26 PROCEEDINGS OF THE NATIONAL MUSEUM vol.83 



(10) PARADIDYMA CINERESCENS, new species 



Male. — Very closely resembles P. derelicfa., from which it diflfers 

 in the following characters: Front at narrowest part (before vertex) 

 0.263 of the head width in one specimen measiired ; second antennal 

 segment distinctly longer than first and nearly one-fourth the length 

 of third; cheeks clothed with sparse black hairs on lower half; 

 palpi brownish black. Thorax and scutellum covered Avith dull 

 cinereous pollen ; postscutellum membranous above ; calypters white. 

 Abdomen subshining, lightly sprinkled with gray pollen, which in 

 most Adews extends to the hind margins of last three segments. 

 Pulvilli grayish, about as long as last tarsal segment. 



Length. — 6 mm. 



FeTnale. — Unknown , 



Type.— Mvile, U.S.N.M. no. 44763. 



Remarks. — One male. Promontory Point, Utah, August 5, 1929 

 (G. F. I^owlton). 



The species has a general pale-gray appearance, in contrast with 

 the decidedly blacker aspect of P. derelicta., to which it is closely 

 allied. The slight structural differences are mentioned in the key. 



(11) PARADIDYMA RETRACTA, new species 



Hind cross vein noticeably retracted; last section of fifth vein 

 more than half the length of preceding; apical cell open; sterno- 

 pleurals two; last three abdominal segments shining black on apical 

 three-fourths or more. 



Male. — Front at vertex 0.228 of the head width in one specimen 

 measured, hardly widened to middle, and not very prominent at 

 antennae ; cheeks, face, and sides of front gray pollinose ; median 

 stripe brownish, as wide as one parafrontal on entire length; ocellars 

 proclinate ; inner verticals developed ; f rontals extending about to 

 apex of second antennal segment, uppermost pair rather weak, recli- 

 nate ; antennae nearly as long as face, black, second segment reddish, 

 one-fourth the length of third; arista blackish, thickened on proxi- 

 mal two-fifths; facial ridges strongly diverging downward, bare 

 except a few hairs next to vibrissae, which are situated on oral mar- 

 gin; parafacials bare outside of the main row of bristles; cheeks 

 sparsely black haired below, about two-fifths the eye height; palpi 

 pale yellow; eyes hairy; beard white. 



Thorax black, gray pollinose; mesonotum marked with four dis- 

 tinct black vittae; scutellum black, subshining, lightly dusted with 

 changeable gray pollen; infrasquamal hairs absent; calypters semi- 

 transparent, Avhit-e; postscutellum normally developed. 



Abdomen mostly shining black, with silvery basal bands on last 

 three segments, which in a favorable angle extend at most over the 



