Ipswich Museum. 149 
uniting Asia with Africa, the progeny of the primary pair created or 
liberated at the hypothetical centre might have travelled to the latter 
continent, and there have propagated and dispersed themselves south- 
ward to the Cape of Good Hope. It is remarkable, however, that 
the Ostrich should not have migrated eastward over the vast plains 
or steppes which extend along the warmer temperate zone of Asia, or 
have reached the southern tropical regions ; it is in fact scarcely 
known in the Asiatic continent, being restricted to the Arabian De- 
serts, and being rare even in those parts which are most contiguous 
to what we may call its proper continent—Africa. If we next con- 
sider the locality of the Cassowary, we find great difficulty in con- 
ceiving how such a bird could have migrated to the islands of Java, 
the Moluccas, or New Guinea, from the continent of Asia. The 
Cassowary is not web-footed like the swimming birds ; for wings it 
has only a few short and strong quills. How could it have overcome 
the obstacles which some hundreds of miles of ocean would present 
to its passage from the continent of Asia to those islands; and 
furthermore, how is it that no individuals have remained in the 
warm tropical southern border of Asia, where the vegetable suste- 
nance of the Cassowary seems as abundantly developed as in the 
islands to which this wingless bird is now exclusively confined? If 
the difficulty already be felt to be great in regard to the insular posi- 
tion of the Cassowary, it is still greater when we come to apply 
the hypothesis of dispersion from a single centre to the Dodo of the 
island of Mauritius, or the Solitaire of the island of Rodriguez. How, 
again, could the Emeu have overcome the natural obstacles to the 
migration of a wingless terrestrial bird from Asia to Australia? and 
why should not the great continent of Asia have offered in its fertile 
plains a locality suited to its existence, if it ever at any period had 
existed on that continent? A bird of the nature of the Emeu was 
hardly less likely to have escaped the notice of naturalist travellers 
than the Ostrich itself ; but save in the Arabian Deserts, the Ostrich 
has not been found in any part of Asia, and no other species of 
wingless bird has ever been met with on that continent : the evidence 
in regard to such large and conspicuous birds was conclusive as to 
that fact. In order that the Rhea, or three-toed Ostrich, should reach 
South America, by travelling along that element on which alone it is 
organized and adapted to make progress, it must, on the hypothesis 
of dispersion from a single Asiatic centre, have travelled northward 
into the inhospitable wilds of Siberia: it must have braved and over- 
come the severer regions of the arctic zone : it must have maintained 
its life with strength adequate to the extraordinary power of walking 
and running over more than a thousand miles of land or frozen ocean 
utterly devoid of the vegetables that now constitute its food, before 
it could gain the northern division of America, to the southern divi- 
sion of which it is at present, and seems ever to have been, confined. 
The migration in this case could not have been gradual, and accom- 
plished by successive generations. No individual of the large 
vegetable-feeding wingless bird that now subsists in South America 
could have maintained its existence, much less hatched its eggs, in 
