316 
ORIGIN OF LIFE IN AMERICA 
against the theory of a former land connection between the 
islands and the mainland. He scarcely discusses the problem 
from a botanical point of view, but assumes that the Gala¬ 
pagos islands are of oceanic origin.* 
Personally, I am in agreement with Mr. Andrew Murray’s 
and Professor Baur’s theory that the archipelago originated 
through subsidence of a land-mass which was connected with 
the mainland. From the latter the islands received the prin¬ 
cipal members of the fauna and flora, and these progressed 
from the one to the other on a solid land surface. Subse¬ 
quently, possibly owing to volcanic disturbance, the land sub¬ 
sided, leaving only the mountain tops with their animals and 
plants as fragmentary relicts of a rich and varied fauna and 
flora. So far I am in agreement with Professor Baur’s theory, 
but I believe that the geological history of the Galapagos 
archipelago forms only part of a much larger and far more 
complex problem. In the first place, it is evident that the 
whole fauna and flora of the Galapagos islands cannot have 
originated in Central America or the West Indies. A large 
proportion of the animals and plants seem to have their 
nearest relations in Ecuador and Colombia. Others point 
to a still more southern or northern origin. If we derive the 
fauna and flora principally from a former land connection 
with the mainland of America, that connection must have had 
several branches. The affinities of the archipelago appear 
to be chiefly with Central America and Ecuador and much 
less with Chile. On the other hand, a certain relationship, for 
instance among the Bulimuli, exists with the southern ex¬ 
tremity of Lower California. All these different areas of 
North, Central and South America may have been joined 
with the Galapagos land-mass by peninsulae, though one or 
more of them may have become disconnected long before the 
others. Dr. Arldt f indicates something of that kind in his 
map illustrating the conditions of land and water in Creta¬ 
ceous times. At least, he connects western Mexico and 
Ecuador by a broad land bridge westward of Central America 
and across the area of the Galapagos archipelago. I ventured 
* Stewart, A., “ Botanical Survey of Galapagos Islands,” p. 239. 
t Arldt, J., “ Entwicklung der Ivontinente,” — Karte 19. 
