178 Psyche ] December 



and cheeks and often also over the clypeus and front. Palpi yellow. The white 

 pubescence, especially on the thorax, gaster and posterior portion of the head is 

 much longer and more silvery. The anterior surfaces of the antennal scapes have 

 a row of erect hairs. 



Described from numerous workers taken from several colonies 

 at Yuma, Arizona, in the same localities as the preceding. 



The craters of this variety are larger than those of the typical 

 yuma, measuring 6-8 in. in diameter, with entrances nearly § 

 in. across. These nests are also more populous. The precise 

 relations of this variety to yuma and to the smaller forms of 

 melliger {seniirufus and testaceus) cannot be determined till the 

 sexual phases have been discovered. Perhaps flaviceps will then 

 have to rank as an independent species. 



M. mexicanus Wesmael. 



Until recently the typical form of this species was not known 

 to occur within the United States. During August 1910 it was 

 discovered in the desert about Hereford in Southern Arizona by 

 Mr. W. M. Mann. Early in November of the same year I found 

 it in the same locality, and Mr. P. Leonard sunultaneously found 

 it on Point Loma, near San Diego, California. So far as known, 

 therefore, it is confined to Mexico and the extreme southern 

 boundary of the United States. It is a less handsome form than 

 the variety horti-deorum, as the yellow of the head and thorax 

 and the brown of the gaster have a dirty grayish tint. Besides 

 these differences in coloration I can detect no others of impor- 

 tance between the two forms. 



The nests of mexicanus at Hereford are not abundant. They 

 resemble those of the variety horti-deorum but are in adobe soil, 

 so hard that I was unable to excavate it to a depth sufficient to 

 expose the honey chambers. Mr. Leonard was more successful 

 at Point Loma. He gives an interesting account of the nests and 

 of the habits of this ant and its repletes (loc. cit.). 



M. mexicanus var. horti-deorum McCook. 



The range of this variety, which was formerly known to occur 

 only in Colorado and New Mexico, has been considerably extended 

 of late. The locality "California" given in my paper {loc. cit. 



