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WILLIAM MORTON WHEELER. 



the longer ones are less reclinate and shorter than in Pogono- 

 myrmex. They are slightly curved upward at their tips. The 

 mandibular ammochaetae are unusually long and curved. 



Cratomyrmex Emery. — This genus is based on a single 

 species, C. regalis, which Emery described from two large female 

 specimens (19 mm. long), taken at Benue in western Africa. 1 

 They resemble Pogonomyrmex in having long hairs on the lower 

 surface of the head, but these hairs are said to be shorter and less 

 regularly arranged than in P. barbatus. 



Stenamma Mayr. — This extensive genus may be divided into 

 six subgenera : Stenamma s. str., Aphcznogaster, Ischnomyrmex, 

 Messor, Goniomma and Oxyopomyrmex. The species of Ste- 

 namma s. str., are moisture-loving ants living in small colonies in 

 the woods of the north temperate zone. The much more 

 numerous species of Aphcsnogaster are widely distributed and 

 occur in a great variety of environments, some even living in dry 

 deserts, but none of them seems to have developed ammochaetae, 

 although the lower surface of the head, like the body in general, 

 is usually provided with coarse erect hairs. From species of this 

 or some very similar group the remaining subgenera, Ischnomyr- 

 mex, Messor, Goniomma and Oxyopomyrmex, seem to have been 

 derived. All of these comprise xerophilous or deserticolous 

 .species with ammochaetae and seed-eating propensities. 



Fig. 4. Ischnomyrmex albisetosus Mayr. 



Ischnomyrmex Mayr. — Our two North American species of 

 this subgenus, /". cockerelli Andre and albisetosus Mayr are closely 

 related and both inhabit the driest deserts of western Texas, New 



1 Voyage de M. Ch. Alluand dans le territoire d'Assinie (Afrique Occidentale), 

 Formicidse. Ann. Soc. Ent. France, LX., 1891, pp. 553—574, PI. XV. 



