ARTHROPODA. 295 



flies, or Devil's Darning-needles (Libellula), well known 

 by the enormous head and thorax, large, prominent eyes 

 (each furnished with twenty - eight thousand polished 

 lenses), and Scorpion - like abdomen; the delicate and 

 short-lived May-flies (Ephemera); Caddis-flies (Phryga- 

 nea), whose larvae live in a tubular case made of minute 

 stones, shells, or bits of wood ; the Horned Corydalis 

 (Corydalus), of which the male has formidable mandibles 

 twice as long as the head; and the White Ants (Termes) 

 of the tropics. 



2. Orthoptera have four wings: the front pair some- 

 what thickened, narrow, and overlapping along the back ; 

 the hind pair broad, net-veined, and folding up like a fan 



FIG. 2. Metamorphosis of a Cricket (Gryllus). 



upon the abdomen. The hind legs are usually large, and 

 fitted for leaping, all the species being terrestrial, although 

 some fly as well as leap. The eyes are small, the mouth 

 remarkably developed for cutting and grinding. The lar- 



