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Tibia- spinous ; tarsi 3- jointed Fam. XXI, Corimalaenidae. 



Tibia not spinous. 



Elytra folded ; tarsi 2-joiiited Fam. XXII, Arthropteridae. 



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



***ScuteIlum 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 cm ved at base ; head cylindrical ; prothorax with a transverse suture 7 



Beak nut curved at base ; head not cylindrical. 



Antenna- inserted on a line below the eyes 6 



Antenna inserted on a h'ne 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, Berytid^. 



6 Membrane with not more than five nervures. 



With ocelli Fam. XXVII, Lygaeidae. 



Without ocelli Fam. XXVIII, Pyrrhocoridas. 



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



7 Head separated from the prothorax. 



^Anterior legs not raptorial ; fore coxa not greatly lengthened. 



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



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



t;J; Anterior legs raptorial; fore coxa greatly lengthened .^ 



Fam. XXXII, Emesidae 

 Head not separated from the prothorax. 



Abd-omen endmg in long, respiratory caudal seta ; antenna very -mall, 3- 



jointed Fam. XXXIII, Nepidse 



Subdivision II, HYDRODROMICA, Ashmead. 

 Head inserted in prothorax. 



Head abnormally lengthened Fam. XXXIV, Hydrometridae. 



Head not greatly lengthened. 



*Ocelli and scutellum present Fam. XXXV, Gerrids. 



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



Division II, PAGIOPODA, Schiodte. 

 Subdivision I, GYMNOCERATA, Ashmead. 



Elytra areolated Fam. XXXVII, Saldidas. 



Subdivision II, CRYPTOCERATA, Ashmead. 



Body boat-shaped, supinate 2 



Body depressed, prone. 



Legs not natatorial ; ocelli present. 



Eyes pedunculate Fam. XXXVIII, Galgulids. 



Legs natatorial ; ocelli wanting. 

 Scutellum large. 



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



Abdomen with strap-like caudal seta Fam. XL, BelostomidEe. 



Scutellum invisible or minute. 



Head overlaps prothorax Fam. XLI, Corisidae. 



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



