8 



ENTOMOLOGY 



or prothorax reduced. Body cylindrical or globular; abdomen with six 

 segments. Ventral tube and furcula usually present, rarely rudimentary. 

 Eyes ocelliform or absent. Antennae of four segments in most genera; 



five or six in a few genera. Integument delicate. 

 Examples, Achorutes (Fig. n), Sminthurus (Fig. 

 12). About seven hundred species have been de- 

 scribed. 



Under the term Apterygota (Apterygogenea, 

 Brauer; Synaptera, Packard) the Thysanura and 

 Collembola, as primitively wingless insects, are 

 conveniently distinguished from all other insects, 

 or Pterygota (Pterygogenea, Brauer). 



3. Orthoptera. -Metamorphosis direct. 

 Mouth parts mandibulate. Wings two pairs as a 

 rule, though not infrequently reduced or absent; 

 front wings coriaceous (tegmina) ; hind pair mem- 

 branous, ample, closely reticulate, plicate along the 

 numerous radiating principal veins. Abdomen 

 with ten or eleven segments. Eight families: For- 

 ficulidae, Hemimeridae(Fig. 13), Blattidae, Mantidae, 

 Phasmidae (Fig. 241), Acridiidae (Fig. 14), Locusti- 

 dae, Gryllidae. Over ten thousand species are 

 known. 



Some authors prefer to separate Forficulidae from Orthoptera as 

 a distinct order, for which Brauer and Packard preserve the old term 

 Derma ptera of Leach, while Comstock uses West wood's term Euplexoptera. 



Hemimeridae consist at pres- 

 ent of two African species whose 

 affinities appear to lie with For- 

 ficulidae, but deserve further 

 study. 



4. Platyptera. Metamor- 

 phosis direct. Mouth parts man- 

 dibulate. Wings, if present, two 

 pairs, delicate, membranous, equal 



FIG. ii. The snow 

 flea, Achorutes nivicola. 

 Length, 2 mm. 



FIG. 12. Sminthurus hortensis. 



1.2 mm. 



Length, 



or hind pair smaller, and with the 



principal veins few and simple. Integument usually thin. Nymphs 



thysanuriform. Two suborders. 



Suborder Corrodentia. Including three families, as follows: 



