194 



THE THEORY OF EVOLUTION 



of which, two genera (Termitoxenia and Termitomyia), 

 not only in their entire form of body, but also in their 

 development and mode of reproduction, strikingly 

 differ not only from all other Diptera but even from 

 all other insects. They possess, namely, no larval 

 form, but effect their post-embryonal metamorphosis 

 in the form of a peculiar ' imaginal evolution ' (Fig. 37). 

 Also the individuals are not sexually separated, but 

 are regularly protandric hermaphrodites a unique case 

 in the insect world. All the morphological and 

 morphogenetic (embryological) characters of this 

 remarkable Diptera of which so far six species are 

 known show themselves to be termitophil adaptive 

 characters. 



Furthermore among the termitophil Diptera must 

 be mentioned the Termitomastini, which, although 

 belonging to another sub-order of the Diptera the 

 Termitoxemni are short-horned, the Termitomastini 

 long-horned present many similarities to them. Also 

 the Termitomastini owe their systematic separation 

 entirely to their adaptive characters fitting them for 

 a termitophil existence. 



A very interesting example of termitophil trans- 

 formation is furthermore shown in the genus Thauma- 

 toxena belonging to the Diptera family of Phoridse. 

 Therein we find that even the organization characters 

 of the two- winged order are so greatly masked by the 

 termitophil adaptation, that two excellent insect experts, 

 Breddin and Borner, described the first species of 

 this genus Thaumatoxena Wasmanni originally not 



