GEXERAL CHARACTERISTICS. 13 



by their means alone that we are able to explain sevei-al apparent anomalies in the 

 geographical distribution of living gi-oups. How, for instance, could we possibly 

 explain the present existence of tapii-s only in such widely remote areas as the 

 Malaj- Peninsula and Islands and South America, xmless we had learnt by geolo<ncal 

 explorations that these animals formerly roamed over large portions of Europe 

 and Asia, from whence their descendants gi-adually migrated to the reoions where 

 they now remain \ 



The former occurrence of an epoch of great cold in the northern hemisphere 

 known as the Glacial period, furnishes us with an explanation of how nearly related 

 animals are now confined to isolated mountain chains ; their ancestors having been 

 enabled, during the prevalence of the cold, to spread over the plains of the temperate 

 regions, from whence thej"^ retreated with the advent of warmer conditions to seek 

 a congenial climate in the nearest mountain region. 



Orders of Mammals may be ilivided into eleven main groups or ordei-s, 



Mammals, which may be arranged as follows, and will be treated of in the same 

 sequence, \-iz. : — 



1. Apes, Monkeys, and Lemui-s — Primates. 



2. Bats — Chiuoptera. 



3. Insectivores — Insectivora. 



4. Carnivores — Carxivora. 



5. Hoofed Mammals — Uxgulata. 



6. Manatis and Dugong.s — Sirenia. 



7. Whales ami Porpoises — Cetacea. 



8. Rodents — RoDEXTlA. 



9. Sloths, Anteaters, etc. — Edextata. 



10. Pouched Mammals — ilARsrpiALiA. 



11. Egg-la \'ing Mammals — Moxotremata. 



-00 



It is not to be supposed that all these groups are separated from one another 

 hj differences of equal importance. For instance, Xo. 10 diflei-s from the preceding 

 gi-oups by charactei-s of far more importance than do any of those nine from one 

 another; while the members of Xo. 11 differ fundamentally, not only from the fii-st 

 nine groups, but almost equally markedly from Xo. 10. 



Ha\-ing said thus much by way of introduction, we proceed to the considera- 

 tion of the first order of Mammals. 



