84 STRONGYLOGNATHUS. 
ard 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 instinet 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, 
S. huberi and 8S. testaceus. SS. hubert, 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 ceespitwm, which they carry off 
as pupe. In attacking the Tetramoriwms 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- 
moriwms 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 Tetramorvum in, so to say, a state of 
