Hemiptera. 77 



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



formed for grasping; beak three-jointed 6 



Front coxae 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 coxae hinged; posterior 



tibiae slender. (Pel6coris, Ambrysus.) NAUCORID^E 



7. Hind coxae hinged; hind legs fitted for swimming; posterior tibiae 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) BELOSTOMATIIXE 



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

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

 PL 14, fig. 324.) NEPIIXE 



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



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



323) NOTONECTDX& 



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

 at most two- join ted, hidden; metasternum furnished with parapleurae; 

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

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



328, 329) CORIXHXE: 



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



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



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

 than the third or as long, rarely shorter 11 



10. Head more or less porrect. (CeratocSmbus) (CERATOCOMBIDJE). 



DIPSOCORmE 



Head inflexed between the prominent front coxae. (Hypselosdma (=Glyp- 

 tocdmbus) SCmZOPTERmE; 



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 coxae hinged (except in a few Miridae) 12 



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

 and socket joint (except in Acanthiidse) 15 



12. Clypeus parallel or subparallel 13 



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



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

 fig. 330) (AC AN THUD fi of authors, CLINOCORIDM) .. CIMICIDAE 



13. Ocelli of both sexes absent; tarsi three- join ted; 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- 



