324 RELATIVE AGES OF THE CRAG 



been levelled, and a wall erected next the sea." I am indebt- 

 ed to the liberality of this gentleman for having, in immediate 

 compliance with my request, forwarded to me a set of shells 

 which he obtained from these beds, that they might be exa- 

 mined and compared with the collections of fossil and recent 

 shells in London. They consist of about 35 species, after 

 omitting certain specimens of Balanus, Pecten, Cardium, and 

 Astarte, too imperfect to be determined. Of these 35 no less 

 than 20 are identical with living species, being to the recent 

 in the proportion of nearly 60 per cent., a per-centage coin- 

 ciding remarkably with that previously obtained from the 

 Norwich crag. No less than 26 moreover of the 35 are iden- 

 tical with species already obtained from the Norwich crag, 

 which, when we consider that the latter has only yielded as 

 yet about 100 marine shells, affords sufficient ground for re- 

 ferring the Yorkshire and Norwich deposits to one and the 

 same period. Some species, moreover, such as the Nucula 

 Cobboldiw, so characteristic of the Norwich beds, were found 

 very abundantly by Mr. Bean near Bridlington. Of the nine 

 species not as yet known in the Norwich crag, five are recent, 

 and the other four appear to differ from any previously known 

 shells, whether fossil or recent. They belong to the genera 

 Astarte, Turritella, Natica, and Margarita, and, like one or 

 two extinct shells near Norwich, they may perhaps prove pe- 

 culiar to the British pleiocene strata. I have received no in- 

 formation at present, either of mammalian remains or of land 

 and freshwater shells, in this Yorkshire portion of the Nor- 

 wich crag. 



Contemporaneous Origin of the Suffolk Crag and the Fa- 

 luns of Touraine. — There is one more subject only to which 

 I shail allude before concluding. When M. Desnoyers first 

 explored the faluns of Touraine and the crag of England, of 

 which he published an account in 1825, 1 after visiting Aid- 

 borough, among other places, and inspecting the coralline 

 crag of that neighbourhood, he ascribed a contemporaneous 

 origin to the Suffolk crag and the French faluns. I was then 

 unwilling to embrace this opinion, for various reasons. In 

 the first place I imagined that the per-centage of recent spe- 

 cies, in all parts of the English crag, was much larger than 

 that of the Touraine beds ; for the shells which I was enabled 

 to submit to the examination of M. Deshayes in 1829, were 

 chiefly derived either from the Norwich beds or the red crag, 

 comparatively small progress having then been made in col- 

 lecting the fossils of the coralline crag. Admitting that some 



1 Mem. de la Soc. d' Hist. Nat. tome ii. p. 238. 



