16 PKOCEEDINGS OF THE NATIONAL MUSEUM vol. 74 



liam Palmer, and C. H. T. Townsend. In all, 23 specimens, of which 

 only six are males. None of these northern specimens have hairs on 

 the first vein except on the apical part, where they are very con- 

 stant. The males have the femora and tibiae yellow in most cases, 

 although sometimes with slight infuscation. Wishing to ascertain 

 beyond question whether the variations observed could have any 

 specific significance I asked C. W. Johnson to look over his tropical 

 material. From his notes and a careful study of our material I 

 believe we are safe in regarding the northern form as belonging to 

 the same species. The color of the legs shows some variation, and 

 among the tropical specimens there is considerable range in the 

 hairs on the basal two-thirds of the first vein which are entirely 

 absent in some of the specimens. 



XANTHODEXIA Van der Wulp 



Xanthodexm Van de2i Wulp, Biologia, Dipt., vol. 2, 1891, p. 256. — Bratjeb and 



Bexgenstamm, Zweifl. Kais. Mu9., pt. 5, 1891, pp. 372, 377; pt. 6, 1898, 



p. 131. 

 Miwthodexia, Bbauer and Beegbnstamm, Zweifl. Kais. Mus., pt. 5, 1891, pp. 371, 



376 ; pt. 6, 1893, p. 131.— Townsend, Ins. Ins. Menst., vol. 4, 1916, p. 7 ; Rev. 



Mus. Paul., vol. 15, 1927, p. 218. 



The type of Xa/nthodexia is Tachma sencea Wiedemann, the only 

 species so far referred to the genus. Mintlwdexia originally con- 

 tained two species, gravipes and flavicomis^ both new, of which 

 Townsend designated the former as type in 1916. I take the type to 

 be the female of sencea Wiedemann. The characters are all discussed 

 under the species. Brauer and Bergenstamm in 1893 erred in the 

 statement that grampes has a hairy first vein ; it is flamcomis which 

 has it. 



122. XANTHODEXIA SERICEA Wiedemann 



TacMn<i sencea WiEiOEMANN, Auss. Zweifl., vol. 2, 1830, p. 316. 



Xanthodexia sericea Van deb Wtjxp, Biologia, Dipt., vol. 2, 1891, p. 256, pi. 6, 



Fig. 11. — Brauer and Bergenstamm, Zweifl. Kais. Mus., pt. 5, 1891, p. 377. 

 Mintlwdexia gravipes Brauejr. and Bergen&tamm, Zweifl. Kais. Mus., pt. 5, 1891, 



p. 376. 



The type of Tachma sericea Wiedemann is a male from Brazil, 

 in poor condition, as Wiedemann said, on account of having been 

 treated with a preserving fluid which has somewhat damaged the 

 surface of the head and body as well as the wings. The type of 

 gravipes is a female from Venezuela (Lindig, 1864). It is in excel- 

 lent condition and the description will be drawn largely from this 

 specimen. Besides the close correspondence between the two types 

 there is a rather unique character in both, which has confirmed my 

 belief that they belong to the same species. It is in the chaetotaxy 

 of the abdomen. The second segment in gravipes has a large pair of 



