June, 1906.] Key to the Order' Thysanura. 547 



EE : Teriinnal segment of antennae long, annulate. 



F; Antennae with 8 segments, abdomen with 2 tubercles. 



Gen: 2 (10) Dicyrtoma. 

 FF; Antennae with 4 segments, abdomen without tubercles. 



Gen: 3 (11) Sminthtirus. 

 DD: Abdomen clyindrical, longer than broad. 



Fam: 6, ENTOMOBRYIDAE. 

 E: Biidy naked or covered with hair. 



F: Antennae of 6 segments. Gen: 1 (12) Orchesella. 



FF: Antennae of 4-5 segments. 



G: 2 ocelli on either side of head. Gen: 2 (1.3) Sinella. 

 GG: 8 ocelli on either side of head. 



H : Dorsal portion of third and fourth abdominal 

 segment approximately of equal length. 

 I : Central part of saltatorial organ not reach- 

 ing over the ventral sucker. 



Gen: 3 (14) Isotoma. 

 II: Central part of saltatorial organ reaching 

 beyond ventral sucker. 



Gen: 4 (15) Corynothrix 

 HH: Dorsal portion of fourth abdominal segment 

 3-4 times longer than third. 



I : Distal end of saltatorial organ curved, 

 without antiapical hooks. 



Gen: 5 (16) Drepanura. 

 II: Distal end of saltatorial organ simple, with 

 antiapical hooks. 



J: Ocelli irregularly arranged, not in 2 

 longitudinal and 4 transverse rows. 



Gen: 6 (17) Entomobrya. 

 JJ: Ocelli symetrically arranged in 2 

 longitudinal and 4 transverse rows. 



Gen: 7 (18) Salina. 

 EE : Body covered with flat scales. 

 F : Antennae of 4 segments. 



G: Distal segment of antennae annulate. 



H: Ocelli present. Gen: 8 (19) Tomocerus. 



HH: Ocelh absent. 



I : Antennae longer than body, saltatoriaL 

 organ with long distal segment. 



Gen: 9 (20) Tritomurus. 

 II: Antennae half as long as body, saltatoriaL 

 organ with very short distal segment. 



Gen: 10 (21) Heteromurus. 

 GG: Distal segment of antennae not anntilate. 



H: Ocelli absent. Gen: 11 (22) Cyphodeirus^ 



HH: Ocelli present. 

 . I: Pronotvim simple, head prominent. 



J: Metathorax enlarged into hump. 



Gen: 12 (23) Campylothorax, 

 JJ : Metathorax simple. 



K: Middle part of saltatorial organ 

 spiny. 



Gen: 13 (24) Dicranocentrus. 

 KK: Saltatorial organ smooth. 



L: Fourth abdominal segment 

 ahnost 3 times as long as 

 third. 

 Gen: 14(25)Pseudosira. 



