296 
ORIGIN OF LIFE IN AMERICA 
with a number of ancient types of animals and plants. In the 
Galapagos islands similar relicts of bygone ages are found, yet 
their presence on the islands is not generally considered to 
be due to a former land connection with the mainland. But 
the question whether the animals and plants inhabiting this 
archipelago are the descendants of purely accidental visitors 
or not, is of more than usual importance in this case. Both 
Mr. Darwin and Dr. Wallace expressed the opinion that the 
Galapagos islands ,are of the oceanic type, and that they 
originated from sub-oceanic volcanoes, having never formed 
part of a continent or any large land-mass. Many of the more 
recent observers have followed the lead of our two great 
naturalists. I need only mention Professor Agassiz, Dr. 
Wolf, Mr. Salvin, Dr. Dali and Dr. Stearns. On the other 
hand, Professor Baur was the first to seriously contest the 
view of these authorities. His researches led to a reconsidera¬ 
tion of the problem presented by the fauna and flora of the 
Galapagos islands and a rejection by many naturalists of the 
theory so ably maintained by Darwin and his followers. 
Islands, as I have already indicated, possess many advan¬ 
tages over continental areas for the study of the laws and 
phenomena of distribution. The islands we are now dealing 
with, moreover, are of the most profound importance in con¬ 
nection with the geological history of the two great American 
continents. We might almost say that the problem of the 
Galapagos fauna presents the key to the solution of the most 
complex and intricate questions concerning the American 
fauna with which we are confronted. It is for this reason 
that, the whole of this chapter will be devoted to an exhaustive 
survey of the Galapagos islands and their inhabitants. 
When Darwin landed on the archipelago in 1835, he noted 
in the first instance the fact that all the islands were formed 
of volcanic rock and that they contained numerous craters. 
The craters he found to consist either of lava and scoriae, or 
of finely-striated sandstone-like tuff. All the latter, which he 
examined, had the southern sides either much lower than the 
other sides, or quite broken down and removed. Pie concluded 
from this fact that all these craters were formed beneath the 
sea, and that their broken state was due to the action of the 
waves produced by the southern trade winds. On the other 
