I left Tungu on the 30th of July, and spent that night at Tallum; where a large party of men had just arrived, with loads of madder, rice, canes, bamboos, planks, etc., to be conveyed to Tibet on yaks and ponies.* [About 300 loads of timber, each of six planks, are said to be taken across the Kongra Lama pass annually; and about 250 of rice, besides canes, madder, bamboos, cottons, cloths, and _Symplocos_ leaves for dyeing. This is, no doubt, a considerably exaggerated statement, and may refer to both the Kongra Lama and Donkia passes.] On the following day I descended to Lamteng, gathering a profusion of fine plants by the way. The flat on which I had encamped at this place in May and June, being now a marsh, I took up my abode for two days in one of the houses, and paid the usual penalty of communication with these filthy people; for which my only effectual remedy was boiling all my garments and bedding. Yet the house was high, airy, and light; the walls composed of bamboo, lath, and plaster. Tropical Cicadas ascend to the pine-woods above Lamteng in this month, and chirp shrilly in the heat of the day; and glow-worms fly about at night. The common Bengal and Java toad, _Bufo scabra,_ abounded in the marshes, a remarkable instance of wide geographical distribution, for a Batrachian which is common at the level of the sea under the tropics. On the 3rd of August I descended to Choongtam, which I reached on the 5th. The lakes on the Chateng flat (alt. 8,750 feet) were very full, and contained many English water-plants;* [_Sparganium ramosum, Eleocharis palustris, Scirpus triqueter,_ and _Callitriche verna?_ Some very tropical genera ascend thus high; as _Paspalum_ amongst grasses, and _Scleria,_ a kind of sedge.] the temperature of the water was 92 degrees near the edges, where a water-insect (_Notonecta_) was swimming about. Below this I passed an extensive stalactitic deposit of lime, and a second occurred lower down, on the opposite side of the valley. The apparently total absence of limestone rocks in any part of Sikkim (for which I made careful search), renders these deposits, which are far from unfrequent, very curious. Can the limestone, which appears in Tibet, underlie the gneiss of Sikkim? We cannot venture to assume that these lime-charged streams, which in Sikkim burst from the steep flanks of narrow mountain spurs, at elevations between 1000 and 7000 feet, have any very remote or deep origin. If the limestone be not below the gneiss, it must either occur intercalated with it, or be the remains of a formation now all but denuded in Sikkim.