HISTERIDAE. 145 



Tribe I.— HOLOLEPTIIVI. 



Body very mucli deprcssod above and below; head extended, 

 with long, prominent mandibles; anteniite inserted under the sides 

 of the front, the elub not reeeived in definite prosternal cavities; 

 mentuni emarginate, entirely covering the base of the maxilltae in 

 our species ; prosternum not lobed in front. 



These species live under the bark of trees; some of them are 

 found in California in decomposing stems of Cactaceae. 



The genus Hololepta, the only one within our territories, is 

 distinguished by tlie mandibles not toothed, the pygidium small 

 and perpendicular. It is divided into two by Marseul, according 

 to the following characters : — 



Prosternum not narrowed in front, mentum flat. Hololepta. 



Prosternum narrowed in front and rounded, mentum with an M-sliaped 



elevated line. Lionota (Lioderma). 



If, lipwever, these characters be considered as valid, then other 

 genera must be established for Californian species. We prefer 

 regarding them as one genus, in which are five groups: — 

 (I. Mentum nearly flat ; prosternum broad, flat. H.fossularis, &c. 

 h. Mentum flat ; prosternum narrowed and rounded at tip. //. Yucateca. 

 <: Mentum concave, without elevated lines ; prosternum sliglitly narrowed, 



truncate, and slightly emarginate at tip. H. vicina. 

 J. Mentum slightly concave, with fine lines ; prosternum slightly narrowed , 



broadly rounded at tip. H. plati/smn. 

 e. Mentum concave, witli strongly elevated lines ; prosternum narrowed, 



almost acute at tip. //. cacti. 



Tribe II.— niSTRIlVI. 



Head retracted, deflexed ; mandibles capable of being applied to 

 the anterior edge of the prosternum, so as to conceal the mouth; 

 mentum subquadrate, not covering the base of the maxilhis. 



This tribe is again formed of two sub-tribes, which differ by 

 the presence or absence of an anterior prosternal lobe; never- 

 theless, in our species of Tribalus, the lobe is so short and broad 

 that they were considered by me as a distinct genus, Cajrosternus, 

 and placed in the second sub-tribe. Onthophilus is placed by 

 Marseul and DuYal in the first, by Lacordaire in the second 

 sub-tribe. 



Prosternum lobed in front. IIistri.m. 



Prosternum truncate in front. tJAi'Ki.Ni. 



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