- [Footnote: space of an hour, and the objects, which at first were
mistaken for a flock of small birds, proved to be small agglomerations of straws or blades of grass. Boussingault sent me some of the straws, which were immediately recognised by Professor Kunth for a species of Vilfa, a genus which, together with Agrostis, is very abundant in the provinces of Caraccas and Cumana: it was the Vilfa tenacissima of our Synopsis Plantarum æquinoctialium Orbis Novi, T. i. p. 205. Saussure found butterflies on Mont Blanc, as did Ramond in the solitudes which surround the summit of the Mont Perdu. When Bonpland, Carlos Montufar, and myself, reached, on the 23d of June, 1802, on the eastern declivity of the Chimborazo, the height of 18096 (19286 E.) feet—a height at which the barometer sank to 13 inches 11-1/5 lines (14.850 English inches), we saw winged insects fluttering around us. We could see that they were Dipteras, resembling flies, but on a sharp ridge of rock (cuchilla) often only ten inches wide, between steeply descending masses of snow, it was impossible to catch the insects. The height at which we saw them was nearly the same at which the uncovered trachytic rock, piercing through the eternal snows, gave to our view, in Lecidea geographica, the last traces of vegetation. The insects were flying at a height of about 2850 toises (18225 E. feet), or about 2600 E. feet higher than Mont Blanc. Somewhat lower down, at about 2600 toises (10626 E. feet), also therefore within the region of perpetual snow, Bonpland had seen yellow butterflies flying very near the ground. According to our present knowledge the Mam-*]*
