390 



ISLAND LIFE. 



[part II. 



tropical families, but several African genera are represented by 

 peculiar species, and there are also some species belonging to 

 two American genera of the Iguanidae, a family which is ex- 

 clusively American ; while a genus of geckoes, inhabiting 

 America and Australia, also occurs in Madagascar. 



Relation of Madagascar to Africa. — These facts taken all 

 together are certainly very extraordinary, since they show in a 

 considerable number of cases as much affinity with America as 

 with Africa ; while the most striking and characteristic groups 

 of animals now inhabiting Africa are entirely wanting in Mada- 

 gascar. Let us first deal with this fact, of the absence of so 

 many of the most dominant African groups. The explanation 

 of this deficiency is by no means difficult, for the rich deposits 

 of fossil mammals of Miocene age in France, Germany, Greece, 

 and North-west India, have demonstrated the fact that all the 

 grea,t African mammals then inhabited Europe and temperate 

 Asia. We also know that a little earlier (in Eocene times) 

 tropical Africa was cut off from Europe and Asia by a sea 

 stretching from the Atlantic to the Bay of Bengal, at which 

 time Africa must have formed a detached island-continent such 

 as Australia is now, and probably, like it, very poor in the 

 higher forms of life. Coupling these two facts, the inference seems 

 clear, that all the higher types of mammalia were developed 

 in the great Euro-Asiatic continent (which then included 

 Northern Africa), and that they only migrated into tropical 

 Africa when the two continents became united by the upheaval 

 of the sea-bottom, probably in the latter portion of the Miocene 

 or early in the Pliocene joeriod.^ 



^ This view was, I believe, first advanced by Professor Huxley in his 

 'Anniversary Address to the Geological Society," in 1870. He says : — ''In 

 fact the Miocene mammalian, fauna of Europe and the Himalayan regions 

 contain, associated together, the types which are at present separately 

 ocated in the South African and Indian provinces of Arctoggea. Now 

 there is every reason to believe, on other grounds, that both Hindostan 

 south of the Ganges, and Africa south of the Sahara, were separated by a 

 wide sea from Europe and North Asia during the Middle and Upper Eocene 

 epochs. Hence it becomes highly probable that the well-known similar- 

 ities, and no less remarkable differences, between the present faunee of 

 India and South Africa have arisen in some such fashion as the following : 



