MONOTOMID^E 93 



toma. There is no trace of punctures on the alternate intervals as 

 in alternatus Schf. 



Leptipsius n. gen. 



This genus, here proposed for the Monotoma striata of LeConte 

 (Bactridium Horn nee Lee.), is rather closely allied to Hesperob&nus 

 but differs in several more or less important particulars, relating 

 principally to the antennae, scutellum and pygidium. The body 

 is very slender and rather depressed, the head abruptly constricted 

 at base as in Hesperobanus but at a much shorter distance behind 

 the eyes, the tempera being very short though rectangular; it is 

 rather singular, with this structure of the head, that striata should 

 have been placed by Dr. Horn in Bactridium, which he defines 

 particularly by the unconstricted base; besides this, however, the 

 abdomen is sculptured in an altogether different way, having no 

 trace of the transverse series of oblong-oval foveae; it is in every 

 respect like that of Hesperobtznus. The antennae differ from those 

 of Hesperobcenus and are almost exactly as in Bactridium, the third 

 joint being very short and the outer joints of the funicle like those 

 which precede them, except for the usual very slight enlargement; 

 in Hesperobcenus the ninth joint is long and obconical. The scu- 

 tellum in the latter genus is rather narrow and distinctly constricted 

 subbasally, while here it is larger and more evenly oval, and the 

 pygidium is very much more elongate and less convex. 



Leptipsius striatus Lee., is very common under bark in southern 

 California and the neighboring parts of Arizona, and one Mexican 

 specimen at hand I cannot distinguish from it in any way. The 

 description of Rhizophagus adustus Rttr., answers to this species 

 almost perfectly, and I have scarcely any doubt that the two are 

 identical. The type of adustus was stated to be simply from 

 North America, without more definite localization, and, in the 

 " Biologia," Dr. Sharp has called a mixture of closely allied forms by 

 that name; a revision should be made of them and adustus more 

 accurately defined. The following species is allied to striatus but 

 has more abbreviated elytra : 



Leptipsius dilutus n. sp. Form oblong-elongate, depressed, parallel, 

 rather shining though strongly micro-reticulate throughout, ferruginous, 

 the elytra more flavate, becoming just visibly clouded apically; head 

 about as wide as the prothorax (cT), a little narrower (9), sparsely 



