246 X DR. HOOKER'S MISSION TO INDIA. 
Polygala abound, with Banana, and the usual larger trees. A fine 
Citrus also occurs, some Sapindacee and Verbenacee, as Premna, 
Clerodendron, Volkameria, and Callicarpa ; shrubby Acanthacee, 
Menispermee, Vitis, &c. Large fish are abundant in the beautifully 
clear water of the river. But by far the most striking feature consists 
in the amazing quantity of superb butterflies, those beautiful tropical 
swallow-tails, black with scarlet or yellow eyes of great size, Nym- 
phalidee, and, indeed, of almost all Orders but Coliadee, which appear 
scarce. They flutter everywhere, or sail majestically through the still 
hot air, skipping from one scorching rock to another, and especially 
loving to settle on the damp sand of the river-edge. There they sit 
by thousands, with erect wings, and, balancing themselves with a 
rocking motion, as their heavy sails incline them to one side or the 
other, they resembled a crowded fleet of yachts on a calm day. Such 
an entomological display cannot be surpassed. Cicindele were very 
numerous, and incredibly active, so were Grylli ; and the great Cicadee 
were everywhere lighting on the ground, where they utter a short sharp 
creaking sound, and anon disappear, as if by magic. Of birds I saw 
none. A few exquisitely beautiful whip-snakes were gleaming in the 
sun: they hold on by a few coils of the tail round a twig, the greater 
part of their body stretched out horizontally, occasionally retracting, 
and darting with unerring aim at some insect in the air or on the twig. 
I caught one by cautiously approaching with a long bamboo. All the 
rocks im situ along the river-bank are very hard, of gneiss, passing 
into clay-slate, dipping like those at Darjeeling at various angles. The 
boulders in the bed were chiefly of similar rocks, but often of mica- 
schist, with garnets, and of gneiss, traversed by quartz veins, in 
various directions. I picked up a good many pieces of trap: some 
were very ponderous and ferrugineous. A large water-worn lump of 
plumbago was found by one of the men,—no limestone was to be 
. seen. The narrowness of the gorge, and excessive steepness of the 
bounding hills, prevented any view, except of the opposite mountain 
~ face, which is one dense forest, conspicuous, as usual, for the Banana. 
Towards evening we arrived at another cane-bridge, still more 
dilapidated than the former, but quite similar in structure. For a few 
hundred yards before reaching it, the path led along the precipitous 
= face of slate-rocks overhanging the stream, which dashed with great 
violence at its foot. Though we could not proceed comfortably, even 
