THE GROUND OR BURROWER BUGS. 71 



or semicircular ; cheeks equalling or slightly surpassing tylus ; 

 antennae 5-jointed, inserted under the sides of head ; beak 4- 

 jointed; pronotum oval or subquadrangular, its front portion 

 not or feebly declivent ; scutellum broad, triangular, tapering 

 behind, its tip reaching only to base of elytral membrane, frena 

 reaching beyond its middle ; elytra widely exposed, the corium 

 broad, its apex truncate ; membrane surpassing abdomen, its 

 veins simple, radiating from the base ; osteolar area usually 

 opaque, smooth or finely granulate ; tibiae armed with strong 

 spines, the front ones often widened and f ossorial ; tarsi 3- 

 jointed. 



As already noted, the members of this family are mainly 

 terrestrial forms which occur in the vicinity of water, where 

 they burrow in the sand or mold about the roots of tufts of 

 grass and other plants or are found beneath stones or other 

 cover, often in the nests of ants. The principal literature avail- 

 able treating of our species is that of Uhler, 1877; Signoret, 

 1881—1884 ; Hart and Malloch, 1919, and Stoner, 1920. The 

 family is poorly represented in North America, but 32 species 

 belonging to eleven genera being there known. Of these 19 

 species representing nine genera occur in the eastern states. 



KEY TO EASTERN GENERA OF CYDNID^E. 



a. Margins of head and pronotum armed with bristly hairs or short 

 spines; tibiae closely set with stout spines; front tibiae more or 

 less compressed; tarsi slender, filiform. (Subfamily Cydninse). 

 b. Scutellum with apex rounded, the coria not meeting behind its tip ; 

 form oval; osteolar canal not long, slender or reaching nearly to 

 end of metasternal plate (except in Macroporus). 

 c. Hind tibiae strongly flattened and curved, their lower face with 

 numerous long bristles, the upper one with many stout spines 

 and bristles ; osteolar opening with only a small external 

 auricle; length, 6.5 — 9 mm. I. Cyrtomenus, p. 72. 



cc. Hind tibiae slender, nearly straight, uniformly spined on both 

 upper and lower faces. 

 d. Head without a deep groove beset with numerous irregular 

 bristles and teeth just within the reflexed margin. 

 e. Pronotum with a distinct impressed sinuate line just behind its 

 front margin; length, 5.5 — 8 mm. II. Pang^eus, p. 73. 



ee. Pronotum without an impressed line behind the front margin. 

 /. Smaller, length less than 4.3 mm. ; osteolar tube slender, two- 

 thirds the length of metasternal plate, prolonged beyond the 

 opening as a curved flattened semicircular lobe; pronotum 

 of male without a deep impunctate concavity. 



III. Geotomus, p. 76. 



