F. R. COLE 41 



Abdomen large and convex. First segment brownish, second segment yellow 

 with a narrow anterior brown margin, and usually a median brown mark; third 

 segment entirely yellow or with a small median brown spot on the anterior 

 margin; the rest of the dorsum of the abdomen yellow. Venter brown, often 

 marked with yellow. Pile of abdomen blackish, erect and fine, and not thick 

 enough to conceal the ground color. Femora brown with dark brown pile. 

 Tips of femora, the tibiae and tarsi whitish yellow with pale yellowish pile. 

 Tips of claw s black. Wings faintly infuscated, darker in costal region. Costa 

 thickened at end of first vein. Wing veins brown. Length, 7.5 mm. 



cf . Very much like the female. The thorax is broader and more robust. 

 The four posterior femora blackish, except tip. Scutellum and praescutellar 

 callosities darker. Pleura usually much darker, in some specimens almost 

 black. Costal margin at end of first vein bulges out and has a spur or tooth- 

 like projection on it. Wings in some specimens pure hyaline. Veins brown 

 at base, pale at apex. Knob of halteres darkened. Venter dark brown with 

 whitish incisures. 



Mr. J. L. King, in his paper on the Hfe history of this species, 

 recorded that twenty-four females varied from four to eight milli- 

 meters in length. A number of male specimens varied from six 

 to nine millimeters. P. flavipes is an eastern species, possibly go- 

 ing as far west as the Rocky Mountains. This species is said to be 

 near P. vinnondii Erichson, and I have a specimen of P. mellii 

 from Queensland, Australia, which is almost the same. There is 

 no difference in structure or wing venation. The median black 

 mark on the abdomen of P. mellii reaches to the tip, the last seg- 

 ment and the genitalia being black. The middle tibiae and the 

 hind pair are black also. 

 Pterodontia misella 

 Fterodoniia misella O. S., Western Diptera. 



"Black; clothed with black pile; scutellum black, obscurely reddish on its 

 latter half; second abdominal segment (that is, the first visible segment; the 

 first true segment is concealed under the scutellum) black, with an obscurely 

 marked reddish spot on each side a little back of the scutellum; segments 3 to 6 

 rufous, the third and fourth with square spots in the middle, that on the fourth 

 being narrower; they are confluent with each other and with the black of the 

 second segment. Venter rufous; hind margins of segments 2 to 5 black. Tegu- 

 lae brownish, with broad dark brown margins. Legs brownish yellow, the four 

 posterior femora black; ungues reddish, black at the tip. Wings subhyaline; 

 veins yellow; venation similar to that of the other species; the usual tooth on the 

 edge of the costa, near the end of the first posterior cell, is very little projecting. 

 Length, 5 mm. 



"Hab. Oregon (H. Edwards). A single specimen. This species is very like 

 P. flampes from the Atlantic States, but is smaller and differs in the coloring 

 of the abdomen." 



TRANS. AM. ENT. SOC, XLV. 



