258 Annals of the South African Museum. 



a pair of teeth or spines. First joint of petiole with a short peduncle, the 

 ventral lamella sometimes bearing a small tooth. Hairs usually clavate. 



$ . Not much larger than the £ ■ Wings with one cubital and 

 one discoidal cell. Otherwise like the $ , except for the usual sexual 

 differences. 



£ . Antennae 12 or 13-jointed. Mandibles narrow, the masticatory 

 margin truncate. Clypeus arched, convex. Mayrian furrows present. 

 Petiole and wings as in the ? ; abdomen narrower. 



The species of this genus are rather timid and slow ants, forming 

 small communities in hollow stems or under bark. Certain species of 

 the genus in N. America and Europe house in their nests other para- 

 sitic ants which are closely allied generically to themselves (Harpago- 

 xenus, etc.). These have ergatoid queens, whose progeny is reared by 

 the workers of the host. 



Key to the ^ $ of Leptothorax. 

 (4). 1. Shoulders of the pronotum sharply angulated ; dorsal profile of thorax 



straight and horizontal, or nearly so. 

 (3). 2. 1st node of petiole a little wider than long, convex above ; 2nd node 



twice as wide as long. .... latinodis, Mayr. 



(2). 3. 1st node of petiole as wide as long, flat above ; 2nd node of petiole one 



and a half times as wide as long. . . angulatus, Mayr. 



(1). 4. Shoulders of the pronotum not sharply angulated ; thorax depressed in 



front of the epinotum, not straight in profile. denticulatus, Mayr. 



L. ANGTJLATTjs, Mayr. (Plate V, figs. 56, 56a.) 

 Verb. Zool. Bot. G-es. Wien, vol. 12; p. 739, $ , 1862. 



$ . 3 - 2 mm. Reddish ochreous, club of antennae and lateral 

 dorsal margins of the thorax and petiole brownish. Head reticulate- 

 rugose, coarsely so at the sides in front of the eyes, the space between 

 the rugosities finely reticulate, and some of the rugae emphasised 

 longitudinally. Upper surface of thorax and of both joints of the 

 petiole strongly reticulate-rugose ; sides of meso- and metathorax 

 finely reticulate. Abdomen and legs microscopically rugulose, smooth 

 and shining. Legs and antennae with a very short and fine pubes- 

 cence, absent from the rest of the body, which has a sparse pilosity 

 consisting of short, thick, erect and clavate hairs. Head, excluding 

 the mandibles, a little longer than wide, a little wider behind than in 

 front, the sides feebly convex, the posterior angles very sharp, the 

 posterior margin straight. Clypeus raised in the middle and pro- 

 longed back between the frontal carinae, with a well-defined median 

 carina and a finer lateral carina on each side. Frontal area indistinct. 

 The frontal carinae are rather wide apart, divergent posteriorly. 



