164 APPENDIX. 



Guiana, and the coast of Venezuela and Colombia. It has also many species in com- 

 mon with the flora of the West Indies. 



" This is accounted for partly by the similarity of their climate and partly by the 

 currents of the sea, which *especially favour the migration of species in this direction, 

 whilst the trade-wind brings light seeds from the West Indies. The striking sameness 

 of the vegetation of the coasts of both oceans affords an important proof of the existence 

 of an earlier watercourse where the Isthmus of Panama now lies, and this is confirmed by 

 geological discovery*. The Chiriqui flora has very little in common with Guatemala and 

 Mexico, and still less with Ecuador and the highlands of Cundinamarca. Araucarias, cin- 

 chonas, and bushy chuquiraguas, which are so conspicuous a feature on the Andes within 

 the tropical zone, no more occur on the Cordilleras of Chiriqui than do Mexican pines or 

 oaks f . Pinus occidentalis %, which is predominant in the forests of the upper regions 

 of Guatemala, is not found here, and seems to reach its southern limits at Fonseca 

 Bay. No true pines are found in the woods of the Panama mountains. The number 

 of endemic species in Chiriqui as compared with those extending to other parts of 

 America is approximately as one to twenty-two. 



" No other country in the world yields so large a number of important facts in 

 connection with the geographical distribution of organisms, for the low-lying land of the 

 isthmus constitutes but a slight barrier between the two oceans, while at the same time 

 it affords a slender connecting-link for the migration of species of animals and plants 

 between the two great halves of the American continent. The flora and fauna of the 

 isthmus, too, when compared with those of West Africa, East Asia, and Polynesia, are 

 of peculiar interest to zoological and botanical geography. 



" A horizontal division of the flora presents three somewhat sharply defined longitu- 

 dinal zones of the dominating features of the vegetation, which also coincide with 

 physiognomical peculiarities of the landscape, namely : — 



" 1. A Littoral zone. — The vegetation of this zone is limited on the narrow dunes to 

 such plants as love a soil strongly impregnated with salt. Further inland, varying 

 according to the nature of the locality, these plants are associated with such as 

 flourish in swampy places. Leguminosse and Euphorbiacese abound on the dunes ; 

 while various species of Acacia and Mimosa greatly preponderate in individual numbers. 

 They are mostly thick-stemmed stately trees, like their congeners in the forests of the 

 interior, yet a certain starved appearance betrays a lack of sufficient nourishment in 

 the sandy soil. 



* The inference is a false one, because the elements of the tropical littoral floras have such a very wide 

 range. 



f A little further on he cites two Mexican species of Quercus as inhabiting the Yolcan de Chiriqui ; and 

 Araucarias can hardly be termed characteristic of the Andes. 



t Probably Pinus montezumce, though the specific limits of the Mexican and Central- American pines are 

 still badly defined. 



