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 



without Claws. P- H9 - ..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, awf-shaped, short and 

 slender. 



J. First and second pairs of wings nearly the 

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



ODONATA. 



I}. 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. 

 J}. 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. 

 ]. Head prolonged into a trunk-like beak. 



p. 184 MECOPTERA. 



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



NEUROPTERA. 



