A covering of dead shells

Anonyme, Tommy Try and what he did in science, New York, D. Appleton,1869, p. 243.

Numerous empty cases of the caddis-worm, also, which had attracted to themselves a covering of dead shells consisting of Limnea, Planorbis, and other species, together with a few fragments of sticks. During the life of the animal, nothing appears but its head and tail ; it thus escapes many attacks from fishes and the larvae of water-beetles (Dytiscus), as it drags its soft and fleshy body along the bottom of its native pool. In the following spring, when I found the animals living in their case, I notice how some species appeared to prefer stone and shells, and others, sticks, straws, and vegetables substances.