258 NATURAL HISTORY OF AQUATIC INSECTS CH. 



Case of vegetable fragments arranged longitudinally or 

 obliquely. Often with a long piece of wood at one end. Pupal 

 case closed with stones. Running water. Halesus radiatus. 



Case curved and tapering behind, of stones and vegetable 

 matter, the stones at the tail-end. Swift streams ; the larva 

 attaches its case in the strongest currents. Halesus auricollis. 



Case of small stones or sand, cylindrical. Streams. Seri- 

 costoma. 



Case flattened, often with larger stones attached at the sides. 

 Rivers and streams. Goera. 



Case quadrangular, of vegetable matter. Rivers and canals. 

 Brachycentrus. 



Cases slender, straight, tapering tubes of fine sand, attached 

 a number together to the stones of streams. Oligoplectrum. 



Case of sand, spirally wound like a snail-shell. S. Europe, 

 America, c., &c. In still water. Helicopsyche. 



Case of fine sand, curved, cylindrical. Still or running 

 water. Fam. Leptoceridc?. 



Case of sand overspread by a sandy shield which projects 

 over the head of the larva. De Geer calls this a " Tortoise- 

 shell case." Still water. Molanna. 



Case of sand, slightly curved, cylindrical. Tail-end closed by 

 a blackish membrane with a central slit. Before pupation the 

 mouth is closed by a single stone. Clear, sub-alpine streams. 

 Odontocerum albicorne. 



Straight or slightly curved, cylindrical cases of fine sand ; 

 tail-end cut off before pupation. Usually in rivers and streams. 

 Leptocerus. 



Case of sand, with long twigs attached. Slow streams, canals 

 and tanks. The larva has the legs, especially those of the third 

 pair, unusually long. Mystacides. 



Case much curved, of fine sand or mud lined with silk. In 

 the spray of waterfalls. Adicella. 



Case of hardened silk. Standing and running water. Setodes. 



Cases fixed, of stones, occasionally inhabited by several larvae. 

 Still or running water. Some Hydropsy chides. 



Larva loosely covered by silken threads, forming a snare. 

 Pupa in solid stony case. Clear rapid streams. Plectrocnemia. 

 Larva covered by vegetable debris, &c., until pupation. Rapid 

 streams. Polycentropus. 



