ART. 4. REVISION OF THE FAMILY THEREVIDAE—COLKE. 103 
blackish brown and strong; stigma brown; cell M-3 open but nar- 
rowed in the margin. 
The specimen described was taken at Springfield, Massachusetts, 
May 19, 1915 (R. T. Webber), and is in the collection of the Boston 
Society of Natural History. 
Type locality.—Indiana. 
Type.—Not in existence. 
THEREVA ALBICEPS Loew. 
1869. Thereva albiceps Lorw, Berlin. Ent. Zeit., vol. 13, p. 166. 
A gray, white pilose species, the head wholly snow-white, antennae 
black. Differing from candidata in having the knob of the halteres 
brownish black. Abdomen of male white pollinose and pilose. Loew 
gives British America (Scudder) and Red River (Kennicott) as the 
habitat. 
Type localities.—“ British America and Red River.” 
Types.—In the Museum of Comparative Zoology at Cambridge. 
Through the kindness of Mr. Nathan Banks, of the Museum of 
Comparative Zoology at Cambridge, I am able to establish the iden- 
tity of this species. One specimen, a female, was loaned from the 
collection of the Museum. This unidentified specimen was from 
the Loew collection and bears the label “‘ British America, Scudder.” 
One of Loew’s types had this same label and, as the original descrip- 
tion fits the specimen examined, there seems to be no doubt of the 
identification. The following notes are made from the examination 
of the specimen: 
The third joint is missing from both antennae, but the first joint 
differs from that of albifrons, being longer and more slender, not much 
wider than the second joint. There are three dark-gray vittae on 
the mesonotum, or areas set off by two widely separated longitudinal 
white stripes; on the outer side of the white stripes there is a line of 
brownish pollen. ‘There are four scutellar bristles. Stem of the 
halteres brownish yellow, the knob blackish brown. ‘The pile of the 
abdomen is sparse and white on the first three segments, short, erect, 
and black on the others. The abdomen is as described by Loew, 
the second, third, and fourth segments with the broad basal brown 
mark divided by a gray median line. The wings are whitish hyaline, 
the veins yellowish on the basal third. 
THEREVA PACIFICA, new species. 
Plate 11, fig. 133. 
Male.—Length 8 mm. Head and appendages black, with black 
pile and bristles; pile of lower occiput and cheeks dense. Third 
joint of antennae slighty shorter than the first and quite slender, 
narrower than the first or second, the arista short (fig. 133); first two 
