OF AETS AND SCIENCES. 107 



rents, and birds, — the prevalent direction of the first from the 

 north-west is adverse to tiie supposition tliat any species of phoeno- 

 gamous plants, at least, would be so introduced. The ocean cur- 

 rents might be considered as more favorable, and as likely to bring 

 accessions from the Californian mainland, contributed from the inte- 

 rior by the Sacramento and other smaller streams. But the winds 

 here again would prove an interposing agency, and by creating a sur- 

 face drift toward the coast would prevent floating seeds from attaining 

 any great distance from it. Such as did succeed in reaching the island, 

 and in obtaining and maintaining a foothold upon it, would probably 

 be wholly Californian. Less certain conclusions might be expected in 

 regard to the agency of birds, but it appears, from the collection of the 

 birds of the island made by Dr. Palmer, that they are all in some 

 measure peculiar to the island itself, " consisting almost entirely of 

 familiar forms of the birds of the Western United States, but showing 

 marked peculiarities, entitling them to recognition as geographical 

 varieties. Nothinff Mexicati about them in the slightest decree." * So 

 that, though they demonstrate a connection between the island and 

 California, yet they also indicate that that connection has only been at 

 a remote period, and that their participation in the introduction of 

 plants must have been slight. 



It might therefore be conjectured, if the island were of comparatively 

 recent formation and always disconnected from the mainland, that its 

 flora would show a meagre list of species almost wholly Californian. 

 Or if, on the other hand, it had at some time been connected with the 

 continent, that then its vegetation would be similar to that of the 

 adjacent peninsula, unless some counteracting influence should have 

 been at work, as would seem to be true of the birds. 



To show to what extent the flora of Lower California difi^ers from 

 that of California proper, reference may be made to the list of plants 

 collected by Xantus at the lower extremity of the peninsula, f as given 

 by Dr. Gray in the 6th volume of the Proceedings of this Academy. 

 Of the 118 phanerogamic species there enumerated, only six are probably 

 found even in extreme Southern California, while thirty others range 

 northward only as far as Sonora, or eastward through Mexico to New 



* Prof. Spencer F. Baird, in letter. 



t The Island of Guadalupe is equally distant from San Francisco and Cape 

 San Lucas, but tliree degrees of latitude nearer to the latter point ; and the dif- 

 ference of latitude between the cape and San Diego is little greater than that 

 between Guadalupe and San Francisco. 



