[73] 



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. 

 Labium 4-dentate. 



Metasternum very long Caloderma. 



Metasternum very short OligopterilS. 



Labrum bidentate Medon. 



Labrum unidentate Lithocharis • 



Lxbrum unarmed. 



Deeply emarginate Dacnochilus. 



Broadly and rather feebly sinuate 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. 



Librurn triangularly emarginate, unarmed Paederus. 



Presternum corneous under and behind the coxae; 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 Slinius. 



Labium 'arge, rounded, ciliate; elytra shorter than the prothorax. 



Stilicopsis. 

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

 triangular, erect. 

 Fourth joint o f the posterior tarsi not lobed, normal LeptOgeniuS. 



II — Ligula tricuspid. 



Prosternal intercoxal luuina deeply emarginate anteriorly; neck extremely 

 slender. 

 Inflexed posterior portion of prouotal hypomera well developed. 



Scopaeus. 



Inflexed portion rudimentary Scopaeodera, 



Prosternal intercoxal lamina interiorly arcuate anteriorly. 



Neck extremely slender LeptorilS. 



Neck one-third as wide as the prothorax Oms. 



