6 COLEOPTERA OF NORTH AMERICA. 



characters except those above given will apply to all of thera, 

 but the special characters of the tribes found in the United States 

 may be thus expressed : — 



Posterior coxae attaining the side margin of body. Anterior coxal cavities 

 open beliind. Mandibles with setigerous puncture. 



II. Trachypachini. 

 Posterior coxae not attaining the side margin of body. 

 Anterior coxal cavities open behind. 



Posterior coxse separated. Labrum bifurcate. III. Cychrini. 



Posterior coxae contiguous. Labrum not bifurcate. 



Mandibles without setigerous puncture externally. IV. Carabini. 

 Mandibles with setigerous puncture. VII. Nebrhni. 



Anterior coxal cavities closed behind. 



Presternum prolonged and dilated, entirely concealing the meso- 

 sternuin. Mandibles with setigerous puncture. Scutellum entirely 

 concealed. I. Omopiironini. 



Prosternum not concealing the mesosternum. 

 Antennae free at base. 



Mandibles without setigerous punctiare. Anterior tibiae strongly 

 emarginate. One supra-orbital seta. VI. Loricekini. 



Mandibles with setigerous puncture. Anterior tibiae feebly emar- 

 ginate. Two supra-orbital setae. V. Elaphrini. 

 Antennae arising either iinder a distinct frontal plate or a ridge 

 which extends backward over the eyes. 

 Body not pedunculate. Posterior coxae separated. Prosternum 

 prolonged at tiji. Mandibles with seta. VIII. Metriini. 

 Body pedunculate, bases of thorax and elytra remote. 

 Posterior coxae separated. 



Anterior tibiae emarginate within, the inner spur remote 

 from the outer. IX. Promecognatuini. 



Posterior coxae contiguous. 



Anterior tibiae emarginate within, the outer apical angle 

 prolonged. X. Scaritiki. 



Tribe I.— OMOPHROIVIIVI. 



This tribe consists of but a single genus, remarkable for its 

 round convex form and the absence of scutellum. 



Antennae slender, inserted under a slight frontal margin, four 

 basal joints glabrous. Eyes round, moderately prominent, distant 

 beneath from the buccal opening. Head deeply inserted, with 

 one supra-orbital seta. Labrum short, emarginate. Mandibles 

 not prominent, arcuate, acute at tip, simple within or slightly 

 toothed near the base, outer side slightly concave with a setige- 



