468 bulletin: museum of comparative zoology. 



Described from tAvo males and numerous workers taken from three 

 colonies at Florissant, Colo. Four workers taken by Prof. T. D. A. 

 Cockerell at Pecos, New Mexico are also referable to this variety. 

 One occasionally finds workers which are intermediate between this 

 variety and the type in possessing a few erect hairs on the anterior 

 surface of the antennal scapes near the base. The nests are in all 

 respects like those of the typical form. 



55. F. MiCROGYNA RASiLis Wheeler. 



F. microgyria var. rasilis Wheeler, Bull. Amer. mus. nat. hist., 1903, 19, p. 648, 



^ 9 c^. 



Worker. Length 4-6.5 mm. 



Closely related to the typical rnicrogyna but avei-aging a little larger. 

 Head slightly longer than broad, very nearly as broad in front as 

 behind, with feebly concave posterior border in the largest individuals 

 and nearly straight sides. Clypeus convex, carinate its entire length, 

 its anterior border somewhat angularly projecting in the middle. 

 Frontal area triangular, as long as broad. Frontal carinae diverging. 

 Antennae rather slender, the basal joints much longer and more slender 

 than the penultimate joints. Maxillary palpi rather long. Thorax 

 shaped as in microgyna, the petiole with a somewhat sharper border. 



Sculpture as in microgyna. Mandibles and frontal area but slightly 

 shining. Legs rather smooth. 



Hairs golden yellow, obtuse, sparser than in microgyna, and stouter, 

 absent on the antennal scapes, gula, and posterior corners of the head, 

 and the eyes and legs, except for the row of bristles on the flexor 

 surfaces of the tibiae, entirely naked. Hairs on the clypeus, thorax, 

 and petiole much less numerous. Pubescence very fine and uniform, 

 not very dense on any part of the body. Color like that of Tnicrogyna. 



Female. Length 5-5.5 mm. 



Averaging a little larger than the female of microgyna and differing 

 in pilosity, sculpture, and color. The gaster is more opaque, the black 

 blotches on the head and thorax are indistinct or entirely lacking, even 

 in mature specimens. The wings are more grayish and the hairs on 

 the head, thorax, petiole, and gaster are sparser, stouter, more clavate 

 and more obtuse. The antennal scapes and legs are without erect 

 hairs. 



Male. Length 6-7 mm. 



Mandibles edentate or quadridentate, their blades broader than in 

 microgyna. Frontal area smooth and shining. Erect hairs on gula 

 less abundant as are also the oblique hairs on the legs. Wings some- 

 what more opaque. 



