Mean temperature 69-5/6° Fahr. " " at 7 A.M. 68 " " at 3 P.M. 71-1/2 " " at 9 P.M. 69 Mean minimum in the night 62-5/7 Highest temperature observed 75 Lowest " " 56 Entire range 19 Mean variation in the 24 hours 10-1/3 Greatest " " 15 Least " " 6 Mean of the dew-point 61-4/5 } " " at 7 A.M. 61.9 } Dry bulb " " at 3 P.M. 62.5 } as above. " " at 9 P.M. 60.9 } The wind generally blows up the valley during the daytime, when the clouds ascend, to be condensed by the colder night-air. Thus we almost invariably had rain at night, generally in a heavy fall, but occasionally in small drizzle, which usually continued until the forenoon. At noon it cleared up for a fine afternoon, and only on two occasions did we have rain throughout the day. The valley, and the course of the river, bear N.N.W. and S.S.E. The three valuable species of chinchonæ found in Tambopata grow in distinct zones as regards elevation, together with other chinchonaceous plants, up the declivitous sides of the ravine. From the banks of the river to about 400 feet up the mountains, the forest consists of bamboos, several genera of palms, tree-ferns, paccays, and other _Leguminosæ_, _Lasionemas_, _Cascarilla Caruas_, and the _Chinchona micrantha_, together with the chinchonaceous tree called by Martinez _Huiñapu_. This is the lower zone. The _C. micrantha_, called by Martinez _verde paltaya_ and _motosolo_,[344] was in flower in May. I met with it constantly in moist low places; and several trees, with their very large ovate leaves, and bunches of white fragrant flowers, were actually drooped over the waters of the river. It produces a good quality of bark, and I collected seven fine seedling-plants of this species.