricht) ; Iceland (Steenstrup and Torell) ; Scandi- 

 navia, 1-130 f. (Miiller and others) ; north of France 

 (De Gerville) ; Vigo Bay (M*^ Andrew) ; and along the 

 coasts of the Mediterranean to the ^gean_, 5-10 f. 

 (Forbes^ as C. Rissoi). 



Chemnitz called the specimens in Spengler's cabinet 

 '^ the negress/' owing to their swarthy complexion. 

 When this Chiton opens its mouth and shows its teeth;, 

 a double row of black glistening points, separated by a 

 central column, is suddenly unfolded, and as rapidly 

 withdrawn ; this operation is repeated several times in 

 the course of a minute. Is it caused by the blind 

 cravings of hunger, or is it a process like that of rumi- 

 nation, or merely for the purpose of keeping the teeth 

 clean ? Mr. Dennis says that all the specimens which 

 he dredged in 17 f., seven or eight miles oflP Blatching- 

 ton, on the Sussex coast, are small and light-coloured in 

 comparison with those procured by him at low water. 

 The largest specimen I have came from Oban, and 

 measures y%ths of an inch in length by | an inch in 

 breadth ; the smallest is not much more than 2^^^^ ^^ ^^ 

 inch long. The fry are broader than the adult, and their 

 granules are tubercular, few in number, and apparently 

 analogous to the external bulbs of the tubular perfora- 

 tions in shells of Brachiopoda. C. cinereus may be dis- 

 tinguished from C. cancellatus by its larger size, ex- 

 panded and compressed shape, finer sculpture, the lateral 

 compartments being inconspicuous, and by its central 



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