390 
ISLAND LIFE. 
[part n. 
tropical families, but several African genera are represented by 
peculiar species, and there are also some species belonging to 
two American genera of the Iguanidse, 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 
great 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 period . 1 
1 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 Arctogasa. 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 fauna? of 
India and South Africa have arisen in some such fashion as the following : 
