ILLUSTRATIONS (1). THE CHIMBOKAZO. 233 



be Diptera, resembling flies, but it was impossible to catch 

 these insects standing on the rocky ledges (cachUla), often 

 less than a foot in breadth, and between masses of snow pre- 

 cipitated from above. The elevation at which we observed 

 these insects was almost the same as that in which the naked 

 trachytic rock, which projected from the eternal snows around, 

 exhibited the last traces of vegetation in Lecidea geographica. 

 These insects were flying at an elevation of 18,225 feet, or 

 nearly 2660 feet higher than the summit of Mont Blanc : and 

 somewhat below this height, at an elevation of 16,626 feet, 

 and therefore also above the region of snow, M. Bonpland saw 

 yellow butterflies flying close to the ground. The mammalia 

 which live nearest to the region of perpetual snow, are, in the 

 Swiss Alps, the hybernating marmot, and a very small field- 

 mouse, (Hypudsous nivalis,) described by Martius, which on 

 the Faulhorn lays up, almost under the snow, a store of the 

 roots of phanerogamic alpine plants.* 1 The opinion prevalent 

 in Europe, that the beautiful rodent, the Chinchilla, whose 

 soft and glossy fur is so much esteemed, is found in the 

 highest mountain regions of Chili, is an error. The Chin- 

 chilla laniger (Gray) lives only in a mild lower zone, and 

 does not advance further south than the parallel of 35°.f 



Whilst among our European Alps, Lecideas, Parmelias, and 

 Umbilicarias but scantily clothe with a few coloured patches 

 those rocks that are not wholly covered with snow, Ave found 

 in the Andes, at elevations of 13,700 to nearly 15,000 feet, 

 some phanerogamic plants which we were the first to describe; 

 as for instance, the woolly species of Fraylejon, (Culeitium 

 nivale, C. rufescens, and C. reflexum, Espeletia grandiflora, 

 and E. argentea) Sida pichinchensis, Ranunculus nubigenus, 

 R. Gusmanni with red or orange-coloured flowers, the small 

 moss-like umbelliferous plant, Myrrhis andicola, and Fragosa 

 arctioides. On the declivity of the Chimborazo, the Saxi- 

 fraga Boussingaulti, described by Adolph Brongniart, grows 

 beyond the limits of perpetual snow on loose blocks of stone 

 at an elevation of 15,770 feet above the level of the sea, and 

 not at 17,000 as has been stated in two admirable English 



* Actes cle la Societe Helvetique, 1843, p. 324. 



+ Claudio Gav, Historia fisica y politica cle Chile, Zoologia, 1844, 

 p. 91. 



