12 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 68 



line with the last spot and apex of second vein, and a third and 

 slightly larger spot almost directly above the first one and in the 

 cell above it, the three forming and almost equilateral triangle; dis- 

 cal cell all dark; inner cross vein and upper extremity of outer one 

 darker than other veins; costal margin in front of apices of auxil- 

 iary and first veins pale. Halteres dusky yellow. 



Bases of frontal bristles but little elevated ; arista very short pubes- 

 cent. Thorax with three pairs of dorsocentrals, one prescutellar pair 

 of acrostichals, one pair of strong intra-alars, and about six series 

 of intradorsocentral setulae; scutellum short, flat above. Veins 3 

 and 4 distinctly divergent apically. P'ore femur without an an- 

 teroventral comb. 



Length, 4 mm. 



Type and paratype. — Female, Cat. No. 28446, U.S.N.M., Barro 

 Colorada, Panama Canal Zone, July 18 and 9 respectively (R. C. 

 Shannon). 



Most closely related to angustipennis (Williston), differing in hav- 

 ing the abdomen entirely yellow, the wing without discal celluar 

 marks, etc. 



Genus MINETTIA Robineau-Desvoidy 



The present concept of the genus Minettia is a rather broad one 

 and it is very probable that with further intensive study it may be 

 split into several genera or subgenera. The typical forms, basing 

 this concept upon the genotype, are robust black species with the face 

 more or less tumid on each side below and the wings without con- 

 spicuous black markings except sometimes at bases. In these the 

 mid tibia has no distinct median bristles on posterior side and there 

 is never a bristle in line between the intra-alar and supra-alar 

 bristles, while all the wing veins are devoid of setulose hairs. In this 

 paper I include some species in the genus which have posterior bris- 

 tles on the mid tibia, as well as some which have the thorax with a 

 bristle in line between the intra-alar and supra-alar bristles. There 

 are also several species in which the wings are conspicuous!}^ marked 

 apically, and which are much less robust than the genotype, without 

 tumid areas on the lower part of face. 



I consider it better to leave these aberrant forms in this genus in 

 the meantime as more material obtained from South America is nec- 

 essary to enable one to arrive at a definite conclusion as to the merits 

 of the characters referred to as generic indices. Any such aberra- 

 tions as are present in the species dealt with in the paper are indi- 

 cated in the text. 



I have grouped the species dealt with according to what I consider 

 to be their relationships. The first four all have the face and scutel- 



