WHEELER: ANTS OF THE GENUS FORMICA. 433: 
form only in Illinois. These are much smaller than the nests of the 
typical aggerans, being rarely more than a foot or 18 inches in diame- 
ter. They are built of coarse materials in open grassy fields. Appar- 
ently melanotica in its deeper pigmentation and its fondness for such 
situations and for lower altitudes bears about the same relation to. 
aggerans that F. pratensis does to the typical rufa in Europe. 
29. F. RUFA OBSCURIPES Forel. 
F. rufa st. obscuripes Forel, Ann. Soc. ent. Belg., 1886, 30, C. R. p. xxix; 
Ibid., 1904, 48, p. 152, 8 ; Wheeler, Ants, 1910, p. 570. 
F. rufa obscuriventris Mayr var. obscuripes Emery, Zool. jahrb. Syst., 1893, 7, 
p. 644, 650, 8. 
WorkKER. Length 3.8-8 mm. 
Similar to the typical rufa of Europe, but the large individuals 
have the head and thorax of a lighter red and entirely or almost en- 
tirely without dark spots on the head and thorax, whereas the legs 
and petiole are blackish brown or reddish brown. The small workers 
are of a much darker color and have the head and thorax spotted with 
brown. Gaster subopaque, deep brown or blackish, covered with 
slightly longer and denser, gray pubescence than the typical rufa, 
while the erect hairs on the gaster, head, and thorax are rather sparse, 
inconspicuous and less numerous than in the true rufa and the sub- 
species pratensis. 'Tibiae without erect or suberect hairs and covered 
merely with appressed pubescence. Gula with a few erect hairs. 
Eyes hairy. 
Host (Temporary). Unknown; probably one of the boreal forms. 
of F. fusca. 
TYPE LOCALITY.— Wyoming: Green River (S. H. Scudder). 
Wyoming: Elk Creek (R. P. Currie). 
Montana: (Amer. Mus. Nat. Hist. Coll.). 
Washington: Loon Lake (S. Henshaw); Rock Lake (A. L. Mislender 
Colorado: Boulder (Wheeler). 
Arizona: Thatcher (R. V. Chamberlin). 
British Columbia: Golden (W. Wenman); Summerland (W. H. 
Britton). 
This form is imperfectly known. Forel insists on regarding it as a 
subspecies, and he may be right, but it should be pointed out that the 
absence of erect hairs on the tibiae is perhaps not as strong a character 
as he supposes. One often finds workers of what I regard as Emery’s. 
rubiginosa (aggerans) that have very few suberect hairs on the tibiae. 
