THE ANCIENT MAMMALS Oy BRITAIN. 31 I 



determined, the Mammoth does not appear to have come 

 into existence at the period of the Forest-bed; but the so- 

 called Straight-tusked Elephant (^Elephas antiquus) was abun- 

 dant, as well as a third species (E. meridionalis), unknown 

 in the higher deposits. This southern Elephant, which takes 

 its name from its occurrence in the upper Pliocene strata of 

 the Val d'Arno, attained enormous dimensions, and is charac- 

 terised by the smallness of the height of the crowns of the 

 molar teeth in comparison with their width, as well as by the 

 large size and lozenge-like form of the discs of ivory enclosed 

 by the enamel-plates on their grinding surface, and the width 

 of the intervening spaces of cement. The enamel-plates them- 

 selves are very thick and smooth, being almost completely 

 devoid of the puckerings characterising those of the Mammoth. 

 Although anyone can see the difference between a typical 

 molar of the southern Elephant and one of the Mammoth, 

 some teeth of the former are very like certain of those of the 

 Straight-toothed Elephant, while some of the latter come very 

 close to those of the Mammoth. It is, therefore, advisable in 

 determining the teeth of fossil Elephants to seek the aid of a 

 specialist. It may be added that remains of the southern 

 Elephant have been met with in a remarkable deposit at Dew- 

 lish, in Dorsetshire, which must consequently be correlated 

 either with the Forest-bed or the upper Crags. 



Among the smaller Mammals we find the Rodents well re- 

 presented in the Forest-bed, some of the species still existing in 

 Britain, while others are now confined to the Continent, and a 

 few are extinct. In the former class we have the Squirrel, the 

 Wood-Mouse (Mus sylvaticus), and the Bank- Vole (Microhis 

 glareolus) ; and in the second the Beaver, the continental Field- 

 Vole {_M. arvalis), and the Siberian Vole (J/, gregalis) ; while 

 of the extinct forms the Giant Beaver ({Trogontherium cuvieri) 

 indicates a genus characteristic of this fortiiation ^nd the upper 



