1899] ORIGIN OF AUSTRALIAN FLORA 283 
lands and of species congeneric with these. A few of these species 
occur also in Western Australia; in the eastern districts they are 
more abundant in the cooler mundane country, and it is especially 
in the latter that are found forms conspecific with, or closely allied 
to, forms now forming part of the Antarctic flora, accepting this term 
in the conventional sense, that is, as embracing genera now largely 
or entirely restricted to southern cold temperate lands. It is admitted 
that these facts do, at first sight, favour the view of migration on a 
large scale followed by partial overpowering of the indigenous flora. 
But when we consider what is known of the history of Australia since 
late Cretaceous times the matter wears a different aspect. We have 
every reason to believe that since these times considerable portions of 
Eastern Australia have enjoyed a climate almost identical with that 
of Indo-Malaya, a climate, too, still prevailing in the north and _ north- 
east. We know, moreover, that in early tertiary times the floras of 
both countries were in a large measure identical. Is there anything 
_ remarkable, therefore, in the evidences of floristic affinity between the 
two regions? It will perhaps be conceded, as Professor Tate himself 
has conceded, that a certain proportion of the Australian species of 
genera common to these two neighbouring areas are descendants from 
the primitive flora, but that by far the larger number are immierants. 
This, however, assumes our possession of complete records respecting 
the two floras from Eocene times to the present; and that we have 
anything like such records is an assertion no competent person would 
take upon himself to maintain. 
But migration there has been, and the number of identical species 
and such a fact as the discovery of outlying forms allied to Indo-Malayan 
on the Bellenden-Ker range in North Queensland prove it, as also does 
the existence of “ Australian” forms on the mountains of New Guinea, 
and in less number in various parts of Indo-Malaya and Eastern Asia, 
if, indeed, these last be not descendants from the primitive flora. 
Moreover, the trend of migration from the north has undoubtedly 
predominated over that from the south. But are we justified in 
assuming from this that any superiority is inherent in the Indo- 
Malayan flora over the Australian? What are the data? A number 
of hygrophilous genera and a certain proportion of hygrophilous species 
are common to the two regions. Now the Indo-Malayan flora, 
exception made for that of Timor; in some measure xerophilous, is and 
has long been a hyegrophilous flora; while in Australia since Eocene 
times, if the view above enunciated be correct, hygrophilous types 
have had to struggle with xerophilous ones, which latter to-day still 
form a large element in its flora. Whatever in this case the means 
whereby migration has been brought about, its trend must, other things 
being equal, have borne direct relation to the size—or what comes 
approximately to the same thing, the comparative floristic richness— 
of the areas between which the interchange has been made. We have 
