THE ORDERS OF THE HEXAPODA. 51 



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 sucki; 



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. 



HIL Tarsi consisting of five segments. 



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



rtain May-flics?) II. PSEUDONEUROPTERA. 



II. Abdomen without many-jointed anal filaments. 



VI. NEUROPTERA. 



GG. Wings with branching veins and comparatively few cross- 

 veins, or veinless. 

 II. T. ; ;si two- or three -jointed. 

 I. Posterior wings smaller than the anterior. (Psocidtf.) 



II. KOPTERA. 



II Posterior wings as large or larger than the ant< 



(Certain Stt: II. PSEUDONEUROPTERA. 



HI I T.irsi four- i ued. 



I. Abdomen with setiform, many- jointed anal fil.mimtv 

 (Cfrf.tni May-flies) II. PSEUDONEUK' in M 



II Abdomen without m.uu- jointed anal filaments. 

 1 Prothorax li<>t >t wings larger than thr M- 



naked or imperceptibh without or 



\\ith few, usually simple, veins. Jaws <m.mlil>lcs)wcllde- 

 I>ed. Palpi small. X IhMK\Mj- 



