avheeler: ants of the genus formica. 461 



49. F. FEROCULA, sp. nov. 



Worker. Length 3.5-6 mm. 



Head, excluding the mandibles, as broad as long, broader behind 

 than in front, with feebly excised posterior border and very slightly 

 convex sides. Mandibles 8-toothed. Clypeus convex, carinate its 

 entire length, with broadly rounded anterior border, but slightly or 

 not at all produced in the middle. Frontal area triangular, as long 

 as broad. Frontal carinae short, diverging. Antennae slender, four 

 basal funicular joints longer and more slender than the penultimate 

 joints. Palpi short. Pro- and mesonotum not very convex, meso- 

 epinotal constriction not very deep, epinotum with subequal base and 

 decliA'ity, the former feebly convex, the latter distinctly concave. 

 Petiole narrow and very low, its anterior surface very convex, its pos- 

 terior surface flattened, its border very blunt and when seen from 

 behind, evenly rounded and entire, not produced upward in the 

 middle. Legs rather long. 



Opaque, finely shagreened; mandibles shining, rather superficially 

 striatopunctate; frontal area smooth and shining, clypeus also more 

 shining than the posterior part of the head. 



Hairs and pubescence golden yellow; the former abundant on 

 the clypeus and mandibles, absent on the remaining portions of the 

 head; dense and erect on the pronotum, epinotum, and petiole, absent 

 on the mesonotum, except at the posterior border. On the gaster the 

 erect hairs are short, obtuse, and rather abundant. Eyes hairless. 

 Pubescence long and rather dense on the head and thorax, scarcely 

 denser on the gaster and not concealing the ground color. Pubescence 

 on the legs long and somewhat oblique on the flexor surfaces of the 

 tibiae. 



Bright yellowish red; mandibles, antennal funiculi towards their 

 tips, and the legs in some specimens, darker. Gaster dark brown, 

 with the anal region and a spot at the base of the first segment red. 

 Very small workers have the upper surface of the head, thorax, and 

 petiole infuscated and the legs darker. 



Described from sixteen workers taken from a single colony at 

 Rockford, Illinois. This and several other colonies of the same species 

 were found nesting in dry, open fields in crater nests 3-4 inches in 

 diameter about the roots of Erigeron canadense and other weeds. The 

 species is evidently allied to F. comata, crinivcntris, ciliata, and oreas, 

 but differs from all of these forms in the peculiar shape of the petiole 

 and the arrangement of the hairs. The female is probably of a pecu- 

 liar aberrant type, like the females of the forms just mentioned. 



