The geographical distribution of animals, with a study of the relations ...

;chap, vi.] MAMMALIA OF THE OLD WORLD. 127ever, a few groups which seem to be late developments or recentimportations into the Palaearctic region, as they occur only inPost-Pliocene deposits. The most important of these are thebadger, glutton, elk, reindeer, chamois, goat, and sheep, whichonly 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 inhabitedsome part of Central Asia in the Upper Miocene period, beingfound in the Siwalik beds. The only exclusively Pliocenegenera in Europe are Ursus, Equits, Hippopotamus, Bos,Elephas,Arvicola, Trogontherium, Arctomys, Hystrix and Lepus ; but ofthese Equus, Hippopotamus, Bos, and Elephas are found in theMiocene deposits of India. Owing, no doubt, in part to thesuperior productiveness of the various Miocene beds, largenumbers of groups appear to have their origin or earliest appearancehere. Such are Insectivora, Felidae, Hyaenidae, Mustelidae,Ursus, Equidae, Tapirus, Ehinocerotidae, Hippopotamidae, Anthracotheridae(extinct), Sus, Camelopardidae, Tragulidae, Cervidae,Bovidse, Elephantidae, and Edentata.Groups which go back to the Eocene period, are, Primatesallied to South American monkeys, as well as some of theLernuridae ; bats of the living genus Vespertilio ; Hyaenodontida?,an ancestral form of Carnivore ; Viverridae ; Canidae (to theUpper Eocene), and the ancestral Arctocyonidae to the LowerEocene ; Hijamarctos, an ancestral type of bears and hyaenasAnchitheridae, ancestral horses, to the Middle Eocene ; Palaeotheridae,comprising numerous generalised forms, ancestors of therhinoceros, horse, and tapir ; Suidoe, with numerous generalisedforms, to the Middle Eocene ;Anoplotheridae and Xiphodontidae,ancestral families of even-toed Ungulates, connecting the ruminantswith the swine ; and lastly, several groups of Eodents,and a Marsupial, in the Upper Eocene. We thus find allthe great types of Mammalia well developed in the earliestportion of the tertiary period ; and the occurrence of Quadrumana, of the highly specialized bats {Vespertilio), of variousforms of Carnivora, and ofUngulates, clearly differentiated intothe odd and even-toed series, associated with such lower forms a&