the entomology of mountain streams little as yet is known: but a few
scattered hints may suffice to show that in them, as well as in the
chalk rivers, a little natural science might help the angler.

The well-known fact that smaller flies are required on the moors than
in the lowlands, is easily explained by the fact that poorer soils
and swifter streams produce smaller insects. The large Phryganeae,
or true caperers, whose caddis-baits love still pools and stagnant
ditches, are there rare; and the office of water-scavenger is
fulfilled by the Rhyacophiles (torrent-lovers) and Hydropsyches,
whose tiny pebble-houses are fixed to the stones to resist the
violence of the summer floods. In and out of them the tiny larva
runs to find food, making in addition, in some species, galleries of
earth along the surface of the stones, in which he takes his walks
abroad in full security. In any of the brown rivulets of Windsor
forest, towards the middle of summer, the pebble-houses of these
little creatures may be seen in millions, studding every stone. To
the Hydropsyches (species montana? or variegata? of Pictet) belongs
that curious little Welsh fly, known in Snowdon by the name of the
Gwynnant, whose tesselated wing is best imitated by brown mallard
feather, and who so swarms in the lower lakes of Snowdon, that it is
often necessary to use three of them on the line at once, all other
flies being useless. It is perhaps the abundance of these tesselated
Hydropsyches which makes the mallard wing the most useful in mountain
districts, as the abundance of the fawn and grey Phryganidae in the
south of England makes the woodcock wing justly the favourite. The
Rhyacophiles, on the other hand, are mostly of a shining soot-grey,
or almost black. These may be seen buzzing in hundreds over the
pools on a wet evening, and with them the sooty Mystacides, called
silverhorns in Scotland, from their antennae, which are of