Wich it enters as far as the shoulders, if we may use the expression

Anonyme, The Family Cyclopaedia a complete Treasury of Useful Information, Londres, War and Lock, 1859, p. 49

It is well know to anglers, as affording them a choice bait, and is found in brooks and running streams, where it makes itself a grotto, cell, or case of a most singular construction, in which it takes up its habitation while awaiting its transformation in the winged state. In the construction of its grotto, it makes choice of a number of tiny shells and small stones, with which it sets about forming a tube-like dwelling or grotto, about the size of a wheat straw, and equally smooth and uniform in the interior. The materials of this its habitation are very variable in their nature. Sometimes stones, the shells of fresh-water molluscs, or the leaflets of Callitriche, and other aquatic plants ; sometimes, merely a loose roll of bark, or an inch-length of straw. As soon, then, as the worm has attained a moderate degree of strength, when kept in an aquarium, it collects together its materials ; if these be leaves, it locates them in a hole of the rockery, and then buries itself under the heap. With a gummy secretion from its own body it now proceeds to stick a few leaflets together and so make a sort of skeleton (fig. 1) wich it enters as far as the shoulders, if we may use the expression. Next, by twisting and turning about, it completely surrounds itself in a strong and durable structure (fig. 2),quite adequate to protect it against fishes, or any other enemy. In well, nigh the same manner they proceed with stones and shells. They generally use a coarse sort of sand and in this case, attach a small pebble to the bottom (fig. 3) to serve as a balance.

But the ingenuity displayed by these stone builders is wonderful. Instinctively knowing that they will them, they choose only suchstones for the underside as will present a smooth surface to the bed of the pond or stream in which they live ; and thus they save themselves an infinity of labour

The favourite shells used by these insects are the different species of Planorbis(fig. 4) ;  nor are they particular that these shells shouldbe cast off ones, as I have seen PLanorbis himself dragged about, a close prisoner in the train of the tyrant.

Those insects that content themselves with a single roll of bark, or a straw, have merely to attach thereto one or two other twigs or pieces of straw, so as to preserve a balance, and give their cases a sufficient weight (fig. 5).