HELIX HORTENSIS. 17 



Disfribidion. — Uecent : generally and abundantly diffused in the British Isles ; 

 on the Continent from Scandinavia to the south of Europe ; Iceland, Greenland, 

 Labrador, Newfoundland, Maine and Massachusetts. 



Fossil: Butleyan Crag : Butley. Pleistocene: Torquay, Ightham 

 (Kent), Grays, Ilford, Copford, Clacton, Stutton, Dog Holes Cavern near Carnforth, 

 and elsewhere. 



Various Lower Pleistocene localities in Savoy, Seine et Marne, and the Alpes 

 Maritimes. Middle Pleistocene : Saxony, Thuringia, and Silesia ; St. Gall in 

 Switzerland. Upper Pleistocene : Silesia, Bavaria (J. W. Taylor), Recorded also 

 by Dr. Dall from the Champlain clays of Portland on the coast of Maine. 



Rcmar/i-s. — Helix liortensis was regarded from the time of Linne to that of 

 Jeffreys as a variety of H. nemorali.<t, but is now considered distinct ; as to this, 

 J. ^Y. Taylor observes : " Its specific status is firmly established by the differences 

 in its organisation." 



The specimen here figured is from the Canham collection in the Ipswich 

 Museum, the box which contains it bearing the inscription, " Helix hortensis, R. G. 

 B "(ell). The upper whorls are somewhat less convex and the suture not so 

 clearly defined as is usually the case with that species ; in some respects it 

 resembles a small form of H. arhvstorum, but it does not show any trace of the 

 spiral striation characteristic of that species, and the mouth has the flattened 

 basal lip of H. liortensis. 



In a map accompanying the paper named above, Dr. Scharff points out that 

 the present distribution of H. hortensis is practically continuous from the British 

 Isles through the Faroes, Iceland, Greenland and Labrador, with Newfoundland 

 and the coast of Maine, being found also in some small islands to which he thinks 

 it could not have been introduced by man, remarking that it presents the most 

 striking piece of evidence we possess in favour of the theory of a pre-glacial 

 land connection between north-western Europe and north-eastern America. If 

 R. G. Bell's reference of the Crag specimen to H. liortensis is correct it seems 

 confirmatory of this view ; such a connection must have been established, moreover, 

 at a time when the polar regions were less encumbered with ice than they were 

 during the glacial period. It has long been known that many species of marine 

 mollusca are now common to both sides of the Atlantic. We shall find as we 

 proceed that there is a considerable amount of correspondence between the 

 Pliocene fauna of Iceland and that of the Crag basin, and that there are shells in 

 the Crag which cannot be distinguished from those said to be living now only on 

 the banks of Newfoundland, or even further west from the latter, in Behring Sea. 



Gould states that he imported a hundred specimens of H. liortensis into North 

 America from England in 1857, and that they increased very rapidly. He 

 does not think, however, that this species was originally introduced from Europe. 



