of the Galapagos Archipelago. 237 



between south and east. A failure of this, the trade-wind, caused the extra- 

 ordinary rise of the thermometer mentioned above. 



The nature of the coasts and surface of the islands is in some measure 

 indicated by the plants contained in the various collections, some of the more 

 generally diffused of which may thus be classified with reference to locality. 



The genera Avicennia and Rhizophora, species of both of which bear the 

 name of Mangrove in different parts of the world, prove that in some of the 

 islands at least (Charles and Chatham) there is a phsenogamic vegetation 

 below high-water mark. On the other hand, from the steepness of the coasts 

 and dryness of the soil near the ocean, there appear to be few maritime plants. 

 Those which I presume to be more strictly such are Cissampelos Pareira, 

 Tephrosia littoralis, Sccevola Plumieri, Convolvulus maritimus, Calystegia 

 Soldanella, Verbena littoralis and Heliotropium Curassavicum, all natives of 

 the South American coast, and to which may probably be added some of the 

 peculiar Amaranthacece. 



The lower parts of the island are very arid and rocky, presenting thickets 

 of starved shrubs and leafless trees, and to these situations are assigned * the 

 weeds of the Flora, such as herbaceous or suffrutescent Malvaceae and Euphor- 

 biacece, many species of Borreria, some Compositce, various Lycopersica, Ver- 

 bence, Galapagoa, Boerhaavia and some grasses ; to which may be added some 

 larger shrubs, as small trees of Acacia, Castela, Cactus and Opuntia. Where 

 marshy land occurs, and this is not uncommon on the summits, several species 

 of Cyperus and Mariscus appear; and to a salt lake, which is beautifully 

 fringed with succulent plants, belong Portulaca, some Amaranthacece, Pleu- 

 ropetalum, and probably Sesuvium. 



On ascending the hills the climate and vegetation both suddenly change, 

 the sea-vapours are condensed on the higher parts of the islands, and a com- 

 paratively luxuriant flora is the consequence. From these more favoured loca- 

 lities are brought the greater number of the very peculiar vegetable forms of 

 the island ; curious arborescent Compositce, which have no near allies in other 

 parts of the globe, and of which there are eight species in this group, all 



* In thus assigning localities to the species, I have been guided in many cases by notes attached to 

 the specimens, in some by the plant growing in islands of a uniform surface and character, and in not 

 a few instances by a knowledge of the situations which the species affect in other parts of the world. 



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