THE PERLID^E. 67 



against some floating object or makes its way to the bank ; 

 the skin then splits open and the insect enters the 

 imago stage direct ; the pupal skin is generally left in the 

 water. 



The other class of larva of the Caddis Fly makes a 

 permanent home by spinning a sac, like a bag, attaching it 

 to some sheltered spot, and covering it with stones, etc. 

 It leaves this home in search of food, and when the 

 pupa stage approaches, it partially closes the aperture and 

 undergoes a pupal phase, similar to the one above described, 

 before it assumes its imago existence. Some well-known 

 forms of the Trichoptera are as follows : The Red 

 Sedge, Silver Sedge, Orange Sedge, Grannom, the Welsh- 

 man's Button, the Cinnamon Fly, the Sand Fly, etc. In 

 Plate XVI. will be seen two exquisite drawings of the 

 larva and the pupa of the Caddis Fly by Mr. Knight, 

 magnified about five diameters. 



Fig. i is the larval condition of the Phryganea, one 

 of the Sedge family. 



Fig. 2 is the pupal stage of the same water insect. 



THE PERLID^E. THE STONE FLY. 



The sub-aqueous existence of the Perlidse, after leaving 

 its egg and until maturity is reached, consists of a crawling 

 and swimming larval condition lasting several months, during 

 which phase it gradually matures and attains by progressive 



F 2 



