4 8o PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



ern and western, but there is another land mass of con- 

 tinental proportions — viz., Australia. This we take as 

 our first example of special cases. It is the most isolated 

 of continents, and the most distinct of all faunal regions. 

 All the animals and plants there are widely different 

 from those of any other region. To show the greatness 

 of this difference we take up more particularly one class 

 only — viz., the mammals. 



Mammals are divided into three subclasses: Euthe- 

 ria, or ordinary typical mammals, found everywhere ex- 

 cept Australia ; Metatheria, or marsupials ; and Proto- 

 theria, or monotremes. Eutheria are perfect young-bear- 

 ers ; the Prototheria are perfect egg-layers ; the Meta- 

 theria are intermediate. The young of these are born 

 in a very imperfectly organized condition, and embry- 

 onic development is finished in the marsupium or 

 pouch. Now, there are about one hundred and fifty 

 species of mammals in Australia, all of which are mar- 

 supials and monotremes. Moreover, monotremes are 

 found nowhere else, and of marsupials only a few opos- 

 sums are found elsewhere, viz., in America, North and 

 South. The only exception to this sweeping differ- 

 ence is the existence of a few bats and a few rats 

 — animals especially liable to dispersal by means of 

 floating logs, etc., and therefore to accidental intro- 

 duction. 



2. Madagascar. — This very large island off the east 

 coast of Africa is separated from the latter by the wide 

 and deep Mozambique Channel. Next to Australia, it is 

 perhaps the most distinct of all faunal regions.' It may 

 be called the home of the lemurs, and has besides many 

 curious forms. All the mammals are peculiar, except 

 such as have been introduced. But it is well to remem- 

 ber that whatever distant resemblances they have are 

 mostly with those of South Africa. 



