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THE GEOGRAPHICAL DISTRIBUTION OF PURPURA LAPILLUS (L.). 

 PART I: IN PAL^ARCTIC WATERS. 



By the Eev. A. H. Cooke, M.A., Sc.D., F.Z.S. 



Read 13th November, 1914. 



It seems possible that investigation into the geographical distribution 

 of some of our common littoral species may produce results of 

 scientific value. The present paper on the distribution of Purpura 

 lapillus (L.) is offered as a first contribution towards this kind of 

 knowledge. 



One preliminary remark may be made. The facts of geographical 

 distribution may be established partly by positive, partly by negative 

 evidence. Negative evidence as to distribution, in the case of 

 a common species of wide extent, naturally operates at the extreme 

 termini of its range, north or south, east or west, as the case may be. 

 In the range of the species under investigation — and equally in the 

 case of all littoral species occurring on tlie west coasts of Europe — 

 negative evidence, by establishing the fact that it has not been found 

 north or south of certain points, will warrant the conclusion that the 

 northern and southern limits of its distribution have been at least 

 provisionally arrived at. 



No attempt has been made in this paper to deal with questions of 

 synonvmy, or to discuss the causes of variation. 



We begin with the far north, in North- West Siberia. P. lapillus 

 does not occur at the mouth of the Yenesei lliver, not having been 

 found there by the Russian expedition sent in 1866 to investigate the 

 corpse of a mammoth (Schmidt 107), or by Nordenskiold's Vega 

 Expedition of 1875-6 (Leche 65). It is not found in the Kara Sea 

 (Collin 17, PfefFer 98, Herzenstein 44, Dautzenberg & Fischer, 

 Voyage of the Belgica, 1907, 25, Voyages of the Hirondelle and 

 Princess Alice, 1898-1907, 27), nor did the Andrew Coats cruise of 

 1898 find it at Kolguev Island (Melvill & Standen 81). It does 

 not occur in Franz Josef's Land (Melvill & Standen 81, Jackson 

 Harmsworth Expedition of 1896-7). Frequent expeditions to 

 Spitzbergen have failed to detect it (Torell 117, Mtirch 87, McAndrew, 

 Phipps, & Leach 76, Jeffreys 54, Friele 37, Hjigg, Swedish Polar 

 Expedition of 1900, 41, Kraiise 61, Pfeffer 99), and Knipovitsch does 

 not include it in his exhaustive resume of the moUuscan fauna of the 

 island (58). Neither Friele (36), dealing with the Mollusca of the 

 Norwegian North Atlantic Expedition of 1877, nor Becher (9«), nor 

 Hiigg (41), record it from Jan Mayen Island. There appears to be no 

 record of collectors from Bear Island. 



The most northern occurrence of the species is in Novaya Zemlya, 

 where it was "captured at the shore of the Matotschin-shar " 

 (or Matthew Strait, which cuts the great island in two) by the 

 fVillem Bareiits Dutch Expedition of 1878-9 (van Lidth de Jeude67). 

 The specimens, which belonged to the var. imhricata, Lam., were 



