196 



WILLIAM MORTON WHEELER. 



louteux, alluvial, j'ai toujours trouve la race agyptiacus Emery, 

 et dans le desert rocailleux la race striaticeps Andre." Now the 

 race or subspecies czgyptiacus has well-developed ammochsetae, 

 and in striaticeps these bristles are also present, though more 

 feebly developed. M. arenarius Fabr., and caviceps Forel, two 

 species peculiar to the dry sandy portions of the Sahara, and 

 apparently also M. bugnioni Forel of the same region, have highly 

 developed ammochsetae, but these are absent in the European M. 

 structor, and in lobicornis, a form discovered by Forel in the oasis 

 at Biskra. 1 



Among our American species, M. pergandei Mayr and julianus 

 Pergande have well-developed ammochsetae, whereas andrei 



Fig. 6. Messor pergandei Mayr. 



Mayr, carbonarius Pergande and stoddardi Emery have only the 

 usual hairs on the lower surface of the head. The habits of car- 

 bonarius , jidianus and stoddardi are unknown but pergandei, as I 

 can assert from my own observations, lives only in the driest por- 

 tions of the deserts of Arizona and California, and andrei and 

 stoddardi are cited only from more humid portions of the latter 

 state. The head of pergandei, which is represented in Fig. 6, 

 shows a fine development of the clypeal, mandibular and gular 

 bristles. The gular series form an arc on each side bounding a 

 distinctly concave median region separated from the convex 

 lower portions of the cheek by a distinct ridge (represented in 

 the figure by a dotted line along the insertions of the bristles). 



1 " Les Formicides de la Province d'Oran (Algerie)," Bull. Soc. Vaud. Sci. Nat. 

 XXX., no. 114, 1894, pp. 31-33. 



