176 Psyche [December 



This subspecies is closely related to the subspecies mimicus, 

 but the petiole of the worker is more compressed anteroposter- 

 iorly and less blunt at the margin, and the color, especially of 

 the head, is much darker in both worker and female. The wings 

 of the female are fully 1 mm. longer, the erect hairs are sparser 

 and more delicate, and the pubescence of both worker and female 

 is more dilute. 



Leonard says that tliis ant "is strictly diurnal in its habits and 

 has been seen feeding upon the white flowers of Mesembryanthettium 

 cequilaterale.'' 



M. melliger mimicus WTieeler. 



I have taken specimens of this widely distributed desert ant at 

 Benson, Arizona, and have received a series of workers, males and 

 females from Kennedy, New Mexico (W. D. Hunter) and several 

 workers from Riverside and Whittier, California (K. J. Quayle). 



M. melliger semirufus Emery. 



This small, light-colored form is common in sandy spots in the 

 desert about Yuma, Arizona. It has also been taken by Mr. P. 

 Leonard at Point Loma, Cala. The specimens from the latter 

 locality have the head and thorax somewhat darker than the 

 Arizona specimens and the gaster reddish at the base, so that 

 they are transitional to the var. testaceus Emery. 



M. lugubris TMieeler. 



This species bears a striking resemblance to certain Formicas 

 of the subgenus Proformica, notably to P. emmoe recently dis- 

 covered by Forel in the deserts of Algiers. The structure of the 

 maxillary palpi and the shallower mesoepinotal constriction 

 alone indicate that the Arizona species is a Myrmecocystus. To 

 my description (Journ. N. Y. Ent. Soc. XVII, 1909, p. 98) I 

 would add that the gula is flattened or slightly concave when 

 seen in profile. 



M. 3mma sp. nov. 



Worher. Length 2.5-3.5 mm. 



Allied to Ivguhris; monomorphic. Head only slightly longer than broad, convex 

 above and below, distinctly broader behind than in front, with broadly rounded 



