14 BULLETIN 117, UNITED STATES NATIONAL MUSEUM. 



The decrease in altitude and the presence of water combine to 

 produce considerable bushy and arborescent growth with a corre- 

 sponding increase in the number of arid Temperate Zone species. 

 Country of essentially this type (see Heller's descriptions under 

 Chospiyoc and Ollantaytambo) prevailed down the Urubamba Valley 

 until we reached a short distance below Torontoy (which see), where 

 at the bottom of the canyon and on the steep slopes arising from it we 

 saw the first traces of forest growth, and at the same time entered the 

 upper border of the Subtropical Zone. 



Paroquets (Aratinga m. mitrata), ant thrushes (TJiamnophilus 

 melanochrous) , flycatchers {Knipolegus) , vireos {Vireosylva j. 

 josephae), warblers {Myioborus m. melanocepJialus and Basileuterus 

 luteoviridis signatus), and other characteristic subtropical species 

 suddenly became common, and a single cock-of-the-rock was seen. 



From this point the vegetation increased in luxuriance. In places 

 the narrow floor of the canyon was grown with highly developed 

 forest which, unbroken, covered the slopes that were not too steep 

 to permit of tree growth. (PI. 6.) 



The region seemed well adapted to the wants of birds, nevertheless 

 comparatively few were seen and it was only by the most diligent 

 collecting that we secured a fair number of specimens. It should, 

 however, be remembered that the season was midwinter (July) and 

 but few birds were in song. Day broke in almost complete silence. 

 An occasional cassique (Ostinops atrovirens) called, a wood wren 

 {HenicorTiina) sang at intervals, but the croak of toucans and the 

 cooing of doves, which form so prominent a part of the morning 

 chorus in the subtropics and humid tropics, were wholly wanting. 



Shortly before reaching San Miguel Bridge, at the base of the 

 mountain on which lie the ruins of Maclm Picchu, made known to 

 the world by Professor Bingham's explorations, the luxuriant forest 

 growth disappears and we quickly pass into the upper border of the 

 arid tropics with its low scrubby growth in which acacias and cacti 

 characterize the vegetation and Tapera naevia and Thraupis episcopus 

 the birds. (PI. 5.) 



Santa Ana, the end of our journey down the valley, is in the heart 

 of this arid Tropical Zone, which extends at least to Echarati where 

 the forest of the humid Tropical Zone is said to begin. This we did 

 not reach and our only collections from it were made by Heller at 

 Rio Cosireni and Rio Comberciato about 50 miles below Echarati. 



From Santa Ana we ascended the mountain slopes to the Sub- 

 tropical Zone at Idma, finding there essentially the same species as 

 occur in this zone above San Miguel Bridge. 



The more detailed description of our collecting stations follows: 



La Raya (altitude 14,010 feet, Puna Zone). — The pass at La Raya 

 on the railroad to Cuzco marks the divide between Titicacan and 



