CARNIVOROUS ANTS 51 



to spring backwards at the slightest danger. I 

 mention these details in my contrast of Mymnecocystus 

 with the harvesters to indicate how greatly do the 

 habits, instincts and special senses vary in the 

 different species of ants. 



The most obvious feature in the appearance of this 

 species is the peculiar manner in which it erects its 

 abdomen when running about. The whole abdomen 

 is extremely mobile, and the slender pedicle, that 

 connects it with the insect's thorax, allows it to move 

 with such extreme freedom as to be either extended 

 horizontally behind or erected vertically in the air 

 at right angles to the remainder of the body. The 

 latter position is the most usual, and gives the ant a 

 terrifying appearance as though it were a dangerous 

 insect armed with a powerful and venomous sting. 

 The ant is really a harmless creature, and I first 

 thought that this attitude was assumed for the purpose 

 of striking terror into its enemies and giving them a 

 false impression of its innocent nature. But this 

 ant has very few enemies, so I suspect that this 

 strange attitude of the abdomen has not a defensive 

 function but is really a balancing agent ; for when the 

 ant is struggling with a heavy burden and attempting 

 to drag it over all kinds of obstacles, it is a great 

 advantage to the insect to have a large abdomen 

 projecting out behind as a counterbalance to the 

 weight, and the ant will naturally turn the abdomen 

 up over the thorax when the jaws are empty and the 

 counterbalance not required. 



I had read of certain ants treating one another with 

 affection, and I have mentioned an instance of the 

 harvesters rescuing their companions when in diffi- 



