36 1 PALEONTOLOGY 



willows, etc.; and during the short sunimer they probably 

 migrated northward, like their contemporary the musk-buffalo 

 which still lingers on, to the 70th degree of N. latitude, re- 

 treating during the winter to more temperate quarters. The 

 mammoth was preceded in Europe by other species of ele- 

 phant — e.g., Elephas priseus, Goldfuss, and Elephas meridionalis, 

 Nesti, which, during the pliocene period, seem not to have 

 gone northward beyond temperate latitudes. 



Genus Hippopotamus, L. — The discovery, in lacustrine and 

 fluviatile deposits of Europe, of the remains of an amphibious 

 genus of Mammal now restricted to African rivers, gives scope 

 for speculating on the nature of the land which, uniting Eng- 

 land with the Continent, was excavated by lakes and inter- 

 sected by rivers, with a somewhat warmer temperature than 

 at present, to judge by a few S. European shells which occur 

 in the fresh-water formations — e.g., at Grays, Essex, where 

 remains of the large extinct Hippopotamus major have been 

 found. The specimen of the lower jaw (fig. 121) was dis- 

 covered in similar deposits on the Norfolk coasts. Other 

 localities are specified in the writer's " History of British Fossil 

 Mammals." 



The first premolar has a simple subcompressed conical 

 crown, and a single root ; it rises early, and at some distance 

 in advance of the second premolar, and is soon shed ; the 

 other premolars form a continuous series with the true molars 

 in the existing species, but in the Hippopotamus major the 

 second premolar is in advance of the third by an interval 

 equal to its own breadth. This and the fourth premolar re- 

 tain the simple conical form, but with increased size, and 

 are impressed by one or two longitudinal grooves on the outer 

 surface, which, when the crown is much worn, give a lobate 

 character to the grinding surface. The true molars are pri- 

 marily divided into two lobes or cones by a wide transverse 

 valley, and each lobe is subdivided by a narrow antero-pos- 



