flies have dark olive bodies; in the end of April and the beginning of May they are found yellow; and in the summer they become cinnamon-coloured; and again, as the winter approaches, gain a darker hue. I do not, however, mean to say that they are the same flies, but more probably successive generations of Ephemeræ of the same species. The excess of heat seems equally unfavourable, as the excess of cold, to the existence of the smaller species of water-insects, which, during the intensity of sunshine, seldom appear in summer, but rise morning and evening only. The blue dun has in June and July a yellow body, and there is a water-fly which in the evening is generally found before the moths appear, called the red-spinner. Towards the end of August, the Ephemeræ appear again in the middle of the day: a very pale small Ephemera, which is of the same colour as that which is seen in some rivers in the beginning of July. In September and October this kind of fly is found with an olive body, and it becomes darker in October, and paler in November. There are two other flies which appear in the end of September, and continue during October if the weather be mild: a large yellow fly with a fleshy body and wings like a moth; and a small fly with four wings, with a dark or claret-coloured body, that when it falls on the water has its wings like the great yellow fly, flat on its back. This, or a claret-bodied fly, very similar in character, may be likewise found in March or April, on some waters. In this river I have often caught many large trout in April and the beginning of May, with the blue dun, having the yellow body; and in the upper part of the stream below St. Albans, and between that and Watford, I have sometimes, even as early as April, caught fish in good condition: but the _true_ season for the Colne is the season of the May-fly. The same may be said of most of the large English rivers containing large trouts, and abounding in May-fly;—such as the Test and the Kennet; the one running by Stockbridge, the other by Hungerford. But in the Wandle at Carshalton and Beddington, the May-fly is not found; and the little blues are the constant, and when well imitated, killing flies on this water; to which may be joined a dark alder-fly, and a red evening fly. In the Avon, at Ringwood and Fordingbridge, the May-fly is likewise a killing fly; but as this is a grayling river, the other flies, particularly the grannam and blue and brown, are good in spring, and the alder-fly or pale blue later, and the blue dun in September and October, and even November. In the streams in the mountainous parts of Britain, the spring and autumnal flies are by far the most killing. The Usk was formerly a very productive trout stream, and the fish being well-fed by the worms washed down by the winter floods, were often in good season, cutting red, in March, and the beginning of April: and at this season the blues and