preposterous length, and ringed prettily enough with black and white.
These delicate fairies make moveable cases, or rather pipes, of the
finest sand, generally curved, and resembling in shape the Dentalium
shell. Guarded by these, they hang in myriads on the smooth ledges
of rock, where the water runs gently a few inches deep. These are
abundant everywhere: but I never saw so many of them as in the
exquisite Cother brook, near Middleham, in Yorkshire. In that
delicious glen, while wading up beneath the ash-fringed crags of
limestone, out of which the great ring ouzel (too wild, it seemed, to
be afraid of man) hopped down fearlessly to feed upon the strand, or
past flower-banks where the golden globe-flower, and the great blue
geranium, and the giant campanula bloomed beneath the white tassels
of the bird-cherry, I could not tread upon the limestone slabs
without crushing at every step hundreds of the delicate Mystacide
tubes, which literally paved the. shallow edge of the stream, and
which would have been metamorphosed in due time into small sooty
moth-like fairies, best represented, I should say, by the soft black-
hackle which Mr. Stewart recommends as the most deadly of North-
country flies. Not to these, however, but to the Phryganeae (who,
when sticks and pebbles fail, often make their tubes of sand, e.g. P.
flava), should I refer the red-cow fly, which is almost the only
autumn killer in the Dartmoor streams. A red cowhair body and a
woodcock wing is his type, and let those who want West-country trout
remember him.

Another fly, common on some rocky streams, but more scarce in the
chalk, is the 'Yellow Sally,' which entomologists, with truer
appreciation of its colour, call Chrysoperla viridis. It may be
bought at the shops; at least a yellow something of that name, but
bearing no more resemblance to the delicate yellow-green natural fly,