iv.J THE COMMON FROG. 49 



Amblystoma, which similarly descend along the high- 

 lands of South-eastern Asia. Urodeles are absolutely 

 wanting in Hindostan, Africa south of the Sahara, the 

 Indian Archipelago, Australia, and New Zealand. As 

 might be expected, that part of Asia which is nearest 

 to North America, namely China and Japan, is the 

 region of the old world most richly peopled by species 

 of Urodela. Altogether the world's surface may be 

 divided according to its Urodele population into three 

 regions. The first will comprise Europe, Africa north 

 of the Sahara, and North-western Asia. The second 

 will include Japan and Eastern Asia. The third will 

 be formed by North America, with a slight extension 

 southwards into South America — a division by no 

 means coinciding with that indicated by the Anoiira. 



The above two orders {Anoiira and Urodela) com- 

 prise all the animals most nearly allied to the common 

 frog, of all those within or outside its own order. 

 There is, however, another small ordinal group of 

 animals which remains to be here noted, because of 

 all existing creatures they come nearest to the frog, 

 after the Urodela. 



