THE ORDERS OF THE HEXAPODA. 5 1 



D. Front wings leathery at base, and membranous at tip, often over- 

 lapping. Mouth-parts formed for sucking. V. HEMIPTERA. 

 DD. Front wings of same texture throughout. 



E. Front wings horny or leathery, forming veinless wing-covers. 

 {Elytra.) 



F. Abdomen with caudal appendages in the form of movable for- 

 ceps. {Earwigs?) III. Orthoptera. 

 FF. Abdomen without forcep-like appendages. IX. Coleoptera. 

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

 F. Under wings not folded. Mouth-parts formed for sucking. 



V. Hemiptera. 

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



III. Orthoptera. 

 CC. The two pairs of wings similar, membranous. 



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



IV. Physopoda. 

 DD. Last joint of tarsi not bladder-like. 



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

 parts formed for sucking. VII. 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 enclosed in a jointed 

 sheath. (Homoptera.) V. Hemiptera. 



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. 



II. Pseudoneuroptera. 

 HH. Tarsi consisting of five segments. 



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

 (Certain May-flies?) II. Pseudoneuroptera. 



II. Abdomen without many-jointed anal filaments. 



VI. Neuroptera. 

 GG. Wings with brandling veins and comparatively few cross- 

 veins, or veinless. 

 H. Tarsi two- or three-jointed. 



I. Posterior wings smaller than the anterior. {Psocidcei) 



II. Pseudoneuroptera. 



II. Posterior wings as large or larger than the anterior ones. 

 (Certain Stone-flies.) II. PSEUDONEUROPTERA. 



HH. Tarsi four- or five-jointed. 



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

 {Certain May-flies.) II. PSEUDONEUROPTERA. 



II. Abdomen without many-jointed anal filaments. 



J. Prothorax horny. First wings larger than the second, 

 naked or imperceptibly hairy. Second wings without or 

 with few, usually simple, veins. Jaws (mandibles) well de- 

 veloped. Palpi small. X. HYMENOPTERA. 



