216 Trans. Acad. Sci. of St. Louis. 



but little diversity in structural characters throughout the 

 genus. The punctures are very minute as a rule and every- 

 where sparse, the surface highly lustrous, the vestiture rather 

 inconspicuous, the head well developed, with the eyes moder- 

 ately large in size and somewhat prominent, the antennae 

 slender, with the first three joints elongate, the subapical 

 about as long as wide and the second and third equal or sub- 

 equal ; the neck is from one-half to two-thirds as wide as the 

 head. The prothorax is obtrapezoidal, wider than long, with 

 the hind ano^les more than right but well marked and not in 

 the least rounded; the elytra are well developed, with very 

 broadly exposed humeri and are but slightly and obtusely 

 produced posteriorly at the sides. The abdomen is broad and 

 rather short, with the first three tergites narrowly but deeply, 

 rectilinearly impressed at base, the impressions subimpunc- 

 tate, having generally a very few widely and irregularly scat- 

 tered coarser but feeble punctures. The legs are long and 

 slender, the hind tarsi filiform, with the basal joint usually 

 fully as long as the next two combined and longer than in 

 typical Gnypeta. The male sexual characters are virtually 

 uniform throughout and consist of a broadly rounded, very 

 shallow sinuation at the tip of the sixth ventral plate. As in 

 Tachyusa, the pronotum is generally impressed along the 

 middle posteriorly in the female and evenly convex in the 

 male, but, in both sexes, there is a short transverse and fre- 

 quently bifoveate impression before the base, as is generally 

 the case in Gnypeta. The genus appears to be local in dis- 

 tribution and confined as far as known to southern California, 

 extending eastward into Arizona. The characters given 

 above being so uniform, no further mention of them will be 

 made, except in certain cases, in the descriptions of the fol- 

 lowing nine species : — 



Abdom^u elliptical in form, widest in the middle and much narrowed at base 

 and apex, the sides evenly arcuate 2 



Abdomen parallel or very nearly so, the sides of the fifth segment moder- 

 ately converging from base to apex 3 



2 — Form rather stout, blackish-piceous in color, the head and entire 

 abdomen black, the legs and antennae pale ; head orbicular, rapidly 

 and arcuately narrowed behind the eyes, the punctures larger and 



