Vol XI] ALEXANDER— NEW D1PTERA 105 



femora brownish yellow, tipped with dark brown; wings pale 

 yellowish, conspicuously variegated with brown on the cross- 

 veins and deflections of veins; cell 1st M 2 long and narrow, m 

 being one-half longer than the basal deflection of Cu x . 



Female. — Length about 8.8 mm.; wing, 9.3 mm. 



Rostrum and palpi brownish-black. Antennae dark brownish- 

 black throughout, the first scapal segment elongate-cylindrical. 

 Head shiny dark brown, sparsely pruinose, strongly narrowed 

 posteriorly, the eyes protuberent. 



Thorax shiny dark brown, very sparsely grayish yellow prui- 

 nose, without stripes. Pleura dark brown, sparsely pruinose. 

 Halteres pale throughout. Legs with the coxae and trochanters 

 obscure yellow; femora brownish yellow, tipped with dark brown; 

 tibiae light brown, tipped with dark brown; tarsi dark brown. 

 Wings with a strong yellowish tinge; cells C and Sc more saturat- 

 ed; a conspicuous brown pattern, arranged as follows: A brown 

 spot at the origin of Rs; a conspicuous seam along the cord, 

 extending from the tip of Sc to the fork of M; Cu and the deflec- 

 tion of Cui seamed with brown; outer end of cell 1st M 2 similar; 

 a brown spot at r and a smaller one at the fork of M 1+2 ; veins 

 dark brown, paler in the saturated areas. Venation : Sc long, Sci 

 ending about opposite the fork of R 2 + s , Sc 2 at the extreme tip of 

 Sci, a little longer than r-m; Rs rather long, almost straight, 

 arcuated at origin; R 2 +* rather short, from one to two times as 

 long as r-m; r at the tip of R\ and on R 2 beyond midlength ; inner 

 ends of cells R 3 and R 6 in alignment; cell 1st M 2 very long and 

 narrow, its inner end conspicuously arcuated; m very long and 

 slightly arcuated, about one-half longer than the basal deflection 

 of Cui and nearly three times the outer deflection of M s ; cell 

 1st M 2 much longer than vein M 3 beyond it and longer than the 

 petiole of cell Mi; cell Mi shorter than its petiole; basal deflec- 

 tion of Cui about its own length beyond the fork of M; distal 

 section of Cui, beyond cell 1st M 2 , about equal to m. 



Abdomen dark brownish black, the pleural membranes paler. 

 Ovipositor with the valves horn-colored, the dorsal shield shiny 

 black; tergal valves of the ovipositor strongly compressed. 



It is possible that Limnophila pteropoccila is more correctly 

 referable to Dactylolabis but this is uncertain. The fly differs 

 strikingly from all other known species in the Nearctic fauna. 



Holotype, female, No. 744, Mus. Calif. Acad. Sci.; E. P. Van 



