CHAP. XIII.] 



THE GALAPAGOS ISLANDS. 



277 



1851, founded on Mr. Darwin's collections^ and a later paper by 

 N. J. Andersson in the Linnma of 1861, embodying more recent 

 discoveries. 



The total number of flowering plants known at the latter 

 date was 332, of which 174 were peculiar to the islands, while 

 158 were common to other countries. Of these latter about 

 twenty have been introduced by man, while the remainder are 

 all natives of some part of America, though about a third part 

 are species of wide range extending into both hemispheres. Of 

 those confined to America, forty-two are found in both the 

 northern and southern continents, twenty-one are confined to 

 South America, while twenty are found only in North America, 

 the West Indies, or Mexico. This equality of North American 

 and South American species in the Galapagos is a fact of great 

 significance in connection with the observation of Sir Joseph 

 Hooker, that the ^peculiar species are allied to the plants of 

 temperate America or to those of the high Andes, while the 

 non-peculiar species are mostly such as inhabit the hotter 

 regions of the tropics near the level of the sea. He also 

 observes that the seeds of this latter class of Galapagos plants 

 often have special means of transport, or belong to groups whose 

 seeds are known to stand long voyages and to possess great 

 vitality. Mr. Bentham also, in his elaborate account of the 

 Compositse,^ remarks on the decided Central American or 

 Mexican affinities of the Galapagos species, so that we may 

 consider this to be a thoroughly well-established fact. 



The most prevalent families of plants in the Galapagos are 

 the Compositse (40 sp.), Graminese (32 sp.), Leguminos^ (30 

 sp.), and Euphorbiacese (29 sp.). Of the Composite most of 

 the species, except such as are common weeds or shore plants, 

 are peculiar, but there are only two peculiar genera allied to 

 Mexican forms and not very distinct ; while the genus Lipochseta, 

 represented here by a single species, is only found elsewhere in 

 the Sandwich Islands, though it has American affinities. 



Origin of the Galapagos Flora. — These facts are explained 

 by the past history of the American continent, its separation at 



1 Journal of tlie Linnean Society ^ Vol. XIIL, '-Botany/'' p. 556. 



