34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



R. H. Beamer (SEC). Allotype, cf, same data as holotype. 

 Paratypes: Arizona: Mud Springs Station, Catalinas (299, July 

 17-20, 1916, "share with Clark and A. N. S. P."), Sunnyside Canyon, 

 Huachuca Mts. (19, July 9, 1940, D. E. Hardy). (In SEC, AMNH.) 

 Remarks: This species appears to be related to R. tersa, from 

 which it can be distinguished by its smaller size, the smaller hyaline 

 spot at the junction of the second and third veins as stated in key, 

 and the male genitalia. It also appears to be related to R. longicornis 

 Van Der Wulp (1898, p. 384, pi. 10, fig. 15), from which it can 

 be distinguished by its lack of hyalinity between second and third 

 veins at theu" junction and the joining or very narrow separation 

 of first and second bands in the discal ceU. 



Rivellia brevifasciata Johnson 



Figure 9,/t-A; 



Rivellia brevifasciata Johnson, 1900a, p. 32G. — Hendel, 1914a, p. 177. — Cresson, 

 1924, p. 229. 



Type Locality: Atco, N. J. (ANSP). 



Males: Body length 3.0-5.2 mm. 



Head: Frons yellowish brown; upper fronto-orbital plates and 

 ocellar triangle blackened. Face with dorsal half pruinose, ventral 

 half shining, smooth, dark brown or black; parafacials and part of 

 orbits ventral to each eye broAvnish yellow. Antenna with first and 

 second segments yellow; third segment with tip, outside, and some- 

 times anterior side of inside blackened, remainder yellow, the tip 

 pointed anteriorly. Anteclj^'peus concolorous with ventral portion 

 of face. Palpi dark bro%\'ii. Postcranium black, pruinose. 



Thorax: Mesonotum dark brown or black with blue-green reflec- 

 tions; strong humeral and posterior dorsocentral setae present, 

 Scutellum and postscutellum concolorous with mesonotum. Pleura 

 concolorous with mesonotum, mostly shining, Mesoplcuron with 

 scattered pale setae on posterior half; pruinose area at dorsal posterior 

 corner in form of right triangle, one side reaching two-thirds distance 

 to ventral posterior corner and the other reaching two-thirds distance 

 to anterior spiracle. Sternopleuron with ventral corner pruinose; 

 disc with few scattered pale setae. Disc of pteropleuron with scattered 

 pale setae, few black setae present ventral to subalar. Hypopleuron 

 with shining central spot, remainder pruinose. Laterotergite com- 

 pletely and densely pruinose. Prosternum black. 



Thoracic appendages: Front legs: Coxae yellow, sometimes with 

 brown spot on outside at base ; femora yellow ; tibiae yellow or brown- 

 ish yellow; tarsi wholl}^ 3^ellow or slightly blackened from second 

 segment. Middle legs: Coxae dark brown on outside at base, re- 



