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REV. THOMAS BROWN ON THE ARCTIC SHELL-CLAY 



Arctic seas, but they vary markedly with the degree of cold. Of this kind are 

 the Natica grasnlandica and the Saxicam rugosa. The Saxicava, for example, 

 is at home everywhere, from the Polar seas to the Canary Islands ; but under 

 an Arctic climate it thickens its shell, and attains a size quite unlike what it does 

 with us. 



To show how completely the specimens from this deposit are of the northern 

 type, I place side by side No. 1, the outline of the shell of the full present British 

 size, as given by Forbes and Hanley, and No. 2 and 3, the same shell, as found 

 in the Elie clay. 



Fig. 7. 



The evidence of the Arctic climate is here very marked. 



3. The third and by far the most numerous class consists of shells, which 

 require the climate of the Polar seas, and really can live nowhere else. 



The two marking and characteristic shells of the deposit are the Leda truncata 

 and the Pecten groenlandicus. Both reach their southern limits on the coast of 

 Norway. Both shells were found by Dr Torell living together in the clayey sea- 

 bottom, in front of the great glacier of Spitzbergen, just as they now lie together 

 in this Elie and Errol clay. Another point of importance is the comparative 

 abundance of this Leda. It is one of the most abundant shells now at Spitzbergen, 

 and it is beyond all comparison the most abundant shell in this deposit, holding 

 the same place that Tellina proxima does in the Clyde beds. The Tellina, on the 

 contrary, is rare at Elie and Errol. I obtained only two or three specimens. The 

 details as to the distribution of other species are not less decisive. 



Buccinium cyaneum is found in Greenland, &c. 



Turritella erosa. — Of this I got only one specimen, and it was not quite perfect. 

 Dr T. says of it, " Almost certainly the same species, yet cannot be positively 

 asserted." It lives in the seas of Greenland. 



Thracia myopsis. — Iceland, Greenland, Spitzbergen, in from 60 to 200 fathoms 

 water. 



Nucula inflata — Spitzbergen, 5 to 150 fathoms. 



Crenella laevigata. — At my first visit to Elie I got a few specimens, which Dr 



