OF NORFOLK AND SUFFOLK. 3*25 



of the identifications then made by M. Deshayes of crag shells 

 with recent species, were erroneous, it was still unavoidable 

 that he should estimate the per-centage for 111 crag shells, 

 gathered indiscriminately from the Norfolk and Suffolk crag, 

 much higher than we now find to hold good in the case of 

 the red or coralline crag taken separately. Secondly, I re- 

 jected the idea of the Touraine beds being contemporaneous 

 with the crag, because I had ascertained that the fossils were 

 almost entirely of distinct species, although the two regions 

 are not 300 miles distant the one from the other. M. Des- 

 hayes also pronounced the testaceous Fauna of the crag to 

 have a very northern aspect, and that of Touraine an almost 

 tropical character : and yet the crag lies in the 52nd, while 

 the faluns are in the 48th degree of latitude. I stated in the 

 first edition of the 'Principles of Geology' (1830), that so 

 great a discordance in the species of Testacea inhabiting two 

 contiguous seas could not be paralleled in the present state 

 of the globe, except where some rare combination of circum- 

 stances occurs, like that on the opposite sides of the Isthmus 

 of Suez, where the Red Sea and the Mediterranean are sepa- 

 rated by a tract of land, connected on the one side with Asia 

 and on the other with the whole of Africa. There are not 

 even 10 per cent of the species of Touraine fossil shells iden- 

 tical with shells of the crag, as Mr. Searles Wood has deter- 

 mined after examining for me a collection of about 240 shells 

 which I obtained, in 1837, from M. Dujardin, the same col- 

 lection from which the figures and descriptions were taken for 

 M. Dujardin's paper on the faluns, in the Transactions of the 

 Geological Society of France. Mr. George Sowerby has also 

 assisted me in the careful examination of the whole of these 

 Touraine shells, and we have come to the conclusion that the 

 recent species are in the proportion of 26 per cent. 



I am now therefore disposed to come round to the opinion 

 of M. Desnoyers, that the red and coralline crag may corre- 

 spond in age generally with the faluns of Touraine ; for al- 

 though the assemblage of fossils in the one has an extremely 

 northern, and that of the other a southern and sub-tropical 

 character, yet they seem to depart almost equally, though in 

 opposite directions, from the type of the nearest existing 

 marine Fauna. In the red crag we observe a large develop- 

 ment of Cyprina, Astarte, and Glycimeris, and of those sec- 

 tions of Fusus, Buccinum, Purpura, and Trochus which are 

 now common in the British or Arctic seas, together with the 

 total absence of even the smallest cones and olives, as well 

 as cowries, except those of diminutive size. In the coralline 

 crag many of the same forms occur, with other genera which 



