3i8 THE RIVER-SIDE NATURALIST. 



them pieces of leaves, like a spirally rolled ribbon ; others 

 enclose themselves in a mass of leaves of any aquatic plants ; 

 others, again, form their abodes of minute pieces of wood ; 

 others construct houses which may be called alive, forming 

 them of shells of various aquatic snails of different kinds 

 and sizes. The case of Leptocerus birnaculatus, formed of 

 mixture of sand and mud, is pyriform, and has its end 

 curiously stopped by a plate formed of grains of sand, with 

 a central aperture. . . . Their mode of proceeding in 

 arranging the necessary compensating balance is still more 

 curious. Not having the power of swimming, but only 

 walking at the bottom of the water, it is of great im- 

 portance that its house should be of a specific gravity, so 

 nearly that of the element in which it resides, and it is 

 essential that it should be equally ballasted in every part as 

 to be readily movable in every position. Under these cir- 

 cumstances our caddis-worms evince their proficiency in 

 hydrostatics, selecting the most suitable substances ; and if 

 the cell be too heavy, gluing to it a bit of leaf or straw, or 

 if too light, a shell or piece of gravel. It is from the neces- 

 sity of regulating the specific gravity, that to the cases, 

 formed with the greatest regularity, we often see attached 

 a seemingly superfluous piece of wood, leaf, or the like." 



A very favourite fly on some rivers in April and May is 

 the GRANNOM, one of this family. Ronalds states that it is 

 of the genus Tinodes ; family, Phryganidce. According to 

 Curtis, the grannom is Linnephilus nervosus; family, Phry- 

 ganea. It is very local in its distribution. 



The RED or CINNAMON SEDGE is Phryganea varia (Curtis). 



The SILVER SEDGE Limnephilus 

 flavicornis (Curtis), or Phryganea 

 rhombtca (Donovan). 



There are forty-eight British 

 species of this genus, varying 

 PH.YGANEA vAR.A. from each other. One species, 



Phryganea grandis, is very large, 

 appearing about the same time as the May-Fly. 



The SILVER HORNS of Ronalds (the dark silver twist of 

 fly-makers, so well known as a first-rate grayling fly) is 



