HISTERIDAE. 143 



8. Antennal club of at least two joints. Cryptorhopalum. 

 Antennal club of one very large securiform joint set obliqui'ly. 



Axinocerus. 



9. Mouth covered by prosternum, wbich is truncate bebind : hind coxje 



not extending to the sides of the body : pubescence, long, erect. 



Apsectus. 



Mouth covered by front legs: prosternum pointed behind; bind coxre 



extending to the sides of tlie body : pubescence obsolete. Orphilus. 



Tlie number of joints of the antennsE is variable in Anthrentis. 

 Apsectus has but one species, found in the Atlantic States; one 

 specimen in my possession was hatched from a tumor on a stem 

 of Ehus radicans. Dearthrus, Acolpus, and Axinocerus are 

 each represented by single species in the Atlantic region. The 

 other genera arc represented on both sides of the continent. 

 The antennae of the males of certain species of Trogoderma are 

 strongly serrate.* 



Fam. XXIX.— HISTERIDAE. 



Mentum corneous, sometimes large and covering tlie base 

 of the maxillas, flat or slightly concave, subquadrate, some- 

 times emarginate or tridentat© in front; ligala almost con- 

 cealed behind the mentum; palpi 3-joiuted, cylindrical. 



MaxilUe with two ciliated lobes, the internal one much 

 smaller; palpi 4-jointed, cylindrical. 



Antenn;e geniculate, capable of being retracted, short, in 

 the second sub-family with the first joint thick, but in the 

 first with the first joint long, the eighth and following ones 

 forming a compact, annulated, rounded, or (rarely) triangular 

 club. 



Prothorax closely applied to the elytra; side pieces not 

 distinct ;f in most of the genera with two cavities to receive 

 the club of the antennae; prosternum frequently lobcd in 

 front, produced behind, articulating with the mesosternum; 

 coxal cavities open behind. 



Mesosternum separating widely the middle coxoa; side 

 pieces large, not divided, sometimes visible from above. 



Metasternum very large, almost connate with the meso- 

 sternum anteriorly; episterna sometimes narrow, sometimes 

 broad, occasionally curved; epimera, broad, large, separated 

 by a fine suture, which is sometimes efl'accd. 



* Tb(! table of genera lias been contributed by Dr. Horace F. Jayne. 

 I In some species there is an elevated line, simubating a suture. 



