WHEELER: ANTS OF THE GENUS FORMICA. 469 
Host (Temporary). F. fusca var. argentea and var. subsericea. 
Type LOCALITY.— Colorado: Manitou (Wheeler). 
Colorado: Ute Pass, Pike’s Peak (11,500 ft.), Colorado Springs, 
Florissant, Wild Horse (Wheeler). 
New Mexico: Pecos (T. D. A. Cockerell). 
Utah: Salt Lake (R. V. Chamberlin). 
Washington: Olympia (T. Kincaid). 
This form was originally described as a variety of microgyna but 
after examining more material than I possessed at the time of its 
description, I am convinced that it should have subspecific rank, at 
least. It has apparently the same range as the typical mcrogyna, 
but is more abundant and forms more populous colonies. These live 
under stones and may occupy several nests covering an area of a 
square meter or more. Between July 11 and August 21, 1903, I 
found, in all, thirteen of these colonies in the neighborhood of Manitou, 
Colo. and during July 1906 I found nearly as many more at Florissant, 
and Wild Horse in the same state. <A few of these colonies were very 
small and young and mixed with workers of F. fusca var. argentea 
and var. subsericea, proving that rasilis is a temporary social parasite 
on these ants. 
56. F. MICROGYNA RASILIS var. SPICATA, subsp. nov. 
WorkKeER. Length 3.5-6 mm. 
Closely resembling the worker of rasilis but even the largest indi- 
viduals have the pro- and mesonotum and nearly always also the 
ocellar region infuscated or blackened, and the hairs on the gaster 
are longer and slightly more numerous. The pubescence on the gaster 
is denser so that this region is gray and its ground color is concealed. 
Legs and antennal scapes without erect hairs. Gula in some speci- 
mens pilose. Frontal area very smooth and shining. 
FemaLe. Length 4.5-5 mm. 
Differing from the female rasilis in having the blunt clavate hairs 
on the head, thorax, and gaster longer and more numerous. ‘This 
is especially true of those on the gaster. Gaster opaque, owing to the 
dense and rather long pubescence. Body and legs brownish yellow, 
with the upper surface of the head, mesonotum, scutellum, meso- 
and metapleurae, gaster, antennal funiculi, and usually also the coxae 
dark brown. Wings grayish hyaline. 
Mate. Length 5.5-6 mm. 
Mandibles broad, usually edentate, more rarely obscurely dentate. 
Petiole very low, scarcely higher than long, its upper surface in profile 
