430 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Worker, FEMALE, and Matz in color and pilosity forming transi- 
tions to F. truncicola. According to Forel, the hairs are like those of 
truncicola but the color, though variable according to the formicaries, 
tends to become more like that of pratensis; the hairs may also become 
shorter and less black. 
The females of this form are said to be very rare (Wasmann). The 
nests, according to Forel, have a structure intermediate between 
those of pratensis and truncicola. 
27. F. RUFA AGGERANS Wheeler. 
F.. rufa McCook, Proc. Acad. nat. sci. Phil., 1884, p. 57-65. 
F. rufa subsp. obscuriventris Mayr, var. rubiginosa Emery, Zool. jahrb. Syst., 
1893, 7, p. 644, 650, 8 (nec @). 
F. rufa subsp. obscuripes var. rubiginosa Wheeler, Ants, 1910, p. 202, 570, fig. 
1 aa 
F. rufa aggerans nom. nov., Wheeler, Psyche, 1912, 19, p. 90. 
WorkKER. Length 3.5-8.5 mm. 
Head and thorax opaque, finely shagreened; mandibles delicately 
striated, smoother and more shining towards their bases, clypeus 
finely longitudinally striated. Frontal area subopaque, less shining 
than in the European forms. Gaster and legs opaque. 
Clothed with suberect, grayish or yellowish hairs, abundant on 
the head, gula, thorax, gaster, and fore coxae, sparser on the tibiae. 
Eyes hairy. Pubescence on the gaster very fine and dense so that the 
character of the surface is concealed and this region has a grayish 
caste. 
Head, thorax, and petiole rather bright red, in large specimens 
immaculate or with only a faint clouding of brown on the divisions 
of the pro- and mesonotum in smaller workers; legs and antennae 
dark red or brown, scapes usually paler; in small workers the whole 
surface of the body may be brown, with the mandibles, clypeus, and 
anterior portion of the head more reddish; medium sized workers 
intermediate in having the pro-, meso-, and epinotum, and the petiole 
more or less infuscated. 
FemaLe. Length8-9 mm. 
Surface of body slightly smoother and more shining than in the 
worker. Gaster, especially, more shining. 
Pilosity as in the worker but the hairs longer and somewhat sparser. 
Pubescence on the gaster in fresh specimens rather dense and conceal- 
ing the very shining surface but apparently very easily rubbed off. 
Tn such specimens the gaster is as smooth and shining as in the Euro- 
pean rufa. 
