OSTEN SACKEN OJT WESTERN DIPTERA. 333 



the island of Sauta Eosa (S. Cal.), through the kiutlness of Mr. H. Ed- 

 wards. 



YoLUOELLA MARGiNATA Say, Jouru. Ac. Phil., vi, 166. — Mexico (Say) ; 

 Waco, Texas (Belfrage) ; a specimen was kindly given by Mr. E. Bur- 

 gess. 



YoLUCELLA AVIDA n. sp. — Face with a narrow brown stripe; cheeks 

 shining, black; abdomen honey-yellow; hind margins of segments and 

 longitudinal narrow dorsal stripe on segments 2-4 black ; wings hyaline ; 

 cross- veins and stigma clouded with dark brown. Length 11-12'"'". 



AutenniE, light-brown; arista of the same color, plumose; third 

 antenual joint about two thirds of the length of the arista, its basal 

 half a little expanded ; face pale whitish-yellow, a narrow black stripe 

 runs from the mouth upward, becoming paler and finally obsolete before 

 reaching the antennae; cheeks black, shining; frontal triangle of the 

 male pale whitish-yellow, beset with black pile; profile straight, with a 

 slight depression under the antennae; eyes densely pubescent. Thorax 

 greenish-black; on each side, between the humerus and the scutellum, 

 a rather broad, dull, honey-yellow stripe ; in front of the scutellum, a 

 yellowish, rather obscure parallelogram, emarginate anteriorly; sides 

 of the dorsum and pleurae beset with yellowish white hairs. Scutellum 

 yellowish, subtranslucent, beset with black hair along the edge. Abdomen 

 pale honey-3"ellow ; first segment black ; the second and third segments 

 posteriorly with a narrow black margin, expanded on eaah side along 

 the lateral margin, and prolonged in the middle in the shape of a Ion . 

 gitudinal black stripe toward the anterior margin; on segment 2, 

 this stripe is broadly expanded, so as to coalesce with the black of the 

 first segment ; on segment 3, on the contrary, it is tapering anteri- 

 orly ; segment 4 with a black cross-band a little beyond the middle , 

 with a subtriangular expansion in the middle, reaching toward the 

 anterior margin ; hypopygium, black ; the abdomen is clothed with short 

 black hairs on its black portions, and with longer yellowish- white pile 

 in the yellow regions, especially on the sides and around the black 

 triangle on the second segment. Femora black; knees and anterior half 

 of the tibiae brownish-yellow ; tarsi black. Wings, hyaline ; latter half 

 of the subcostal cell and the interval between the auxiliary and first 

 longitudinal vein as far as the stigma brownish ; stigma dark brown • 

 central cross veins and small cross-vein with well defined, although 

 small, brown clouds; the second vein ends in the first, some little dis- 

 tance before the tip of the latter. 



Hab. — California (G. R. Crotch). A single male. 



YoLUCELLA SATUR n. sp. — Face altogether yellow; cheeks yellow, 

 except a black stripe from the lower corner of the eye to the anterior 

 oral edge ; abdomen honey-yellow, first segment black, hind margin of 

 segments 2 and 3 with a narrow black border, that of the second seg- 

 ment connected with the black first segment by a broad black stripe 



