1907.] 



STUDIES ON THE LIMPET. 



867 



very favourable for the study of the two types of shell. The 

 shore was covered with bouldei'S, some of rough knobby granite, 

 others of smooth polished greenstone. The rough type of limpet 

 occurred on the granite, and harmonised in colour with the greys 

 and browns of the weathered rock. The smooth type occurred on 

 the dark greenstone, and was usually dark in colour. It should 



Text-fig. 223. 



Text-fio-. 224. 



Text-fiiT. 225, 



Text-fig. 220. 



Text-fig. 227. 



Text-fio-. 228. 



Text-fig". 223.— A typical "smooth " shell. 

 Text-iig'. 225. — Outline of margin of same. 

 Text-fig. 227. — Marginal outline of a small 

 "smooth" shell. 



Text-fig. 224.— A typical '-roug^h" shell. 

 Text-fig. 226. — Outline of margin of same. 

 Text-fig. 228.— Marginal outline of a small 

 "rough" shell. 



be remarked that the smooth type occurs only on very smooth 

 stones, and that for this reason it is not in every locality that 

 limpets are distinctly separable into rough and smooth types. In 

 places where no polished stones are to be found, there are usually 

 no smooth limpets, but only various shades of rough. 



