THE ABDOMKV. 13 



The abdomen consists of six segments, in the queens 

 and workers, that is to say in the females, and seven m 

 the males. In the Formicidae the first segment, as a 

 general rule, forms a sort of peduncle (known as the scale 

 or knot) between the metathoraz and the remainder of 

 the abdomen. In the Myrmicidae two segments are 

 thus detached from the rest. 



The Poneridae form, as regards the peduncle, and 

 in some other respects, an intermediate group between 

 the Formicidae and the Myrmicidae. The second abdo- 

 minal segment is contracted posteriorly, but not so 

 much so as to form a distinct knot. 



The form of the knot offers in many cases valuable 

 specific characters. 



I am disposed to correlate the existence of a 

 second knot among the .Myrmieidio with their power 

 ^ stiiiijinj,', which is wanting in tin; Fonnicul:c. 

 Though the principal mobility of the abdomen is 

 given in the former, as in the latter, by the joint 

 between the metathorax and the knot, still the second 

 segment of the peduncle must increase the flexibility, 

 which would seem to be a special advantage to those 

 species which have a sting. It must indeed be 

 admitted that CEcophylla 1 has a sting, and yet only 

 one knot; but this, of course, does not altogether 

 negative my suggestion, which, however, I only throw 

 out for consideration*. 



1 Prtc. Linn. Soc* Tol. T. p. 101. 



