CHAP. XII.] 
the oriental region. 
3G1 
of specific and generic forms which have coincided with, and been 
to a large extent dependent on them. We have, therefore, true 
causes at work, and our only suppositions have been as to how 
those causes could have brought about the results which we 
see ; and however complex and unlikely some of the supposed 
changes may seem to the reader, the geologist who has made a 
study of such changes, as recorded in the crust of the earth, 
will not only admit them to be probable, but will be inclined 
to believe that they have really been far more complex and 
more unexpected than any supposition we can make about 
them. 
There is one other external relation of the Malayan fauna 
about which it may be necessary to say a few words. I have 
supposed the greatest westward extension of the Malayan area 
to be indicated by the Maidive islands, but some naturalists 
would extend it to include Madagascar in order to account for 
the range of the Lemuridm. Such an extension would, however, 
render it difficult to explain the very small amount of corre- 
spondence with a pervading diversity, between the Malayan and 
Malagasy faunas. It seems more reasonable to suppose an 
approximation of the two areas, without actual union having 
ever occurred. This approximation would have allowed the 
interchange of certain genera of birds, which are common to 
the Oriental Eegion and the Mascarene islands, but it would 
have been too recent to account for the diffusion of the lemurs, 
which belong to distinct genera and even distinct families. This 
probably dates back to a much earlier period, when the lemurine 
type had a wide range over the northern hemisphere. Sub- 
jected to the competition of higher forms, these imperfectly 
developed groups have mostly died out, except a few isolated 
examples, chiefly found in islands, and a few groups in Africa. 
In our discussion of the origin of the Ethiopian fauna, we 
have supposed that a close connection once existed between 
Madagascar and Ceylon. This was during a very early tertiary 
epoch ; and if, long after it had ceased and the fauna of Ceylon 
and South India had assumed somewhat more of their present 
character, we suppose the approximation or union of Ceylon 
