BAMIFICATION OF THE MOUNTAINS. 305 



this tract in so eastern a longitude (probably long. 74), is 

 the more remarkable, as we find at four degrees of latitude 

 further north, neither a rock nor a hill on the east of 

 Xeberos, or the mouth of the Huallaga (long. 77 56'). 



We have just seen that the spur of Beni, a sort of lateral 

 branch, loses itself about lat. 8 ; the chain between the 

 Ucayali and the Huallaga terminates at the parallel of 7, in 

 joining, on the west of Lamas, the chain of Chachapayas, 

 stretching betwen the Huallaga and the Amazon. Finally, 

 the latter chain, to which I have given the designation of 

 * central,' after forming the rapids and cataracts of the 

 'Amazon, between Tomependa and San Borja, turns to north- 

 north-west, and joins the western chain, that of Caxamarca, 

 or the Nevados of Pelagatos and Huaylillas, and forms the 

 great knot of the mountains of Loxa. The mean height of 

 this knot is only from 1000 to 1200 toises : its mild climate 

 renders it peculiarly favourable to the growth of the cin- 

 chona trees, the finest kinds of which are found in the 

 celebrated forest of Caxanuma and Uritusinga, between the 

 Rio Zamora and the Cachiyacu, and between Tavacona and 

 Guancabamba. Before the cinchona of Popayan and Santa 

 Fe de Bogota (nor. lat. 2| to 5), of Huacarachuco, Huain- 

 alies, and Huanuco (south lat. 9 to 11), became known, the 

 group of the mountains of Loxa had for ages been regarded 

 as the sole region whence the febrifuge bark of cinchona 

 could be obtained. This group occupies the vast territory 

 between Guancabamba, Avayaca,0fia, and the ruined towns of 

 Zamora and Loyola, between lat. 5 and 3^. Some of the 

 summits (the Paramos of Alpachaca, Saraguru, Savanilla, 

 Gueringa, Chulucanas, Guamani, and Yamoca, which I 

 measured), rise from 1580 to 1720 toises, but are not even 

 sporadically covered with snow, which in this latitude falls 

 only above 1860 to 1900 toises of absolute height. East- 

 ward, in the direction of the Rio Santiago and the Rio de 

 Chamaya, two tributary streams of the Amazon, the moun- 

 tains lower rapidly : between San Felipe, Matara, and Jaen 

 de Bracamoros, they are not more than 500 or 300 toises. 



As we advance from the mica-slate mountain of Loxa 

 towards the north, between the Paramos of Alpachaca and 

 Sara (in latitude 3 15'), the knot of mountains ramifies 

 into two branches, which comprehend the longitudinal 



TOL. III. X 



