My remarks respecting the position of _C. Calisaya_ trees, on the sides of the ravine, only apply to the forest below Lenco-huayccu; above that position they are not found so high up the sides of the mountains, probably owing to their greater proximity to the snowy region of the cordillera. The nearest snow may be about forty miles from Lenco-huayccu, as the crow flies. I also found that the _Calisaya fina_ was most abundant about the Yana-mayu, while the variety called _morada_ was plentiful in the upper part of the ravine. But it was very difficult for an unpractised eye to detect the slightest difference between these two varieties, until their leaves were placed side by side, when that of the _morada_ appeared to be just a shade darker green. Dr. Weddell has, in his work, named the _Calisaya morada_, as a distinct species, _C. Boliviana_, but I understand that he is now of opinion that it is scarcely more than a variety of the _Calisaya vera_, its bark being very generally collected and sold as that of the latter. No plants which I saw in the forests could be compared, for vigour and regularity of growth, with the tree which I have already described as having been planted on the edge of a clearing; and I think this tends to prove that plenty of light and air is essential to the vigorous growth of the _C. Calisaya_, so long as there is a sufficient supply of moisture, and protection from the direct rays of a scorching sun for the first year or two. The _C. Calisaya_ is undoubtedly the most delicate and sensitive of all the species of chinchona. Above the region occupied by _C. Calisayas_, in the forests, is the third or upper zone, from 600 to 800 feet above the river. Here, amidst very dense humid vegetation, covered with ferns and mosses, are first met the trees of _C. pubescens_, and _Pimentelia glomerata_, and a little higher up are numerous trees of the two valuable species of _C. ovata_, namely, α _vulgaris_ and β _rufinervis_, with very large ovate leaves, the latter being distinguishable by the deep red of the leaf-veins. The _Cascarilla bullata_ grows with them, and extends still higher up the sides of the mountains. The bark of the β _rufinervis_ variety is habitually used to adulterate the Calisaya, which it very closely resembles, and is called _zamba morada_ by the cascarilleros, while the α _vulgaris_ variety is known as _morada ordinaria_. Martinez said that the _zamba morada_ was very tenacious of life, and that, having once thrown away a branch amongst some moss, he found it a fortnight afterwards, still throwing out shoots. Both varieties of _C. ovata_ yield valuable barks.