THE PERMANENCE OF CONTINENTS. 
123 
to become elevated; and, after enormous denudation, to be 
converted into land. 
But even altogether apart from what is to be learned from 
the Cretaceous rocks, it is not apparent that continents have 
been uninterruptedly permanent. Australia and Asia, Africa 
and Madagascar, New Zealand and Australia, Europe and 
America, are all supposed to have been united at some more or 
less remote period ; and to explain the present distribution of 
organisms, seas of a thousand fathoms depth are bridged over 
as often as it happens to be deemed requisite. But it is still 
questionable whether these former land connexions, which are 
admitted by Mr. Wallace, will be found sufficient to explain all 
the past as well as present peculiarities of distribution. For 
instance, a much more southerly land connexion between Eng- 
land and America seems required to explain the presence of 
tropical American plants, such as palms, in our Eocene, because 
their absence in beds of corresponding age in the United States 
and Greenland implies that they did not pass along the northern 
route traced out for them. If sea-beds have been elevated to 
the extent of a thousand fathoms, and if there are forces capable 
of elevating the highest mountains in the world from below the 
sea level within a comparatively recent period, why are 4 hypo- 
thetical continents bridging over the deep oceans ’ ‘ so utterly 
gratuitous and entirely opposed to all the evidences at our com- 
mand/ as Mr. Wallace wishes us to believe ? There appears 
to be no valid reason why Europe should not have been con- 
nected with South America, by the so-called Atlantic ridge, or 
even Australia with South America by way of Easter, Gambier, 
and the Fiji Isles ; for if these great banks, with islands occa- 
sionally rising to the surface, do not mean changes of level in 
the sea bottom, whether of elevation or depression, what do 
they mean P 
To take other instances, in which Mr. Wallace’s explanations 
do not seem to be the best solution of the facts. Sir Joseph 
Hooker, in his singularly interesting introductory essay to the 
New Zealand flora, stated that seventy-seven plants are common 
to New Zealand, Tasmania, and South America, comparatively 
few of which are universally distributed species. Further, 
there are upwards of 100 genera or well-marked groups of 
plants almost confined to lands of the south temperate zone, 
effecting ‘ a botanical relationship or affinity between them all, 
which every botanist appreciates/ For reasons which appear 
to be unanswerable, he has rejected the theory that these plants 
were transported across the seas which now separate these lands, 
| and considers that the plants of the Southern Ocean are ‘ the 
remains of a flora that had once spread over a larger and more 
continuous tract of land than now exists in that ocean/ and that 
