where the barometer had fallen to 14·84 inches, we found winged insects buzzing around us. We recognised them to be Diptera, resembling flies, but it was impossible to catch these insects standing on the rocky ledges (_cuchilla_), often less than a foot in breadth, and between masses of snow precipitated 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, (Hypudæus nivalis,) described by Martius, which on the Faulhorn lays up, almost under the snow, a store of the roots of phanerogamic alpine plants.[JC] 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 Chinchilla laniger (Gray) lives only in a mild lower zone, and does not advance further south than the parallel of 35°.[JD] 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, we 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. (Culcitium 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 Saxifraga 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 journals.[JE] This Saxifrage, discovered by Boussingault, must therefore be regarded as the highest growing phanerogamic plant in the world.