ANNOTATIONS AND ADDITIONS. 155 



are hailed with joy by those who come from the sea-coast, 

 as indicating a climate where, so far as experience has 

 hitherto shewn, the deadly malady of the black vomit (Yo- 

 mito prieto, a form of yellow fever) does not reach. The 

 lower limit of oaks, and more particularly of the Quercus 

 xalapensis (one .of the 22 Mexican species of oak first de- 

 scribed by us), is on the road from Yera Cruz to the city of 

 Mexico, a little below the Yenta del Encero, 2860 (3048 

 E.) feet above the sea. On the western side of the high- 

 lands between the city of Mexico and the Pacific, the limit 

 is rather lower down, for oaks begin to be found near a hut 

 called Yenta de la Moxonera, between Acapulco and Chil- 

 panzingo, at an absolute elevation of 2328 (2480 E.) feet. 

 I found a similar difference in the height of the lower limit 

 of pine woods on the two sides of the continent. On the 

 Pacific side, in the Alto de los Caxoues north of Quaxini- 

 quilapa, we found this limit for Pinus Montezumse (Lamb.), 

 wlu'ch we at first took for Pinus occidentalis (Swartz), at an 

 elevation of 3480 (3709 E.) feet; while towards Yera Cruz, 

 on the Cuesta del Soldado, pines are first met with at a 

 height of 5610 (59bO E.) feet. Therefore both the kinds 

 of trees spoken of above, oaks and pines, descend lower 

 on the side of the Pacific than they do on the side of 

 the Antillean sea. In ascending the Cofre di Perote, I 

 found the upper limit of the oaks 9715 (10354 E.) feet, 

 and that of the Pinus Montezumas at 12138 (12936 E.) feet 

 above the sea, or almost 2000 (2132 E.) feet higher than 

 the summit of Etna. Considerable quantities of snow had 

 fallen at this elevation in the month of February. 



