274 PROCEEDINGS OF THE ACADEMY OF [MajT^ 



summits of the Andes. Mr. Jorgensen has kindly furnished us with 

 the following information on these two provinces, which he has 

 examined with considerable care. "Provincia de Mendoza is 

 unusually dry and exceedingly hot (extreme heat 42° C). Rain 

 falls as a rule in local showers, although occasionally there are heavy 

 rainfalls with terrific thunderstorms. As a rule, the sky is cloudless,, 

 and the temperature, even in summer, often falls to a considerable 

 degree at night. In the district around the town of Mendoza it 

 freezes not rarely at night during the 'winter' months (May-Septem- 

 ber), although even at this elevation to see a layer of snow in the 

 morning is rare, and in any event, even in the coldest months, snow 

 never has the opportunity of laying, for it can be quite hot towards 

 midday. Only high up and in the front range of the Cordillera de 

 Mendoza the snow lays for long periods in the very coldest months. 

 In the lowlands, or rather the flat lower lying districts, east of the 

 Cordilleras, the ground is composed of alluvial strata of an ash-gray, 

 finely powdered clay soil, which bears a rich bush vegetation, the 

 gray color of which, together with its adaptation to the climate, points 

 to an ancient desert vegetation. A large proportion of the plants,, 

 quite apart from the cacti, are thorny and spiky, the Spanish name 

 'Espinales' thus suiting the district admirably. The grass fruits 

 are often prickly and also in a single instance mechanical flycatchers.. 

 Many of the plants here are very aromatic or contain quantities of 

 resin. At the transition point between the lowlands and the Cor- 

 dilleras, the ground is more or less rising, here and there swamps are 

 to be found, often strongly impregnated with saltpeter, and nearly 

 everywhere are to be found stones (rolling stones), or even pieces of 

 rock, mixed with the earth. The front ranges of the Cordilleras,, 

 which rise to the west of the city of Mendoza, are partly solid rock 

 and partly products of disintegration. These are covered with the- 

 very same plants as the lowland (Covillea divaricata, Gourhcea decor- 

 ticans, Prosopis campestris and alpataco, Acacia furcata, Senecia 

 mendocinus, Suoeda divaricata, etc.). Localities: Mendoza (767 

 meters above the sea), Chacras de Coria (936 meters), nine kilometers 

 more southerly, both at the foot of the first range, Precordillera de 

 Mendoza; Punta del Agua and Blanco Encalada (1,068 meters) in 

 the mountains and railroad stations on the Ferro Carril Transandina ;, 

 Potrerillos (1,368 meters) and San Ignacio (1,325 meters), railroad 

 stations in a large valley in the second range, Cerro Negro, on the 

 Rio Mendoza; Pedregal (696 meters), seventeen kilometers east of 

 Mendoza, swamps; La Paz (504 meters), forty-eight kilometers 



