293 



I think we find an example of this in Cyprina islandica L. 

 In a short treatise ^) I have settled that this well-known bivalve 

 is a typical boreal form. The northern limit of its distri- 

 bution may be drawn from the upper "warm» area of the White- 

 Sea and the Murman-Coast north of Iceland to the ]\ew-Found- 

 land-Bank and the southern part of St. Lawrence-Bay. Dead 

 shells of Cyprina islandica have, however, several times been 

 taken at the southern West-Greenland (at the colony Jakobs- 

 havn and in the Davis-Strait) where the species does not live 

 at present. They originate thus from a warmer period of Green- 

 land's history. Unfortunately we do not know the beds in 

 which the shells have been deposited^). 



On the other hand we may point out the situation of some 

 layers in which shells occur of another bivalve from a warmer 

 period viz. Anomia ephippimn L. This bivalve is like the 

 preceding species a boreal form. At Europe it stops at the 

 Murman-Coast and at the »warm» area of the White-Sea. it 

 does not invade the eastern Murman-Sea which forms a part 

 of the Arctic-Sea's «cold» area and with regard to the fauna 

 is characterized by the fact that the boreal animal forms dis- 

 appear and are replaced by high-arctic ones^). On the America 

 side it is going a little further north than Cyprina islandica viz. 

 to the coast of Labrador, but it has never been taken living 

 at the Greenland coast. Fossil it has on the contrary been 

 taken in two places on Greenland's west-coast by J. A.D. Jensen. 



^) Ad. S.Jensen: Studier over nordiske Mollusker. II. Су2)ггпа islandica . 

 Vidensk. Medd. Naturhist. Foren. Kbhvn. 1902, p. 33. 



*) The shell of Isocardia cor previously mentioned by W. C. Brögger 

 and by myself (1. с 1902, p. 41) was recorded to have been taken by 

 the Swedish Expedition of 1871 in the Davis-Strait. However, having 

 visited the Riks-Museum in Stockholm 1 have arrived at the conclusion 

 that it ought not to be taken into consideration, as an error in label 

 possibly has taken place. 



^) N. Knipowitsch: Zur Kenntniss der geologischen Geschichte der Fauna 

 des Weissen und des Murman-Meeres; Verhandl. Kais. Russ. Mineralog. 

 Gesellsch. St. Petersburg, Bd. XXVIII, No. 1, 1900. 



