36 B. GEASSI AND A. SANDIAS. 



9. If the Termite colony were headed only by royal forms, 

 such as have been described, without sign of wings, the 

 phenomenon would occasion no surprise, but all valid proof 

 would be wanting that the Termitidse themselves had ever 

 possessed wings. 



This consideration may throw some light on the origin of 

 the Thysanura. My researches on these insects showed that 

 their characters are partly primitive, and partly connect them 

 intimately with the Orthoptera (s. str.). Such a connection 

 seemed, however, to be contra-indicated by the hypothesis, 

 which I accepted, that the Thysanura have never possessed 

 wings, structures of which I have been unable to find the least 

 indication. 



But I am compelled to reject this hypothesis, owing to what 

 I have seen take place in Termitidae under my eyes, and to 

 admit that the Thysanura may originally have possessed 

 wings, which they have subsequently and entirely lost. They 

 must be descended from primitive forms in which the first 

 abdominal segment remained independent, with its sternite 

 complete and not fused with the metasternum as in Termi- 

 tidse; and not a few winged Orthoptera (s. lat.) are known to 

 exist which have the first abdominal sternite separate as in 

 Thysanura. 



And this leads me to regard the division of Insecta 

 into Apterygogenea and Pterygogenea as unfounded, 

 whatever Brauer may assert.^ 



In other words, I admit that all existing species of 

 insects may once have possessed wings. 



Historical Accounts and Developments. 



I leave to the writer of a complete monograph on the Ter- 

 raitidse ihe task of elucidating point by point the contribu- 

 tions to a knowledge of them which Dr. Sandias and I have 

 made and set forth, but I cannot here pass in silence over 

 some preceding accounts of special significance. 



1 ' Zool. Anz.,' 1888, pp. 598—600. 



