_A_. The volcano of Aconcagua (32° 39' S.). Its height has been stated, in 1835, by Captain Fitzroy, as 21,767 feet, Pentland's correction assigning 22,431 feet; while Captain Kellet, of the frigate _Herald_, gives it as 21,584 feet. Miers and Darwin are both of opinion that the Aconcagua is still in activity, which is denied by Pentland and Gilliss. The most recent measurement of Aconcagua--that by Pissis in 1854 (see Gilliss, Vol. I. p. 63)--makes the height 20,924 feet. M. Pissis has published, in the "Anales de la Universidad de Chili," for 1852, the geodetical elements of his survey, which is based upon eight triangles. Aconcagua being probably the highest mountain in the New World, a new measurement is eminently desirable. Neither Dhawalagiri, with his 4930 toises, nor Kintsinjunga, measured by Colonel Waugh, with his 4406 toises, are any longer considered the highest mountains in the Himalaya range, but the Deodunga (Mount Everest), which is 29,003 English feet, equal to 27,212 Paris feet, or 4535 toises. _B._ The volcano Maipu (34° 17' S., height 16,572 feet), ascended by Meyen. The trachytic rock on the summit has broken through the Jurassic strata, in which Leopold von Buch has ascertained, from heights of 9000 feet, the existence of _Exogyra couloni_, _Trigonia costata_, and _Ammonites biplex_. This volcano has no streams of lava, but only eruptions of volcanic slags. It would be most desirable that Dr. Hochstetter should examine this remarkable protrusion of dislocated strata. _C._ The volcano Antuco (37° 7' S.), the geology of which was described by Pöppig, is a lofty basaltic crater, having a trachytic cone rising up in its centre to an elevation of 8672 feet. It was observed in full activity by Domeyko in 1845. Gilliss gives an account of an eruption in 1853. According to Domeyko, a fresh-burning cone was thrown up on the 25th of November, 1847, which remained in activity for a whole year. Molina considers the Nevada Descabezado (35° 1' S.), ascended by Domeyko, to be the highest mountain in Chili; but its height is estimated by Gilliss at only 12,300 feet. The most southerly volcanoes are the still active Corcovado (43° 12' S.), 7046 feet; Yanteles (43° 29' S.), 7534 feet; and the Volcan de San Clemente, opposite the granite formation on the peninsula of Tres Montes. Still further south, in 51° 41' S., another, the Volcan de los Gigantes, is laid down on the old maps of South America, by La Cruz Olmedella, as opposite the archipelago of La Madre de Dios. Should the _Novara_ return to Europe through the Straits of Maghellanes, it would be very desirable the members of the Expedition should visit the locality from which Prince Paul of Würtemberg, after long zoological travels through North America, has, within the last year, brought back to Germany a very large collection of specimens.