NORTH AMERICAN COLEOPTERA. 229 



Labium bilobed Lathrobium. 



Labium transversely truncate Trachysectus. 



First joint of the posterior tarsi distinctly longer than the second. 

 Neck rather wide, not less than one-third as wide as the prothorax. 

 Anterior tarsi very slightly or not at all dilated. 

 Labrum 4-dentate. 



Metasternum very long Caloderma. 



Metasternum very short OligOpterUS. 



Labrum bidentate Medon. 



Labrum unidentate Lithocharis- 



Labrum unarmed. 



Deeply emarginate Dacnochilus. 



Broadly and rather feebly siuuate Lena. 



Labrum entire. 



Elytra much shorter than the prothorax Liparocephalus. 



Anterior tarsi strongly dilated. 



Labrum unidentate Aderocharis. 



Labrum entire, truncate Ramona. 



Neck extremely slender; labrum bidentate Stilicus. 



B — Fourth tarsal joint bilobed. 



Labrum triangularly emarginate, unarmed PsBderus. 



Prosternum corneous uuder and behind the coxse; the side pieces of the 

 pronotum connate with the intercoxal process. 



SUNII. 



Third joint of the maxillary palpi normal; fourth minute, subulate. 

 Posterior tarsi with the fourth joint lobed beneath. 



Labrum bidentate Sunius. 



Labrum 'arge, rounded, ciliate; elytra shorter than the prothorax, 



Stilicopsis. 



Third joint of maxillary palpi securiform; fourth minute, not subulate, 

 triangular, erect. 

 Fourth joint of the posterior tarsi not lobed, normal Leptogenius. 



II — Ligula tricuspid. 



Prosterual intercoxal lamina deeply emarginate anteriorly; neck extremely 

 slender. 

 Inflexed posterior portion of pronotal hypomera well developed. 



Scopaeus. 



Inflexed portion rudimentary Scop3BOdera. 



Prosterual intercoxal lamina inferioiiy arcuate anteriorly. 



Neck extremely slender LeptorUS. 



Neck one-third as wide as the prothorax Orus. 



