Vol. I] STEWART— BOTANY OF THE GALAPAGOS ISLANDS 239 



The deposit rests on a nearly level and extensive lava flow with a 

 greatest observed elevation of about 60 ft. above the present sea-level. 

 Where the sands have been hardened into crusts in thin layers, they 

 carry abundant and nicely preserved specimens of marine molluscan 

 and echinoid forms. ,.,,,, 



"Toward the interior and higher levels of the island the deposit 

 exists only as little island-like exposures which have escaped the great 

 recent flow of lava that has poured down over this old beach to conceal 

 its exact and higher levels of distribution. This deposit should be 

 placed as late Pliocene or early Quarternary." 



Outside of the few localities mentioned above, there is no 

 evidence of a general elevation, so far as has been observed, 

 and it is not improbable that during the period of general sub- 

 sidence there might have been times in which it ceased and 

 during which local elevation took place. Mr. Ochsner states 

 further: "I am much in favor of the theory of subsidence. 

 With additional thought and study given the matter I feel that 

 the testimony of my collected facts and observations will go to 

 prove this theory nearly a fact." 



In conclusion it might be said that however true Dr. Baur's 

 theory may be in regard to the union of the islands into one 

 large one, there is no strong evidence to show that they were 

 ever connected with the mainland. The biological conditions 

 at the present time are more against this theory than for it. 

 The botanical conditions do not offer absolute proof that the 

 islands have ever been connected with each other, but the 

 weight of the evidence is more in favor of this theory than 

 against it. 



Origin of the Flora 



If it be assumed that the Galapagos Islands are of 

 oceanic origin, there are but three means by which seeds and 

 spores could have been brought to the islands, outside of the 

 agency of man. These are: winds, oceanic currents, and 

 migratory birds. 



Winds 



If winds were an important agent in bringing seeds and 

 spores to these islands, those families of plants which have the 

 smallest seeds and spores would be the most apt to be dis- 

 tributed in this way. Of all the families of vascular plants 

 none are better adapted for wind distribution than are the ferns. 

 Such being the case, there should be a larger number of species 

 of ferns on the islands common to the region from which the 

 prevailing winds blow than from any other. As the winds 



