200 THE THEOKY OF EVOLUTION 



species of one and the same genus of host Ants. It is 

 therefore easily comprehensible that the differences 

 between Dinarda and Chitosa can be raised to the 

 value of generic distinguishing characters, while those 

 between the various bicoloured Dinarda forms attain 

 at the highest the value of specific characters. Thereby 

 is the demonstrative power of the argument deduced 

 from the evolution of our Dinarda forms also extended 

 to the genera of Dinarda and Chitosa. 



A second example, but certainly of only recent 

 species formation, is presented by the transformation 

 of East Indian and African Wandering Ant guests into 

 Termite guests. Within the hemipterous genera of 

 Doryloxenus and Pygostenus, whose entire generic 

 types are only to be explained by adaptation to the 

 mode of life of Wandering Ants (Dorylus and sub-genus 

 Anomma), there are found namely amongst numerous 

 dorylophil species also a few termitophils which, together 

 with the generic characters which indicate Dorylus 

 guests of the offensive type, show special specific 

 characters, which render them proper termitophil species. 

 Since, however, we can only explain the systematic 

 generic characters of these hemiptera, which belong to , 

 the sub-family of the Pygostenini, by adaptation to 

 the dorylophil mode of existence (see above, p. 191), 

 we must logically explain the specific characters which 

 deviate from the dorylophil relatives, and are shown 

 by the few termitophil species as follows, viz. : that 

 these, geologically speaking, in quite recent times, have 

 become transferred from the mode of life with Wandering 



