RELATIONS OF THE GLACIAL FAUNA. 97 



1. Relation of the Scotch glacial fauna to the existing fauna of the Scotch waters. 



From the results of Mr. J. Gwyn Jeffrey's dredging expedition in the Hebrides^ it 

 may be concluded that — 



(1) The invertebrate fauna of the district is chiefly northern, and for certain 

 species peculiar to the Hebrides no locality has been recorded between that and the 

 Mediterranean. The fauna of the Hebrides must have obtained this characteristic 

 subsequently to the Glacial Epoch. 



(2) The Hebrides constitute the southern limits of many northern species, such as 

 Lima elliptica (not yet found fossil), Leda pygmcea (an abundant glacial fossil), Trochus 

 Groenlandicus (also abundant as a glacial fossil). 



Of the Mollusca catalogued from the Scotch glacial beds none are extinct species, but 

 some Arctic forms are absent from the neighbouring sea, while some species ranging within 

 the Arctic circle may be characterised as very common in glacial clays and very rare as 

 living specimens. 



Of the species of Ostracoda catalogued from the Post-tertiary beds — 

 18 are extinct, so far as at present known ; 



10 are distinctly boreal or Arctic, although living in British waters ; 

 and none of the remainder are of southern type. 



2. Relation of the Scotch glacial fauna to the glacial fauna of the north of Europe. 



Prof. Sars gives sixty-one species of Mollusca collected from twenty beds of the old 

 Glacial Epoch in Norway. Of these sixty-one species we have obtained forty-eight from 

 the glacial clays of Scotland. Moreover, the characteristic species of some of the 

 Norwegian clay beds are precisely identical with those of the Scotch beds. 



At Moss, e.g. on the Christiania Ffiord the prevailing shell is Leda Arctica, which is 

 also very characteristic of the Errol clay. 



The climate of south-west Norway was undoubtedly more extreme than at present 

 during the Glacial Epoch, and, so far as the evidence of the fauna reaches, the same severe 

 climate extended over Scotland. 



Of the forty-five fossil species of Ostracoda noted in the " Glacial and Post-glacial " 

 beds of Norway all, except eight, are fossil in the Scotch beds, and all, except one, are 

 living in British and Norwegian seas. 



'Annals and Magazine of Natural History,' 1866, 1867, 1868. 



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