ART. 17. FLIES OF THE GENUS TACHYTEECHUS GREENE. 5 



Tyfe, Male.— Allotype, female, Cat. No. 24130, U.S.N.M. 



A male and the female from Nanaimo, British Columbia Biolog- 

 ical Station, June 25-28, 1920; E. P. Van Duzee, collector. Two 

 males returned to the California Academy of Sciences. 



Allied to vorax but is easilj^ separated from this species by the 

 shape of the wing and the apical spot ; the face being much shorter ; 

 color of the face and front and the abdomen being bright green in- 

 stead of bronze. 



2. TACHYTRECHUS ROTUNDIPENNIS, new species. 



Fig. 2. 



Male. — Face twice as wide on lower part as immediately below 

 the antenna ; face stops far short of lower edge of eyes and it is 

 heavily coated with a golden yellow dust, dull; front dark green 

 dusted with dark brown around the sides ; ocellar triangle blackish, 

 ocelli reddish. Orbital cilia black on apical half, white on lower 

 half. Mouth parts brownish 1)lack. Antennae black, first joint 

 about three-fourths the length of the second and third together, 

 beset with short black hairs above; arista black and thickened gradu- 

 ally on the basal half. Thorax and scutellum bronze green with 

 dark-brown dust, sides of thorax bronze heavily dusted with white. 

 Abdominal segments broadly green at their bases and dusted with 

 white, especially on each side ; at the apex of each segment is a dark, 

 bare, bronze area. Hypopygium large, dusted with yellowish-white 

 except a small area on each side at apex ; lamellae large, about three 

 times as long as wide, brown black, cilia black, quite long on outer 

 edge. Femora dark bronze green coated with a white dust, apex 

 of fore and middle pair broadly, hind pair more narrowly yellow; 

 all tibiae yellow, apices of tibiae and entire tarsi infuscated with 

 reddish brown. Wings very broadly rounded on the apical half 

 and with a slight indentation of the margin at the fifth vein. A 

 large round, black dot at tip of wing, bisected by the fourth vein, 

 behind this is a smaller white dot somewhat triangular in form; 

 tegulae pale j^ellow with long black cilia; halteres deep yellow, 

 slightly darker at base. 



Female. — Like the male except the wing does not have the spots. 



Length 5 mm. 



Type locality. — " Delaware VIII " (no other data) , from Dr. J. M. 

 Aldrich. 



Described from two males and two females. 



Type., male. — Allotype., female and two paratypes. Cat. No. 24131, 

 U. S. N. M. 



One male and two females from Manahawkin, New Jersey, Sep- 

 tember 5, 1910; H. S. Harbeck, collector. 

 3136— 22— Proc.N.M.Yol.60 38 



