A Monograph of the Formicidae of South Africa. 373 



deeply emarginate. Mandibles elongate, the internal and external 

 margins often much longer than the masticatory, which is generally 

 armed with acute teeth. A complete scrobe present. Eyes small and 

 placed low down on the sides. Frontal carinae widely divergent' 

 forming the upper boundary of the scrobes. Thorax widest in front, 

 narrowed laterally and depressed above at the meso-epinotal suture, 

 both thoracic sutures more or less defined. Epinotum often bidentate 

 or bispinose. Declivity of epinotum often furnished with a foliaceous 

 or membranaceous margin on each side. Petiole generally covered, 

 at least at the sides, with a spongy mass of material, probably 

 formed by a coalescence of spatulate hairs. First segment of petiole 

 with the peduncular and nodal portions distinct ; 2nd node wider 

 than the 1st, transverse. Abdomen generally very convex below, 

 flattened above. Legs fairly long and slender, the middle and 

 posterior tibiae without calcaria. Pilosity usually composed of clavate 

 and spatulate hairs. 



9 ■ Like the £ , except the usual sexual differences in the structure 

 of the thorax. Eyes larger than in the ^ ; ocelli present. Wings 

 with an open radial cell and one median cell, the cubital and discoidal 

 cells absent. 



$ . Antennae 13- jointed. 



Distribution. Both hemispheres. 



Key to the $ $ of Strumigenys. 



(14) 1. Mandibles distinctly toothed. 



(11) 2. Mandibles armed with 3 or 4 teeth near the apex; all, or at least 



three of them very long, acute and spiniform. 

 (10) 3. Mandibles half as long as the head, or very nearly so.* 

 (5) 4. Last joint almost twice as long as the rest of the flagellum. 



Traegaordhi, Santschi. 



(4) 5. Last joint not more, or less than one-third longer than the rest of 



the flagellum. 

 (7) 6. Sides of the head very convex . . . . irrorata, Santschi- 



(fi) 7. Sides of head not very convex, obliquely rectilinear or slightly con- 

 cave in the median third. 

 (!») 8. Mesonotum distinctly depressed behind ; dorsum of epinotum hori- 

 zontal ......... Arnoldi, Forel. 



(5) 9. Mesonotum not depressed behind, merely feebly convex over its 



whole length ; dorsum of epinotum oblique . Havilandi, Forel. 



(3) 10. Mandibles distinctly less than half the length of the head. 



Havilandi, race Marleyi, Arnold. 



* N.B. — In this key, and in the subsequent descriptions, the head is measured 

 along the median line, from the anterior margin of the clypeus to the middle 

 of the occipital margin. The measurement of the mandibles excludes the 

 portion hidden beneath the clypeus. 



