NORTH AMERICAN COLEOPTERA. 87 



This species may be known from either of the preceding by the 

 thorax being not wider at base than at apex. The punctuation is a 

 little finer than in debilis, but coarser than in consjnda. 



Occurs in New Mexico, Utah, Nevada, California and Arizona. 



The genus Monoxia, as instituted by LeConte, contained merely 

 the smaller species. He divided them primarily into two series from 

 the form of the claws, which Crotch first recognized as merely sexual 

 differences (Proc. Acad. 1873, p. 56). 



While the arrangement above is not exactly in accord with Crotch's 

 apportionment of the synonymy, the fact remains that three of Le- 

 Conte's species are males and three females. Another character used 

 by LeConte will be found to have but little value, and that is the 

 oblique impression of the elytra. This may occur in either sex, but 

 may be considered rather a male than a female characteristic. No 

 mention has been made of it in the foregoing description. 



TRIARIUS Jacoby. 



Head free, eyes oval, entire ; labrum moderate in length, not emar- 

 ginate; maxillary palpi not very stout, the last two joints nearly 

 equal in length, the terminal conical. Antennae slender. Thorax 

 broader than long, slightly narrower at base than apex ; scutellum 

 oval at tip. Elytra oblong, parallel, the epipleurse limited by a dis- 

 tinct marginal line and extending three-fourths to apex ; prosternum 

 very narrowly separating the coxse, the cavities open behind, although 

 very narrow in some specimens ; metapleurae moderate in width, 

 parallel; ventral segments nearly equal in length, the fifth longer; 

 femora moderately stout, tibise slender, but broader at tip ; all the 

 tibiae with a well-developed spur; hind tarsi with the first joint not 

 longer than the next two ; claws bifid. 



This genus was proposed for an insect (T. mexicanus) previously 

 described by Dr. LeConte as Phyllobrotica livida. As correctly re- 

 marked by Mr. Jacoby, the armed tibiae and the bifid claws forbid 

 its entrance in the genus in which Dr. LeConte placed it. On the 

 other hand I cannot agree with Mr. Jacoby that it has any special 

 affinity with Phyllobrotica, the elytral epipleurae being quite as well 

 marked as in the vast majority of the members of the entire tribe. 

 The relationship seems rather with Dlabrotica, the only character of 

 moment separating it being the separation of the front coxae by the 

 prosternum. 



Two species are known to tue : 



TKANS. AM. ENT. SOC. XX. MAY, 1893. 



