58 
Psyche 
[June 
turn striate in a dorso-posterior direction, sides of second 
segment smooth; propodeum, in dorsal aspect, smooth but 
for sparse and minute setigerous punctation; first abdom- 
inal segment with two sharp, transverse, sinuate carinae 
dorso-anteriorly, posteriorly with small tubercles, declivous 
surface largely smooth, with scattered setigerous puncta- 
tion; pygidium microscopically punctulate, dull. 
Head, in front view, evenly convex posteriorly, a distinct 
gibbosity in front of the eyes ; face with a prominent black 
spine between the antennae ; ocelli slightly less than 0.04 mm. 
in diameter, posterior pair 0.22 mm. from each other and 
0.31 mm. from the eyes; first segment of the flagellum about 
as broad as long, equal to the pedicel and shorter than the 
second. Thorax, in dorsal view, with parallel sides; in 
lateral view, with a distinct notch between the pronotum 
and the second segment, humeral angles of the pronotum 
rounded obliquely, posterior margins forming a rounded 
right angle, second segment broadly depressed ; median ven- 
tral gibbosity on the propodeum faint. 
Holotype : One female taken by myself at Towner, North 
Dakota, June 27, 1933. 
This species differs distinctly from paratypes of M. 
( Myrmosa ) banksi Bradley 1 in the Museum of Comparative 
Zoology in color, smaller size, larger ocelli and their disposi- 
tion, less distinct propodeal gibbosity, sculpturing and in 
other characters. It is much smaller than M. thoracica 
Blake, which is associated by Bradley and Melander with 
M.. ( Myrmosa ) unicolor Say, and differs also in color, 
sculpturing and shape. From the description of M. 
{Myrmosa) blakei Bradley it differs in smaller size, color, 
in the shape of humeral angles, smaller ocelli and their dis- 
position and in the presence of distinct posterior metathor- 
acic spines and of dorsal carinse on the basal abdominal 
segment. 
1 Bradley, J. C. — Contributions towards a Monograph of the Mutilli- 
dae and their Allies of America North of Mexico. IV. A Review 
of the Myrmosidae. Trans. Amer. Ent. Soc., No. 764, 1917. 
