THEORY OF DESCENT. 17 
by the absence of insectivora, goats, antelopes, oxen, 
cranes, and bustards. 
3. The Australian Region, comprising Australia, Tas- 
mania, New Guinea, and the Indian Archipelago as 
far as Celebes and Lombok. It is characterised by 
the presence of monotremata, marsupials, birds of 
paradise, honey-eaters, cockatoos, lyre-bird, mega- 
podes, and ceratodus ; also by the absence of placental 
mammals except a few rodents and bats, and the 
absence of vultures, woodpeckers, and tailed amphi- 
bians. 
4. The Novozelanian Region, including New Zealand and 
the neighbouring islands. It is characterised by the 
absence of all mammalia except seals, whales, and 
two bats, the absence of reptiles except a few lizards, 
and the absence of amphibia except one frog: by the 
presence of moas, kiwi, kakapo, and the tuatara 
(Sphenodon) which forms a peculiar order of reptiles, 
connecting the lizards and crocodiles, and is allied to 
animals that lived in the triassic period. 
The geographical relations of the New Zealand Fauna, Hutton, 
Trans, N. Z. Institute, v. p. 227. 
THEORY OF DESCENT. 
If it be true that all life has proceeded from previously 
existing living matter, it follows, as a matter of course, that 
all the various kinds of animals and plants on the earth are 
due to successive variations from an original organism, that 
is to descent with modification, and there are many reasons 
for thinking that this really is the case. | : 
That offspring differ from their parents, and thus give 
rise to varieties, is a well-known fact, and it is impossible to 
place any limit on this variation, The study of Palzeonto- 
Cc 
