12 THE THORAX. 



The thorax is generally considered to consist, as in 

 other insects, of three divisions the prothorax, meso- 

 thorax, and metathorax. I have elsewhere, however, 

 given reasons into which I will not at this moment 

 enter, for considering that the first abdominal segment 

 .has in this group coalesced with the thorax. The 

 thorax bears three pairs of legs, consisting of a coxa, 

 trochanter, femur, tibia and tarsus, the latter composed 

 of five segments and terminating in a pair of strong 

 claws. 



In the males and females the meso- and meta- 

 thorax each bear a pair of wings, which, however, in 

 the case of the female, are stripped off by the insects 

 themselves soon after the marriage flight. 



The workers never possess wings, nor do they show 

 even a rudimentary representative of these organs. Dr. 

 Dewitz has, however, pointed out that the full-grown 

 larvae of the workers possess well-developed * imaginal 

 disks,' like those which, in the males and females, de- 

 velope into the wings. These disks, during the pupal 

 life, gradually become atrophied, until in the perfect 

 insects they are represented only by two strongly 

 chitinised points lying under the large middle thoracic 

 spiracles. No one unacquainted with the original 

 history of these points would ever suspect them to be 

 the rudimentary remnants of ancestral wings. 1 



The thorax also bears three pairs of spiracles, or 

 breathing holes. 



' Zeit. f. mitt. Zool., vol. xxviii. p. 555. 



