THE ANTS. 255 



believe that the two insects were different forms of 

 the same sex of the same species. They are much 

 larger than the workers, and have the head smaller 

 and the abdomen much larger in proportion to their 

 bulk ; but the mandibles and antennae resemble those 

 of the workers in form. The most striking distinction 

 is to be found in the structure of the thorax, the three 

 segments of which are united into a more or less oval 

 mass, a mode of formation which evidently stands in 

 connexion with the fact, that the females, when first 

 excluded from the pupa skin, are furnished with four 

 well- developed wings, on which they are able to rise 

 freely into the air. It is from this great difference be- 

 tween the perfect and imperfect females that the name 

 of HETEROGYNA*, given to the tribe, is derived. 



In the males, as in the females, the head is smaller 

 in proportion than in the workers, but the antennae 

 are longer and more slender than in either of the 

 other kinds of individuals, and composed, as in most 

 of the Aculeate Hymenoptera, of thirteen joints in- 

 stead of twelve ; whilst instead of a serrated margin, 

 the mandibles are terminated by a blunt point. The 

 thorax is larger and the abdomen much smaller in 

 proportion than in the females, and the former also 

 bears two pairs of ample wings. 



The general oeconomy of the curious society thus 

 constituted is as follows. During the greater part of 

 the year, as already stated, the nest is occupied by a 

 great number of workers and a few fertile females. 

 The latter are regarded with great respect by the work- 

 ers, and appear to make frequent progresses through 

 the nest for the purpose of depositing their eggs, 



* Gr. heteros> different, gune, a female. 



