NEW FORMICID.E FROM BARRO COLORADO ISLAND. 167 



funiculi are distinctly more transverse. The thorax, abdomen 

 and legs are very similar to those of impexus, but the inferior 

 angles of the pronotum, the pair of tubercles on this segment and 

 the two pairs of tubercles on the mesonotum are somewhat larger 

 and more acute and the lateral marginations of the gaster are 

 more pronounced, as are also the three broad longitudinal 

 depressions near its base on the dorsal side. 



The pilosity and pubescence are decidedly more abundant than 

 in impexus. The former is longer and more completely covers the 

 integument, the latter is also longer and more conspicuous, 

 especially on the dorsal surface of the body. The hairs are 

 blackish at the base, with long, slender, flexuous, pale grayish or 

 yellowish tips. The color of the body and appendages in mature 

 specimens is rich ferruginous brown, with somewhat darker 

 mandibles. 



Female. Length 5-5.5 mm.; wings 6.3 mm. 



Similar to the worker. Backward extensions of the frontal 

 carinae and of the carinae of the cheeks more acute, so that the 

 antennal scrobes are more strongly developed. Mandibles 

 coarsely striatopunctate. Pronotum with a blunt tubercle on 

 each side, the inferior angles not very distinct. Mesonotum 

 subrectangular, slightly longer than broad, flattened above, with 

 a feeble Y-shaped impression. Scutellum less than twice as broad 

 as long, bluntly bidentate behind. Epinotum declivous, with a 

 pair of blunt longitudinal ridges terminating in blunt teeth. 

 Petiole and postpetiole each with a pair of blunt longitudinal 

 ridges above. The large first gastric segment is broader behind 

 than in front, with straight sides, which are marginate; the three 

 longitudinal impressions on the dorsal surface somewhat more 

 distinct than in the worker. 



Pilosity and especially the pubescence even longer than in the 

 worker. Color darker, more brown and less reddish. Wings 

 rather strongly and uniformly infuscated ; veins and pterostigma 

 pale, but very narrowly outlined with blackish. 



Male. Length nearly 3 mm. 



Head, including the eyes, as long as broad, somewhat narrowed 

 behind, with straight posterior border and rounded posterior 

 corners. Eyes rather large and convex, the ocelli small and 



