1891.] The Origin of the Galapagos Islands. 309 
species began ; an originally single species was differentiated in 
many different forms; every island developed its peculiar races. 
What seems to me to be a support of the subsidence theory is 
the fact mentioned by Wolf, that the flora of the Galapagos at 
elevations of about goo feet is typically that of the Andes at an 
elevation of 9,000 feet. How could this alpine flora be explained 
by the theory of elevation ; what is the reason that plants charac- 
teristic of an elevation of 9,000 feet are found at an elevation of 
900 feet? This peculiar fact is also explicable by the theory of 
subsidence. I have shown above that an elevation of 300 fathoms, 
or 550 m., would bring together all the central islands. There 
are two lines of soundings made by the Fish Commission Steamer 
“Albatross,” one between the Galapagos and Panama, and one to 
Acapulco. The deepest sounding of the first line is 1,927 fath- 
oms (3,470 m.), at 6° 44’ N., 80° 27’ W.; that of the other is 
2,256 fathoms, at 11° 45’ N., 97° 3’ W. 
We need only an elevation of about 10,000 feet to connect the 
Galapagos with America. This would give the highest mountain 
on the Galapagos an elevation of 14,700 feet. This height is 
reached by many mountains and very often surpassed. The eleva- 
ticn of goo feet on the Galapagos of to-day would correspond to an 
elevation of 10,900 feet. This is, of course, only an approximate 
value, which may be less or more. But there is no very great 
difficulty in adopting such an amount of subsidence. 
The next question is, Is it not possible to determine during 
which geological period this subsidence of the Galapagos grup, 
which we have to accept, has taken place? If any form becomes 
isolated for long a time it preserves the original general character 
that it possessed at the time of its isolation. This we see very 
well exemplified by the study of isolated dialects of a language. 
Í believe, therefore, that the peculiar genera we find to-day on the 
Galapagos have not originated there, but have been preserved in 
their old condition. Let us again take the tortoises as an exam- 
ple. The tortoises found on these islands belong to the true land 
tortoises Testudinidz ; they represent, together with the forms from 
the islands round Madagascar and the peculiar Manouria from 
India and the Sunda Islands, the oldest living representatives of 
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