468 PREHISTORIC EUROPE. 



attention to the occurrence in the postglacial beds of Tapes 

 decussatus [Venus], Linn., a mollusc which, he says, does not 

 now^ occur on the Norwegian coast, but is distributed from 

 the Mediterranean to England. In the postglacial deposits the 

 shells of this species are as large as those of the largest living 

 specimens in the Mediterranean. Quite recently, however, this 

 mollusc has been found by G. 0. Sars living on the west coast 

 at Bergen. Another species (Pholas Candida, Linn.) mentioned 

 by Michael Sars as having now apparently retired south from 

 the Norwegian coast has since been met with by Loven. 

 Jeffreys says it ranges from Iceland and Norway to Algeria, 

 Sicily, and the Black Sea. Many of the shells, indeed, which 

 are most abundant in the postglacial deposits of Sweden and 

 Norway, where they occur commingled with arctic and boreal 

 species, are, as Jeffreys remarks, 1 of rather a southern type. 

 Such are Ostrea edidis, Tapes pullastra, Corbula gibba, Aporrhais 

 pes-pelicani, and some already mentioned. And, according to 

 Michael Sars, the mollusca of the Norwegian postglacial beds 

 comprise 175 species, of which 75 are arctic, 59 boreal, and 41 

 Lusitanian-Mediterranean. The same naturalist has also pointed 

 out that perfectly-identical species are found living in the North 

 Sea and the Mediterranean, although they have not been met 

 with upon the intervening coasts of the Atlantic. 2 From these 

 facts he has inferred that some communication between the 

 North Sea and the Mediterranean must have existed across the 

 low grounds of Europe at a comparatively recent geological date. 

 But, as we shall afterwards see, the facts admit of another and 

 more probable explanation. 



The postglacial clays which occur in the east of Sweden 

 present a strong contrast to those of Western Sweden and 



by Sars and Kjerulf, Universitets-program for 1860, L, and "Om de i Norge fore- 

 kommende fossile Dyrelevningar fra Qvartser Perioden," etc., by M. Sars, Uni- 

 versitets-program, 1864, I. A translation of the first of these papers will be found 

 in Edinburgh New Philosophical Journal, vol. xviii., New series, p. 1. 



1 British Association Reports, 1863, p. 74. 



2 Sars mentions Nephrons norvegicus, L. ; Lota abyssorum, Nilss. ; Sebastes 

 imperialis, Cuv. ; Macrourus (Lepidoleprus) ccelorhynchus, Cerithium vulgatum, 

 Brug. ; and Monodonta limbata, Phil. 



