I have seen with pleasure that the travels of Sir Robert Schomburgk have fully confirmed these early views. The part of his map which gives the course of the Essequibo and the Rupunuri is entirely new and of great geographical importance. It places the Pacaraima chain in 3° 52′ to 4° North latitude (I had given it 4° to 4° 10′), and makes it reach the confluence of the Essequibo and the Rupunuri, in 3° 57′ N. lat. and 60° 23′ W. long. from Paris (58° 01′ from Greenwich). I had placed this spot half a degree too far to the north. Sir Robert Schomburgk calls the last named river Rupununi, according to the pronunciation of the Macusis; he gives as synonymes of Rupuniri, Rupunuwini and Opununy, the Carib tribes in these districts having much difficulty in articulating the sound of the letter _r_. The situation of Lake Amucu and its relations to the Mahu (Maou) and Tacutu (Tacoto) are quite in accordance with my map of Columbia in 1825. We agree equally well respecting the latitude of the lake, which I gave 3° 35′, and which he finds to be 3° 33′; but the Caño Pirara, (Pirarara) which connects the Lake of Amucu with the Rio Branco, flows from it to the north, instead of to the west as I had supposed. The Sibarana of my map, of which Hortsmann places the source near a fine mine of rock-crystal, a little to the north of the Cerro Ucucuamo, is the Siparuni of Schomburgk’s map. His Waa-Ekuru is the Tavaricuru of the Portuguese geographer Pontes Leme; it is the tributary of the Rupunuri, which approaches nearest to the Lake of Amucu.