hymenoptera . 
639 
larvae and pupae to their own nests, and bring them up with 
their own, and they in turn work hard for their captors, and 
take great interest in their welfare and success. When a 
party of marauders comes back without any booty their 
slaves give them a cold reception; but if they come back 
laden with plenty of larvae and pupae, the slaves rush out 
and meet them with apparent delight and exultation. 
Some species of slaveholders (e.g., Formica difficilis) 
work side by side with their slaves. However, in one species 
(Polyergus rufescens of Europe) the masters have depended 
upon their slaves so long that they cannot build their own 
nests or feed themselves or care for their young, but have 
only retained the power of fighting to get more slaves. 
Huber tells of placing several of these slaveholders by 
themselves, where nearly all helplessly starved, although 
there was plenty of food all around them. Then a slave was 
introduced, which at once set to work and made a nest and 
fed those still alive, thus saving from death its stupid 
masters. 
The classification of the ants is still in a very imperfect 
state. Many of our common species are still undescribed, 
and the limits of the families have not yet been determined. 
But, if we except a few species found in Texas and Utah, 
our described species represent only three families. These 
can be separated by the following table: — 
TABLE OF FAMILIES OF THE FORMICINA, 
A. Peduncle of the abdomen consisting of a single segment. 
B. Abdomen not constricted between the second and third seg¬ 
ments (the first segment forms the peduncle), p. 64 o..FormiciDjE p 
BB. Abdomen constricted between the second and third segments, 
p. 642.. Poneridjs. 
AA. Peduncle of the abdomen consisting of two segments. p. 642. 
MYRMICIDiE. 
