Cn. XIIL] ANTWERP CRAG. 207 



stated in the table, there are 11 Northern species all common to the 

 Norwich Crag, in which last we have also 4 additional inhabitants of 

 the Arctic regions ; so that there is good evidence of a continual re- 

 frigeration of climate during the Pliocene period in Britain. The 

 presence of these Northern shells cannot be explained away by suppos- 

 ing that they were inhabitants of the deep parts of the sea ; for some 

 of them, such as Tellina calcarea (=T. obliqua) and Astarte borealis, 

 occur plentifully, and sometimes with the valves united by their liga- 

 ment, in company with other littoral shells, such as My a arenaria and 

 Littorina rudis, and evidently not thrown up from deep water. Yet 

 the Northern character of the Norwich Crag is not fully shown by 

 simply saying that it contains 12 Northern species. It is the pre- 

 dominance of certain genera and species, such as Rhynchonella psittacea, 

 Tellina calcarea, Astarte borealis, Scalaria groenlandica and Fusus 

 carinatus which satisfies the mind of a conchologist as to the Arctic 

 character of the Norwich Crag. In like manner, it is the presence of 

 such genera as Pyrula, Columbeila, Terebra, Cassidaria, Pholadomya, 

 Lingula, Discina, and others, which give a southern aspect to the 

 Coralline Crag shells. 



The cold, which had gone on increasing from the time of the Cor- 

 alline to that of the Norwich Crag, continued, though not perhaps 

 without some oscillations of temperature, to become more and more 

 severe after the accumulation of the latter, until it reached its maxi- 

 mum in what has been called the glacial epoch. The marine fauna of 

 this last period contains, both in Ireland and Scotland, recent species 

 of mollusca now living in Greenland and other seas far north of the 

 areas where we find their remains in a fossil state. 



Antwerp Crag. — Strata of the same age as the Red and Coralline 

 Crag of Suffolk have been long known in the country round Antwerp 

 and on the banks of the Scheldt, below that city. More than 200 spe- 

 cies of testacea had been collected by MM. De Wael, Nyst, and others, 

 when I visited Antwerp in 1851, of which two-thirds were indentified 

 with Suffolk fossils by Mr. Wood. Among these he recognized Lin- 

 gula' Bumortieri of Nyst (fig. 160), which I found in. abundance in 

 what was called by M. de Wael the Middle Crag. More than half of 

 the shells of this Antwerp deposit agree with 

 living species, and these belong in great part to 

 the fauna of our Northern seas, though some 

 Mediterranean species appear among them. I 

 also met with numerous cetacean bones of the 

 genera BalcenopAera and Ziphius in the Upper 

 Antwerp Crag. They are not roUed, as if 

 washed out of older beds, and I infer that the L™g^a Dum^tieH,^ 



1 m Antwerp and Suffolk Crag. 



animals to which they belong once coexisted in 

 the same sea with the associated fossil mollusca.* 



* Lyell cn Belgian Tertiaries, Quart. Journ. Geol. Soc, 1852, p. 282. 



