Henry Doddrige Gordon, The History of Harting, Londres, W. Davy & Son, 1877, pp. 364-365.
A complete collection of the cases of Caddis-worms, must be a singularly interesting one, some of the specie will be seen to be botanists, others conchologists, and others again mineralogists, thus presenting in their economy of stricking analogy to Onustus, an exotic genus of marine molluscs, which incorporate within the substance of their own shells, as fast as they secrete them, fragments of minerals, shells and other materials. One specimen in our own collection (Onustus conchyliophorus), when looked at in its natural position, has the appearance of a small conical heap of portions of shells and entire shells, thrown together in « most admir’d disorder, » but so closely, that no part of the shelly substance in which they are embedded is visible.
The cases of the species of Phryganea proper are formed exteriorly of portions of leaves ingeniously spun together in close spiral order. Those of Limnephilus flavicornis, so abundant in the South Garden ponds, are formed of empty shells, among which however, may occasionally be found one still containing its natural living inhabitant, which, for the credit of the caddis-worm, we hope may have been thus appropriated by mistake. Other individuals of the same species encase their tubes with small seeds, or short lengths of tiny rushes of fine twigs, arranged either transversely or longitudinally. Limnephilus lunatus prefers a coating of grains of sand, but as the quantity of this heavy material increases with the length and diameter of its tube, which, according to Pictet, it enlarges gradually to keep pace with its own growth, it lashes on to one side or the other, or both, without any regard to symmetry, a spar or two of some lighter material, as if to lessen its gravity. Another curious case, which we have often dredged up in the conchological spoon-net, is that of Molanna augustata. This is entirely coated with fine sand, and instead of being tubular, like the others, is nearly flat, with a very oblique aperture at its larger extremity. Many other varieties of cases we have found, some of which, attached to the underside of stones are very rudimantary, while some species of caddis-worm content themselves with cases almost exclusively formed of silk, and others even dispense with the case altogether.