The Artigua--I shall call it so, to do what I can to save the name from oblivion--is woefully polluted by the gold-mining on its banks, and flows, a dark muddy stream, through the village of Santo Domingo, and just below it precipitates itself one hundred and twenty feet over a rocky fall. One of the forest roads leads down its banks for several miles to some small clearings, where a few scattered, Spanish-speaking Indians and half-breeds cultivate maize and plantains. After leaving Santo Domingo, it at first follows the left bank of the stream, through low bushes and small trees of second growth, then crosses a beautiful clear brook coming down from the east, and finally winding round a slope covered with great trees and dense undergrowth, reaches the site chosen for the machinery at Pavon, where a large space has been cleared, much of which is covered with grass. After descending a steep hill, the Artigua, with its muddy water, is crossed. Here, in the dry season, in the hot afternoons, the wet sandy banks were the favourite resorts of multitudes of butterflies, that gathered in great masses on particular moist spots in such numbers that with one swoop of my net I have enclosed more than thirty in its gauzy folds. These butterflies were principally different species of Callidryas, yellow and white, mixed with brown and red species of Timetes, which, when disturbed, rose in a body and circled about; on the ground, looking like a bouquet; when rising, like a fountain of flowers. In groups, by themselves, would be five or six specimens of yellow and black Papilios, greedily sucking up the moisture, and vibrating their wings, now and then taking short flights and settling again to drink. Hesperidae, too, abounded; and in a favourable afternoon more than twenty different species of butterflies might be taken at these spots, the finest being a lovely white, green, and black swallow-tailed Papilio, the first capture of which filled me with delight. Near the river were some fallen-down wooden sheds, partly overgrown with a red-flowered vine. Here a large spider (Nephila) built strong yellow silken webs, joined one on to the other, so as to make a complete curtain of web, in which were entangled many large butterflies, generally forest species, caught when flying across the clearing. I was at first surprised to find that the kinds that frequent open places were not caught, although they abounded on low white-flowered shrubs close to the webs; but, on getting behind them, and trying to frighten them within the silken curtain, their instinct taught them to avoid it, for, although startled, they threaded their way through open spaces and between the webs with the greatest ease. It was one instance of many I have noticed of the strong instinct implanted in insects to avoid their natural enemies. I shall mention two others. The Heliconidae, a tribe of butterflies peculiar to tropical America, with long, narrow, weak wings, are