28o Hominoxious Arthropods 



ii. Posterior coxae rotating. 



j. Claws preapical; aquatic forms. Gerrid^e and VeliaDjE 

 jj. Claws apical. 



k. Prosternum without stridulatory sulcus (notch for 

 beak) . 



I. Tarsus with three segments; membrane with two or 



three longitudinal cells from which veins radiate; 



rarely with free longitudinal veins (Arachnocoris) 



or veins nearly obsolete (Arbela); clavus and 



corium coriaceous; ocelli rarely absent. .NABlD.a; 



Reduviolus ( = Coriscus) subcoleoptratus (fig. 19 g), 



a species belonging to this family, occurring in 



the United States, has been accused of biting 



man. This insect is flat, of a jet black color, 



bordered with yellow on the sides of the abdomen, 



and with yellowish legs. It is predaceous, 



feeding on other insects. 



II. With other combinations of characters. Hydro- 



METRID^, HeNICOCEPHALID^, N^OGEID^, MESO- 

 VELIAD^, JOPPEICID^ 



kk. Prosternum with stridulatory sulcus (notch for beak) ; 

 with three segments, short, strong. 



I. Antenna filiform or sometimes more slender apically, 



geniculate; wing membrane with two or three 

 large basal cells; scutellum small or moderate 



REDUvnD.ffi; 



For a key to the genera and species see next page. 



II. Last antennal segment clavkte or fusiform; wing 



membrane with the veins often forked and ana- 

 stomosing; scutellum large; tarsi each with two 

 segments; fore legs strong. ( = Phymatid^) 



Macrocephalid^ 



ee. Clavus noticeably narrowed towards the apex, never extending 



beyond the scutellum, the two not meeting to form a commissure; 



head horizontal, much prolonged between the antennae, on each 



side with an antennal tubercle, sometimes acute; ocelli absent; 



meso- and metastemum simple; tarsi each with two segments; 



body flattened (fig. 19c). Aradid^, including Dysodiid^. 



dd. Pulvilli present (absent in one AustraUan family Thaumatocorid^ 



in which case there is a membranous appendage at the tip of the 



tibia). CAPSlD.ffi; ( = MlRlD.ff;),* Eotrechus (in family Gerrid^), 



N^OGAID^, TlNGITID^, PlESMIDjE, MyODOCHID^, CoRIZID^, 



Coreid^, Alydid^, Pentatomid^, Scutellerid^, etc. 

 bb. Apex of head directed ventrally, beak arising from the hinder part of the 

 lower side of the head; sides of face contiguous to the front coxs; first 



♦Professor C. R. Crosby who has been working upon certain capsids states that he and his 

 assistant have been bitten by Lygus pratensis, the tarnished plant bug, by Chlamydatus associatus 

 and by Orthotylus flavosparsus, though without serious results. 



