Over a South Atlantic Continent 449 



there Is a distinct community of descent with plants of the 

 West Indies — Robinson's statement notwithstanding — is 

 proved by 60 of them being likewise found there. The 

 number also common to the Indies and to Columbia, 

 Venezuela, Guiana, Ecuador, and Peru, strongly suggest a 

 southward migration of types, when structural details are 

 considered. The marked affinity with Mexico is specially 

 noteworthy, and speaks strongly for migrational inter- 

 change. 



Of the 204 endemic species, the larger number belong 

 to genera that have allied and continental species on the 

 islands, and so which are included In the 157 above men- 

 tioned as being continental. But further a few genera like 

 Cypenis, Peperomia, Telanthera, Acalypha, Euphorbia, 

 Ipomoea, Cordia, Borreria, and Scalesia Include about 

 90 species that seem truly to have evolved within the 

 Islands, as divergent types from a few other and more 

 primitive ones. 



The genus Phoradendron, with Its four endemic species, 

 forms a strong argument in favor of a continental origin 

 for the Islands and their organisms. For It Is typically 

 tropical American in 46 of the nearly 70 species, that all 

 form parasitic attachment on trees from N. America south- 

 ward to Chile. Even if the berries survived a sea-voyage, 

 as castaways on a seashore, they would there need to be 

 transported to some appropriate tree, on which as parasites 

 they could grow, and on which alone they would germinate. 



Nearly all of the above facts then favor Baur's view 

 that the Galapagos formed the western part of a more 

 extended South American continent, while the degree of 

 variation in many of the endemic species from allied conti- 

 nental ones, affords some measure of the rate and amount 

 of such variation-tendency that may be shown after isola- 

 tion had been effected. 



The flora of Cocos Island, that Is about midway be- 

 tween Costa Rica and the Galapagos, indicates nearer affini- 

 ty with Columbia, N. Brazil, and Guiana, as might be ex- 

 pected from Its geographic position. The Cocos, Gala- 

 pagos, and Juan Islands then eminently favor a former wide 

 extension of the western S. American coast, from South 



