216 THE TRICHOPTERA. 



The larvse hatched from these eggs, which, like the 

 perfect insects, are well known to the angler, who 

 calls them Straw- worms, Cadis- worms, and Rough 

 Coats, in allusion to a peculiarity which will be after- 

 wards noticed, are soft grubs of a more or less cylin- 

 drical form, with the head and three anterior segments 

 of the body of a more horny texture than the rest ; 

 they are furnished with six rather long, jointed legs, 

 by the aid of which they creep slowly along the 

 bottom of the water, and the mouth, unlike that of 

 the parent, is armed with strong jaAvs. Respiration 

 is effected by means of a series of filamentous tufts 

 arranged along the sides of the abdomen. 



But the most singular thing connected with these 

 larvae is the faculty which they possess of forming a 

 portable habitation for the protection of their soft 

 bodies, which they appear very justly to suppose would 

 constitute too tempting morsels for the voracious fishes, 

 their cohabitants of the water, if left freely exposed to 

 view. These consist of tubes composed of various ex- 

 traneous materials, such as fragments of leaves, straws, 

 small sticks, sand, and stones ; and some species even 

 make use of the shells of the small freshwater mol- 

 lusca in the construction of their domicile, without 

 paying much attention to the feelings of the rightful 

 owners of the dwellings thus appropriated"^. The 

 building materials are united into a tube of the 

 required form by means of delicate silken threads, 

 which the larva spins from a spinneret situated be- 

 neath the labium, and, according to M. Pictet of 

 Geneva, the creature increases the size of its habita- 

 tion by the addition of materials at the mouth, at the 

 same time cutting off a portion of the opposite end. 



* A few foreign species make a spiral case like a small shell. 



