94 



Psyche 



[Jt 



dibles with two large apical and numerous smaller basal teeth. Clypeus flattened, 

 its anterior border slightly reflected and in the middle sinuately excised. Frontal 

 area triangular, rather indistinct. Frontal carinse large, with rounded external 

 borders, their surface scarcely concave in the middle, continued behind as a pair of 

 straight, diverging ridges to the posterior corners of the head. Vertex with two 

 shorter, parallel ridges. There is also a short oblique ridge running mesially along 

 each inner orbit half way to the ridge continued back from the frontal carina. 

 Antennae long; scapes reaching somewhat more than \ their length beyond the 

 posterior corners of the head, slender at the base, thickened distally and again 

 more attenuate at the apex. Pronotum with a slender, lapped-shaped inferior and a 

 stout, pointed superior spine on each side, without an anteromedian paired or 

 unpaired tubercle. Mesonotum on each side in front with a stout, blunt protuber- 

 ance and behind with three small protuberances, two of which are hardly more than 

 tubercles. Mesoepinotal constriction pronounced. Epinotum with subequal 



Fig. 1. Trachymyrmex arizonensis Wheeler. Worker; a, head; 

 6, thorax and abdomen seen from above; c, same seen in profile. 



base and declivity, the latter sloping, the former flattened and bearing a pair of 

 longitudinal ridges which diverge slightly behind and terminate in the spines. 

 These are acute and rather slender, a little longer than broad at their bases, directed 

 outward and backward and but very slightly upward. Petiole with a narrow and 

 very short peduncle; its node with a bitubercular summit, seen from above as long 

 as broad, rounded behind, with parallel sides; in profile it is acutely angular, with 

 straight anterior and posterior declivities, the former a little longer than the latter. 

 Postpetiole nearly twice as broad as the petiole, broader behind than in front; its 

 posterior border with a rounded lobe on each side and a rounded excision in the 

 middle. Its upper surface is distinctly concave behind, so that in profile it is highest 

 in front, with a short, straight anterior and a somewhat longer, concave posterior 

 slope. Gaster oval, slightly broadest behind the middle, its first segment with only 



