The Female of Formica Opaciventris Emery (Formicidae)

The 2orms of Formica exsecta constitute a. small, well defined group of ants easily recognized by the excavated, or broadly emarginate, occipital border o2 the head. Only three of the North American variants are now considered valid (Creighton, 1950, or synonymy). All the castes o. Formica exsecto.ides and F. ulkei have been described previously, but the worker and male alone were the castes hitherto known 2or F. opaciventris, the 2emale having escaped collection. I am now able, however, to fill this gap by presentation o the description o the opaciventris queen. Dr. Creighton cites the mountains o Colorado and Wyoming as the range of this species, and states that it appears to be confined to high intermountain valleys, and does not occur on the eastern slope o the Rockies. The nests he observed were built in hard, stony soil, and consequently differed much rom the nests .of the eastern exsectoides and ulkei which are usually in moist, spongy earth.