NEW FORMICID/E FROM BARRO COLORADO ISLAND. 177 



somewhat flattened, its basal border rather straight. Legs short 

 and slender. 



Mandibles somewhat shining, finely punctate. Head subo- 

 paque, densely, finely and evenly longitudinally rugulose, the 

 rugules straight and feebly diverging from between the frontal 

 carinae to the posterior corners. Thorax, petiole and postpetiole 

 also subopaque but the pro- and mesonotum, and especially the 

 scutellum, more shining; the pronotum indistinctly and very 

 finely longitudinally striate. Gaster shining, with rather numer- 

 ous, minute, piligerous punctures. 



Hairs yellowish, suberect, sparse, more numerous on the gaster, 

 fine and subappressed on the appendages. 



Ferruginous red; legs, funiculi, except the articulations, and 

 gaster paler and more yellowish; borders of mandibles and 

 clypeus brown or blackish. 



Worker. Length 0.9 mm. 



Head shaped somewhat as in the soldier, but much smaller, 

 with evenly convex sides and more feebly excised posterior border. 

 Eyes and ocelli absent. Mandibles less convex, with oblique 

 blades, bearing three large apical teeth and a small basal tooth. 

 Clypeus resembling that of the soldier. Frontal carinae very 

 short. Antennae g-jointed, the scapes reaching to the middle of 

 the sides of the head ; the terminal joint of the club proportionally 

 longer than in the soldier, joints 2-6 of the funiculus decidedly 

 shorter and more transverse, fully twice as broad as long. The 

 thorax lacks the scutellar and metanotal sclerites and has a small 

 but distinct mesoepinotal constriction. Epinotum small, with 

 subequal base and declivity, the former slightly convex, the latter 

 sloping, the angle between the two obtuse and rounded. Petiolar 

 and postpetiolar nodes subequal, the latter nearly as long as 

 broad, rounded on the sides, without tubercles. Gaster much 

 smaller than the head, with somewhat concave anterior border. 



Smooth and shining, with scattered piligerous punctures, which 

 are most distinct on the head, especially on its sides. 



Pilosity much as in the soldier but the hairs are decidedly 

 shorter and of more uniform length. Clypeus with four stout 

 bristles. Hairs on the front directed transversely, on the sides of 

 the head forward. 



