trout stream and a heronry are to flourish in the same neighbourhood, the former must be covered in with netting, especially during the spawning season. Another bird which is an enemy to both salmon and trout in their fry stage is the black-headed gull. This bird with its laughing cry hovers over the stream and never lets slip an opportunity of snapping up a brown trout or silvery samlet that has left its place of refuge. The late Francis Francis was fully aware of this fact, and he set down both gulls and terns as most notorious offenders. A couple of hundred gulls will devour at least a thousand smolts per day; and the birds may be seen at Loch Lomond travelling to and from Gull Island and the burns all day, each with a trout or parr in its beak. This must have a considerable effect on the future supply of grilse in the Tweed. As to what part the pretty white-breasted dipper plays in the economy of salmon rivers and trout streams naturalists are by no means agreed. Frank Buckland said that one might as well shoot a swallow skimming over a turnip-field as a dipper over the spawning beds. And this view of the dipper's economy we believe to be the right and just one. Last autumn we had occasion to walk over many miles of trout streams. In these, fish of every size were upon the gravel beds which constitute the spawning "redds." Almost at every turn the white chemisette of the brook bird glinted from some grey stone and went piping before us up stream. As many of these were seen actually rummaging among the pebbles, some few were shot for examination. Although the post-mortems were carefully conducted, no trace in any single instance of the presence of ova of either trout or salmon could be found, but only larvæ of water-haunting insects, roughly representing the four great families of trout-flies. In opposition to the above, however, it must be admitted that individual dippers have been seen with tiny fish in their bills, and even to feed their young ones upon them. Birds in confinement have also been fed upon minnows, but this _penchant_ might be an acquired one. It may be asserted, then, that the ouzel has been known to eat fish, but that fish forms no chief portion of his food; and finally, that it would be quite incorrect to describe it as a fish-eating bird, and therefore as an enemy to salmon and trout. The birds will not long stay where the water is slow or logged; they must have the white foam, the torrent, the pebbly reaches, and the shallows. In fact, they could not obtain their food under conditions other than these. The mountain burns abound with various aquatic insects and their larvæ, and in limestone districts in innumerable fresh-water molluscs. As already shown, not only is the ouzel innocent of destroying eggs of salmon and trout, but it is indirectly beneficial to a fishery. It is well known that among the chief enemies to spawn are the larvæ known as caddisworms, that of the dragon-fly, May-fly and stone-fly, and also of