76 AMERICAN DIPTERA. 



Aiiorostonia opaca Coqiiillett. 



" Head yellow, opaque, white pruinose, the front aiid upper part of the occiput 

 tinged with bluish gray, a velvet-black spot between the antennae and each eye, 

 antennse brownish, the arista marked before the middle with a white ring, palpi 

 yellow, proboscis brown ; body brown, opaque, bluish-gray pruinose, mesonotuni 

 with four, the pleurae witli one brownish pruinose vittse ; sternopleura bearing 

 numerous short bristly hairs and with two stout bristles; legs yellow, opaque 

 grayisli pruinose, except a polished spot at base of the posterior side of the first 

 two pairs and a streak on the posterior side of the hind ones; wings whitish, 

 marked with large pale gray spots and with a black cloud covering the small and 

 hind cross-veins, a small black spot beneath apex of auxiliary vein, one slightly 

 before middle of antepenultimate section of the fourth vein, and several smaller 

 spots on some of the other veins; the gray color fills the whole marginal cell 

 beyond apex of auxiliary vein, nearly the entire second half of the submarginal, 

 etc.; length 7 mm. A female specimen captured by the writer. 



''Habitat. — Los Angeles County, Cal. 



" Type. — Cat. No. 5500, U. S. N. M." Original description. 



This species is not represented in the material examined. From 

 its resemblance to viaculata, it is probably a sand dune form, 

 although nothing has been reported about its habits. 



Aiiorosloiiia Uia<-ulafa Darlington, n. sp. (PI. IV, figs. 4 and 5). 



Length 4.5 mm.; of wing, the same. 



General color gray, wings spotted, cheeks cream colored. 



Occiput, vertex and front gray; lower part of the front somewhat yellowish 

 and pubescent; the two pairs of vertical and three pairs of fronto-orbital bristles 

 arise from brown spots; a rather broad brown stripe extends from the ocellar 

 bristles to the base of the occiput; antennae brown, third joint oval, arista white 

 for about one-third its length at the proximal end ; cheeks about one and a half 

 times the width of the eye; eyes transversely ovate; a black spot connects the 

 base of the antenna with the anterior somewhat angular margin of the eye; 

 vibrissae rather small. 



Thorax gray; dorsum ash-gray; the dorsocentral bristles arise from large, 

 distinct brown spots and the small hairs arise from small brown dots; the 

 humeri, the lateral edges of the thorax, and the pleurie, have a reddish-gray 

 tinge; scutellum gray, bare except the ordinary four bristles, which arise from 

 large brown spots, the apical pair confluent; the raesopleura has one large and 

 one small bristle on the posterior edge, othei wise bare; the sternopleura with 

 one strong bristle on the upper edge and *vitli rather long, somewhat scattering 

 pubescence below. 



Abdomen gray, the small hairs arising from l)rown dots; hypojiygium of the 

 male gray, globose, and sparsely covered with very short pubescence. 



Wings whitish, with large brown blotches; there is a blackish spot on the 

 auxiliary vein at its tip, one on the small cross-vein, and a small one on the 

 anterior end of the hind cross-vein, forming a straight row ; the jiosterior end of 

 the hind cross-vein also a little infuscated. 



Legs pale yellow, except the femora, which are gray. 



