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 North 
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 
