HISTORY OF SOUTH AMERICA 
387 
water since the close of the Mesozoic Era. The testimony is 
of a threefold character. It is founded on our knowledge of 
geology, of palaeontology, and of the geographical distribu¬ 
tion of living animals and plants. Richness, as Dr. Wallace 
observed, combined with isolation, is the predominant feature 
of neotropical zoology. Nevertheless, he thinks that early 
during the Tertiary Era, the zoological differences between 
the N©arctic and Neotropical, that is to say, between the North 
and South American regions, were probably even more radical 
than they are now. South America, he argues, was then a 
huge island or group of islands—a kind of Australia of the 
New World—chiefly inhabited by the imperfectly organised 
group of edentate mammals. Dr. Wallace* believes, more¬ 
over, that there must have been one or more ancient lan,d 
connections between the two continents, perhaps in Eocene 
or Miocene times, admitting ancestral types of monkeys and 
the members of the camel-tribe (Llamas) from the north to 
South America. 
Dr. Wallace’s opinions, expressed thirty-five years ago, 
were founded entirely on the distribution of living animals. 
Rapid strides have been made since that time in our know¬ 
ledge of the fauna of 1 South America. The geology of certain 
districts is being worked out. Botanists have made great 
progress in mapping out the distribution of plants, while the 
most astonishing discoveries have been disclosed principally 
among the past inhabitants of the continent. Thus we are 
now in a very different position from that of Wallace, when 
he pronounced upon the physical changes of South America 
during the past, on the strength of his zoological know¬ 
ledge. 
We are particularly indebted to Dr. von Ihering’s re¬ 
searches on the fauna and flora of South America, which he 
conducted during many years of devoted labour, that our in¬ 
formation on the main features of distribution has advanced 
so rapidly. During his long residence in southern Brazil he 
collected, and is still collecting, data bearing principally on 
the question of the geological history of the continent; and 
since his scattered papers have recently been reprinted in 
* Wallace, A. R., “ Distribution of Animals,” II., p. 58. 
L.A. 
Z 
