jcilKD LIFE IN THE UEUBAMBA VALLEY OF PERU. 21 



Subtropical Zone, and a short distance below the bridge one passes 

 into the arid Tropical Zone. Above the bridge and for the greater 

 l^art of the way to Torontoy, the mountain slopes, and favorable 

 places at the bottom of the canyon are covered with a highlv de- 

 veloped, luxuriant cloud forest, the home of such characteristic 

 species of the humid subtropics as Pliaromaclirus auriceps and 

 Bupieola p. peruviana. (PI. 6.) 



Mr. Heller's description of this locality is appended: 



Immediately below Machu Picchu, on the floor of the valley, is the Bridge of San 

 Miguel, over which passes all the traffic between Cuzco and the lower part of the valley. 

 At this point the walls of the valley rise perpendicularly for 3,000 or 4,000 feet, and in 

 some places, such as opposite the base of Machu Picchu, the walls are 5,000 feet high. 

 The stream margin of the waters for a short distance above the bridge is bordered by 

 wide, gravelly bars and forest-grown flats of river allu^ium. The bridge stands at 

 6,000 feet altitude and enjoys a singularly mild and equable climate. The nights are 

 delightfully cool and the days are semitropical. Much of the canyon at this point is 

 shaded from the direct rays of the sun part of each day by towering cliffs which rise 

 vertically from the floor. A great variety of tree growth occms along the stream and 

 the sides of the valley where talus slopes offer a foot-hold for vegetation. The largest 

 of the trees is one of the Leguminosae of the genus Erythrina which bears a profusion of 

 carmine flowers. This tree is found scattered through the forest bordering the river; 

 its great swollen trunk and wide-spread crown giving it a peculiarly distinct appear- 

 ance. Upon talus slopes and new ground generally gi"ow clumps of the graceful 

 trumpet-trees, Cecropia, the drooping, lobed, peltate leaves giving them a graceful 

 distinction. Killer figs, with strangling limbs and roots fastened to the wall of cliffs 

 or growing as epiphytes on the trunks of other trees, rear themselves in every available 

 nook. A common riverside tree is the pacay, bearing spherical heads of flowers which 

 are a favorite source of food for hummingbirds. Small ferns of many kinds abound in 

 the shade of other trees. Both bamboo and palms are wanting in the immediate 

 neighborhood of San Miguel Bridge. The common trees bordering the stream or 

 growing on the alluvial flats were willows and aldere. (PI. 7.) 



Heller Expedition, June 17-eTuly 10, 1915; Chapman Expedition, 

 July 7, 18, 19, 1916; 269 specimens of 74 species. 



Cedrohamha (altitude 12,000 feet, junction of humid Temperate 

 and Puna Zones). — Although Holler collected only 54 specimens at 

 and near Cedrobamba they form, from a faunal standpoint, the most 

 important part of the entire Urubamba collection. Of the 30 species 

 represented, 18 were not found elsewhere, while 8 of the remaining 

 12 were found only in the Occobamba Valley or above Torontoy, 

 localities which evidently lie in the zone (humid Temperate) which 

 finds its upper limit at Cedrobamba. (PI. 8.) 



Heller's description of this locality is appended: 



The high and narrow ridge upon which the ancient city of Machu Picchu is situated 

 rises in a series of undulations to the southward, the first wave being the peak of 

 Machu Picchu, a second CcorihuajTachina, and the third in a northerly direction the 

 ridge on which stand the ruins of Cedrobamba. The camp at Cedrobamba, which 

 had an altitude of 12,000 feet, was placed a hundred feet below the ruins at the head 

 of one of the tributaries of the Rio Acobamba, a rushing mountain torrent which adds 

 its waters to the Urubamba a mile below San Miguel Bridge. Cedrobamba is situated 



