670 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [NoV. 14, 



rocks and stones. C. Verd I, (rfe Rochebrune). Not Arctic, nor 

 Asiatic, nor American. 



Fossil. Pliocene : Red Crag. Post-tertiary, especially in raised 

 sea-beaches : Scandinavia, Great Britain and Ireland, France, and 

 Italy; 0-1360 ft. 



An extremely variable species, as regards shape, size, position of 

 the apex, sculpture, colour, inner coating, habitat, and every other 

 characteristic than that of being conical. All the North-Atlantic 

 so-called species, except P. ferruginea or safiana, but including the 

 varieties noticed in ' British Conchology ' and P. lusitanica of 

 Gmelin or punctata of Lamarck, run one into another by insensible 

 gradations. 



Although the following more properly relates to the habits of the 

 Mammalia than to those of the Mollusca, it is not devoid of interest 

 in this place. In a letter from Dr. Fleming to Prof. Jamieson 

 (Mem. Wern. Soc. 1823), he says that at Scalpa, "in the course of 

 conversation with the keeper of the lighthouse Mr. Reid, a judicious 

 observing man, I was informed that rats (the brown or Norway rat, 

 which abounds in the Hebrides) after a shower go down upon the 

 rocks, while the Limpets are crawling about, and by a sudden jerk 

 with their noses detach them from the rocks for food. Should the 

 first effort fail, another is never attempted against the same indi- 

 vidual, now warned and adhering closely to the rock ; but the rat 

 proceeds instantly to others still off their guard, until enough of food 

 has been procured." See also an interesting paper by Mr. J. Clark 

 Hawkshaw on the habits of the Common Limpet in the * Journal of 

 the Linnean Society' (Zoology) for 1878. 



As may be expected, the synonyms are numerous, and include 

 P. vulgaris of Belon, whose name is older than that of Linne by 

 about two centuries. 



i/ Helcion pellucidum, Linne. 



Patella pellucida, L. S. N. p. 1260. 



H. pellucidum, B. C. iii. p. 242, pi. v. f. 4 ; v. p. 199, pi. Iviii. 

 f. 1, 2. 



' Porcupine' Exp. 1869 : St. Donegal B. 1870 : Atl. Vigo B. 



Distribution. Iceland, Faroe I., N. Cape to Mogador, Mediter- 

 ranean {Linne) 1 Antibes {Martin, f. Petit) ? ; 0-20 fms., usually on 

 LaminaricB. 



Fossil. Pliocene : Sicily {Seguenza). Post-tertiarv : Norway, 

 Scotland, and N. Ireland ; 0-130 ft. 



In the 'Philosophical Transactions' for 1696 Sir Robert Sibbald 

 mentioned this as the " Oval Limpet " in his letter to Dr. Lister on 

 Skye shells. 



There are at least half a dozen synonyms. On the other hand, 

 Cantraine thought it very possible that Helcion pellucidum, Tectura 

 virginea, and Gadinia gussoni (the last being his Patelloidea vitrea) 

 belong to one and the same species ! Lamarck gives the type of the 

 present genus {Helcion pectinatum) as Mediterranean on the 

 authority of Born. 



