Hemiptera. 77 



■5. Front coxse placed at or near the front margin of the prosternum; front legs 



formed for grasping; beak three-jointed 6 



Front coxse placed at the hind margin of the short prosternum; legs fitted for 

 swimming; hind tarsi with no claws; membrane without veins; hemelytra 

 sometimes wholly coriaceous, strongly convex 8 



6. Membrane reticulate; beak provided with very small labial palpi 7 



Membrane without veins; beak without labial palpi; hind coxse hinged; posterior 



tibise slender. (Pelocoris, Ambrysus.) NAUCORIDiiE [^ 



7. Hind coxse hinged; hind legs fitted for swimming; posterior tibia; flattened and 



fringed, the hind femora usually sulcate; tip of abdomen with two retractile 

 appendages. Giant water-bugs. (Belostoma, Lethocerus, Zaitha) (PI. 



14. fig. 342) BELOSTOMATK)^ - 



Hind coxse rotating; hind legs formed for walking; abdomen with long breathing 

 tubes at apex. Water scorpions. (Nepa, Ranatra) (PI. 13, fig. 313; 

 PI. 14, fig. 324.) NfiPID^ 



8. Body convex above; head inserted into prothorax; beak four- or three-jointed; 



front tarsi not flattened. Back swimmers. (Notonecta) (PI. 14, fig. 



323) NOTONECTIDiE 



Body flat above; vertex of head free from the prothorax; beak unjointed, or 

 at most two-jointed, hidden; metastemum furnished with parapleurse; 

 front tarsi flattened, one-jointed, middle legs long, hind legs formed for 

 swimming. Water boatmen. (Corixa) (PI. 13, fig. 322; PI. 14. figs. 

 328, 329) CORIXID^ ' ^' 



9. First two joints of antennse very short, last two long, pilose, the third thickened 



at base; ocelli present; veins of the hemelytra forming cells 10 



Third joint of antennse not thickened at the base, the second jomt often longer 

 than the third or as long, rarely shorter 11 



10. Head more or less porrect. (Ceratocombus) (CERAT0C03IBID.I;) . 



DIPSOCORID^ 



Head inflexed between the prominent front coxse. (Hypselosoma ( = Gli/p- 



iocdmbus) SCHIZOPTERIDiE 



11. Meso- and metasterna composite, very rarely the sutures obsolete, in which 



case the clypeus is triangular (Cimicidae); cuneus of the fully winged forms 



more or less distinct; hind coxse hinged (except in a few Miridse) 12 



Meso- and metasterna simple; hind coxse nearly globose, rotating with a ball 

 and socket joint (except in Acanthiidae) 15 



12. Clypeus parallel or subparallel 13 



Clypeus triangular, broader apically; ocelli absent; wings never fully developed. 



Bedbug family. (Cimex [C. lectularius. Bedbug]) (PI. 13, fig. 321; PL 14, 

 fig. 330) {ACANTHIIDM of authors, CLINOCORID^) . .CTMICIDM V 



13. Ocelli of both sexes absent; tarsi three- jointed; beak four-jointed; membrane 



with two basal cells, the outer one small, or with a single cell which is broad- 

 ened apically or rarely suboval, very rarely (Myrmecophyes) with irregular, 

 free veins; beak with the first joint rarely shorter than the head. Leaf- 



