110 Coleo})terological Notices. 



base, the single discal stria very close to the sutnre, distinct, extending to 

 basal third, coincident with the suture just before the apex : having rows of 

 excessively minute, feeble, posteriorly attenuated punctures, attended by 

 finely impressed lines which are continuous to the basal stria ; entire surface 

 covered with a dense system of short, closely crowded, longitudinally aciculate 

 reticulations, which are strongly marked toward apex and the sides but some- 

 times very feeble or obsolete on the upper portions. Abdomen polished, with- 

 out the usual minute reticulation, rather coarsely, asperately punctate, very 

 coarsely pubescent. Legs normal, not very robust ; posterior tarsi slender, 

 three-fourths as long as the tibise, with the basal joint about one-third as 

 long as the second. Length 1.7-2.4 mm. 



Southern California ; Arizona ; New Mexico. 



The metasternum is excessively minutely, sparsely punctate, 

 reticulate in wavy lines laterally ; the process is rather wide, ex- 

 tending very slightly beyond the coxsb, broadly rounded aud finely 

 beaded at apex, the mesosternum very narrowly visible and decliv- 

 ous at the sides in front of the coxiB as usual. The third joint of 

 the maxillary palpi is distinctly longer than wide, the fourth scarcely 

 wider, elongate fusiform and nearly twice as long as the third. 



In one specimen the discal stria does not quite attain the middle 

 of the elytra, and in several other respects this species seems to be 

 very variable. In the five typical representatives obtained by Mr. 

 G. W. Dunn, in Southern California, or the northern part of Lower 

 California, the form is generally very slightly narrower than the 

 majority of a large series taken by Mr. H. F. Wickham, at various 

 localities in Arizona and New Mexico, and the type has a distinctly 

 longer development of the metasternal process than can be observed 

 in the others, this process gradually shortening by insensible degrees, 

 until in one of the broader forms from New Mexico, the mesosternum 

 instead of being deeply excavated under the apex of the process, is 

 simply strongly declivous. There is also marked variation in the 

 width of the process and its degree of obtuseness, in some specimens 

 being very broadly rounded and in others very narrowly so, in the 

 latter case leaving much more of the declivous mesosternum visible 

 at the sides of the apex. 



The dense aciculato-reticulate sculpture, which is unique, and the 

 single discal stria, taken in connection with the sternal and tarsal 

 characters of Olibrus, show that this species is an isolated and highly 

 specialized form, without any near congeners — although in rufipes 

 there is a feeble indication of the sculpture here so highly developed ; — 

 and for this reason, as well as the fact that there appears to be no 



