1915.] Wheeler, Additions to the Ant-Fauna of North America. 399 
Reddish testaceous; gaster and legs yellow; borders of mandibles, anterior 
border of head and occipital groove black. 
Worker. Length 3-3.5 mm. . 
Head subrectangular, as broad as long, with nearly straight posterior border and 
very feebly convex sides, with the eyes just in front of the middle. Mandibles with 
oblique blades furnished with two large apical and several smaller basal teeth. 
Clypeus convex, with entire, rounded anterior border. Antennz similar to those of 
the soldier, but with the scapes extending a little beyond the posterior corners of the 
head. Thorax differing from that of the soldier in being more slender, with the 
mesonotum and base of epinotum long and rather straight in profile and the spines 
reduced to minute, erect teeth. Petiolar node compressed, sharp and transverse as 
in the soldier, but the border, seen from behind, is straight and entire. Postpetiole 
about twice as broad as the petiole, rounded in front above, without lateral conules, 
the sides rather straight behind, in profile feebly convex above. Gaster a little smaller 
than the head. 
Shining; mandibles somewhat opaque; their bases and the cheeks longitudinally 
rugulose and punctate; sides of meso- and epinotum irregularly rugulose-punctate. 
Hairs white, long, of unequal length, moderately abundant, erect on the body, 
on the legs and scapes shorter and more oblique. 
Black; mandibles brownish yellow, with black teeth; clypeus, antenne, tarsi, 
funiculi, articulations of legs and posterior borders of gastric segments brown, 
Described from several soldiers and workers taken from a number of 
colonies in the desert at Hereford and Benson (alt. 3600 ft.), in Southern 
Arizona. This species is very closely related to Ph. macclendoni Wheeler, 
but both the soldier and worker are larger, the former is monomorphic, has 
the frontal area distinct and the rugosity not extending so far back on the 
head and the petiole and postpetiole are of a different shape when seen 
from above, the latter being larger, rounded above and with blunter sides, 
the thorax is more extensively sculptured, etc. The workers of the two 
species are more similar, but besides the difference in size, that of macclen- 
dont is brown, with darker head and gaster. 
The nests of Ph. miltticida are small craters, 3-5 inches in diameter. 
When I found them at Hereford and Benson during November 1910, they 
were covered with masses of chaff, showing that the ant is a true harvester. 
Only workers could be obtained by the most diligent excavation of the 
nests, but among the chaff on nearly all the craters the workers had deposited 
numerous heads and dismembered bodies of soldiers. Mr. W. M. Mann, 
who collected at Hereford during August took living soldiers in the nests 
and from his specimens the foregoing description of the soldier is drawn. 
It appears, therefore, that all the individuals of this caste are regularly killed 
off by the workers on the approach of winter, probably after they have 
broken open all the hard seeds collected by the workers. Such a slaughter 
of the members of a large caste during a season when their activities are no 
longer required, when they would simply be a burden on the colony by con- 
