238 PATELLID^. 



position of the apex, sculpture, and inside lining. I 

 once considered mj^self an adept at picking out the 

 variety depressa (or " China limpet/^ as it has been 

 called) by merely seeing the outside ; but I have since 

 failed, and a recent examination and comparison of a 

 great many living individuals of each form has quite 

 convinced me that they are not separate species. The 

 fifth variety inhabits flat stones and slabs of rock at low 

 water, often in places where streams empty themselves 

 into the sea ; in its younger state it is the P. aspera 

 of Philippi. The common limpet is fossil in raised 

 beaches, including that near Macclesfield at a height of 

 500-600 ft. (Darbishire), Moel Tryfaen, 1300-1400 ft. 

 (Capt. Lowe), Fort William 10 ft. (J.O.J.), and the Red 

 Crag (S. Wood); Uddevalla (Hisinger and Malm); newer 

 glacial formation near Christiania, 120 ft. (Sars); Palermo 

 (Philippi) . Its distribution in a recent state comprises 

 every coast between the Lofibden Isles (Sars) and the 

 ^gean (Forbes); and Weinkauff has enumerated it as 

 an Algerian species. The variety intermedia has been 

 found in Brittany by Cailliaud, and in Spain by 

 M*^ Andrew. Philippi noticed the variety depressa as 

 fossil in an ossiferous cavern at Mardolce, in Sicily ; and 

 it inhabits the shores of France, Spain, Italy, Greece, 

 and North Africa. 



The limpet appears to have formed a considerable part 

 of the food of the primitive inhabitants of North Britain, 

 where heaps of their shells are continually being turned 

 up. In the ruins of a so-called Pictish fort near Ler- 

 wick the shells are partially calcined; and those of 

 the common periwinkle, which are also found there, 

 must have been subjected to the action of fire in order 

 to extract the animals. Roasted limpets are capital 

 eating. A few years ago I was a guest at a dinner- 



