438 ZOOLOGICAL GEOGRAPHY. [PART III. 
the Himalayas had risen to any great height, and when a large 
part of what are now the cold plateaus of Central Asia may 
have teemed with life, some forms of which are preserved in 
Africa, some in Malaya, and a few in Celebes. Here may 
have lived the common ancestor of Sus, Babirusa, and Phaco- 
cherus ; as well as of Cynopithecus, Cynocephalus, and Macacus ; 
of Anoa and Bubalus; of Scissirostrum and Huryceros; of Ceyx, 
Ceycopsis, and Ispidina. Such an origin accounts, too, for the 
presence of the North-Indian forms in Celebes ; and it offers less 
difficulties than a direct connection with continental Africa, which 
once appeared to be the only solution of the problem. If this 
south-eastward extension of Asia occurred at the same time as 
the north-eastward extension of South Africa and Madagascar, 
the two early continents may have approached each other suffi- 
ciently to have allowed of some interchange of forms: Tarsius 
may be the descendant of some Lemurine animal that then 
entered the Malayan area, while the progenitors of Cryptoprocta 
may then have passed from Asia to Madagascar. 
It is true that we here reach the extremest limits of specula- 
tion ; but when we have before us such singular phenomena as 
are presented by the fauna of the island of Celebes, we can hardly 
help endeavouring to picture to our imaginations by what past 
changes of land and sea (in themselves not improbable) the actual 
condition of things may have been brought about. 
IT. Australia and Tasmania, or the Australian Sub-region. 
A general sketch of Australian zoology having been given in the 
earlier part of this chapter, it will not be necessary to occupy much 
time on this sub-region, which is as remarkably homogeneous as 
the one we have just left is heterogeneous.. Although much of 
the northern part of Australia is within the tropics, while Vic- 
toria and Tasmania are situated from 36° to 43° south latitude, 
there is no striking change in the character of the fauna 
throughout the continent ; a number of important genera extend- 
ing over the whole country, and giving a very uniform character 
to its zoology. The eastern parts, including the colonies of New 
South Wales and Queensland, are undoubtedly the richest, several 
