270 SOUTH AMEEICA— THE ANDES EEGIONS. 



The lower zone formed by the fringe of thickets is disposed obliquely to the sea- 

 level, descending lower on the south-east slopes exposed to the moist trade winds. 

 The rain wa'er which feeds the arborescent vegetation develops scarcely any 

 springs and but few rivulets. Issuing slowly from the upper clays, the brooks 

 nearly everywhere disappear in the porous lavas of the lower slopes. For the same 

 reason these islands are destitute of guano, although the headlands are the resort 

 of multitudes of birds. The salts, dissolved by infiltration, disappear in the ground. 



Flora and Fauna. 



Despite its distance from the continental seaboard, the insular flora presents 

 an essentially American character. The species, however, are generally distin- 

 guished by their smaller foliage and less brilliant flowers ; there is also an 

 absence of lianas, while orchids and other epiphytes are rare, and in some islands 

 nothing is seen but cactuses. The forests are not bound together in a compact 

 mass of verdure b}^ the coils of trailing plants, like the tropical woodlands of the 

 New World. Palms, musacese, araceae are all absent, and it would almost seem 

 as if, by some strange phenomenon, the flora of the lofty equatorial Andes, as 

 seen at an altitude of 10,000 feet on the flanks of Pichincha, had been bodily 

 transported to the Galapagos volcanoes, only 1,000 feet above sea-level. On the 

 highest summits round the edge of the craters are seen herbaceous growths 

 like those of the paramos on the elevated Andean plateaux. 



In the insular fauna, studied by Darwin, the great naturalist found numerous 

 arguments in favour of the evolutionary doctrine which he afterwards formulated 

 in his Origin of Species. Few oceanic archipelagoes constitute a more distinct 

 biological world in the original form of its plants and animals. The species, how- 

 ever, are not numerous compared with those of tropical regions lying under the 

 same latitude, although during the histoi^ic period increased by new types intro- 

 duced from the Old and New Worlds. 



The primitive mammalian fauna is represented by a single variety of the 

 mouse, and even this was met by Darwin only in Chatham, easternmost member of 

 the archipelago. lie, however, determined the presence of twenty- six species of 

 land birds, all peculiar to the Galapagos except a sparrow resembling the North 

 American lark. One of the most remarkable forms is a bird of prey, already 

 described in 1546 by Pivadeneira under the name of hennoso girifaUe, " beautiful 

 gerfalcon" {erarirex gnlapagoenHis), which destroyed multitudes of young turtles. 



Since Darwin's voyage the naturalist Habel, who lived six months in the 

 archipelago with the orchilla collectors, has doubled the number of known birds. 

 The avifauna at present comprises fifty- eight peculiar species, including one 

 discovered by Markhara, and several islands, such as Albemarle, Hood, Tower, 

 Wenman, and Culpeper, still remain to be explored. Amongst the diiïerent 

 bird-forms several closely resemble each other, and according to a hypothesis of 

 Darwin these descend from a single species, branching off in various direc- 

 tions during the course of ages. At the arrival of the first navigators these 



