16 PHYSICAL FEATURES ETC. 
low hot country of Vera Cruz. Snakes of the genus Crotalus are common in the. 
neighbourhood of Orizaba, but disappear entirely in the wet and cloudy zone about 
Xometla, being again represented by a small species with a poor rattle at an elevation 
of 13,000 feet. Of harmless snakes, only Zropidonotus scalaris. was met with, a 
representative of a typically northern genus. A small lizard, Sceloporus microlepidotus, 
also has a great vertical range from the hot plains of Oaxaca to the upper tree limit of 
Citlaltepetl. 
At their highest camp, 12,500 feet, were stunted pines and juniper, while at their 
feet grew asphodel and tussock grass, which continued to an altitude of nearly 
14,000 feet. At 14,400 feet they reached what appeared to be permanent patches of 
snow, but the white summit of the peak, which from this side they found impracticable 
of ascent, was still 4000 feet above them. | 
At a later date Dr. Gadow, however, ascended the peak itself, an elevation of 
18,200 feet, approaching it on the north-east side from La Barbara. 
Proceeding in a south-easterly direction from Cordova (2700 feet) there was dense 
tropical vegetation on limestone formation all along the foot of the slopes. Eastward 
the country showed open savannas, followed by lagoons, swamps, and low forests 
in the neighbourhood of Agua Fria. The Rio Papaloapan with its many tributaries 
carries an enormous volume of thick yellow water, and for months the low ground 
is to a great extent submerged. Further on, Dr. Gadow describes low undulating 
erazing land, until he reached the railway which crosses the Isthmus of Tehuantepec. 
The eastern slope is clad with humid evergreen forests, but farther west the line 
crosses a ridge at an altitude of rather less than 1000 feet, and passes through dense 
tropical forests with occasional open patches, but on the Pacific coast a drier type of 
vegetation prevails. From Salina Cruz and Tehuantepec north-westwards to the City 
of Oaxaca the land again ascends towards the high plateau. The hills at first are 
covered with low vegetation, until at 3000 feet pines and oaks appear, but nowhere is 
there continuous forest. The general character of the country is dry. Deep gorges 
and sandy river beds alternate with an intricate system of hills and patches of 
xerophile vegetation. Looking south from an altitude of 5300 feet, the tierra caliente 
appears to be densely covered with wood, while to the north is seen a flat, almost 
treeless plateau, with here and there outcropping barren ridges of volcanic nature, or 
with wooded slopes of Paleozoic formation. 
The whole of the Western or Pacific slope is much drier than that of the Atlantic, 
and the vegetation is consequently less dense. Pine trees descend to about 2000 feet, 
and cacti prevail. 
It was on this occasion that, in company with Mr. Julius Flohr, I made a three days’ 
expedition on mule-back from Mexico City to the Cave of Cacahuimilpa, stopping 
at the pretty little town of Cuernavaca en route, from which a fine view of the 
western slope is obtained. 
