Key to the Orders of Insects. 9 



32. Abdomen consisting of ten or eleven segments, no ventral sucker at its base, no- 



terminal springing apparatus 33 



Abdomen consisting of six segments or less, with a forked sucker on the first 

 ventral segment and usually with a springing apparatus (furcula) near the 

 tip beneath. (Class COLLEMBOLA) 37 



33. Basal three segments of the abdomen with ventral styles; antennae absent; 



no cerci but a short anal tube present; head pear-shaped; prothorax short. 



(Class MIRIENT6MATA) PROTURA (Page 83) 



Ventral styles occurring to the seventh segment; antennae thread-like; cerci 

 present; prothorax not short 34? 



34. Body never scaly; mouthparts concealed except for the palpi; apex of the ab- 



domen without a median process. (Class CAMPODEOIDEA) 35 



Body usually covered with minute scales; tips of the mouthparts visible; abdo- 

 men with a median cerciform appendage. (Class THYSANtlRA) 36 



35. Eleventh tergite nearly or quite covered by the tenth; cerci jointed; anal 



valves very distinct RHABDURA (Page 82) 



Eleventh tergite fused with the tenth; cerci single-jointed forming strong 

 forceps; anal valves not distinct DICELLURA (Page 82) 



36. Body flattened; eyes not extending over the front; maxillary palpi five- or six- 



jointed; eleventh tergite partly covered by the tenth 



LEPISMATOIDEA (Page 81) 



Body convex above; eyes large, extending over the front; maxillary palpi seven- 

 jointed; eleventh tergite not covered by the tenth 



MACHILOiDEA (Page 81) 



37. Abdomen comprising six evident segments; body lengthened, subcylindrical ;. 



fourth segment of the abdomen often much lengthened 



ARTHROPLEONA (Page 82) 



Abdominal segments in part fused; body subglobular, the abdomen little longer 

 than wide SYMPHYPLEONA (Page 83) 



38. Underside of abdomen entirely without legs 30 



Abdomen bearing false legs beneath which differ from those of the thorax; body 



cylindrical, the thorax and abdomen not distinctly separated; larval forms. 54 



39. Antennae long and distinct '. 40 



Antennae short, not pronounced; larval forms 52 



40. Abdomen terminated by strong movable forceps; prothorax free. Earwigs 



DERMAPTERA (Page 15) 

 Abdomen not ending in forceps 41 



41. Abdomen not strongly constricted at the base, broadly joined to the thorax, 42 

 Abdomen strongly constricted at the base; prothorax fused with the meso- 



thorax. Ants, etc HYMENOPTERA (Page 19} 



42. Head not prolonged into a beak 43- 



Head produced into a mandibulate beak; species found about snow. (Boreus) 



PANORPAT^I (Page 46) 



