418 



ISLAND LIFE. 



[part II. 



helps to supply us with a practical demonstration of them. We 

 find that the entire group contains just that amount of Indian 

 forms which could well have passed from island to island ; that 

 many of these forms are slightly modified species, indicating 

 that the migration occurred during late Tertiary times, while 

 others are distinct genera, indicating a more ancient connec- 

 tion ; but in no one case do we find animals which necessitate 

 an actual land-connection, while the numerous Indian types of 

 mammalia, reptiles, birds, and insects, which must certainly 

 have passed over had there been such an actual land-connection, 

 are totally wanting. The one fact which has been supposed to 

 require such a connection — the distribution of the lemurs — 

 can be far more naturally explained by a general dispersion of 

 the group from Europe, where we know it existed in Eocene 

 times ; and such an explanation applies equally to the affinity 

 of the Insectivora of Madagascar and Cuba ; the snakes (Herpe- 

 todryas, &c.) of Madagascar and America ; and the lizards (Cryp- 

 toblepharus) of Mauritius and Australia. To suppose, in all these 

 cases, and in many others, a direct land-connection, is really 

 absurd, because we have the evidence afforded by geology of 

 wide differences of distribution directly we pass beyond the most 

 recent deposits; and when we go back to Mesozoic — and still 

 more to Palaeozoic — times, the majority of the groups of animals 

 and plants appear to have had a world-wide range. A large 

 number of our European Miocene genera of vertebrates were 

 also Indian or African, or even American ; the South American 

 Tertiary fauna contained many European types ; while many 

 Mesozoic reptiles and mollusca ranged from Europe and ISTorth 

 America to Australia and New Zealand. 



By direct proof (the occurrence of wide areas of marine 

 deposits of Eocene age), geologists have established,, the fact 

 that Africa was cut off from Europe and Asia by an arm of 

 the sea in early Tertiary times, forming a large island-continent. 

 By the evidence of abundant organic remains we know that all 

 the types of large mammalia now found in Africa (but which are 

 absent from Madagascar) inhabited Europe and Asia, and many 

 of them also North America, in the Miocene period. At a 

 still earlier epoch Africa may have received its lower types of 



