60 WZIANUAL OF THE MOLLUSCA. 
Il. BorREAL PROVINCE. 
The Boreal Province extends across the Atlantic from Nova 
Scotia and Massachusetts to Iceland, the Faeroe and Shetland 
Tslands, and along the coast of Norway from North Cape to the 
Naze. 
Of the 289 Scandinavian shells catalogued by Dr. Lovén,* 
917, 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. 
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 Hurope. 
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.{ 
BOREAL SHELLS COMMON TO EUROPE AND NORTH AMERICA. 
* British Species. 
*Teredo navalis. *Lucina borealis. 
*#Pholas crispata. ? ,, divaricata. 
*Solen ensis. * Cryptodon flexuosus. 
* (Panopzea) Norvegica. * Astarte borealis. 
*Mya arenaria. * ,,  triangularis? (quadrans, G.) 
* ,, truncata. * Cyprina Islandica. 
*Thracia phaseolina (Conradi, Couth). ? (Cardium Islandicum, U.S.—N. Zemla). 
Mactra ponderosa (ovalis, G.) Yoldia limatula. 
? Montacuta bidentata. » arctica, Gr. (= myalis). 
*Turtonia minuta. *Leda pygmea. 
? Kellia rubra. * ,, caudata. 
? Lepton nitidum (fabagella, Conr. ?) ? ,, mnavicularis (lucida, Lovén ?) 
*Saxicava rugosa (arctica). *Nucula tenuis. 
Tellina solidula, var. (fusca, Say). *Mytilus edulis. 
% ,,  calcarea (sordida, Couth). *Modiola modiolus. 
* Index Molluscorum Scandinavie; extracted from the ‘“‘ Ofversigt af K. Vet. 
Akad. Forh.” 1846. The climate of Finmark is much less severe than Russian Lap- 
land ; Hammerfest has an open harbour all the year. 
+ Report on the Invertebrata of Massachusetts. 1841. 
{ Forbes, Memoirs of the Geol. Survey, 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 abound. 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 owls, 
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 Scomberoidee (Mackerel-tribe) which feed on the surface, have been previously 
noted as traversing many degrees of longitude in the Atlantic: but the existence of 
the ground-feeding Gadoidee in very distant localities must be attributed to a different 
cause, as it is not probable that any of them wander out of soundings or ever approach 
the mid-seas,””—Report Zool, N, America, p, 218, 
