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occupied by a cactaceous growth. Although there are many 

 Opuntias, the predominant forms are of the giant Cereus type. 

 The most conspicuous and truly gigantic of them is locally known 

 as "cardon" and is, I believe, a species of Pachycereus. I have 

 seen a single tree under which, I believe, almost an entire 

 company of mounted cavalry might gather. These species 

 bear, for the most part, delicious edible fruits. Among the 

 rocks on the hillsides, great numbers of mammillarias and other 

 dwarf species are encountered. 



We cannot get much farther south than Oaxaca without 

 getting into the truly tropical vegetation of the lowlands. Indeed, 

 we have only to cross the great mountain range south of this 

 canyon, a distance of some fifteen miles, to find ourselves in the 

 fever infested fens of the Tuxtepec valley. 



Here of course the flora is almost totally distinct from any- 

 thing that has been described. The trees are the huge giants 

 which characterize our American tropics and the vines which 

 bind them together are great woody climbers with trunks several 

 inches in diameter and branches extending for hundreds of feet. 

 A variety of palms, some of them of exceeding beauty, occupy 

 the slopes and among them are gigantic, as well as curious and 

 beautiful aroids and superb cycads. Huge ferns, fuchsias, be- 

 gonias and oxalids occupy the ledges and steeper banks, and both 

 terrestrial and arboreal orchids are abundant. The rivers are 

 bordered by great Fici, and several species of spondias, and the 

 swamps are filled with the peculiar Glumaceae and showy aquat- 

 ics which characterize similar situations throughout our tropics. 

 Of this tropical region, time will not permit me to speak, but 

 I can say that, while its general character is like that of Central 

 America, its specific characters are largely unknown. 



College of Pharmacy, 

 New York. 



