HEXAPODA 43 



I. Tarsi with a single claw which is opposed by a toothed projection 

 of the tibia. (Lice), p. 92 Anoplura 



II. Tarsi two-clawed, p. 94 Hemiptera 



DD. Terrestrial insects not parasites. 



E. Mouth-parts apparently retracted within the cavity of the head so that 

 only their apices are visible, being overgrown by folds of the genae. 

 F. Abdomen consisting of ten or eleven segments. (Campodeida; and 



Japygidae). p. 45 Thysanura 



FF. Abdomen consisting of not more than six segments, p. 47 



COLLEMBOLA 



EE. Mouth-parts mandibulate, either fitted for chewing or with sickle- 

 shaped mandibles formed for seizing prey. (See also EEE.) 

 F. Larvae with abdominal prolegs. 



G. Prolegs armed at the extremity with numerous minute hooks. 



(Caterpillars), p. 183 Lepidoptera 



GG. Prolegs not armed with minute hooks. 



H. With a pair of ocelli, one on each side. (Larvae of saw-flies). 



p.3 2 9 Hymenoptera 



HH. With many ocelli on each side of the head. p. 178. .Mecoptera 

 FF. Without abdominal prolegs. 



G. Body clothed with scales. (Machilidse and Lepismatidae) . p. 45 



Thysanura 



GG. Body not clothed with scales. 

 H. Antennae long and distinct. 



I. Abdomen terminated by strong movable forceps, p. 125 



Dermaptera 



II. Abdomen not terminated by forceps. 



J. Abdomen strongly constricted at base. (Ants, etc.) p. 329 



Hymenoptera 



JJ. Abdomen not strongly constricted at base. 



K. Head with a long trunk-like beak. (Boreus). p. 178 



Mecoptera 



KK. Head not prolonged into a trunk. 



L. Insects of small size, more or less louse-like in form, with 

 a very small prothorax, and without cerci. (Book-lice 



and Psocids). p. 83 Corrodentia 



LL. Insects of various forms, but not louse-like, prothorax not 

 extremely small; cerci present. 

 M. Hind legs fitted for jumping, hind femora enlarged. 

 (Wingless locusts, grasshoppers, and crickets), p. 49 



Orthoptera 



MM. Hind femora not greatly enlarged, not fitted for 

 jumping. 

 N. Prothorax much longer than the mesothorax; front 

 legs fitted for grasping prey. (Mantidas). p. 49 



. Orthoptera 



NN. Prothorax not greatly lengthened. 

 O. Cerci present; antennae usually with more than 

 fifteen joints, often many-jointed. 

 P. Cerci with more than three joints. 



Q. Body flattened and oval. (Blattidae). p. 49 



Orthoptera 



QQ. Body elongate. 

 R. Head very large. {Termopsis). p. 63 



ISOPTERA 



RR. Head of moderate size. p. 49 



Orthoptera 



PP. Cerci short, with one to three joints. 



Q. Body linear with very long linear legs. 



(Walking-sticks), p. 49 Orthoptera 



QQ. Body elongate or not, if elongate the legs 

 are not linear. 

 R. Body elongate; front tarsi with first joint 

 swollen, p. 87 Embiidina 



