518 CALIFORNIA ACADEMY OF SCIENCES. 



ing to the view above presented the answer is evident. 

 These peculiar species did once inhabit the mainland and 

 have been either destroyed or transformed in the struggle 

 with invaders. They are therefore iveaker species. The 

 same unfitness which made them succumb 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 beginnings 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 presented. 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 expect, 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 suggests, as a possible explanation, a former 

 connection of these islands with some other continent. I think 

 not. The substantial permanence of continental land masses 

 and oceanic basins, with only marginal changes, at least 

 during later geological times — taken together with the com- 

 parative recency of the flora of California — renders this ex- 

 planation extremely improbable. The above presented 

 view suggests another and far more probable 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 



