260 PROCEEDINGS OF THE AMERICAN ACADEMY. 



alike than either is to tliat of the iutervening Indefatigable; Jervis 

 lying near James has a greater common floral element with the more 

 distant Charles ; the florulae of the Seymour Islands have a greater 

 number of plants in common with Charles, Chatham, and Albemarle than 

 with Indefatigable, of which the Seymour Islands are merely a detached 

 spur. Although a high percentage of ferns has been recorded on James, 

 not a single representative of this group has thus far been found on the 

 adjacent Indefatigable. The common floral element between Duncan 

 and the relatively remote Chatham is greater than with any of the three 

 large islands, James, Indefatigable, and Albemarle, which to a consider- 

 able extent surround it. In fact, the only cases in which it appears that 

 proximity between two islands has brought about any marked similarity 

 on their floras are on the one hand Narborough and Albemarle, and 

 on the other Gardner and Charles, and even in the former of these 

 pairs, the likeness is by no means close, for not over 71 per cent of the 

 plants of Narborough have been observed on Albemarle. 



These anomalies in the different florulae must find their explanation in 

 peculiarities of climate and soil, together with an element of chance — 

 arising partly from imperfect exploration, and parth' from the accidents of 

 seed-dispersal. Although they are not fully explained by the theory that 

 these are islands of emergence casually seeded, they are much less in 

 accord with the Baur theory of subsidence ; for, were the florulae rem- 

 nants of a common flora persisting upon islands separated by gradual 

 subsidence, it is evident that those islands would jwssess the most floral 

 similarity which were nearest together and divided by the shallowest 

 channels, since these would have been separated from each other more 

 recently than the remoter islands, which are cut off" by a greater depth of 

 ocean. As we find no such relation prevailing in the Galapagos Islands, 

 but have observed just the reverse, namely, that the more distant islands, 

 separated by relatively deep channels, often show greater floral similarity 

 than the nearer ones, it is necessary to conclude that the botanical evi- 

 dence, so far as it has yet been made out, is opposed rather than favorable 

 to the subsidence theory. 



Addenda. 



Plants collected on the Galapagos Islands hy Dr. Franz Steindachner 

 of the Hassler Expedition. 



After the greater part of the present paper was in type, I received 

 through the kindness of Dr. A. Zahlbruchner and Dr. A. Heimerl of 



