DISTRIBUTION OF ORDERS. 237 



6. Rodentia. Very widely distributed ; occurring in all the regions, but in Madagascar 

 and Australia only represented by Muridce. They attain their largest development in 

 S. America. 



The order is of great geological antiquity, for some living genera extend back to the 

 Eocene. Rodents probably originated in the Palsearctic region, whence migrations 

 took place at an early date to S. America and S. Africa, allowing time for great 

 specialization. 



7. Proboscidea. Elephants are now limited to the Ethiopian and Oriental regions, but 

 formerly had a much wider extension. 



Palaearctic forms occur from Miocene to Pleistocene times, and elephants have lived in 

 India since the Miocene period. Numerous fossil examples occur in the Pliocene and 

 Pleistocene deposits of N. and S. America. 



8. Hyracoidea. Almost entirely limited to the Ethiopian region, but range northwards 

 as far as Syria. 



9. Insectivora. Very widely distributed, and represented by numerous specialized 

 forms. Absent from S. America and Australia. 



This order is a very ancient one, as shown by the fact that Miocene forms mostly belong 

 to existing families. Extinction appears to be slowly taking place, and has led to many 

 cases of discontinuous distribution, e.g., the Centetidce, represented by Solenodon in the 

 W. Indies, and Centetes, with four other genera, in Madagascar. 



10. Cheiroptera. Bats, as might be expected, are found in all the great areas, but the 

 Frugivora are absent from the Nearctic and Neotropical regions, as are the Horse-shoe 

 bats (Rhinolophidce) among insectivorous forms. On the other hand, the Leaf-nosed bats 

 (Phyllostomidce) are almost exclusively Neotropical. 



Fossil bats, very like recent species, date from Eocene times, and the order is un- 

 doubtedly one of extreme antiquity. 



11. Carnivora.(a) Fissipedia. Occur in all the regions, except, perhaps, the 

 Australian (the "native dog "of Australia is only doubtfully indigenous), but are 

 especially characteristic of the Ethiopian and Oriental, which possess almost all the 

 Viverridce and Hycenidce, with a great many of the Felidce and Mustelidce. Two genera, 

 Cryptoprocta and Proteles, constituting distinct families, are limited respectively to 

 Ma'dagascar and S. Africa. Bears, however, are absent from the Ethiopian region, 

 and are only represented by one species in the Neotropical region, which is also very poor 

 in other Carnivora. The Procyonidce are small bear-like forms, found in the Nearctic 

 and Neotropical regions, and include the racoons (Procyon), coatis (Nasua), and 

 kinkajous (Cercoleptes). 



Fossil Carnivores date back to the Lower Eocene, but the recent families were not then dif- 

 ferentiated. The order appeai-s to have originated in the northern half of the Old World. 



(6) Pinnipedia. Seals are limited to cold and temperate seas, and are also found in the 

 Caspian, Sea of Aral, and Lake Baikal, all of which, at no very distant epoch, were con- 

 nected with the Arctic Ocean. 



Walruses characterise the North Polar regions. 



12. Prosimice. (a) Cheiromyini. Only one form, the aye-aye (Cheiromys) which is 

 restricted to Madagascar. 



(b) Lemurini. Practically limited to the Ethiopian and Oriental regions. Indris, 

 Lemur, and four other genera are only found in Madagascar. Tarsius constitutes a 

 distinct family, and is limited to Sumatra, Banca, Borneo, and Celebes. 



Lemurs date back to the Eocene in Europe. 



13. Primates. (a) Arctopitheci and (6) Platyrrhini are confined to the Neotropical 

 region. 



(c) Catarrhini are found only in the Old World. 



Cynomorpha are especially Ethiopian and Oriental, but also extend into the Pate- 

 arctic region, and into the Australian region as far as Timor. 



Anthropomorpha present a marked example of discontinuous distribution. See 

 p. 222. 



The order dates back to the Eocene. 



Origin and Migrations of the Mammalia. The Class, and most likely all the 

 Orders, originated in the Northern Hemisphere. Australia was isolated at a very early 

 date, and therefore has preserved a very ancient Mammalian fauna. S. America and S. 

 Africa were severed somewhat later, to be afterwards re-united, and they also have 

 preserved some very ancient forms. The northerly connection between the Eastern 

 and Western Hemispheres was then broken, not only by submergence of land, but also 

 by a lowering of temperature. The Oriental and Ethiopian regions were also marked off 

 by the formation of the Himalayas and the desert zone stretching from the Sahara to 

 Central Asia. 



