KEY TO CLASSES AND ORDERS OF ANIMALS SS 



41(42) Head prolonged into a trunklike beak. (Comstock, 

 184; Lutz, 56.) Order Mecoptera 



42(41) Head not prolonged into a beak. (Comstock, 175; 

 Lutz, 53.) Order Neuroptera 



43(29) Wings with branching veins and comparatively few 

 cross- veins or veinless. 44 



44(47) Tarsi two or three jointed. 45 



45(46) Posterior wings smaller than the anterior. (Lutz, 

 76; Comstock, 98.) Order Corrodentia 



46(45) Posterior wings as large as or larger than the anterior 

 ones. (Comstock, 93; Lutz, 40.) 



Order Plecoptera, in part 



47(44) Tarsi four or five jointed. 48 



48(49) Abdomen with bristle-like, many-jointed anal fila- 

 ments. (Comstock, 86; Lutz, 40.) 



Order Plectoptera or Ephemerida 



49(48) Abdomen without bristle-like, many-jointed, anal 

 filaments. 50 



50(51) Prothorax horny; first wings larger than the second, 

 naked or imperceptibly hairy. Second wings without, 

 or with few, simple veins. Jaws (mandibles) well 

 developed; palpi small. (Comstock, 599; Lutz, 406.) 



Order Hymenoptera 



51(50) Prothorax membranous, or at most parchment-like. 

 Second wings as large or larger than the first, folded 

 lengthwise, with many branching veins. First wings 

 naked or thinly clothed with hair. Jaws (mandibles), 

 inconspicuous; palpi long. Mothlike insects. (Com- 

 stock, 186; Lutz, 57.) Order Tricoptera 



