102 Coleopterological Notices. 



Colorado (Yeta Pass). Mr. Schwarz. 



I have only seen one specimen of this remarkable species. 



OLIBRUS Erichs. 



The genus Olibrus differs from Phalacrus in only two very im- 

 portant particulars, but in a large number of characters which must 

 be considered of more or less subsidiary value. The two most 

 marked differences are found in the mode of antennal insertion, and 

 in the size of the scutellum. In Phalacrus and its allies with large 

 scutellum, the antennae are inserted far under the epistoma in very 

 deeply excavated cavities in front of the eyes, the anterior margin 

 of the head being arcuate continuously with the eye throughout the 

 width, while in the genera with small scutellum, the epistomal edge 

 is deeply sinuate laterally, and the points of antennal insertion more 

 visible from above. In the structure of the sterna the two genera 

 are identical. The posterior tarsi and tibial spurs are, however, 

 slightly longer than in Phalacrus, but I cannot regard this as of 

 such decisive importance as the two characters mentioned. The 

 small foveas near the eyes, visible in the genera with large scutellum, 

 are generally obsolete in the others. From Stilbus this genus differs 

 much more radically than it does from Phalacrus, in the very im- 

 portant structure of the mesosternum behind the middle coxae. 



In two characters Olibrus stands almost alone in the family, 

 the one relating to the form of the terminal joint of the antennae, 

 the very strongly constricted terminal process so perfectly developed 

 here being merely indicated in Phalacrus, and almost entirely obso- 

 lete in Stilbus, the other relating to the punctures of the elytral 

 series, which are never transversely crescentiform, but if modified 

 at all from fine simple points, distinctly attenuate posteriorly ; this 

 form of elytral punctuation I have not found to exist elsewhere, 

 except in Olibroporus.^ It is true there are many species of Stilbus 

 which are perfectly devoid of the peculiar crescentiform punctures, 

 but in this case the punctures simply disappear and never assume 

 the elongate form here alluded to. 



In the absence of the terminal line of robust setiform spinules at 



1 There is an undescribed South African species before me, in whicli the 

 punctures at the sides become slightly dilated, but although it is apparently 

 assignable to Olibrus, I am not entirely certain that it really belongs to that 

 genus. 



