486 Annals of the South African Museum. 



gaster, such as the coleopterous Myrmedonia, Conurus, Xenalluaudia. 

 and a few Paussidae and the orthopterous Myrmecophila. 



Most of the species of the genus are tree-ants, making their nests 

 under the bark, in hollow branches or forming carton nests, which 

 may be either sheltered in cavities in the trees or attached to branches, 

 reeds and bushes. The character of the nest built by any one species 

 is not invariable. Thus rufo-nigra, which in Natal usually builds 

 large carton nests attached to the branches of a tree or shrub, is, 

 according to my experience, always found in S. Ehodesia to make 

 its nest in hollow branches, empty galls or under stones without the 

 elaboration of any carton-like substance. Very few of our Ehodesian 

 species nest as a rule in the ground, although young incipient nests 

 may occasionally be found in that situation. 



J 



Key to the ^ ^ of Cremastogaster. 



(46) 1. Antennae 11-jointed. 



(3) 2. Antennae exceptionally long, extending back as far as the petiole, and 



one-third of the scape extending beyond the hind margin of the head 



Schultzei, Forel. 

 (2) 3. Antennae of usual length. 



(7) 4. Head distinctly longer than wide, parallel-sided or nearly so. 

 (6) 5. First joint of petiole trapezoidal ; scapes short, reaching the posterior 

 third of the head ..... nigronitens, Santschi. 

 (5) 6. First joint of petiole oblong, one-third longer than wide ; scapes longer, 

 reaching the posterior fourth of the head 



Welmani, Forel, race retusa. 



(4) 7. Head as wide as, or wider than long, very rarely a trifle longer than 



wide, the sides more or less convex. 

 (17) 8. First joint of petiole not trapezoidal. 



(10) 9. Head and thorax strongly striate; 1st joint of petiole subpyriform, 



longer than wide, not much wider in front than behind 



arborea, Mayr, race melano gaster, Em. 

 (9) 10. Head and thorax not strongly sculptured ; 1st joint of petiole not sub- 

 pyriform. 

 (12) 11. First joint of petiole quadrate, wider than long 



sordidula, Nyl., var. rectinota, Forel. 



(11) 12. First joint of petiole longer than wide. 



(16) 13. First joint of petiole minutely bidentate near the posterior margin ; 



the 2nd node globose and without even a trace of a median groove. 

 (15) 14. Epinotum sharply and widely reticulate, its dorsal lateral margins 

 strongly convex ; abdomen elongate, not cordate 



transvaalensis, Forel. 

 (14) 15. Epinotum not sharply reticulate, the lateral dorsal margins straight 

 and divergent ; abdomen cordate 



Muralti, Forel, race livingstonei, Santschi. 



