54 COLEOPTERA OP NORTH AMERICA. 



These are small, shining, usually ovate, sometimes slender in- 

 sects, of a brown color, more or less clothed with erect hairs. 

 They are found variously, near water, under stones, in ants' nests, 

 and under bark, and are frequently seen flying in the twilight. 



The general form is that of Pselaphidae, from which they differ 

 by the long elytra and the conical distant posterior coxae. 



Our genera are : — 



Antennae geniculate ; first joint as long as the two following. Microstemma. 

 Antennae straight ; 



First joint of labial palpi very short ; 

 Posterior trochanters long, situated in the axis of the thighs. 



EuMiCKtrs. 

 Posterior trochanters small, on the internal face of the thighs. 



Scydm^nus. 

 First joint of labial palpi distinct ; 



Prothorax quadrate, not wider than the elytra. Edtheia. 



Prothorax transverse, wider than the elytra. Cephennium. 



Eutheia has occurred in Russian America, and Cephennium in 

 the Atlantic States. Scydmaenus is represented by numerous 

 species on both sides of the continent. Eumicrus is represented 

 by Eu. Zimmermanni in the Southern States. 



Fam. ix.— pselaphidae. 



Mentum small, corneous, more or less quadrate; ligula 

 very small, membranous, with large diverging paraglossae; 

 labial palpi very small. 



Maxillae with membranous ciliated lobes, the outer much 

 larger than the inner; palpi usually very long, and 4-jointed. 



Mandibles usually broad and short, with the tip curved 

 and acute. 



Antennae 11-jointed (rarely 10-jointed) in the second sub- 

 family; 1- to 6-jointed in the first, usually clavate, rarely 

 moniliform. 



Eyes composed of large lenses, sometimes wanting. 



Prothorax with the side pieces not distinct; prosternum 

 almost obsolete between the coxae, coxal cavities open behind. 



Mesosternum short, obsolete between the coxae. 



Metasternum large, side pieces simple. 



Elytra truncate, short, leaving the abdomen exposed ; 

 wings, when present, folded beneath the elytra. 



Abdomen with five or six free but not flexible ventral 



