FLIES OF GENUS RIVELLIA — NAMBA 41 



Thoracic appendages: Legs yellow except for tarsi of front and 

 hind legs which are blackened from the third segment and tarsi of 

 middle legs which are blackened from the fourth segment. 



Wing (fig. 7,a) length 3.3 mm., width 1.5 mm. Bands yellowish 

 brown. First and second bands faintly joined at costal margin; 

 third and fourth bands narrowly joined at costal margin; second and 

 third bands not joined in discal cell. The part of first basal cell con- 

 tiguous to second basal cell banded at base, with semicircular hyaline 

 spot anterior to apex of second basal cell. Section of fourth vein 

 proximad of anterior crossvein with definite bend. Halteres yellow. 



Abdomen: Tergites shining, smooth, yellowish brown. Disc of 

 first tergite with pale setae. Genitalia (fig. 7,c,d) with apical part of 

 aedeagus consisting of a flattened base and two long terminal tubes, 

 one somewhat shorter than the other. The tips of the tubes are 

 rather peculiar. Each is excavated at the tip with a central cone 

 arising from the bottom of the pit. From the apex of each cone a 

 tiny tube protrudes. The gonopores are apparently located at the 

 apices of these tubes. 



Allotype: Female. Body length about 5.0 mm.; wing length 4.0 

 mm., width 1,7 mm.; ovipositor sheath yellow on basal half, blackened 

 on apical half. Otherwise similar to holotype. 



Paratypes: 7 males, 14 females. Body length of males 4.7-5.5 

 mm., of females 4.2-5.7 mm.; wing length of males 3.2-4.2 mm., of 

 females 3.2-4.0 mm. Both sexes with third segment of antenna 

 sometimes blackened at tip and outside; second and third bands of 

 wing often definitely joined in discal cell. Otherwise essentially 

 similar to holotype and allotype. 



Specimens: Holotype, cf", Manhattan, Kans., June 15, 1932, 

 C. W. Sabrosky (USNM 61857). Allotype, 9, Manhattan, Kans., 

 June 8, 1932, C. W. Sabrosky (USNM). Paratypes: Iowa: County 

 3 (19, June 22, 1936, D. Millspaugh; 19, 16", June 27, 1936, on 

 same pin, D. Millspaugh; 19, June 26, 1936, Mabel Jaques; 19, 

 June 27, 1936, D. Millspaugh; 299, Icf, July 1, 1936, D. Mills- 

 paugh; 299, 2c^cf, July 1, 1936, M. E. Barnes). Kansas: Clark 

 County (19, June, "1,962 ft.," F. H. Snow); Saline County (19, 

 June 7, 1933, C. W. Sabrosky). Minnesota: (Icf, Univ. Minn., 

 No. 18, sub. 10); Olmsted County (19, Icf, July 1904, on same pin. 

 C. N. Ainslie). South Dakota: Brookings (19). Texas: Admore 

 (19, Apr. 11, 1907, "on Salix," F. C. Bishopp); Harris County 

 (19, Aug. 13, 1928, L. D. Beam); Victoria (19, Apr. 16, 1907, 

 W. A. Hooker; 19, June 24, J. D. Mitchell). No data, Ic^. (In 

 UM, ISC, CU, USNM, SEC, and CWS.) 



