other zones. Elevation above the level of the sea gives this cooler temperature even in the hottest parts of the earth; and Cypresses, Pines, Oaks, Berberries and Alders, (nearly allied to our own) cover the mountainous districts and elevated plains of Southern Mexico and the chain of the Andes at the Equator. Thus it is given to man in those regions to behold without quitting his native land all the forms of vegetation dispersed over the globe, and all the shining worlds which stud the heavenly vault from pole to pole. (37)

These and many other of the enjoyments which Nature affords are wanting to the nations of the North. Many constellations, and many vegetable forms,—and of the latter, those which are most beautiful, (palms, tree ferns, plantains, arborescent grasses, and the finely-divided feathery foliage of the Mimosas),—remain for ever unknown to them. Individual plants languishing in our hot-houses can give but a very faint idea of the majestic vegetation of the tropical zone. But the high cultivation of our languages, the glowing fancy of the poet, and the imitative art of the painter, open to us sources whence flow abundant compensations, and from whence our imagination can derive the living image of that more vigorous nature which other climes display. In the frigid North, in the midst of the barren heath, the solitary student can appropriate mentally all that has been discovered in the most distant regions, and can create within himself a world free and imperishable as the spirit by which it is conceived.

ANNOTATIONS AND ADDITIONS.

(1) p. 3.—“ On the Chimborazo, eight thousand feet higher than Etna."

Small singing birds, and even butterflies, are found at sea at great distances from the coast, (as I have several times had opportunities of observing in the Pacific), being carried there by the force of the wind when storms come off the land. In the same involuntary manner insects are transported into the upper regions of the atmosphere, 16000 or 19000 feet above the plains. The heated crust of the earth occasions an ascending vertical current of air, by which light bodies are borne upwards. M. Boussingault, an excellent chemist who, as Professor at the newly instituted Mining Academy at Santa Fé de Bogota, visited the Gneiss Mountains of Caraccas, in ascending to the summit of the Silla witnessed, together with his companion Don Mariano de Rivero, a phenomenon affording a remarkable ocular demonstration of the fact of a vertically ascending current. They saw in the middle of the day, about noon, whitish shining bodies rise from the valley of Caraccas to the summit of the Silla, which is 5400 (5755 E.) feet high, and then sink down towards the neighbouring sea coast. These movements continued uninterruptedly for the

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 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

malia which live nearest to the region of perpetual snow are in the Swiss Alps, the Marmot which sleeps through the winter, and a very small field-mouse (Hypudæus nivalis), described by Martins, which on the Faulhorn lays up a store of the roots of phænogamous alpine plants almost under the snow. (Actes de la Société Helvétique, 1843, p. 324.) The beautiful Chinchilla, of which the bright and silky fur is so much prized, is often supposed by Europeans to be an inhabitant of the high mountain regions of Chili: this, however, is an error; the Chinchilla laniger (Gray) only lives in the mild temperature of the lower zone, and is not found farther south than the parallel of 35°. (Claudio Gay, Historia fisica y politica de Chile, Zoologia, 1844, p. 91.)

While on our European Alps, Lecideas, Parmelias, and Umbilicarias form only a few coloured patches on the rocks which are not completely covered with snow, in the Andes, beautiful flowering phænogamous plants, first described by us, live at elevations of thirteen to fourteen thousand feet (13700 to nearly 15000 E.) We found there woolly species of Culcitium and Espeletia (C. nivale, C. rufescens, and C. reflexum, E. grandiflora, and E. argentea), Sida pichinchensis, Ranunculus nubigenus, R. Gusmanni with red or orange-coloured blossoms, 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 limit of perpetual snow on loose boulders of rock, at 14796 (15770 E.) feet above the level of the sea, not at 17000, as stated