60 



itkmjAL OF THE MOLLUSCA. 



II. Boreal Province. 



The Boreal Province extends across the Atlantic from Nova 

 Scotia and Massachusetts to Iceland, the Faeroe and Shetland 

 Islands, and along the coast of Norway from North Cape to the 

 Naze. 



Of the 289 Scandinavian shells catalogued by Dr. Loven,* 

 217, or 75 per cent, are common to Britain, and 137 range as 

 far as the North coast of Spain. 



The boreal shells of America are described by Dr. Gould, f 

 From these lists it appears that out of 270 sea-shells found on 

 the coast of Massachusetts north of Cape Cod, more than half 

 are common to Northern Europe. 



Many of the species, it is believed, could only have extended 

 their range so distantly by means of continuous lines of con- 

 necting coast, now no longer in existence. J 



BOREAL SHELLS COMMON TO EUROPE AND NORTH AMERICA. 



* British Species. 



* Teredo navalis. 

 •Pholas crispata. 

 *Solen ensis. 

 *(Panop8ea) Norvegioa. 

 *Mya arenaria. 



* „ truncata. 



*Thracia phaseolina (Conradi, Couth). 



Mactra ponderosa (ovalis, G.) 

 ? Montacuta bidentata. 

 •Turtonia minuta. 

 P Kellia rubra. 



P Lepton nitidum (fabagella, Conr. ?) 

 *Saxicava rugosa (arctica). 



Tellina solidula, var. (fusca, Say). 



* „ calcarea (sordida, Couth). 



•Lucina borealis. 

 ? „ divaricata. 

 •Cryptodon flexuosus. 

 •Astarte borealis. 



* „ triangularis? (quadrans, G.) 

 *Cyprina Islandica. 



? (Cardium Islandicum, U.S.— N. Zemla). 

 Yoldia limatula. 

 „ arctica, Gr. (= myalis). 

 •Leda pj'gmeea. 



* „ caudata. 



? „ navicularis (luoida, Loven?) 

 •Nucula tenuis. 

 •Mytilus edulis. 

 *Modiola modiolus. 



* Index Molluscorum Scandiiiaviae ; extracted from the " Ofversigt af K. Vet. 

 Akad. Forh." 1846. The climate of Finmark is much less severe than Rassian Lap- 

 land ; Hammerfest has an open harbour all the year. 



t Report on the Invertebrata of Massachusetts. 1841. 



X Forbes, Memoirs of the Geol. Siu-vey, i. p. 379. Sir John Richardson, when 

 speaking of the cod-tribe and turbot-tribe, says:— "Most of the fish of this order feed 

 on or near the bottom, and a very considerable number of the species are common to 

 both sides of the Atlantic, particularly in the higher latitudes, where they abouud. It 

 does not appear that their general diffusion ought to be attributed to migration from 

 their native haunts, but rather that in this respect they are analogous to the owla, 

 which, though mostly stationary birds, yet include a greater proportion of species 

 common to the old and new worlds than even the most migratory families. Several of 

 the ScnmberoideeE (Mackerel-tribe) which feed on the surface, have been previously 

 noted as traversing many degrees of longitude in tlie Atlantic : but the existence of 

 the ground-feeding Gadoide^ in very distant localities must be attributed to a different 

 cause, a« it is not probable that any of tliem wander out of soundings or ever approach 

 the mid-seas."— Report Zool. N. America, p. 218. 



