52 ARTHROPODS 



AA. Antennae at least as long as the head, usually free, rarely 

 (Phymatidae) fitting in a groove under the lateral margin of 

 the pronotum. 



B. Body of various forms, but, when linear, with the head 

 shorter than the thorax. 



C. Last segment of the tarsi more or less split, and with the 

 claws inserted before the apex. 



D. Body usually elongated ; prothorax narrow ; beak four- 

 jointed; second and third pairs of legs extremely long and 



slender Hydrobatidae. 



DD. Body usually stout, oval, and broadest across the pro- 

 thorax; beak three-jointed; legs not extremely long. 



Veliidae. 

 CC. Last segment of the tarsi entire, and with the claws in- 

 serted at the apex. 

 D. Antennae four-jointed. 

 E. Wing covers of various forms or absent, but not re- 

 sembling network. 

 F. Beak three-jointed. 

 G. Wing covers when well developed, with a cuneus; 

 those forms in which the adult has rudimentary wing 



covers have no ocelli Acanthiidae. 



GG. Wing covers when well developed, without a cu- 

 neus ; those forms in which the adult has rudimentary 

 wing covers have ocelli. 

 H. Ocelli wanting. 



L Body linear Emesidae. 



n. Body greatly flattened Aradidae. 



in. Body of ordinary form Reduviidae. 



HH. Ocelli present, though sometimes difficult to see. 

 L Beak very long, reaching to^or beyond the in- 

 termediate coxae Saldidae. 



II. Beak not reaching the intermediate coxae. 

 J. Front femora somewhat thickened, but much 

 less than half as wide as long. .. .Reduviidae. 

 FF. Beak four-jointed. 

 G. Front legs fitted for walking. 



