136 
Psyche 
[October 
structure of the hypopygium affords the most reliable distinc- 
tions for identifying the species, and fortunately can be easily 
discerned without relaxing. 
Key to the Neartic Species of Lasiopogon. 
1 . Bristles of body and legs wholly or in part whitish ; mystax 
white; abdomen rather dull 2. 
Bristles black (not including the long straggling white seti- 
form hairs sometimes present on underside of femora) . . . 5 . 
2. Legs entirely black, coated with gray pollen 3 . 
Front tibiae with basal two-thirds and middle tibiae with 
base yellowish ; median and lateral stripes of thorax brown- 
ish median stripe very feebly divided by a paler line; ab- 
domen dusted with blackish brown, hind margins gray. 
(Ariz.) arizonensis Schaeffer 
3. Abodmen sericeous with short and long white pile; hypopy- 
gium with yellow fringe at base above; thorax bivittate 
on dorsocentral rows, (on sand. Pacific Coast) 4 . 
Abdomen less pilose, base of segments rufous; thorax with 
four nearly median brown vittse. {KQhc.).quadrivittata Jones 
4. Lateral valves of hypopygium emarginate at apex and with 
a rectangular corner at end of upper edge ; bristles typically 
wholly whitish; scutellum lightly dusted with fulvous. 
(Cal.) arenicola 0. S. 
Valves with rounded apex and with a broadly obtuse upper 
corner; lateral bristles of thorax black; scutellum cine- 
reous-dusted. (Wash.) actius, n. sp . 
5. Mystax wholly or in large part white 6 . 
Mystax wholly black 9 . 
6. Tibiae and tarsi and sometimes femora also, reddish brown; 
wings lightly infumated; abodmen shining black, only 
hind angles of segments pruinose. (on low damp ground. 
Mass., N. J.) terricola Johnson. 
Legs wholly black in ground color ; wings quite hyaline . . 7 . 
7. Large robust species measuring 12 mm.; abdominal seg- 
ments marked with two anterior semicircular blackish 
