J. LeConte — Flora of Coast Islands of California. 459 



pose, largely prevent the colonization of common American 

 forms on the islands, although some such colonization has in 

 fact taken place. But with the prevailing winds in this direc- 

 tion, why have not all the peculiar island species been long ago 

 colonized on the mainland ? According to the view above 

 presented the answer is evident. These peculiar species did 

 once inhabit the mainland, and have been either destroyed or 

 transformed by the struggle with invaders. They are there- 

 fore weaker species. The same unfitness which made them suc- 

 cumb then, still forbids their successful colonization. This 

 brings me to the next point. 



There are quite a number of rare and peculiar forms found 

 struggling for existence in the southern counties which are 

 found very abundant on the islands. This certainly looks like* 

 the beginning of colonization. This is indeed Mr. Greene's 

 view, and is rendered all the more probable by the fact that 

 the ocean currents probably drift in that direction. But there 

 is at least another explanation suggested by the view above pre- 

 sented. These may be, and probably are, remnants of Pliocene 

 indigenes still undestroyed, but ready to perish. From this 

 point of view their place far south is just what we might ex- 

 pect, for the main invasion was from the north. 



But there is still a last point to be explained. Lavateras are 

 unknown in the New World, except on these islands, where 

 there are four species. But they are found in the Old World, 

 in the Mediterranean region and in Australia. Mr. Greene sug- 

 gests, as a possible explanation, a former connection of these 

 islands with some other continent. I think not. The substantial 

 permance of continental land masses and oceanic basins, with 

 only marginal changes, at least during later geological times — 

 taken together with the comparative recency of the flora of 

 California — renders this explanation extremely improbable. 

 The above presented view suggests another and far more prob- 

 able explanation. 



The existence of Lavateras in such widely separated localities 

 as Australia, the Mediterranean region and the coast islands of 

 California, shows unmistakably that existing species are but 

 remnants of an old, once very abundant and widely spread 

 genus, with numerous species. They are now dying out. They 

 have been mostly destroyed and replaced by newer and stronger 

 forms. I conclude, therefore, that in Pliocene times several 

 species of Lavatera existed all over the coast region of Califor- 

 nia, but probably mostly in the then coast range, viz : the 

 islands ; for they love the sea coast. They have all been de- 

 stroyed by change of environment, physical and organic, except 

 those isolated on the islands and thus saved from the effects of 

 invasion. 



