chap, vi.] MAMMALIA OF THE OLD WORLD. 127 



ever, a few groups which seem to be late developments or recent 

 importations into the Palsearctic 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, Eleplias, 

 Arvicola, Trogontherium, Aretomys, Hystrix and Lepus ; but of 

 these Equus, Hippopotamus, Bos, and Eleplias 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, Felidse, Hyaenidae, Mustelidae, 

 Ursus, Equidae, Tapirus, Ehinocerotidae, Hippopotamidae, An- 

 thracotheridae (extinct), Sus, Camelopardidae, Tragulidae, Cervidae, 

 Bovidae, Elephantidse, and Edentata. 



Groups which go back to the Eocene period, are, Primates 

 allied to South American monkeys, as well as some of the 

 Lemuridse ; bats of the living genus Vespertilio ; Hyaenodon- 

 tidae, an ancestral form of Carnivore ; Viverridae ; Canidae (to the 

 Upper Eocene), and the ancestral Arctocyonidae to the Lower 

 Eocene ; Hyccnarctos, an ancestral type of bears and hyaenas ; 

 Anchitheridae, ancestral horses, to the Middle Eocene ; Palaeo- 

 theridae, comprising numerous generalised forms, ancestors of the 

 rhinoceros, horse, and tapir ; Suidae, with numerous generalised 

 forms, to the Middle Eocene ; Anoplotheridae and Xiphodontidae, 

 ancestral families of even-toed Ungulates, connecting the rumi- 

 nants with the swine ; and lastly, several groups of Eodents, 

 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 



