10 



ENTOMOLOGY 



2. Collembola. No metamorphosis. Mouth parts entog- 

 nathous and typically mandibulate, with occasional secondary 

 suctorial modifications. Wings invariably absent. Thoracic 

 segments simple and similar or prothorax reduced. Body 

 cylindrical or globular; abdomen with six segments. Ventral 

 tube and furcula usually present, rarely rudimentary. Eyes 

 ocelli form 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 described. 



FIG. 13. 



FIG. 14. 



Hemimerus talpoides. 

 Length, 11.5 mm. After 

 HANSEN. 



Schistocerca americana. Slightly reduced. 



Under the term Apterygota (Apterygogenea, Brauer; 

 Synaptera, Packard) the Thysanura and Collembola, as primi- 

 tively wingless insects, are conveniently distinguished from all 

 other insects, or Pterygota (Pterygogenea, Brauer). 



3. Orthoptera. Metamorphosis direct. Mouth parts man- 

 dibulate. Wings two pairs as a rule, though not infrequently 

 reduced or absent; front wings coriaceous (tegmina) ; hind 



