FAM. EMPIDID/E 25 
or ending in a spearhead point; eighth segment of the female often widened or distorted, the ninth 
segment elongate, drying in a characteristic way in museum specimens usually by becoming compressed 
and showing chitin ridges above. Hind legs robust, the hind cox larger than the others, the trochan- 
ters as large as the middle coxa and in the male often armed with a spine beneath, the hind femora 
clavate, bearing strong spinous bristles beneath, which may arise from more or less developed tubercles, 
more pronounced in the male, above often with two subapical bristles, middle tibi; with a series of 
extensor bristles, long apical bristles present on the anterior tibize, anterior tarsi bearing long bristles both 
above and below, hind tibie curved, geniculate at the knee, the inner surface of the hind tibize edged 
and in the males of the $urpureus group excavated also, pulvilli large, empodium hair-like.  Halteres 
black in all the species; calypteres large and heavily fringed. Wings with large anal angle, often dark- 
ened in color toward the base, costa stopping at the fourth vein, no basal bristle, costal hairs long and 
abundant, costal cell sometimes widened, auxiliary vein straight, lying close to the first vein into which 
it vanishes at the middle of the wing, first vein ending considerably beyond the middle of the wing, 
second vein usually including a darkened stigma, third vein simple, the pedicel of the second and third 
veins short, arising beyond the middle of the elongate basal cells, discal cell large, elongate, located 
beyond the middle of the wing, complete, emitting two simple posterior veins, anal crossvein curved but 
continuing toward the hind margin, anal vein veak but complete. 
Tyne species : E. jurpureus Walker (Pl. 1l, Fig. 3), Coquillett's designation, 1903.  Coquillett 
separated this genus from Hybos because of the contiguous eyes, short proboscis, lack of setulae beneath 
the hind tarsi and black halteres. Additional characters are to be found in the more or less densely 
pilose mesonotum which shows no trace of dorsocentralor serial bristles and is devoid of pollinose coating. 
The ovipositor is drawn out, unlike in Hybos, and the pygidium is complex. In all the species the first 
posterior cell is narrower at the apex than opposite the posterior crossvein. 
Geographical distribution. 
'The species are confined to North and South America. They are szstival, occurring most abun- 
dantly in meadowlands, and are not common in shady mountainousregions. The males of some species 
exhibit peculiar characters in the hind legs, which are more robust and spinose than in the female, and 
in some species the femora bear stout spinigerous tubercles, which however, are unlike those of Lactis- 
tomyia in being confined to a short extent and not distributed along the whole under surface. The females 
of many of the species resemble each other so closely that they can be identified only with difticulty. 
Identification characters in the genus are largely drawn from the secondary sexual structures of the male. 
Variation is great, however, including even the bristles and tubercles of the hind legs and the conforma- 
tion of the pygidium, which structures afford the most dependable indices to the species. "The known 
species are related to each other in the manner shown by the following table. 
TABLE OF THE KNOWN SPECIES OF EUHYBOS 
(BASED MAINLY ON MALE CHARACTERS) 
ri. Pulvilli normal; second joint of anterior tarsi shorter than 
DD HpuDIBDeBPAIDrSUes eoru DES E um LU EE II LP IPC NC CEU cer ee con 2. 
Anterior pulvilli greatly lengthened; first and second joints 
of anterior tarsi equally long; posterior dorsocentral 
Ge IE uA UE E RM A iab uec ice ca es 38. 
