7204 Mollusks. 



be found to be a general nile with regard to the limpet, that the nearer 

 high-water mark the shell is taken, the higher spired, more strongly 

 ribbed and smaller it will be ; and that the lower down it lives, the 

 flatter, less ribbed and larger it becomes. The above-mentioned form, 

 which has the flat skin of the low-water variety, with the strong ribs 

 of the high-water form, was found just beyond low-water mark. 



*P. pellucida {Patella ccerulea). Not uncommon on Laminariae, but 

 the specimens are always small. 



Acmsea testudinalis {Lottia testudinalis, Patella testudinalis. 

 Patella Clealandi). Few British shells can compete with this limpet 

 in beauty. In the Clyde it is very abundant, though somewhat 

 locally so. The kind of locality in which it should be looked for is 

 among beds of large stones, when laid bare at the lowest spring 

 tides; it rarely occurs except on detached pieces of rock. On 

 the Bute shore, from Scolag round to Rothesay, it may be taken in 

 great abundance. Varieties occasionally are of an uniform dark 

 brown, while others are nearly pure white. Acmjea testudinalis is a 

 peculiarly interesting mollusk, on account of its steady migration 

 southwards. This fact is noticed by Forbes and Hanley, who trace 

 its wanderings down the western coast from Scotland to Bangor, in 

 Ireland, and, at a subsequent period, as far south as Dublin and the 

 Isle of Man. At that time it was not known in the east of Scotland 

 nor anywhere on the shores of England. A little later, however, it 

 was met with in great abundance on the shores of the Moray Firth ; 

 in 1856 it was noticed in the Faroe Islands, Northumberland, by 

 Mr. Tate, and at Whitburn, in Durham, by the Rev. G. C. Abbes; 

 and in 1857 Mr. Albany Hancock fell in with it at Roker, yet further 

 south on the coast of Durham. We have a strong proof that the 

 species has only recently arrived at the last-named localities, in the 

 fact that it has occurred in spots which have been thoroughly 

 explored by Dr. Johnston, Mr. Alder, Mr. Hancock and other well- 

 known naturalists, whose keen eyes could not have overlooked so 

 conspicuous a shell. We shall probably hear before long that it has 

 put in an appearance at Whitby or at Scarborough. 



*A. virginea {Lottia virginea. Patella virginea). On stones and 

 at roots of Laminaria3 from low- water mark to twelve fathoms; 

 common. 



Pilidium fulvum {Patella Forhesii, Patella fulva, Pilidium ruhrum). 

 "This mollusk was first announced as a member of the British Fauna 

 by Mr. Smith, of Jordan Hill, who dredged it in the Clyde, off" Arran." 

 — F. 8$ H. In one confined spot just outside Lamlash Bay, a little to 



