280 DIPTERA 
the middle femora or tibie. Wings narrow, anal angle much reduced, costa a little thicker beyond the 
ending of the first vein, marginal cell usually long, the second vein ending at the outer fifth of the wing, 
but sometimes (P/oneulisca) recurved, the second basal cell surpassing the first usually by two or more 
times the length of the crossveins, both crossveins small, the posterior transverse, no trace of an anal 
cell, hind margin rather short-ciliate but sometimes fringed; the wings. are usually marked with two dark 
crossbands leaving a central more or less complete hyaline fascia between them, the base and apex 
hyaline. 
Type species : T. conexa, Meigen (Pl. 4, Fig. 29). Theapplication of the name Tachydromia 
has been the subject of considerable dispute, the history of which I have given in Psyche (Vol. 17, 
p. 41-48 [1910]). When Meigen erected the genus Tachydromia in 1803 he assigned to it two species, 
cursitans and. címicoides, one or the other of which must be selected as its type. In 1827 Macquart . 
formed the genus PlatypalPus for those species grouped about cursifams, and thus, by elimination, 
cimicoides became the type of Tachydromia. But Meigen's identification of the Fabrician cimicoides was 
erroneous, and later he described this species as comsexa. This species was definitely assigned as the 
type of Tachydromia by Coquillett in 1903. According to the established laws of priority there is no 
reason for rejecting the name Platyfalpus, although this has been done by the majority of dipterists, 
apparently on the principle of « follow the leader ». The recently resuscitated name Coryneta, Meigen, 
1800, has been used by Kertész to replace Tachydromia (— Platypalpus) in his Catalogus. 
Loew's genus Phoneutisca was established on bimaculata, an Alaskan species with recurved second 
vein and subterminalarista. I have this species now from British Columbia and Alaska. The male 
has curiously formed palpi, which slightly surpass the proboscis, the basal half slender and white, the 
apical half wide and black, deeply and broadly emarginate on the outside. This sex also has the 
second section of the costa thickened and there is a brown spot somewhat smaller than the stigmal spot 
beneath where the first vein attains the costa. In as much as other species of Tachydromía have the 
arista subterminal and the second vein recurved (e. g. enecator, Melander, incompleta, Becker) and the male 
of Tacoma, which isa true Tachydromia, has similarly formed palpi, it is evident that the name Poneu- 
tisca can not have even subgeneric standing. It may interest those entomologists who insist on using 
the name Tachista for this group that Loew erected the genus PAoneutisca a year before he published 
Tachista. 
The species of Tachydromia are extremely agile, running about with quick TEES DUO, on 
the ground, over stones, boards, grass, etc. They carry the wings flat over the back and rarely make 
use of them in fiight. They are predatory and nimbly chase microdiptera for prey. 
NORTH AMERICAN SPECIES OF TACHYDROMIA 
t. A pruinose spot on propleurze above front coxe, rarely absent; wings 
with two dark bands which rarely are united in front; the distance 
between the two crossveins more than twice the length of the hind 
CrOMSVEIR ^20. 0. a. o8 (UR. o» s n on UN AE RUsEocA DE ud I NE 
Crossveins approximated or meeting. . . . . ag UR o ones e cr 
2. Second vein abruptly curving or bending forward at apex, the seme 
cell obliquely truncated. . . . . UC d ac. cq c d a 
Second vein not shortened, the marginal cell enibar pointed; ubi B 
halteres usually pale. . . v AS EN e) M 
3. Male palpi expanded apically into two black lobos; MEA at DES. EA dI EL 
Male palpi narrow and black; legs black except for tarsi, tibi not 
deformed ; second vein straight; halteres dark. (Alask.,, Wyo., Queb.) T. gNEcATOoR, Melander. 
