I said just now, that happy was the sportsman who was also a naturalist. And, having once mentioned these curious water-flies, I cannot help going a little farther, and saying, that lucky is the fisherman who is also a naturalist. A fair scientific knowledge of the flies which he imitates, and of their habits, would often ensure him sport, while other men are going home with empty creels. One would have fancied this a self-evident fact; yet I have never found any sound knowledge of the natural water-flies which haunt a given stream, except among cunning old fishermen of the lower class, who get their living by the gentle art, and bring to indoors baskets of trout killed on flies, which look as if they had been tied with a pair of tongs, so rough and ungainly are they; but which, nevertheless, kill, simply because they are (in _colour_, which is all that fish really care for) exact likenesses of some obscure local species, which happen to be on the water at the time. Among gentlemen-fishermen, on the other hand, so deep is the ignorance of the natural fly, that I have known good sportsmen still under the delusion that the great green May-fly comes out of a caddis-bait; the gentlemen having never seen, much less fished with, that most deadly bait the “Water-cricket,” or free creeping larva of the May-fly, which may be found in May under the river-banks. The consequence of this ignorance is that they depend for good patterns of flies on mere chance and experiment; and that the shop patterns, originally excellent, deteriorate continually, till little or no likeness to their living prototype remains, being tied by town girls, who have no more understanding of what the feathers and mohair in their hands represent than they have of what the National Debt represents. Hence follows many a failure at the stream-side; because the “Caperer,” or “Dun,” or “Yellow Sally,” which is produced from the fly-book, though, possibly, like the brood which came out three years since on some stream a hundred miles away, is quite unlike the brood which is out to-day on one’s own river. For not only do most of these flies vary in colour in different soils and climates, but many of them change their hue during life; the Ephemeræ, especially, have a habit of throwing off the whole of their skins (even, marvellously enough, to the skin of the eyes and wings, and the delicate “whisks” at their tail), and appearing in an utterly new garb after ten minutes’ rest, to the discomfiture of the astonished angler.