322 HISTORICAL PALAZSONTOLOGY. 
general characters, possess molar teeth which have their crowns 
furnished with conical eminences or tubercles placed in pairs 
(fig. 247, B), instead of having the approximately flat surface 
characteristic of the grinders of the Elephants. As in the 
latter, there are two upper incisor teeth, which grow perma- 
nently during the life of the animal, and which constitute great 
tusks ; but the Mastodons, in addition, often possess two lower 
incisors, which in some cases likewise grow into small tusks. 
Three species of Jastodon are known to occur in the Upper 
Miocene of the Siwalik Hills of India; and the Miocene de- 
posits of the European area have yielded the remains of four 
species, of which the best known are the JZ. dongirostris and the 
M. angustidens. 
Whilst herbivorous Quadrupeds, as we have seen, were 
extremely abundant during Miocene times, and often attained 
gigantic dimensions, Beasts of Prey (Carnivora) were by no 
means wanting, most of the principal existing families of the 
order being represented in deposits of this age. Thus, we find 
aquatic Carnivores belonging to both the living groups of the 
Seals and Walruses ; true Bears are wanting, but their place 
is filled by the closely-allied genus Amphicyon, of which various 
species are known; Weasels and Otters were not unknown, 
and the Ayenictis and ILctitherium of the Upper Miocene of 
Greece are apparently intermediate between the Civet-cats and 
the Hyzenas ; whilst the great Cats of subsequent periods are 
more than adequately represented by the huge “‘ Sabre-toothed 
Tiger ” (AZachazrodus), with its immense trenchant and serrated 
canine teeth. : 
Amongst the Rodent Mammals, the Miocene rocks have 
yielded remains of Rabbits, Porcupines (such as the AZystrix 
primigenius of Greece), Beavers, Mice, Jerboas, Squirrels, and 
Marmots. All the principal living groups of this order were 
therefore differentiated in Middle Tertiary times. 
The Cheiroptera are represented by small insect-eating Bats; 
and the order of the Insectivorous Mammals is represented by 
Moles, Shrew-mice, and Hedgehogs. 
Lastly, the Monkeys (Quadrumana) appear to have existed 
during the Miocene period under a variety of forms, remains 
of these animals having been found both in Europe and in 
India ; but no member of this order has as yet been detected 
in the Miocene Tertiary of the North American continent. 
Amongst the Old World Monkeys of the Miocene, the two 
most interesting are the Pliopithecus and Dryopithecus of France. 
The former of these (fig. 248) is supposed to have been most 
nearly related to the living Semmnopitheci of Southern Asia, in 
