156 PHYSIOGNOMY OF PLANTS. 



The more considerable the heights at which the Mexican 

 Coniferse are first met with, the more striking it appears to 

 find in the Island of Cuba (where, indeed, on the borders of 

 the torrid zone, northern breezes sometimes cool the atmo- 

 sphere down to 6^ Reaumur, 46.6 Fah.), another species 

 of pine (P. occidentalis of Swartz), growing in the plains or 

 on the low hills of the Isla de Pinos, intermixed with palms 

 and mahogany trees (Swietenias). Columbus mentions a 

 small pine wood (Phial) in the journal of his first voyage 

 (Diario del 5 de Nov. 1492), near Cayo de Moya, on the 

 north-east of the Island of Cuba. In Hayti also, Pinus 

 occidentalis descends from the mountains to the sea-shore, 

 near Cape Samana. The trunks of these Pines, carried by 

 the Gulf-stream to the Islands of Graciosa and Fayal in the 

 Azores, were among the chief indications from which the 

 great discoverer inferred the existence of unknown lands to 

 the west. (See my Examen crit., T. ii. p. 246 259.) Is 

 it true that in Jamaica, notwithstanding the height of its 

 mountains, Pinus occidentalis is entirely wanting? We 

 may also ask what is the species of Pinus found on the 

 eastern coast of Guatimala, as P. tenuifolia (Benth.) proba- 

 bly belongs only to the mountains near Chinanta ? 



If we cast a general glance on the species which form the 

 upper limits of arborescent vegetation in the northern 

 hemisphere, from the frigid zone to the equator, we find, be- 

 ginning with Lapland, that according to Wahlenberg, on the 

 Sulitelma Mountain (lat. 68) it is not needle-trees which 

 form the upper limit, but that birches (Betula alba) extend 

 much higher up than Pinus sjlvestris ; whilst in the tern- 



