CHAP. VI. ] MAMMALIA OF THE OLD WORLD. 127 
ever, a few groups which seem to be late developments or recent 
importations into the Palearctic region, as they occur only in 
Post-Pliocene deposits. The most important of these are the 
badger, glutton, elk, reindeer, chamois, goat, and sheep, which 
only occur in caves and other deposits of Post-Pliocene age. 
Camels only occur in the Post-Pliocene of Siberia (Merycotherium), 
although a true Camelus of large size appears to have inhabited 
some part of Central Asia in the Upper Miocene period, being 
found in the Siwalik beds. The only exclusively Pliocene 
genera in Europe are Ursus, Equus, Hippopotamus, Bos, Elephas, 
Arvicola, Trogontherium, Arctomys, Hystriz and Lepus ; but of 
these Equus, Hippopotamus, Bos, and Elephas are found in the 
Miocene deposits of India. Owing, no doubt, in part to the 
superior productiveness of the various Miocene beds, large 
numbers of groups appear to have their origin or earliest appear- 
ance here. Such are Insectivora, Felide, Hyznide, Mustelide, 
Ursus, Equide, Tapirus, Rhinocerotide, Hippopotamide, An- 
thracotheridz (extinct), Sus, Camelopardide, Tragulide, Cervide, 
Bovide, Elephantide, and Edentata. 
Groups which go back to the Eocene period, are, Primates 
allied to South American monkeys, as well as some of the 
Lemuride ; bats of the living genus Vespertilio ; Hyzenodon- 
tide, an ancestral form of Carnivore; Viverride ; Canide (to the 
Upper Eocene), and the ancestral Arctocyonide to the Lower 
Eocene; Hycnarctos, an ancestral type of bears and hyznas; 
Anchitheridz, ancestral horses, to the Middle Eocene; Paleo- 
theridz, comprising numerous generalised forms, ancestors of the 
rhinoceros, horse, and tapir; Suid, with numerous generalised 
forms, to the Middle Eocene; Anoplotheridz and Xiphodontide, 
ancestral families of even-toed Ungulates, connecting the rumi- 
nants with the swine; and lastly, several groups of Rodents, 
and a Marsupial, in the Upper Eocene. We thus find all 
the great types of Mammalia well developed in the earliest 
portion of the tertiary period; and the occurrence of Quadru- 
mana, of the highly specialized bats (Vespertilio), of various 
forms of Carnivora, and of Ungulates, clearly differentiated into 
the odd and even-toed series, associated with such lower forms as 
