8O THE STUDY OF INSECTS. 



FF. Under wings folded lengthwise. Mouth-parts formed 



for biting, p. 104 ORTHOPTERA. 



CC. The two pairs of wings similar, membranous. 



D. Last joint of tarsi bladder-like or hoof-like in form and 



\vitlioutclaws. p. 119 ..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, p. 191.. .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. (Homoptera^) p. 121. 



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. 



I. Antennae inconspicuous, awl-shaped, short and 

 slender. 



J. First and second pairs of wings nearly the 

 same length ; tarsi three-jointed, p. 89. 



ODONATA. 



JJ. Second pair of wings either small or wanting; 

 tarsi four-jointed, p. 86 EPHEMERIDA 



II. Antennae usually conspicuous, setiform, filiform 

 clavate, capitate, or pectinate. 



J. Tarsi two- or three-jointed. 



K. Second pair of wings the smaller, p. 98. 



CORRODENTIA. 



KK. Second pair of wings broader, or at least 

 of the same size as the first pair. p. 93. 



PLECOPTERA. 

 JJ. Tarsi four-jointed ; wings equal, p. 95. 



ISOPTERA. 



HH. Tarsi consisting of five segments. 



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

 ments. (Certain May-flies) p. 86. EPHEMERIDA. 



II. Abdomen without many-jointed anal filaments. 

 J. Head prolonged into a trunk-like beak. 



p. 184 MECOPTERA. 



J. Head not prolonged into a beak. p. 175. 



NEUROPTERA. 



