It will be also unavoidable to forego the examination of the sedimentary rocks, rich in fossils, between Honda, Bogotà and Ibagues, the Mastodon fields (_Campos del Gigante_), and the Salto de Tegumidama on the plateau of Bogotà, the wax palm (_Ceroxylon Andicola_), and the Azufrales of the Passo de Quindiu, the volcanoes of Tolima, measured by myself and ascended by Boussingault, and of Paramo de Ruiz (4° 15' N.), as also the two volcanoes of Popayan, the Puracé and the much more interesting but now extinct Sotará. As a middle course, I may suggest a disembarkation, not exactly at Guayaquil, but on the gold and platinum coast of the Choco, near San Buenaventura, so as to proceed thence to Popayan, and afterwards return to the volcanoes of the province of Pasto, which are highly important, and so on to Quitó, by way of Guachucal, Tulcan, and Villa de Ibarra, rejoining the frigate only at Guayaquil. I believe, however, it would be more advisable to select Quitó as the starting-point, whence to examine the important elevated volcanic region De los Pastos (between 2° 20' and 0° 56' N.), containing the volcano of the town of Pasto, the volcanoes of Tuguerres, Chiles and Cumbal, and the Azufral de Pasto, and not to land at any port of the Choco coast, not even from the Bahia de Cupica, which for half a century I have recommended in vain on account of its vicinity to the Rio Naipi, one of the tributaries of the Atrato. In drawing up a list of names of the volcanoes of the renowned lofty plateau of Quitó, I may include, Imbaburu, Cotocachi, Rucu, Pichincha, Antisana, the much-disputed question of the stony walls like streams of lava, on the east slope of Tana Volcan, and Reventazon de Ansango; Cotopaxi, with its strange inexplicable quarries of pumice, of Guapecho and Zumbalica, in the neighbourhood of Llactacunga and San Felipe, the pumice containing oligoclase, not glassy felspar, deposited in strata, like any rock _in situ_ for a considerable distance on all sides of Cotopaxi; Tunguragua (mica slate), studded with garnets, and beds of granite, which dip under the former, and have themselves been pierced by the trachytes of Tungurahua at Rio Puela and the Hacienda de Ganace; the hills of Moya, near the village of Pelilco, cast up in the celebrated earthquake of 7th February, 1797, and still in a state of activity; the Chimborazo, which M. Jules Rémy, accompanied by an Englishman named Princkley, was in the belief they had ascended, on the 3rd of November, 1856, to the very summit, "_mais sans s'en douter_." Poggendorff, (Vol. X. p. 480), has clearly demonstrated that the boiling point given by Rémy for the summit, would not give 6544 mètres (little different from my own trigonometrical admeasurement of 6530 mètres), but fully 7328 mètres. As I distrust my own half-barometical measurements, I have vainly implored travellers, these fifty years past, to have a new series of trigonometrical observations made of the summit of Chimborazo. The merit,