HEXAPODA 41 



E. Wings horny, without veins. Hind legs not fitted for jumping, p. 127 



COLEOPTERA 



EE. Wings parchment-like with a network of veins. Hind legs fitted for 

 jumping, p. 49 . . Orthoptera 



CC. Wings membranous. 



D. Abdomen with caudal filaments. Mouth-parts vestigial. 



E. Halteres wanting, p. 74 Ephemerida 



EE. Halteres present (males of Coccidae). p. 109 Homoptera 



DD. Abdomen without caudal filaments. Halteres in place of second wings. 



Mouth-parts formed for sucking, p. 286 Diptera 



RB. With four wings. 

 C. The two pairs of wings unlike in structure. 



D. Fore wings reduced to slender club-shaped appendages; hind wings fan- 

 shaped with radiating veins. Minute insects, p. 176 Strepsiptera 



DD. Front wings leathery at base, and membranous at tip, often overlapping. 



Mouth-parts formed for sucking, p. 94 Hemiptera 



DDD. Front wings of same texture throughout. 



E. Front wings horny or leathery, being veinless wing-covers. {Elytra.) 

 F. Abdomen with caudal appendages in form of movable forceps, p. 125 



Dermaptera 



FF. Abdomen without forceps-like appendages, p. 127 Coleoptera 



EE. Front wings leathery or parchment-like with a network of veins. 

 F. Under wings not folded; mouth-parts formed for sucking. 



G. Beak arising from the front part of the head. p. 94 .... Hemiptera 

 GG. Beak arising from the hind part of the lower side of the head. 



p. 109 Homoptera 



FF. Under wings folded lengthwise. Mouth-parts formed for chewing. 



p. 49 Orthoptera 



CC. The two pairs of wings similar, membranous. 



D. Last joint of tarsi bladder-like or hoof-like in form and without claws. 



Wings with fringe of long hairs, p. 89 Thysanoptera 



DD. Last joint of tarsi not bladder-like. 



E. Wings entirely or for the greater part clothed with scales. Mouth-parts 



formed for sucking, p. 183 Lepidoptera 



EE. Wings naked, transparent, or thinly clothed with hairs. 



F. Mouth-parts arising from the hinder part of the lower surface of the 

 head, and consisting of bristle-like organs inclosed in a jointed sheath. 



p. 109 Homoptera 



FF. Mouth-parts in normal position. Mandibles not bristle-like. 

 G. Wings net-veined, with many veins and cross-veins. 

 H. Tarsi consisting of less than five segments. 



I. Antennae inconspicuous, awl-shaped, short and slender. 



J. First and second pairs of wings of nearly the same length; 

 tarsi three-jointed, p. 77 Odonata 



J J. Second pair of wings either small or wanting; tarsi four- 

 jointed, p. 74 Ephemerida 



II. Antennas usually conspicuous, setiform, filiform, clavate, capitate, 



or pectinate. 

 J. Tarsi two- or three-jointed. 



K. Second pair of wings the smaller, p. 83 Corrodentia 



KK. Second pair of wings broader, or at least the same size as 



the first pair. p. 81 Plecoptera 



JJ. Tarsi four-jointed; wings equal, p. 63 Isoptera 



HH. Tarsi consisting of five segments. 



I. Abdomen with setiform, many-jointed anal filaments. (Certain 



mayflies), p. 74 Ephemerida 



II. Abdomen without many-jointed anal filaments. 



J. Head prolonged into a trunk-like beak. p. 178 Mecoptera 



JJ. Head not prolonged into a beak. p. 66 Neuroptera 



GG. Wings with branching veins and comparatively few cross-veins, or 

 veinless. 

 H. Each of the veins of the wing extending along the middle of a 



brown line. p. 87 _ Embiidina 



HH. Wings not marked with brown lines. 



