Sometimes pyriform

Anonyme,« Scientific Museum », New York, Scientific American, vol. 8 n°44, juillet 1853, p. 352.

The larvae of these insects are know as caddice-worms ; «  they may be seen at the bottom of shallow water, resembling pieces of wood or stone ; they inhabit cases, sometimes pyriform, polygonal, and horn-shaped or at others in the form of a flutted cylinder orspirally-rolled ribbon ; these they carry with them, protuding a short distance, but with drawing on alarm, although a close fit to the body, the insect has the power of turning round it. Its proficiency in hydrostatics is shown by its attention to the specific gravity use of its house, to which, if too heavy, a bit of straw is glued, or, it too light, a peeble.