84 STKONGYLOGNATHUS. 



and feed them : under these circumstances they re- 

 mained in perfect health, while, but for the slaves, 

 they would have perished in two or three days. Ex- 

 cepting the slave-making ants, and some of the Myr- 

 mecophilous beetles above described, I know no case 

 in nature of an animal having lost the instinct of 

 feeding. 



In P. rufescens, the so-called workers, though 

 thus helpless and idle, are numerous, energetic, and 

 in some respects even brilliant. In another slave- 

 making ant, Strongylognathus, the workers are 

 much less numerous, and so weak that it is an un- 

 solved problem how they contrive to make slaves. 

 In the genus Strongylognathus there are two species, 

 8. huberi and S. testaceus. S. huberi, which was 

 discovered by Forel, very much resembles Polyergus 

 rufescens in habits. They have sabre-like mandibles, 

 like those of Polyergus, and their mode of fighting is 

 similar, but they are much weaker insects ; they make 

 slaves of Tetramorium ccespitum, which they carry off 

 as pupae. In attacking the Tetramoriums they seize 

 them by the head with their jaws, just in the same 

 way as Polyergus, but have not strength enough to 

 pierce them as the latter do. Nevertheless, the Tetra- 

 moriums seem much afraid of them. 



The other species, Strongylognathus testaceus, is 

 even weaker than S. huberi, and their mode of life is 

 still in many respects an enigma. They also keep the 

 workers of Tetramorium in, so to say, a state of 



