SUPPLEMENT. 



BRITISH PLIOCENE STRATA. 



British Pliocene Strata — Proofs from fossil shells of a gradual refrigeration of 

 climate in England, at the successive periods of the Coralline, the Eed, and 

 the Norwich Crag — Searles Wood's Monograph on the Crag Mollusca. The 

 Crag Mastodon, a Pliocene species — Different assemblages of fossil Mammalia 

 in the freshwater and drift deposits of the Valley of the Thames — Fossil 

 Musk-buffalo in the drift near London and near Berlin. 



Since the appearance of the fifth edition of this work, Mr. Searles 

 Wood has brought to a conclusion his important Monograph on the 

 Crag and Upper Tertiary shells of Britain.* The results of his con- 

 scientious examination of so many hundred species of testacea, in so 

 far as they bear on Geology, will be found to agree with the classifica- 

 tion adopted in the text (pp. 152 — 165, &c), especially as relates to 

 the position of the several divisions of the Crag in the great European 

 series of formations. But we may also deduce from the same Mono- 

 graph clear evidence of a gradual refrigeration of climate, which went 

 on in the area of England from the time of the older to that of the most 

 modern Pliocene strata, a refrigeration which was inferred from the 

 Crag shells in 1846, by the late Edward Forbes.f No analysis of this 

 excellent treatise has been drawn up for us by Mr. Wood himself: we 

 have therefore inserted the following tables, to point out many general 

 conclusions to which the conchological data seem to lead. In drawing 

 them up I have had the able assistance of Mr. S. P. Woodward, the 

 well-known author of the "Manual of the Mollusca, Recent and 

 Fossil."! 



Number of known Species of Marine Testacea in the three English 

 Pliocene Deposits, called the Norwich, the Bed, and the Coralline 



Crags. 



Brachiopoda 6 



Conchifera - - - - 206 



Gasteropoda .... 230 



Total- - - - 442 



* Paleontographical Society, 1848 to 1856. 



f Mem. of Geol. Survey, London, 1846, p. 391. 



% London: 1853-6. 



