﻿s 



ME. E. B. NEWTOjST ON A FOSSILIFEROUS [vol. lxxii, 



similar molluscan fauna to that occurring in the Scottish deposits 

 has been found in the rocks of Iceland which Gwyn Jeffreys con- 

 sidered as Post-Tertiary and Searles Wood as ' not later than 

 Middle Red Crag.' * 



Reference may also be made to Jamieson's account of some 

 semi-fossil shells of Arctic character, dredged by Robert Dawson 

 from glacial beds underneath the sea, off the Aberdeenshire coast, 

 from 3 to 8 miles away from land, at a depth varying from 30 to 

 45 fathoms. Similar shells had even been brought up by fishermen's 

 lines at a distance of 30 miles from the coast, and none of the 

 species were thought to occur alive in that district. 3 Besides this, 

 we have Alfred Tylor's account 3 of fossil marine Arctic shells 

 dredged off the Shetland Islands by Gwyn Jeffreys in about 

 90 fathoms of water — the species being stated to occur fossil in 

 Sweden and still living in extreme Arctic seas. 



These records of fairly late fossiliferous deposits beneath the sea 

 are of great interest, but scarcely assist us in understanding the 

 history of the present rock. 



This North Sea limestone is of a dark-grejdsh colour, and is 

 built up almost entirely of shell-remains belonging chiefly to the 

 Pelecjrpoda. Microscopical tests have proved it to be highly 

 siliceous, thus accounting for its great hardness and tenacity, which 

 have frequently militated against complete development of some of 

 the organisms, especially when the attempt was made to expose in- 

 ternal characters ; otherwise, speaking generally, the fossils are well 

 preserved, and many of their liner external markings are perfectly 

 displayed. It has been possible to determine 23 different forms of 

 mollusca, ten being Gastropoda, while the remainder belong to the 

 Pelecypoda, a new species being included in that group. 



If the material had been more dismantled, some additional forms 

 might have been available for study, although in that case the 

 larger block would have diminished in value as a museum specimen. 



The shells are essentially of southern character, although it is 

 interesting to mention that one of the commonest forms is the 

 large Cyprina islandica, which is so well known as existing in 

 boreal seas and around our British coasts, but has never been 

 recorded from the Mediterranean : its origin, however, is to be 

 found in the Vindobonian stage of the Miocene Period. I have 

 mentioned this species incidentally, because it frequently occurs in 

 the Scottish and Icelandic deposits previously mentioned, which 

 I consider of much later age than the present limestone. 



Occasional small brown masses of wood}' structure 4 occur in 



1 Q. J. G. S. vol. xli (1885) p. 96. 



2 Ibid. vol. xxi (1865) p. 200. 



3 Ibid. vol. xxv (1869) p. 8. 



4 The occurrence of drift-wood in the Coralline Crag near Sudbourn Church 

 was mentioned by Clement Reid (• The Pliocene Deposits of Britain ' Mem. 

 Geol. Surv. 1890, p. 28) ; but, so far as can be ascertained, no such material 

 has been systematically described. 



