HEX APOD A 217 



H. With paired lateral filaments on most or on all of the ab- 

 dominal segments. (Sialidae). p. 281 Neuroptera 



See also Haliplidae and Gyrinidae. p. 464 Coleoptera 



HH. Without paired lateral filaments on the abdomen, p. 464. 



Coleoptera 



CC. Terrestrial insects. 

 D. External parasites. 



E. Infesting the honey-bee. (Braula). p. 773 Diptera 



EE. Infesting birds or mammals. 



F. Body strongly compressed. (Fleas), p. 877 Siphonaptera 



FF. Body not strongly compressed. 



G. Mouth-parts formed for chewing. (Bird-lice), p. 335. 



Mallophaga 



GG. Mouth-parts formed for piercing and sucking. 



H. Antenn.Te inserted in pits, not visible from above. (Pupi- 



para). p. 773 Diptera 



HH. Antennae exserted, visible from above. 

 G. Tarsi with a single claw which is opposed by a toothed pro- 

 jection of the tibia. (Lice), p. 347 Anoplura 



GG. Tarsi two-clawed, p. 350 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. (Campodeidae and 



Japygidae). p. 220 Thysanura 



FF. Abdomen consisting of not more than six segments, p. 225. 



: Collembola 



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

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

 F. Larvas with abdominal prolegs. 



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



(Caterpillars), p. 571 Lepidoptera 



GG. Prolegs not armed with minute hooks, 



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



p. 884 Hymenoptera 



HH. With many ocelli on each side of the head. p. 550 



Mecoptera 



FF. Without abdominal prolegs. 



G. Body clothed with scales. (Machilidae and Lepismatidse). 



p. 220 Thysanura 



GG. Body not clothed with scales. 

 H. Antennae long and distinct. 



I. Abdomen terminated by strong movable forceps, p. 460. 

 Dermaptera 



II. Abdomen not terminated by forceps. 



J. Abdomen strongly constricted at base. (Ants. etc.). 



p. 884 Hymenoptera 



JJ. Abdomen not strongly constricted at base. 



K. Head with a long trunk-like beak. {Boreiis). p. 550. 



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. 331 Corrodentia 



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

 prothorax not extremely small; cerci present. 

 M. Hind legs fitted for jumping, hind femora en- 

 larged. (Wingless locusts, grasshoppers, and 



crickets), p. 230 Orthoptera 



MM. Hind femora not greatly enlarged, not fitted 

 for jumping. 



