1013] AhxanJcr—.\e,r Xtolropieat Anlorhlni 43 



running caudiiJ; sides of the scloritu between I lie i)seiuli>siiliiiiil foves (humeral 

 pits) and the Irnnsverse suture, almost filled with a large rounded dark hrown 

 spot, this mark not touching the dark median villa (as in mclanoccjilialdj; scutum, 

 with the exterior front angles darkened; sculellum and post-nolum very dark 

 cheslnut-browu. Pleurjc, propleura? yellowish; mesoi)!euric very dark brown, 

 almost black. Ilaltcres pale at base, stem brown, knob bright yellow. L<gs: 

 coxa; and trochanters briglit yellow, abruptly contrasted with the dark pleunil and 

 sternal coloring; femora light yellow, the apical portions abruptly dark lirownisli- 

 black, these dark tips rather broadest on the fore-femora; libia dull yellow, Ihe 

 extreme tip brown, broadfst again on the fore-tibia; tarsi dark brown. \\'ings: 

 hyaline, stigma dark brown, square; wings broadly banded with pale greyish-brown, 

 the innermost band extending from the origin of Rs to the end of iJnd Anal, almost 

 diamond-shaped, the breadth sub-equal to the length; the middle fascia is a paler 

 continuation of the stigma, across ihe cord of the wing and ending al Isl .Anal, 

 rather narrowest near the fork of M; the ajjical band is rather darker and fills out 

 the wing tip, its inner margin straight and embracing Ihe outer end of cell Isl Mj. 

 Venation: (See fig. a.) : Cell 1st M: very elongate, rather square al ils inner end; 

 veins beyond cell 1st M. (discal) short, so that that portion of M1+2 between cross- 

 veins r-m and m, is longer than the distal segment of Mi+j. The type has Ihe 

 cell 1st Mt open, coufluenl with cell Mi, due to the disappearance of tin- <iuter 

 deflection of vein Mj. 



Abdomen: tergum dark brownish-black, the apices of the segments broadly 

 paler; 7th tergile orange-yellow; 8th blackish; valves of the ovipositor pale, 

 orange-yellow; sternum similar, but the pale apical margin even broader, cm- 

 bracing the apical half of the sclerite. 



Holotype, 9, Sonsonate, Salvador, Cent. Am. (Frederick Knab, Coll.) Para- 

 types, 9 9 . Aguna, Guatemala, Cent. Am. (alt. 2000 ft.) (Dr. G. Kisen, coll.) 



Type and one paratypc in U. S. Nat. Mus. Coll. (N'o. 15,124). 



One paratype in author's collection. I take pleasure in naming this handsome 

 species after the "Father of American Dipterology," Baron C. 11. von Oslen 

 Saekcn. 



This specie.s falls in tlie polila group, the .species of wliicli may 

 be separated by the following key: 



1. Thoracic priescutum entirely shiny black 2 



Thoracic priescutum more or less orange-yellow or brownish 4 



2. Pronotum yellowish. (Colombia) trlfasciata Knd' 



Pronotum black 3 



3. Small species ( cf, length, 2.5-3 mm.) ; legs with the basal two-thirds 



yellowish-tawny. (Brazil) j)o/?7n O. S.> 



Larger species ( 9, length, 5 ram.); leg dark brown. (Costa Rica) . .roslrala End." 



'Enderlein, Zoolog. Jnhrbuch abth. f. Syst.; vol. 32, pt. 1; p. 69, 70; Rr. Ri (1912). 



•Osicn Sackon, Berl. Ent. Zeiischr.; vol. 32, pt. 2; p. 189 (l887). 



•Enderlein. Zoolog. Jahrbuch abth. f. Syst.; vol. 32, pt. 1; p. OS, 09; fig. Qi (l912). 



