236 EXTINCT MONSTERS. 
plaster cast of an egg found in certain surface deposits in 
Madagascar. In the same case may be seen bones of the Dodo 
from the isle of Mauritius. Unlike New Zealand, Madagascar 
possesses no living wingless bird. But in the neighbouring island 
of Mauritius the Dodo has been exterminated less than three 
centuries ago. The little island of Rodriguez, in the same 
geographical province, has also lost its wingless Solitaire. 
It will thus be seen that we have three distinct groups of giant 
land birds—the Moas, the Dromornis, and the A‘pyornis,—occu- 
pying areas at present widely separated by the ocean. 
This raises the difficult but very interesting question, how they 
got there; and the same applies to their living ancestors. The 
ostrich proper, Struthio camelus, inhabits Africa and Arabia ; but 
there is evidence from history to show that it formerly existed in 
Beluchistan and Central Asia. And, going still further back, the 
geological record informs us that, in the Pliocene period, they 
inhabited what is now Northern India. In Australia we have 
the Cassowary (Casuarius) and the Emeu (Dromaius); in New 
Zealand, the Apteryx (or Kiwi). Now, as none of these birds can 
either fly or swim, it is impossible that they could have reached 
these regions separated as they now are; and it is hardly 
likely that they arose spontaneously in each district from 
totally different ancestors. But the new doctrine of evolution 
affords a key to the problem, and tells us that they all sprang 
from a common ancestor, of the struthious type (probably 
inhabiting the great northern continental area), and gradually 
migrated south along land areas now submerged. In this way 
we get some idea of the vast changes that have taken place in 
the geography of the world during later geological periods. 
Perhaps they were compelled to move south until they reached 
abodes free from carnivorous enemies. Having done so, they 
evidently flourished abundantly, especially in New Zealand, where 
there are so few mammals, except those recently introduced 
by man. 
