336 AMERICAN PACHYBRACHYS (cOLEOPTERa) 



15. Pachybrachys purus new species 



Subcylindric, rather strongly convex, pale yellowish testaceous, 

 feebly shining, integuments very minutely alutaceous, virtually 

 immaculate, the thoracic markings pale brownish, diffuse and 

 barely detectable; elytral punctures pale brown, those of the 

 prothorax much finer and scarcely or but little darker than the 

 surrounding surface. Ave. length 4 mm. Colorado River. 



Head moderately punctate, more closely on the vertex and in a triangular 

 frontal area, spots faint. Eyes separated in the male by a distance subequal 

 to the vertical width of their upper lobes, or by about one and three-fourths 

 times the length of the basal joint of the antennae; in the female by two and 

 one-half times the length of the basal antennal joint; ocular lines distinct and 

 at rather less than one-fourth the distance from the eye to the median line. 

 Antennae attaining the hind coxae in the male, or the humeri in the female, 

 terminal joint and apices of several of the outer joints dusky. 



Prothorax moderately transverse, sides convergent from base to apex, 

 more feebly so in basal fifth, feebly arcuate; surface finely not very closely 

 nearly evenly punctate, with a few minute interstitial punctures; side margins 

 narrowly smooth, the median hne sometimes imperfectly so. 



Elytra not ( 9 ) or just perceptibly (cT) wider at base than the prothorax, 

 slightly narrowed posteriorly; punctures not very coarse, striae not impressed, 

 apical portion of the first and second, and the seventh and eighth throughout 

 regular, otherwise striae much confused, though variably so; scutellar area 

 rather closely confusedly punctured; marginal interspace wide, impunctate; 

 submarginal interspace narrower but nearly even throughout. 



Body beneath entirely pale; legs pale, femoral clouds very faint. 



Length 3.5 to 4.5 mm; width 1.75 to 2.5 mm. 



Distribution. — Occurs along the Lower Colorado River in 

 California and Arizona. Three examples only are before me, 

 the type a female collected by myself at Yuma, Cal., July 3; 

 a male collected by Dr. Fenyes at Yuma, Apr. 22, and a female 

 taken by Professor Wickham at East Bridge, Ariz., Aug. 21 

 (Leng. Coll.). 



This is a very neat and pretty species, easily separable from 

 all others by the tabular characters. The front claws in the 

 male are noticeably a little larger than, the others but not con- 

 spicuously so. 



IG. Pachybrachys mellitus Bowditch 



Robust, dark honey yellow, immaculate, integuments very 

 minutely alutaceous but rather strongly shining, punctures not 

 or scarcely darker; eyes rather distant, ocular lines fine and quite 



