10 ENTOMOLOGY 
2. Collembola.—No metamorphosis. Mouth parts entog- 
nathous and typically mandibulate, with occasional secondary 
suctorial modifications. Wing's 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 
ocelliform or absent. Antenne of four segments in most 
genera; five or six in a few genera. Integument delicate. 
Examples, Achorutes.(Fig. 11), Sminthurus (Fig. 12). 
About seven hundred species have been described. 
Big: 13: leiadery ab 
Hemimerus  talpoides. 
Length, 11.5 mm.—After 
HANSEN. Schistocerca americana. Slightly reduced. 
Under the term Apiterygota (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 
