708 THE AMERICAN NATURALIST.  [VOL. XXXV. 
sorties like Polyergus, for Adlerz succeeded in finding a nest 
of Tomognathus with two species of auxiliaries (L. acervorum 
and muscorum). 
The mixed nests of Tomognathus-Leptothorax may contain 
males, queens, and workers of both the dominant and victim- 
ized species, a condition not known to occur in the case of 
other dulotic nests. The males of Tomognathus (Fig. 16, a) 
resemble the males of Leptothorax so closely that Adlerz failed 
Fic. 16.— T'omognatA blevis Mayr (after Adlerz); æ., male; 3., female (ergatoid). 
to distinguish them till he published his second study (96). 
The female is also of such a remarkable character that it, too, 
was originally overlooked. This sex is apterous (Fig. 16, 4) 
and resembles the worker except in possessing ocelli and à 
receptaculum seminis. : 
The industrial instincts of Tomognathus are very rudi- 
mentary. It rarely or never excavates. It is able to feed 
itself if food is within reach, but it does not go in quest of 
provisions. This it leaves to the Leptothorax auxiliaries, by 
whom it is usually fed. Occasionally it may be seen caring 
for the larvæ. A number of Tomognathus which were isolated 
with larvæ and some food managed to live for 135 days, but 
the larvæ died or shriveled up. It seems probable, therefore, 
that Tomognathus depends on its slaves to a certain extent 
even for the care of its larvæ. When the colony is compelled 
to move to a new nest, the Tomognathus are usually deported 
by the Leptothorax ; only rarely are the rôles reversed. 
