90 
one-third times as long as the second, arista thickened on the basal 
half, the penultimate joint scarcely longer than wide; thorax thinly 
gray pollinose, marked with four black vitta', three postsutural and 
three sternopleural macrochaetae, scutellum bearing four marginal pairs, 
abdomen thinly gray poll i nose on the last three segments, which bear 
marginal macrochaetae; front tarsi noticeably dilated; middle tibia* 
each bearing three or more macrochaetae on the front side near the 
middle, hind tibiae not ciliate outwardly; wings hyaline, the base yel- 
low, third vein bearing three or four bristles near the base, bend of 
fourth vein angular and bearing a stamp about as long as the small 
crossvein, the vein beyond it strongly arcuate, hind crossvein near last 
fourth of distance Prom the small to the bend; calyp teres white; length, 
9 mm. Colorado. Two female specimens collected by Mr. Carl V. Baker. 
Type No. 3587, U. S. National Museum genalis n. sp. 
Genus EXORISTOIDES, new genus. 
The characters of this genus, of which johnsoni is the type species, 
may be gleaned from the table of genera on preceding pages of this 
work and from the description of this species given below: 
Third joint of antenna' concave on the front edge, three or four 
sternopleural macrochaetae, apex of scutellnm and of abdomen 
black: black, the palpi, and sometimes the base of the third 
antenna] joint, yellow; front in male three-fourths as wide as, in 
the female slightly wider than, either eye, two pairs of orbital 
bristles in the female, wanting in the male, frontal bristles 
descending to the arista, cheeks one-fourth as wide as the eye 
height, vibrissa' on a line with front edge of oral margin, two or 
three bristles above each, antenna' almost as long as the face, 
the third joint in the male live, in the female two and one-third, 
times as long as the second, arista thickened on the basal two- 
fifths to three-fifths, the penultimate joint slightly longer than 
broad: thorax gray pollinose, marked with four black vitta', 
three postsutural macrochaetae, scutellum bearing three long- 
marginal pairs and a short apical pair; abdomen thinly gray 
pollinose and with reflecting darker spots, last three segments 
bearing discal and marginal macrochaetae; middle tibiae bearing 
three or more on the front side of each near the middle, front tarsi 
of female greatly dilated, front pul villi of male almost as long 
as the last tarsal joint; wings hyaline, first vein bearing two or 
more bristles on the outer half, third vein bristly almost to the 
small crossvein, bend of fourth vein almost rectangular, desti- 
tute of an appendage, vein beyond the bend strongly arcuate, 
hind crossvein nearly straight, slightly beyond middle between 
the small and the bend; calypteres white; length, to 7 mm. 
Eastport, Me.; Franconia, 1ST. IT.; Westville and Clementon, 
N. J. Three males and three females, collected May 30 and July 
