250 



FRESH-WATBB AQTJAEIA. 



there will be noticed an insect much slenderer than either of 

 the former, and instead of the spine-like projections at the 

 end of the body, there will be some beautiful leaf -like appen- 

 dages — often of considerable length. This is the larva of one 

 of the Agrionides. 



All these larvae, to whatever sub-family they belong, are 

 extremely predaceous, and get their living by preying upon 

 their weaker companions of the water. They occasionally do 

 not hesitate, if food is scarce, to become cannibals. Unlike 

 some aquatic carnivorous creatures, such as Nepa cinerea, 



Fig, 155. Pup^e of Duagon-flies. 



they do not kill unless to satisfy hunger. Nor are they 

 quarrelsome. 



They obtain their prey in a most extraordinary manner. 

 They are really hypocrites, for they wear a "mask.'' This 

 "mask" is a deadly and very curious apparatus. It is a re- 

 markable arrangement of the lower lip or labium, and consists 

 of several joints. The first joint is about ^in. long, more or 

 less, according to the size and species of the insect, and it is 

 also about one-third of its length broad, and very thin. One 

 end of this piece is fixed, so to speak, under the chin of the 

 animal, and at the other end there is attached a somewhat 

 similar joint, but rather broader at its further extremity. At 



