PURPURA. 283 



quently a succession of tubercular rows^ forming internal 

 varices. None of the specimens which I have seen 

 from Canada and the United States are as large as ours ; 

 and I am consequently disposed to take a view opposite 

 to that which Forbes suggested^ viz. that this species is 

 of American origin^ and was introduced to the European 

 shores during the glacial epoch. The common character 

 of the fossils of that period in both continents shows 

 that a close connexion by continuity then existed 

 throughout the circumpolar area ; and there is no evi- 

 dence that any migration took place from one continent 

 to the other. We must go back to the antecedent epoch 

 in order to trace the origin of this species ; and we there 

 find that it occurs for the first time in the Red Crag of 

 Suff'olk. It is remarkable how the numerous varieties 

 figured by Mr. S carles Wood from that formation cor- 

 respond with those of the adjacent coast. 



The present species was named by Lister Purpur(js 

 anglicanm, or ^^ white couvins ; ^^ it is the Buccinum 

 Cornubiense of Petiver, " le sadot ''■' of Adanson, ^' the 

 purple-marking whelke " of Borlase^ B. piirpuro-bucci- 

 num of Da Costa/ jB. angUcum of Gmelin^ and B. angli- 

 canum of Lamarck ; the vulgar name in Ireland^ accord- 

 ing to Smith and Rutty^ is " horse winkles : '"' the fry 

 is probably B. breve and B. Iceve of Adamses papers in 

 the ' Linnean Transactions.-' The P. lapillus of Risso 

 is Buccinum hcBmastoma of Linne. This latter species 

 inhabits the North Atlantic, from Brest southwards to 

 the Azores (including the coast of Senegal) _, as well as 

 the Mediterranean and Archipelago -, Morch gives the 

 Brazils as a locality, in the sale catalogue of the Count de 

 Yoldi^s collection of shells. Between forty and fifty 

 years ago Mr. Charles Macculloch picked up tliree speci- 

 mens of this shell near St. Peter^s Port, Guernsey, at 



