MARSHALL: ADDITIONS TO "BRITISH CONCHOLOGY." 65 



preserved rats which have been found drowned by limpets, their 

 tongues having been firmly pressed to the rocks. There may be a 

 connection between this practice of limpet-eating by colonies of 

 rodents, and the various " Rat Islands" that are scattered round our 

 coasts. 



P. vulgata L. — The fry are very curious, and may be found in 

 dwarf sea-weeds during March and April. This extremely common 

 species was very rare during the Crag period, only two small speci- 

 mens, three-eighths of an inch in diameter, being recorded by Searles 

 Wood. 



Var. elevata Jeffr. — Jersey and Guernsey. This must not be 

 confused with high-spired examples, which are to be found of all 

 the varieties and of all sizes. 



Var. picta Jeffr. — Exposed rocks in the Channel Islands; Torquay ; 

 Tenby ; Butt of Lewis. I regard this as a stunted form of the var. 

 i/itermedia. 



Var. intermedia Knapp. — Usually rounder than the type. 

 Tenby. 



Var. depressa Penn. — In a few cases this is beautifully rayed 

 inside. 



A monstrous specimen of the last variety from Guernsey has the 

 whole of the crown filled in with a pearly deposit, and it is difficult to 

 realise how the animal accommodated itself inside the shell. Another 

 monstrous form of the type from Torbay is circular and almost fiat, 

 like a penny-piece ; it was empty, but its tenant could not have 

 resembled the normal type. A uniform pale yellow variety inhabits 

 caves at Sark. 



Helcion pellucidum L. — Specimens as large as Jeffreys' figures 

 and dimensions are not often met with. The fry swarm in sea-weeds 

 in March, April, and May ; they have a spiral apex, similar to that of 

 Patella. A form from Eigg Island, in the Hebrides, is whitish, semi- 

 transparent, and exceedingly thin. 



Var. elongata Jeffr. — Killala Bay (Miss Warren) ! Sutherland- 

 shire (Baillie) ! Bordeaux Harbour, Guernsey ; Borough Island and 

 Torbay, S. Devon. The young of this are remarkably elongated. 



Tectura Aud. M.E. — It is not easy to decide between the con- 

 flicting claims of Tectura and Acincea for precedence. Technically, it 

 should be Acm ea Eschscholtz, but morally it should be Tectura Aud. 

 M.E. Mr. W. H. Dall 1 on the one hand, and Dr. R. Boog 

 Watson' 2 on the other, have exhaustively stated and re-stated all the 



Amer. J. Conch., 1871, p. 37. 



' Challenger' Gasteropoda, p. 28—9. 



