March, 1914-] WhEELER : AntS FROM HiDALGO, MeXICO. 43 



Forel in the shape of the epinotum, as Forel has shown. In the 

 two former species it is sloping and rounded and not cuboidal. Min~ 

 utMii and miuinntui nest in the ground under stones, carhonariinn 

 and cbciiinum in the cavities of plants (twigs, under bark, between the 

 overlapping leaves of Tillandsias. etc.). 



10. Monomorium minimum subsp. cyaneum new subspecies. 



Worker. — Differing from the worker of the typical form in coloration, the 

 body being deep, metallic blue ; the antennae and legs black, with the bases of 

 the funiculi, mandibles, mouthparts, tarsi and articulations of the legs piceous. 



Female. — Apterous, but with the thorax shaped very much as in the typical 

 minimum though distinctly smaller and more slender. Head more shining 

 above. Body and legs black, the latter with yellow articulations and tarsi. 



Described from numerous workers and females taken at Guerrero 

 Mill under stones in rather damp places on the sides of canyons. 



11. Monomorium minimum subsp. compressum new subspecies. 



Worker. — Indistinguishable from that of the typical minimum. 



Female. — Smaller, less than 3 mm. long; apterous and more worker-like in 

 the structure of the thorax than the subsp. cyaneum and ergatogyna Wheeler, 

 the mesonotum and scutellum very small. Moreover the thorax is distinctly 

 constricted both dorsally and laterally just in front of the epinotum. The 

 mesoepinotal suture is deep, the epinotum rather swollen, longitudinally im- 

 pressed in the middle and in profile shaped like that of the worker. Head 

 rather short, more shining than in the typical minimum and the punctures 

 smaller than in this form and in cyaneum ; petiole narrower. Pilosity white, 

 much shorter and very much sparser. 



Described from four females and several workers taken at San 

 Miguel beneath a stone. This may be a distinct species, but its exact 

 position can hardly be determined till its male and those of the allied 

 forms have been carefully studied. 



12. Solenopsis picea Emery. 



A dozen workers taken from nests under stones at Guerrero Mill 

 are referable to this form, which was originally described from Costa 

 Rica. 



13. Solenopsis minutissima Emery. 



Several workers from a rather large colony found nesting under 

 a stone at San Miguel agree very closely with some Argentine cotypes 

 of this species given me by Dr. F. Silvestri. One of the workers 

 is larger and has larger, distinctly pigmented eyes, but is probably 



