296 
COMPARATIVE ZOOLOGY. 
Fig. 265 .—Metamorphosis of an Hemipter, Water-boatmau (NotonectO). 
vse and pupae are active, and resemble the imago. They 
are nearly all vegetarian. Each family produces charac¬ 
teristic sounds (stridulation). The representative forms 
Fig- 266 .—Seventeen-year Cicada (Cicada septendecim): a , pupa; b, the same, after 
the imago, c, has escaped through a rent in the back; d, holes in a twig, where 
the eggs, e, are inserted. 
