4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 82, art. 1 



coxae ; hind tibiae with three longer bristles and some short hairs, all 

 the metatarsi much shorter than the following joints taken together; 

 claws elongate, very slender and delicate, thickened on base. 



Abdomen very short-ovate, rounded behind, somewhat flattened, 

 little wider than thorax and same length, a little longer than wide ; 

 basal segment short, first sternite much wider than second; second 

 to fourth sternites exposed, second longer than wide, all narrow, no 

 membrane visible except narrowly at base of second sternite; no 

 marginals on first segment, only a single pair of very short appressed 

 median marginals on second segment, marginal row on third segment 

 but only one median marginal pair erect, erect marginal row on 

 fourth segment; first hypopygial tergite with marginal row and 

 inferior aspect, second with same aspect but no marginal row; 

 hypopygium ventral and rather large, lobes of fifth sternite moder- 

 ately large and sternite set forward to near midventer. 



OLIGOOESTRUS OESTROIDEUS, new species 



Figures 1, 2 



Length of body, 5 mm; of wing, 4 mm. One male, Bariloche^ 

 Nahuel-Huapi Lake, Argentina, collected by Raymond C. Shannon.^ 



Dusky, more or less silvery pollinose. 



Head entirely yellow in ground color except the occellar triangle 

 and the upper half of the posterior surface, in which, however, the 

 true occiput is yellow almost down to the neck; parafrontal and 

 parafacial thin yellowish pollinose. Cheek shining and frontal 

 stripe rather deep yellow without perceptible pollen. The space 

 inside the lunule below is shining with a dark translucent appear- 

 ance. Thorax, abdomen, and legs black; tip of scutellum distinctly 

 yellow. INIesonotum with rather dense tessellated brownish-yellow 

 pollen, the stripes changing greatly with the angle of view. Dorsum 

 of abdomen rather evenly and thinly covered with gray pollen,, 

 somewhat denser on fourth segment. Wings gray; squamae white 

 including rim. 



Type.— Male, U.S.N.M. No.. 43802. 



^ Mr. Shannon collected three specimens of this fly on the same date ; only one was sent 

 to Doctor Townsend, which becomes the type ; one is retained by Mr. Shannon ; the third 

 is to be deposited in the British Museum. All are males. 



The drawings for the two figures herein were made by Mrs. Eleanor Carlin, through the- 

 kindness of the Bureau of Entomology. — J. M. Aldrich. 



U. S. GOVERNMENT PRINTINS OFFICE: 1932 



