Chap. X. 
STATE OF DEVELOPMENT. 
337 
more recent forms must, on my theory, be higher than 
the more ancient; for each new species is formed by 
having had some advantage in the struggle for life 
over other and preceding forms. If under a nearly 
similar climate, the eocene inhabitants of one quarter 
of the world were put into competition with the exist¬ 
ing inhabitants of the same or some other quarter, 
the eocene fauna or flora would certainly be beaten 
and exterminated; as would a secondary fauna by an 
eocene, and a palseozoic fauna by a secondary fauna. 
I do not doubt' that this process of improvement has 
affected in a marked and sensible manner the organ¬ 
isation of the more recent and victorious forms of life, 
in comparison with the ancient and beaten forms ; but 
I can see no way of testing this sort of progress. 
Crustaceans, for instance, not the highest in their own 
class, may have beaten the highest molluscs. From 
the extraordinary manner in which European pro¬ 
ductions have recently spread over New Zealand, and 
have seized on places which must have been previously 
occupied, we may believe, if all the animals and plants 
of Great Britain were set free in New Zealand, that in 
the course of time a multitude of British forms w^ould 
become thoroughly naturalized there, and would exter¬ 
minate many of the natives. On the other hand, 
from what we see now occurring in New Zealand, and 
from hardly a single inhabitant of the southern hemi¬ 
sphere having become wild in any part of Europe, 
we may doubt, if all the productions of New Zealand 
were set free in Great Britain, whether any consider¬ 
able number would be enabled to seize on places now 
occupied by our native plants and animals. Under this 
point of view, the productions of Great Britain may be 
said to be higher than those of New Zealand. Yet 
the most skilful naturalist from an examination of the 
Q 
