DERIVATION OF THE FLORA AND FAUNA 405 



periods. At times the subantarctic bog and heath must have occupied considerable 

 areas north of their present range, but during all this shifting to and fro many 

 species may have been lost, some of them surviving on Masafuera. The glaciers 

 did not come down to the coast of Central Chile, but the climate was cold and 

 numerous ancient stenotopic types, some of them surviving on Juan Fernandez, 

 perished. 



The influence of the glacial periods cannot have been very destructive on 

 the islands. Some plant species reduced their range and became rare or extinct; 

 several, apparently with a very narrow physiological amplitude, are on the verge 

 of extinction today. In Masafuera, the timberline was lowered, I suppose, and the 

 forest patches in the valleys came down toward the sea. Masatierra has no climatic 

 upper timberline. In a depression on the summit of the highest peak. El Yunque, 

 Driniys, JiiaJiia, Cuminia, Escallonia, Rhethiodendron, Dicksonia, etc. etc., luxuriate 

 more than anywhere else, thanks to the constant humidity. 



