INTRODUCTION. XXXV 



of a former rich series of British Mammalia to its present 

 scanty proportion, has been caused by human agency ; and 

 we may reasonably conjecture that the rest of the great 

 change has been the consequence of a series of gradual 

 and consecutive dyings-out of species ; since certain con- 

 ditions of the pliocene and post-pliocene Mammalia are 

 irreconcilable with the hypothesis that they all simulta- 

 neously perished by a sudden and violent catastrophe, like 

 that which Cuvier deduced from the phenomenon of the 

 frozen Mammoth."' Evidence will be given in the present 

 work in proof, that the Elephants and Rhinoceroses of 

 pliocene Britain, were adapted to live in a northern or 

 temperate climate ; and since the Hippopotamus, their con- 

 temporary and associate, was a different species from the 

 present African one, it might also have been able to exist 

 beneath a less sultry sky than that of Africa. 



Thus, in the endeavour to trace the origin of our ex- 

 isting Mammalia, I have been led by the researches de- 

 tailed in the present work, to view them as descendants 

 of a fraction of a peculiar and extensive Mammalian Fauna 

 which overspread Europe and Asia at a period geolo- 

 gically recent, yet incalculably remote and long anterior 

 to any evidence or record of the human race. It would 

 appear, indeed, from the comparisons which the present 

 state of Palaeontology permits to be instituted between the 

 recent and extinct Mammalian Faunae of other great natu- 

 ral divisions of the dry land, that these divisions also seve- 

 rally possessed a series of Mammalia, as distinct and peculiar 

 in each, during the pliocene period, as at the present day.-f - 



When such a comparison is restricted to the Fauna of 

 a limited locality, especially an insular one like Great 



* See the interpretation of that striking fact in pp. 261, 270. 

 t See ' Report of the British Association,' 8vo. 1844, p. 237. 



c 2 



