218 Trans. Acad. Set. of St. Louis. 



one-half wider and a fourth longer than the prothorax and very much 

 wider than the head, broadly convex, impressed on the suture toward 

 base; abdomen toward base much narrower than the elytra but rapidly 

 broadening, so that the apex of the fourth segment is somewhat wider 

 than the elytra, the fifth segment obtrapezoidal and nearly as long as 

 the two preceding combined; legs slender. Male with the fifth ventral 

 unmodified, the sixth having a triangular incisure at apex about one- 

 half deeper than wide, the surface feebly impressed in prolongation 

 thereof. Length 3.2 mm.; width 0.55 mm. Texas (Houston and Lu< 



ling) nitidaLec. 



Form, sculpture and coloration almost completely similar to nitida, the dark 

 subapical cloud of the abdomen usually confined to the discal parts of 

 the fifth segment only and the general color rather paler than in nitida; 

 head nearly similar but with much less broadly rounded basal angles, 

 the truncate part of the base wider and more transverse; prothorax 

 nearly similar, the elytra larger and relatively more elongate, the ab- 

 domen notably broader and less dilated posteriorly, the fifth segment 

 much shorter than the two preceding. Male with the fifth ventral un- 

 modified, the sixth having a moderately large notch at apex, the emargin- 

 ation triangular with straight sides and angulate apex and nearly twice 

 as wide as deep, the adjacent surface not at all impressed. Length 3.1 

 mm.; width 0.6 mm. California (Yuma and the Needles), sonorica n. sp. 



These species are both rather abundant and somewhat re- 

 semble certain ants in their movements and coloration. Nitida 

 was originally described under the generic name Echiaster. 



Stilici. 



The few generic types of this well-marked subtribe are 

 remarkably consistent in the form of the tarsi, neck and 

 gular sutures and differ among themselves principally in 

 modifications of the labrum, maxillary palpi, prosternurn and 

 sculpture of the integuments. The hind tarsi are more or 

 less elongate throughout, with the basal joint always distinctly 

 longer than the second and sometimes as loner as the next two 

 combined but varies considerably in relative elongation, even 

 within the limits of Stilicus itself. The neck is always very 

 slender and not variable in width, as it is in the Scopaei, and 

 the gular sutures are invariably coalescent and unified at least 

 toward base. The anterior tarsi are generally very slightly 

 dilated and spongy-pubescent beneath. The genera known 

 to me may be briefly described as follows : — 



