1955] 
Wilson and Broivn — Formica 
123 
equivalent size the longest may not exceed 0.06 mm. 
Mr. P. B. Kannowski has recently expressed the opinion 
to us (in litt.) that what we call “the gilvescens form” 
perhaps represents a distinct species distinguished by the 
following characters supplemental to pilosity: occiput 
more rounded, petiole blunter and usually with an 
emarginate dorsal border, gaster usually lighter in color. 
We have examined in detail 54 nest series from all over 
the eastern United States (excluding available western 
samples, which may be complicated by the presence of 
possible sibling species such as curiosa and ivheeleri) . We 
have noted a weak tendency, with many exceptions, toward 
correlation in Kannowski’s characters, but we have not 
been able to detect significant bimodality in any character 
or character combination. 
F. subintegra appears to be an obligatory slave-maker, 
and the proportion of slaves to subintegra workers is 
normally higher than the corresponding ratio in subnuda 
nests. Subintegra occurs largely within the United States, 
usually at lower latitudes and altitudes than subnuda. It 
takes a great variety of slaves, including members of the 
fusca, pallidefulva and neogagates groups, and it can occupy 
a wide range of habitats from mesic even to somewhat 
xeric. 
Formica curiosa Creighton (fig. 2) 
Formica curiosa Creighton, 1935, Amer. Mus. Novitates, 
no. 773, pp. 5-8; worker, queen. Type locality: Lake 
McGregor, near Kalispell, Montana. 
This species is presumed distinguishable by the queen, 
which is concolorous yellowish red. A careful examina- 
tion of part of the type series has failed to reveal any 
characters which will surely separate the worker caste 
of curiosa from the worker caste of subintegra as we 
broadly conceive of it here. We have noted several char- 
acter trends, however, which may prove significant as 
more collections are made in the future. 
(1) The placement of the eye as described by Creighton 
may have some merit as a character, and we have at- 
tempted to refine it as follows : in the six curiosa syntypes 
