CHITON. 225 



notches deep, 9 on the head-plate, 8 on the tail-plate, and 2 

 on each of the other plates, making altogether 29. L. 0-5. 

 B. 0-275. 



Var. ohlo7iga. Larger, longer, and more arched. L. 0*65, 

 B. 0-35. 



Habitat : On rocks, stones, old shells, and the 

 " roots ^^ of Laminaria saccharina, between low-water 

 mark and 20 i., from South Devon to Shetland ; it is 

 common in the west of Scotland and Lerwick Sound, 

 where also the variety occurs. Fossil at Fort William 

 (J. G. J.). The only southern locality that I can find 

 recorded is the Adriatic, according to Olivi ; but its 

 northern range is very extensive, and comprises Spitz- 

 bergen (Phipps, fide Scoresby); Godhaab, E. Green- 

 land, 50-150 f. (Wallich); S. Greenland (Eschricht); 

 Iceland (Mohr, Steenstrup, and Torell); Norway, 

 Sweden, and Denmark, 1-150 f. (Spengler and many 

 others); White Sea (Baer, fide MiddendorfF); North- 

 east America, from Cape Cod northwards (Gould, 

 Mighels, and Stimpson). 



This pretty species was first noticed as British by 

 Professor Jamieson, in the first volume of the ' Memoirs 

 of the Wernerian Society^ (1811), from rocks in the 

 island of Unst, and almost simultaneously, in the same 

 volume, by Captain Laskey, from Duobar. It may 

 always be distinguished from C. margmatus by its red- 

 dish-brown colour, narrower and more arched shape, 

 broader girdle, and especially by its smooth and glossy 

 appearance. Young shells are longitudinally veined, 

 showing the internal tubular structure. 



It is extremely probable that the C. ruber of Linne 

 may have been the species which Fabricius afterwards 

 described with greater precision as C. marmoreus ; and 

 there can be no doubt that the C. Icevis of Pennant was 



l5 



