450 



bulletin: museum of comparative zoology. 



middle, humeri projecting and bluntly angulate, surface flat, except for a very 

 shallowly concave portion at the middle of anterior fourth, sides nearly straight, 

 converging behind to basal portion of declivity which is less than half as broad 

 as the front margin. Base of declivity with two pairs of triangular spines the 

 anterior of which are less than half as long as their distance apart at base, the 

 posterior pair a little longer and less widely separated; surface between the 

 spines concave, strongly declivous to the declivity of epinotum which is broader 

 than the base, twice as broad as long, flat above, with rather strong margins 



Fig. 17.- — Archaeomyrmex cacabau Mann. a. Dorsal view of thorax and petiole. 

 Lateral view of thorax and petiole, c. Front view of head. 



b. 



laterally. Petiole from above subquadrate, a little longer than broad; in 

 profile slightly longer than high, dorsal surface flat, a little longer than posterior 

 face, bituberculate apically, posterior face with two tubercules, similar to 

 those above but more approximated. Postpetiole twice as broad as long, 

 broadest in front, with the anterior border straight and elevated into a strong 

 margin; anterior surface fiat. Gaster very short and broad, first segment 

 only visible from above, concave at basal border, broadest at posterior third. 

 Legs stout. 



Shining. Mandibles punctate, middle portion of clji^eus very smooth and 

 shining. Head with regular costate striae which are straight on the front and 

 evenly curving on the sides and vertex, posterior corners smooth and shining. 

 Thorax above with a series of eleven stronger longitudinal costae, which termi- 



