146 COLEOPTEKA OF NORTH AMERICA. 



Sub-Tribe 1. — Histrini (genuiui). 



The genera of this sub-tribe live in excrements, or under the 

 bark of trees; one genus (Iletserius) is found only in the nests of 

 ants, early in spring. According to our views, modified by con- 

 sulting the authors above mentioned, they may be thus arranged: — 



A. Aiitennal cavities anterior, open in front, closed beneath more or less 



completely by the pectoral plate. 2. 



2. Antennal club oval, pubescent, i;snally distinctly annulated. 3. 

 Antennal club obconical, solid, glabrous. G. 



3. Mandibles moderately prominent, labrum trapezoidal. 4. 

 Mandibles retracted, clasping the epistoma, labrum transverse. 5. 



4. Antennal club broadly oval, distinctly annulated, elytra not acutely 



margined. Hister. 



Antennal club elongate oval, apparently solid, but pubescent, elyti'a 



acutely margined. Tribalister. 



.5. Prosternum broad, lobe short ; antennal club truncate. Tribalus. 



Prosternum moderate, lobe distinct ; antennal club rounded. 



Epierus. 

 6. Prosternal lobe normal ; epistoma truncate. Hetaerius. 



Prosternal lobe broad, thin and deflexed ; epistoma bifurcate. 



Echinodes. 



B. Antennal cavities under the angle of the thorax, closed in front, open 



beneath. 

 Prosternum scarcely lobed in front ; scape of antennse moderate. 



Onthophilus. 

 Prosternum distinctly- lobed ; scape of antennse as long as tlie funiule. 



Peploglyptus. 



C. Antennal cavities at the middle of the inflexed portion of thej-horax, 



near the sides. 

 Tibiie all dilated, the anterior with large terminal spurs. 



Dendrophilus. 

 Middle and posterior tibiae slender. 



Anterior tibise dilated, with large terminal spur. Paromalus. 



Anterior tibise feebly dilated, with small spur. Anapleus. 



Hister, as above defined, contains several of the genera adopted 

 by Marseul, which are separated in the following manner: — 



Anterior tibise with the tarsal groove well defined ; middle and posterior 



tibise subdentate. 

 Prosternal lobe prominent. 



Anterior tibiae toothed within near the base. Cylistix. 



Anterior tibise not toothed within. Platysoma. 



Prosternal lobe narrow, not prominent. Omalodes. 



