558 HISTORICAL PALEONTOLOGY. 



shells belong to existing species. The Post-Tertiary deposits 

 are divided by Sir Charles Lyell into Post-Pliocene, in which 

 the shells belong entirely to existing species, but some of the 

 Mammals are extinct; and the Recent, in which the shells and 

 the Mammals alike belong to existing species. 



The Recent deposits do not properly concern the Palaeonto- 

 logist, but the Zoologist, since they contain the remains of none 

 but existing animals. The Post-Pliocene deposits, on the 

 other hand, contain the remains of various extinct Mammals, 

 and therefore properly form part of the domain of the palaeon- 

 tologist. The deposits of the Post-Pliocene period may be 

 divided into those which preceded the Glacial period, those 

 which were formed during the Glacial epoch, and those which 

 are Post-Glacial. 



I. PRE-GLACIAL DEPOSITS. The chief pre-glacial deposit of 

 Britain is found on the Norfolk coast, reposing upon the Newer 

 Pliocene (Norwich Crag), and consists of an ancient land-sur- 

 face which is known as the " Cromer Forest-bed." 



This consists of an ancient soil, having embedded in it the 

 stumps of many trees, still in an erect position, with remains 

 of living plants, and the bones of recent and extinct quadru- 

 peds. It is overlaid by fresh-water and marine beds, all the 

 shells of which belong to existing species, and it is finally sur- 

 mounted by true "glacial drift." While all the shells and 

 plants of the Cromer Forest-bed and its associated strata belong 

 to existing species, the Mammals are partly living, partly ex- 

 tinct. Thus, we find the existing Wolf, Bison, Reindeer, 

 Beaver, Walrus, &c., side by side with three extinct Elephants, 

 the Rhinoceros, and Hippopotamus, and a gigantic extinct 

 Beaver. Among the Elephants are two Pliocene species, viz., 

 Elephas meridionalis and Elephas antiquus. The third species 

 is the Mammoth (Elephas primigenius), which has not as yet 

 been detected in strata of Pliocene age. The following list is 

 given by Mr Boyd Dawkins as comprising the most important 

 Mammals as yet known in the " Forest-bed : "- 



LIST OF PRE-GLACIAL MAMMALS. 



Ursus Arvfrnensis. 



Ursus speltrus (? Elruscus). 



Sorex. 



Mygale mosehata, 



Talpa Europaa. 



C trims megaceros ? 



Cervus capreolus. 



Cenms elaphus. 



Cervus Sedgwickii. 



Cervus ardcus. 



Bos primigenius. 

 Hippopotamus major. 

 Eauus fossilis. 

 Rhinoceros megarhinus. 

 Rhinoceros Etruscus. 

 Elephas antiquus. 

 Elephas meridionalis. 

 Arvicola amphibia. 

 Castor fiber. 

 Trogontherium Cuvieri. 



