OSTEN SACKEN ON WESTERN DIPTERA. 



275 



the joint. Knob of halteres white, black at base. Wings hyaline ;. 

 veins brown, except those at base and near the costa, which are pale 

 yellow ; fourth posterior cell closed. 



J2a&.— Yosetnite Valley, California, Jane 9-11, common. Seven males . 



Is very like Thereva candidata Loew from the Atlantic States, but differs 

 in having a few black bristles on the face each side of the antennae ; 

 the femora dark to the very tip ; the tarsi brown, except at base ; the 

 wing- veins darker ; the third antennal joint likewise darker. 



Family SCEKOPINID^E. 

 As I have no Californian species of this family, I will describe the 

 following remarkable species from Missouri :— 



Scenopinus bulbosus n. sp., $ 9 . First posterior cell closed, peti- 

 olate ; head, thorax, and the sides of the abdomen sparsely covered with 

 coarse, pollen-like grains. Length 5-5£ mm . 



Antennas black, hardly reddish at the suture between the second and 

 third joints. Head and thorax blackish-bronze color ; the front $ is an 

 acute triangle, meeting the triangle of the vertex ; the line of contact 

 of the eyes is thus a very small one ; in the 9 , the eyes are not contig- 

 uous, but separated by the moderately broad front; both front and ver- 

 tex, in both sexes, are sparsely covered with yellowish- white, coarse, 

 pollen-like grains. Thorax stouter and more gibbous than in 8. fenes- 

 tralis, covered above and on the sides with the same pollen-like grains, 

 j which are not dense enough, however, to conceal the ground-color. 

 ; Abdomen black above ; its sides and the venter covered with the same 

 1 grain-like pollen. Halteres brown; legs black; roots of the tarsal 

 joints more or less yellowish. Wings subhyaline (c?), slightly brown- 

 ish anteriorly ($) ; costal cell brownish; first posterior cell closed, the 

 , fourth vein being incurved toward the third, and ending in it at a con- 

 siderable distance from the margin of the wing ; the petiole thus formed 

 J is about equal in length to the posterior transverse vein in the $ ; a lit- 

 tle shorter in the 2 . The second submarginal cell is nearly as long as 

 j the first posterior (therefore much longer than in fenestralis) ; the dis- 

 ! tance between the two cross- veins is a little shorter than the great cross- 

 I vein. 



Hab. — Missouri, in July (0. V. Eiley). 



The grains of pollen which distinguish this species appear, under a 

 ! magnifying power of 100-150, like elongated bulbs inserted on short 

 ! stalks. 



Obs.-~ This species shares the closed first posterior cell with the new 

 I genus Atrichia, formed by Loew for a Mexican Scenopinid (Centur., vii, 

 j 76) ; the latter, however, is described as elongated, slender, with slen- 

 ; der feet, characters which by no means belong to 8. bulbosus. The name 

 j Atrichia, revived by Dr. Loew from Schrank's Fauna Boica, 1803, where 

 it was used for Scenopinus, cannot be maintained, as, in the mean time, 

 the same name has been used by Mr. Gould, in 1844, for a genus of 



