670 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [Nov. 14, 
rocks and stones. C. Verd I, (de 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 Linné by 
about two centuries. 
HELCION PELLUCIDUM, Linné. 
Patella pellucida, L. 8. N. p. 1260. 
H. pellucidum, B. C. iii. p. 242, pl. v. f. 4; v. p. 199, pl. lviii. 
i: 
‘Porcupine’ Exp. 1869: St. Donegal B. 1870: Atl. Vigo B. 
Distribution. Iceland, Faroe I., N. Cape to Mogador, Mediter- 
ranean (Linné)? Antibes (Martin, f. Petit)? ; 0-20 fms., usually on 
Laminarie. 
Fossil. Pliocene: Sicily (Seguenza).  Post-tertiary: 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. 
