OF HARTING. 365 



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 em- 

 bedded 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 Limne- 

 philus flavicornis, so abundant in the South Garden 

 ponds, are formed of empty shells, among which, 

 however, may occasionally be found one still con- 

 taining 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 or fine twigs, arranged 

 either transversely or longitudinally. LimnepJtilus 

 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 

 angustata. 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 

 rudimentary, while some species of caddis-worm con- 

 tent themselves with cases almost exclusively formed of 

 silk, and others even dispense with the case altogether. 



When the larva has attained its full development, it 

 spins a cable, with which it securely moors its case to 

 a stone or some other firm support, and carefully 

 closes the aperture at each extremity with an open 

 network of silk. Through this network the water, 



