LAEViE OP WATER-PLIES. 245 



before it " annexes " a stell, wtetlier the owner of it has left 

 or not; for it is by no means an unusual thing to find a 

 caddis-case composed of shells in which the animals still live. 

 This is rather hard upon the poor molluscs, for they have 

 to be carried about as their captor wishes. It is a very 

 good plan for those who are collecting fresh-water shells to 

 examine the cases made by the lai-vse of L. flavicornis. Of 

 course, it will be readily seen that the tubes formed of such 

 a variety of materials must often be very irregvilar, as well 

 as apparently cumbersome. 



The larvae of L. lunatus make a case of sand or vegetable 

 material, to which they attach long pieces of stick, which 

 project at either end (c. Fig. 151). These long bits of wood 

 seem to act as balancers. This case is generally found in 

 stagnant or very slow-running water. 



The larvsB of L. vittatus make a ciu'ved case of fine sand. 

 It may be likened in shape to an elephant's tusk, and in 

 appearance it is somewhat similar to e, Fig. 151. 



The larvae of L. pellucidus make cases chiefly composed of 

 whole leaves, laid almost flat against each other. The " worm " 

 itself is inclosed in a tube vfithin the leaves. This is by no 

 means an uncommon case in some parts of the country. It 

 is generally found in stagnant water. 



The larvae of the genus Stenophylax live in streams, and 

 make their tubes of tiny pebbles (6, Fig. 161). Sometimes 

 when the water is very swift, the cases are fastened slightly 

 to large stones. If the collector will take the trouble to 

 examine the lower part of large stones in quick-running 

 streams, he will frequently find bunches of very small gravel 

 attached to that pai-t. So firmly are they fastened that it 

 requires quite a strong pressure of the finger or thumb to 

 remove them. These bunches are fixed cases of the Caddis- 

 worm. The larvae of Caddis-flies found in quick-running 

 water ai'e not suitable for the aquarium. 



As the Caddis-worm grows, it enlai-ges its case by making 

 an addition to the larger end. When this is done, the case 

 is shortened at the other end. While the Caddis-worm is 

 moving from'/place to place, it protrudes its body juSt suffi- 



