1923 ] 
The Genus Cyrtopogon 
107 
24. Scutellum and most of thorax shining; pile of abdomen 
yellow and black. (B. C. ,Alta., Wash.) (Can. Ent. 1922, 
277) willistoni Curran. 
Base of scutellum and much of thorax brown pollinose; 
pile of abdomen yellow. (N. M., Utah, Id., Col., Neb.) 
plausor O. S. 
25. Gray pruinose marks of abdomen confined to hind 
angles of segments; pile of face deep golden; pile of hypo- 
pleurse yellow, of abdomen yellow except at end; tibiae 
abruptly black on apical half. (N. S., Queb., Ont., N. H., 
Mass., N. Y., Ct., N. J., N. C., Fla., 111.) (If legs are 
entirely dark chestnut, see alleni) .... falto Walk, 
Gray pruinose marks following hind margins of abdominal 
segments; pile of face whitish, black on sides; hind tibiae 
not black apically 26 . 
26. Hairs of hypopleurae black; abdominal fasciae narrowly 
interrupted, sometimes entire in female; pile of abdomen 
mainly black. (Col., N. M., Cal., Id., Wash., B. C.) 
montanus Lw. 
Hairs of hypopleurae white; abdominal fasciae entire; pile 
of abdomen white Male unknown. (Cal., N. M., Or.) 
leucozona Lw. 
27. Middle segments of abdomen with complete fasciae; male 
front tarsi elongate, tarsal hairs chiefly white, long on 
upper side of basal three joints of hind pair, tarsal hairs of 
female chiefly black; hypopleural hairs black; halteres 
blackish brown; extensor hairs of hind tibiae white. (Cal., 
Wash., B. C.) (If hind tibiae are dark chestnut color, 
see montanus) longimanus Lw.. 
Fasciae of abdomen interrupted, sometimes reduced tO) 
lateral spots; crossveins, etc., usually clouded 28. 
28. Fasciae broader than long, following the hind margins; 
front tarsi of male slender. 29 . 
Fasciae confined to hind angles of segments 30 . 
29. Front tibiae and tarsi of male with not dense white pilef 
which does not conceal the ground-color: hind tarsi o. 
