492 
THE DISTRIBUTION OF ANIMALS AND PLANTS. 
marvellous tale of the physical changes which had taken 
place in various parts of the world since they came into ex- 
istence. As an instance, the lecturer mentioned that the 
series of islands, great and small, extending from the Malay 
peninsula to New Guinea and Australia, looked like a series 
of natural stepping-stones. There was no truth more fre- 
quently forced upon the mind of the geological student than 
the doctrine of alternate upheavals and submergencies. Ail 
the islands in the sea were but the tops of submarine mountans 
and indicated sunken land. Frequently the animals and plants 
on the larger islands enabled us to get at the approximate 
time when the submergence had taken place. This was the 
case with the islands of the Malay Archipelago. As far as 
Borneo and Flores all the islands had an Indian flora and 
fauna. On some of the larger islands there existed the 
elephant, rhinoceros, and tapir, of the same species as those 
inhabiting the neighbouring Indian continent. Now, these 
animals could not have swum across ; they must, therefore, 
have existed over the area before the more extended peninsula 
had been broken up into islands. It had been ascertained by 
soundings that these islands were connected by a shallow sea, 
• not more than two hundred feet in depth, so that an upheaval 
to that amount would again attach them to the Indian con- 
tinent, as continued dry land. But when we came to the 
islands beyond Flores, and which the casual eye looking 
upon a map would believe to be a continuance of these 
stepping-stones, naturalists found quite a distinct fauna and 
flora. The distance between these tw r o groups of islands 
was only fifteen miles, and yet the animals and plants of each 
group were as distinct in their character as those of the old 
and new w r orlds. How was this ? The Straits of Celebes and 
Lombok had running through them a very swift current, so 
that animals could not pass from one group to the other. It 
had been ascertained that the w'ater in these straits was more 
than 600 feet in depth. It shallowed again as they approached 
Australia and New Guinea, so that an upheaval of 200 feet 
would connect these islands with Australia as a previous one 
had done with India. All the animals and plants in this second 
group of islands w r ere of Australian affinities. Such birds as 
the cockatoo and the lories, and such animals as marsupials, 
abounded. The reason, therefore, of the difference between 
these two groups of islands was to be ascribed to the fact that 
long before they were insulated by the depression of the two 
areas into their present form the greater Australian and Indian 
continents were still separated by the deep water in the Strait 
of Celebes, so that their fauna and flora had been distinctly 
