HISTERIDAE. ?5 



mentuin emarginate, entirely covering the base of the maxillae in 

 our species ; presternum not lobed in front. 



These species live under the bark of trees ; some of them I have 

 found in California in decomposing stems of Cactaceae. 



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

 distinguished by the mandibles not toothed, the pygidium small 

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

 to the following characters : — 



Presternum not narrowed in front, menturn flat. Hololepta. 



Presternum narrowed in front and rounded, mentum with an M-shaped ele- 

 vated line. Lionota (Lioderma). 



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

 genera must be established for Californian species. I prefer re- 

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



<i. Mentum nearly flat ; prosternum broad, fiat. H. fossularis, &c. 



I. Mentum flat ; prosternum narrowed and rounded at tip. II. princeps. 



c. Mentum concave, without elevated lines; prosternum slightly narrowed, 



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



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



broadly rounded at tip. H. platysma. 



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



almost acute at tip. H. cacti. 



Tribe II.— HISTRINI. 



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 maxillae. 



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

 the presence or absence of an anterior prosternal lobe ; neverthe- 

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

 they were considered by me as a distinct genus, Caerosternus, and 

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

 seul and Duval in the first, by Lacordaire in the second sub-tribe. 



Prosternum lobed in front. Histrini. 



Prosternum truncate in front. Saprini. 



Sub-Tribe 1.— Histrini (genuini). 



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

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

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

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



