1877.] The Geographical Distribution of Animals, - 157 
THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS: 
GENERAL CONCLUSIONS. 
BY ALFRED R. WALLACE, 
a now closed our survey of the animal life of the 
whole earth, — a survey which has necessarily been encum- 
bered with a multiplicity of detail, — we proceed to summarize 
the general conclusions at which we have arrived, with regard to 
the past history and mutual relations of the great regions into 
which we have divided the land surface of the globe. 
All the paleontological no less than the geological and physical 
evidence, at present available, points to the great land masses 
of the northern hemisphere as being of immense antiquity and 
as the area in which the higher forms of life were developed. In 
going back through the long series of the Tertiary formations 
in Europe, Asia, and North America, we find a continuous suc- 
cession of vertebrate forms, including all the highest types now 
existing or that have existed on the earth. These extinct ani- 
mals comprise ancestors or forerunners of all the chief forms now 
living in the northern hemisphere ; and as we go back farther and 
farther into the past, we meet with ancestral forms of those 
types also, which are now either confined to or specially char- 
acteristic of the land masses of the southern hemisphere. Not 
only do we find that elephants and rhinoceroses and hippopot- 
ami were once far more abundant in Europe than they are now 
in the tropics, but we also find that the apes of West Africa and 
Malaya, the lemurs of Madagascar, the Edentata of Africa and 
South America, and the marsupials of America and Australia 
were all represented in Europe (and probably also in North 
America) during the earlier part of the Tertiary epoch. These 
facts, taken in their entirety, lead us to conclude that during 
the whole of the Tertiary and perhaps during much of the Sec- 
ondary periods, the great land masses of the earth were, as now, 
Situated in the northern hemisphere ; and that here alone were 
developed the successive types of vertebrata, from the lowest to 
the highest. In the southern hemisphere there appear to have 
en three considerable and very ancient land masses, varying in 
extent from time to time, but always keeping distinct from each 
other, and represented, more or less completely, by Australia, 
South Africa, and South America of our time. Into these 
| Chapter xvi. of The Geographical Distribution of Animals. New York : Harper 
and Brothers 
