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Tibiiie spinous ; tarsi 3-joiiited Fam. XXI, Corimalsenidae. 



Tibia; not spinous. 



Elytra folded ; tarsi 2-jointed Fam. XXII, Arthropteridas. 



Elytra straight ; tarsi 3 -jointed Fam. XXIII, Scutelleridae. 



***Scutelluin flattened, attenuated, usually rounded at tip, or long triangular, but 



not nearly covering the whole abdomen. 

 Tibia; not spined ; tarsi 2- or 3-jointed Fam. XXIV, Pentatomidae. 



5 Beak curved at base ; head cylindrical ; prothorax with a transverse suture 7 



Beak not curved at base ; head not cylindrical. 



Antennre mserted on a line below the eyes 6 



Antenna; inserted on a line before the eyes. 



Membrane always with more than five nervures, often numerous. 

 *Legs not especially slender, most frequently thickened, spined or foliaceous ; 



forms various Fam. XXV, Coreidae, 



**Legs long and slender, femora clavate Fam. XXVI, Berytidae. 



6 Membrane with not more than five nervures. 



With ocelli Fam. XXVII, Lygaeidae. 



Without ocelli Fam. XXVIII, Pyrrhocoridae. 



Membrane with one or two cells ; no ocelli Fam. XXIX, Capsidae. 



7 Head separated from the prothorax. 



JAnterior legs not raptorial; fore coxre not greatly lengthened. 



Beak usually long, slender, 4-jointed Fam. XXX, Nabidae. 



Beak usually short, stout, 3-jointed Fam. XXXI, Reduviidae. 



JJAnterior legs raptorial ; fore coxk greatly lengthened 



Fam. XXXII, Emesidae. 

 Head not separated from the prothorax. 



Abdomen endmg in long, respiratory caudal seta: ; antenna; very -^mall, 3- 



jointed Fam. XXXIII, Nepidae. 



Subdivision II, HYDRODROMICA, Ashmead. 

 Head inserted in prothorax. 



Head abnormally lengthened Fam. XXXIV, Hydrometridae. 



Head not greatly lengthened. 



*Ocelli and scutellum present Fam. XXXV, Gerridae. 



**Ocelli and scutellum wanting Fam. XXXVI, Velliidae. 



Division II, PAGIOPODA, Schiodte. 

 Subdivision I, GYMNOCERATA, Ashmead. 



Elytra areolated Fam. XXXVII, Saldidae. 



Subdivision II, CRYPTOCERATA, Ashmead. 



Body boat-shaped, supinate 2 



Body depressed, prone. 



Legs not natatorial ; ocelli present. 



Eyes pedunculate Fam. XXXVIII, Galgulidae. 



Legs natatorial ; ocelli wanting. 

 Scutellum large. 



Abdomen without strap-like caudal setce Fam. XXXIX, Naucoridae. 



Abdomen with strap-like caudal setx Fam. XL, Belostomidae. 



Scutellum invisible or minute. 



Head overlaps prothorax Fam. XLI, Corisidae. 



2 Head inserted in prothorax ; legs natatorial Fam. XLII, Notonectidae. 



