494 ANTS. 



nest). The thief ants then gradually became marauders ("mixed 

 colon}-). With increasing dependence on their auxiliaries, which 

 showed itself in tin- dwindling of the worker instincts and the disap- 

 pearance of the mandibular teeth, the difficulty of founding colonies 

 by means of winged females increased and led to the development of 

 the ergatoicl forms. In these the ancient lestobiotic and predatory 

 in-tincts united with the newly acquired female instincts, so that the 

 ergatoids became incomparably better fitted for founding colonies than 

 the winged forms, which therefore tended to extinction. \Ve must 

 still, however, endeavor to explain why the winged females have never 

 been found in the colonies of northern Europe. This may be accounted 

 for in two ways. We may regard the winged female either as a rever- 

 sion or as the lingering vestige of a not yet completely eliminated 

 winged form. The latter alternative seems to be indicated by the 

 remoteness of the locality in which this form occurs from the true 



FIG. 275. A, Harpago.retnis ainericaniis worker and B, its host, Leptothorax curri- 



spinosus worker. (Original.) 



geographical range of the species. The development of this sex would 

 probably be unequally advanced in two regions differing so much in 

 climate and other conditions. But we must wait to see whether this 

 ant does not occur also in other regions, perhaps in northern Germany." 

 2. Harpagoxenus auicricanus (Fig. 275, A}. This species, which 

 is smaller and of a darker brown color than subleris, seems to be 

 extremely rare. To my knowledge it has been taken on only three 

 occasions. The type specimens, describe by Emery (1893-94), were 

 found by Pergande at Washington, D. C., in a nest of Leptothorax 

 curvispinosus (Fig. 275, B}, but no observations on the relations 



