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Show 276 ISLAND LIFg. (PART IT. birds, and other animals, as we find to be the case in many small and remote islands. 1 Jllora of the Galapagos.-The plants of these islands are so much more numerous than the known animals, even including the insects, they have been so carefully studied by eminent botanists, and their relations throw so much light on the past history of the group, that no apology is needed for giving a brief outline of the peculiarities and affinities of the flora. The statements we shall make on this suqject will be taken from the Memoir of Sir Joseph Hooker in the Linncean Tra:Lsactions for 1 Juan Fernandez is a good example of a small island whi~h, with tii:1e and favourable conditions, has acquired a tolerably rich and h1ghly peculiar flora and fauna. It is situated in 34° S. Lat., 400 miles from the coast of Cl1ile, and so far as facilities for the transport of living organisms an; concerned is by no means in a favourable position, for the ocean-current~ come from the south-west in a direction where there is no land but the Antarctic continent, and the prevalent winds are also westerly. No doubt, however, there are occasional storms, and there may have been intermediate islands, but its chief advantages are, no doubt, its antiquity and its varied surfaue, offering many chances for the preservation and increase of whatever plants and animals have chanced to reach it. The island consists of basalt, greenstone, and other ancient rocks, and though only about twelve miles long its mountains are three thousand feet high. Enjoying a moist and temperate climate it is especially adapted to the growth of ferns, which are very abundant; and as the spores of these plants are as fine as dust, and very easily carried for enormous distances by winds, it is not surprising that there are twenty-four species on the island, while the remote period when they first received their vegetation may be indicated by the fact that four of the species are quite peculiar. The same general character pervades the whole flora and fauna. For so sma1l an island it is rich, containing a considerable number of flowering plants, four true land-birds, about fifty species o·f insects, and twenty of land-shells. Almost all these belong to South American genera, and a large proportion are South American species; but several of the plants and insects, half the birds, and the whole of the land-shells are peculiar. This seems to indicate that the means of transmission were forme1 ly greater than they are now, and that in the case of land-shells none have been introduced for so long a period that all have become modified into distinct forms, or have been preserved on the island while they have become extinct on the continent.-For a detailed examination of the causes which have led to the modification of tho humming·birds of Juan Fernandez see the author's 1'Topical Natur·e, p. 140; wh1le a general account of the fauna of the i~:ilanu is given in his Gaogntphical Distr·ibution of Animals, Vol. II. p. 49. CIIAl' . Xlll.] TilE GALAPAGOS ISLANDS. 277 1851, founded on.lVIr. Da~win's collections, and a later paper by N. J. Andersson m the Lwncea of 1861, embodyino- more recent discoveries. 0 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 nativ.es of so~e 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, w bile twenty are found only in North America the West Indies, or Mexico. This equality of North America~ a.ml.South A.merican species in the Galapagos is a fact of great sigmficance In connection with the observation of Sir Joseph Hooker, that the pec~~lia?· 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 Compositre,1 remarks on the decided Central American or Mex~can a~nities of the Galapagos species, so that we may consider th1s to be a thoroughly well-established fact. The most. prevalent families of plants in the Galapagos are the Compos1tre (40 sp.), Graminere (32 sp.), Leguminosre (30 sp.), and Euphorbiacere (29 sp.). Of the Compositre most of the speci~s, 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 Lipochreta, represented here by a single species, is only found elsewhere in the Sandwich Islands, though it has American affinities. 0Tigin of .the Galapagos FloTa.-These facts are explained by the past history of the American continent, its separation at 1 Joumal of the L~nnean Society, Vol. XIII., c: Botany, a p. 556. |
