OSTEN SACKEN ON WESTERN DIPTERA. 323 



Columbia aud in the White Mountains), only larger, 8-9""" long ; the 

 hind femora are altogether red, with only a slight brownish shade before 

 the apex. 



Chilosia sp. — Saucelito, Cal., April 2. Two males. Not unlike 

 Chilosia tristis Loew from the Atlantic States. 



Chilosia sp. — Lagunitas Creek, April 15. A single male. Eyes pu- 

 bescent, and therefore different from all the species from the Atlantic 

 States described by Mr. Loew. 



As in the Atlantic States the species of the corresponding genera are 

 yet very little known, it is not worth the while to describe Californian 

 species here. 



Melanostoma tigrina n. sp. — Dark metallic-green; abdomen velvet- 

 black ; segments 3 and 4 each with an olive-green metallic cross-band, 

 the first interrupted, the second connected with the olive-green hind 

 margin of the segment ; fifth segment metallic-greenish ; legs black, 

 tibise brownish-red. Length 8-8.5""". 



MaJe. — Face and front metallic-greenish-black ; the face with a white 

 pollen forming transverse, irregular, dottedripples, the intervals of which 

 show the ground-color ; the cheeks and a stripe running over the facial 

 tubercle are bare of pollen ; upper oral edge somewhat upturned and 

 facial tubercle projecting; antennae black, third joint and arista brown; 

 front faintly and evenly grayish-pollinose, and with erect black pile; ver- 

 tical triangle metallic-green, with black pile. Thorax metallic-bluish- 

 green, clothed with dull grayish pile, more whitish on the pleurae. Hal- 

 teres brownish. Abdomen elongated-elliptical; first segment greenish- 

 black; the second velvet-black, opaque, its lateral edge metallic-olive- 

 green, with a small subtriangular expansion ; third segment anteriorly 

 with an interrupted metallic-olive-green cross-band nearly half as broad 

 as the segment, but expanded on the sides along the whole lateral mar- 

 gin ; the posterior half of the segment is of a velvet-black, which does 

 not quite reach the lateral margin ; the fourth segment is like the third, 

 except that the olive-green cross-band is not interrupted, or only sub- 

 interrupted, and connected by a longitudinal olive-green stripe, cutting 

 through the velvet-black portion with the narrow olive-green hind mar- 

 gin of the segment ; thus the velvet-black on this segment forms a broad 

 interrupted cross-band, not quite reaching the lateral margin ; fifth 

 segment and hypopygium metallic-green. Femora metallic-green ; knees 

 yellowish-brown; tibiae yellowish-brown or brownish-yellow at the base, 

 darker toward the tip, especially the last pair; tarsi black, first joint of 

 the middle tarsi brown ; first joint of the hind tarsi iucrassate. Wings 

 subhyaline; stigma brownish-yellow. 



Hab. — Saucelito, Marin County, Cal., April 2; Yosemite Valley, June 

 13. Two males. 



The abdomen of this species is broadest at the hind margin of the sec- 

 ond segment. 



Melanostoma sp.— Petaluma, California, April 28. Abdomen more 



