2G2 
NORTH AMERICAN MYRMOSIDAE 
22. Anterior metatarsus with a row of three erect spines on the posterior 
liorder, and two smaller ones on the inner surface; diameter of the pos- 
terior ocelli 1.8 times as great as their distance from the eyes. Length, 
12 mm eriopis new sj^ecies 
Anterior metarsus without erect spines along the edge, two small ones on 
the posterior surface; diameter of the posterior ocelli 1.2 times as great 
as their distance from the eyes; sagittae short, thick and blunt (figures 
41 and 42). Length, 8 mm arenivaga new species 
23. Ocelli small and not prominent, the transverse diameter of the hind pair 
scarcely more than equal to one-half their distance from the ej^es, and 
approximately equal to their distance from the front ocellus; carina of 
the mandible with an angular elevation at base. Color black. Length, 
8 mm., slender micrommata new species 
Ocelli larger, prominent, sometimes very large, the transverse diameter of 
the posterior pair but little less than their distance from the eyes, usually 
equal to or greater than the same, and equal to at least twice their dis- 
tance from the anterior ocellus (24) 
24. Head and bocty black, or, if the thorax is red or reddish, at least the legs 
are fuscous; stigma black; petiole longer, with its neck longer and more 
slender than in the following (25) 
Color brownish orange to castaneous. The abdomen and thorax are both 
always castaneous or yellowish, and if the head is black the legs are 
testaceous or reddish, not fuscous; stigma sometimes brown, more often 
j'ellow; petiole with a short neck or none at all (26) 
25. Small slender species, entirely black. Length, 8 mm atrata (Blake) 
Larger species, less slender, usually with more or less dark red on the 
thorax, sometimes entirely black. Length, 10 mm nuda Fox 
26. Width of the petiole at its apex equal to its lateral length, its thickness 
from two-thirds to three-fourths thereof (29) 
Width of the petiole at its apex from .6 to .8 of its lateral length, its thick- 
ness from one-half to three-fifths thereof (27) 
27. Ocelli small, the transverse diameter of the posterior pair less than their 
distance from the eyes (28) 
Ocelli large, their transverse diameter nearly one-half again as great as 
their distance from the eyes; color brownish orange. Length, 10 mm.; 
stout nevadensis Fox 
28. Carina on the mandible not reaching more than half way to the base; 
width of the petiole .8 of its lateral length, its thickness .6 thereof; 
color brownish orange. Length, 10 mm subquadrata Fox 
Carina on the mandible reaching the base where it is strongly and angu- 
larly elevated; width of the petiole .6 of its lateral length, its thickness 
less than .5 thereof; reddish castaneous; head black. Length, 8 mm., 
slender dentata new species 
29. Edge of the clypeus preceded by a transverse lamina or tubercle (30) 
IMargin of the clypeus emarginate, not thickened, but the apical portion of 
the clypeus prominent, without a transverse lamina or tubercle; en- 
tirely brownish orange, stigma concolorous inaequalis Fox 
