PROFESSOR OWEN ON THE GENUS DINORNIS. 15 
In England, for example, our Moles, Water-voles, Hares, Weasels, Stoats, Badgers and 
Foxes are of the same species as those that existed when the Hippopotamus swam the 
rivers, the Hyzna, Bear and Lion lurked in the caves, and the Rhinoceros and Elephant 
trod the land. So likewise the remains of small Sloths and Armadillos are found asso- 
ciated with the Megatherium and Glyptodon in South America; and the fossil remains 
of species as diminutive as the present Kangaroos and Dasyures occur abundantly in 
Australia with those of herbivorous Marsupials as large as Tapirs and Rhinoceroses, and 
of carnivorous Marsupials as large as the Lion or Tiger. So likewise in New Zealand 
we find that the small Apteryx has co-existed with the great Dinornis and Palapteryz. 
We have not a particle of evidence that any species of bird or beast that lived during 
the pliocene period has had its characters modified in any respect by the influence of time 
or of change of external influences. In proportion to its bulk is the difficulty of the 
contest which, as a living organized whole, the individual of such species has to 
maintain against the surrounding agencies that are ever tending to dissolve the vital 
bond, and subjugate the living matter to the ordinary chemical and physical forces. 
Any changes, therefore, in such external agencies as a species may have been originally 
adapted to exist in, will militate against that existence in a degree proportionate, per- 
haps in a geometrical ratio, to the bulk of the species. Ifa dry season be gradually 
prolonged, the large Mammal will suffer from the drought sooner than the small one: 
if such alteration of climate affect the quantity of vegetable food, the bulky Herbivore 
will first feel the effects of stinted nourishment: if new enemies are introduced, the 
large and conspicuous quadruped or bird will fall a prey, whilst the smaller species 
conceal themselves and escape. Smaller animals are usually, also, more prolific than 
larger ones. 
The actual presence, therefore, of small species of animals in countries where 
larger species of the same natural families formerly existed, is not the consequence 
of any gradual diminution of the size of such species, but is the result of circum- 
stances, which may be illustrated by the fable of the ‘oak and the reed’: the smaller 
and feebler animals have bent and accommodated themselves to changes which have 
destroyed the larger species. We find, nevertheless, that the same peculiar forms or 
families of animals exist and characterize particular portions of dry land, such ¢. q. as 
South America, Australia, and New Zealand, at the present day, as at a period long 
antecedent to Human history or existence; and although many species have perished, 
there has been no general sweeping away of the peculiar aboriginal land animals of those 
continents or islands. But just as the smaller Sloths and Armadillos still linger in 
South America, so the smaller Kangaroos, Wombats, Dasyures, and other Marsupials 
have continued to exist in Australia, and a few species of the comparatively diminutive 
wingless birds of the genera Apteryx and Brachypteryz still exist in the island where 
their peculiar families were once much more richly represented and by species on a 
far larger scale. 
