On the morning of May 7th, when we commenced our retreat, it was pouring with rain, and the forest was saturated, our bodies sodden, our hands crumpled like washerwomen's, and our powder damp. We had to wade across many little streams falling into the Tambopata. The first, after leaving the Yana-mayu, was called Churu-bamba, because it empties itself just opposite an island (_churu_, in Quichua). The next stream was _Uma-yuyu_, _uma_ being water in Aymara, and _yuyu_ a plant with a large cordate dock-like leaf, used in _chupes_. Thus every little stream and hill had received a name from the cascarilleros of former times, from some peculiarity of position or other similar circumstance, which would easily impress it on the memory. What an improvement on the nomenclature in new countries discovered by Englishmen, where we have an endless succession of Jones's rivers, Smith's mountains, and Brown's islands! Near the banks of these streams there are very large snail-shells, and Martinez described the snails as "large kind of hornets, all made of flesh, which do not sting." He called them _Mamachuru_, or "Mother of the Island." On reaching the precipice of Ccasa-sani we scrambled along its slippery sides, in the pouring rain, to collect plants of _C. Calisaya_, and obtained twenty-one good ones. They were growing in a similar situation to those above the Yana-mayu, in company with a number of _Aceite de Maria_ trees (_Elæagia Mariæ_),[340] and completely exposed to the sun, without any shade whatever. Passing the precipice, we continued our damp weary journey, Martinez pointing out everything that was noticeable by the way, especially the _palo santo_ (_Guaiacum sanctum_), a very tall tree, the stem 60 to 70 feet high, without a branch, with a few short horizontally spreading branches at the summit, with pinnate leaves. When the bark is cut, a host of stinging ants come forth. There was also a plant, which he called _achira silvestre_ (_Canna achira?_) with a rhizome, and bunches of rank red berries. We passed through groves of paccays (_Mimosa Inga_), a creeping legume with bright flowers, wild coca, many _Lasionemas_, with their large coarse leaves drooping over the river, and a melastomaceous plant with a crimson fruit. After having been nearly carried away by the force of the Challuma river, in wading across it, I reached Gironda's hospitable shed, after a journey of more than thirty miles, in pouring rain.