288 DIPTERA 
Geographical distribution. 
1. D. atricebs, Boheman, Vet. Akad. Fórh. Stockholm, 1851, p. 19o [1852] C. & N. Europe. 
(Tachypesa); Zetterstedt, Dipt. Scand. Vol. 12, p. 4603 [1855] 
(Tachypeza); Roeder, Wien. Ent. Zeit. Vol. 3, p. 291 (1884); 
Wahlgren, Ent. Tidskr. Vol. 31, p. 89, f. 18 (191o). 
melanocephala, Loew, Zeit. Ent. Breslau, Vol. 17, p. 31 (1863). 
2. D. ? * diabolica, Meunier, Ann. Sc. Nat. (Zool.) Vol. 7, p. 89, 100, pl. 5, Baltic Amber. 
f. 3, 4 [1908] (Elafhropeza). 
5. GENUS TACHYEMPIS, NOV. GEN. 
Characters. — Very small species, less than two millimeters in size, usually cinereous pollinose 
on the pleurz as well as on the notum.  Occiput flattened, without bristles; front broadly V-shaped, 
its sides outwardly bowed ; ocelli variable in size, one pair of diverging ocellar bristles and usually in 
front of them a pair of minute convergent setulz; one pair of vertical bristles, all the bristles small. 
Eyes contiguous below the antennz obliterating the face and cheeks, bare, the lower facets large, the 
emargination at the antennz: deep. Antenna short, two-jointed, without a seta beneath, the last joint 
oval, with subterminal arista. Proboscis very short, vertical, the palpi variable in width, but typically 
oval, densely hairy and white. Thoracic bristles variable, a double row of acrostichals may be present 
or absent, one humeral, two notopleural, two or four scutellar bristles, Abdomen comprising seven 
segments and the rather large pygidium, the segments usually with evident lateral pits. Legs simple, 
not enlarged, short-pubescent, no spines, spurs or bristles on the tibiz, last tarsal joint and the pulvilli 
small; the front femora are a little the stoutest. Wings hyaline or nearly so, the costa not fringed; basal 
cells short, the posterior crossvein near the basal third of the wing but beyond the anterior crossvein, 
second and third sections of the costa nearly equal. 
Type species : T. agens, Melander. 
The following North American species make a natural group with the exception of calva and 
simplicior, which are aberrant in any of the genera. These species all possess pittings at the lateral 
margins of the tergites of the abdomen and are more or less pollinose. Two African species with clear 
wings, described by Dr. Bezzi as Tachista, appear to belong here. 
KEY TO THE AMERICAN SPECIES OF TACHYEMPIS 
1. Disk of mesonotum polished, devoid of all dust; humeri 
prominent . . . "OFEN UID SRAWCIN. MENU D M EcL NE 
Thorax and abdomen sabolidinin. the disk more or less 
dusted; humeri generally smaller. . . . QORSN CVM V Qc ACD 
2. Legs largely or wholly black; front of male falvins-polliuils 
between antennz and front ocellus; base of pygidial hook 
with two strong bristles on right side . . . . . . . T. NIGRA, nov. sp. (1). 
(1) Taohyempis nigra, nov. sp. — Male. Length 1.5 mm. Black, vertex and disk of thorax polished. Ocelli 
small, front fulvous-pollinose between antennz and front ocellus, entire occiput with dark brown coating, one pair each of 
black vertical and ocellar bristles; basal joint of antenne yellow to reddish, outer joint black, the subdorsal arista black, 
two and a half times the antennal length; palpi broad, glistening white, with a few yellow setze.  Mesonotum nearly bare, 
about three minute acrostichal and seven dorsocentral hairs, notopleural suture, scutellar area and pleurz densely velvety 
dark brown pollinose, becoming silvery toward and on coxe, one notopleural, one supra-alar and one pair scutellar black 
