74 THE DARWINIAN THEORY 



of fossils with regard to camels is very imperfect, 

 but still points in a fairly definite direction. Fossil 

 camels are found in South America, in Brazil; in 

 North America, in Texas, California, Kansas, and 

 Virginia. In Asia, in the Himalayas, Merycotherium, 

 a large fossil camel, is found widely distributed over 

 Siberia, extending to the extreme coast. 



Now, there was almost certainly a former land 

 connection between Asia and North America, across 

 the Behring Straits, which are narrow and shallow. 

 Hence the conclusion is, that there is strong reason 

 for holding that camels originated in North America, 

 and thence spread in two directions, southwards to 

 South America, and westwards through Asia ; and 

 that their areas of distribution, though now dis- 

 connected, were once continuous. 



B. Marsupials. — These constitute a large group 

 of animals, of which there is a great variety of 

 forms, the kangaroo and opossum being perhaps the 

 best known examples. Marsupials are a well-marked 

 group, which in their habits, appearance, and struc- 

 ture, especially as regards the skeleton and teeth, 

 curiously simulate the higher divisions of mammals. 

 Carnivorous, insectivorous, and herbivorous forms 

 are all well established and differentiated. The 

 ant-eater or Myrmecobius, and fruit-eater or Phalan- 

 ger, are found in this group, which is characterised 

 by low organisation and great tenacity of life. 



Marsupials occur in two chief regions : 



(i.) Australian region. — The wombats and Myr- 

 mecobius occur only in Australia and Tasmania, 

 kangaroos and phalangers extending northward to 



