EXTERNAL STRUCTURE. 



15 



Squamula 



Fig. 28. Stipes, Volsella, and Sagitta of Formica rufibarbis (dissected out). 

 (Donisthorpe. ) 



sists of a single grooved piece, the gorgeret, on which run the stylets, 

 a pair of smooth, slender, pointed appendages. When at rest the 

 stylets do not extend beyond the gorgeret, but when an ant uses 



Squamula 



Stipes 

 Lacinia 



Volsella 



Spatha 



Fig. 29. c? genitalia of Ponera punctatissima. 



its sting, it thrusts the whole apparatus into the object attacked, 

 and the stylets are pushed alternately further into the wound, 

 beyond the tip of the gorgeret. 



Volsella 

 Stipes 



iW 



Sagittae 

 Fig. 30. ( genitalia of Myrmica scabrinodis. (Crawley.) 



