TACHINIDAE OF AUSTRALIA 15 
character (but great care is often needed in examining them as they are easily 
overlooked). They occur haphazardly in various genera in all the subfamilies 
but are of rare occurrence in Goniinae (mainly confined to some Blondeliini) 
and Proseninae (but occurring at least in some Chetogaster). 
inner vertical setae. The main pair of erect setae standing on the summit of the 
vertex (Innere Stirnborsten of Mesnil) (Text-fig. 3). 
This pair of setae is almost universally present in Tachinidae, though it is 
sometimes weak and hair-like in Phasiinae and some aberrant tribes. The two 
setae are most often subparallel to each other but are sometimes directed inwards 
and crossed, especially in some Tachininae. Subparallel inner verticals are the 
rule in Goniinae though genera with cruciate inner verticals occur (e.g. 
Phorocerosoma). 
interfrontal area. The median area of the frons between the parafrontals 
(interfrontalia, frontalia, frontal vitta, Stirnstreifen of Mesnil) (Text-fig. 2). 
In forms in which the head is holoptic or the eyes strongly approximated 
the interfrontal area is extensively obliterated and the parafrontals meet in 
part in the mid line of the frons. 
intermediate abdominal tergites. The middle two of the apparent four main 
abdominal segments when seen from above, i.e. tergites 3 and 4 collectively. 
intra-alar setae. The setae of the mesonotum standing external to the dorso- 
central setae and approximately in line with the middle of the postalar 
callus (Text-fig. 4). 
The number and arrangement of these setae are of great taxonomic 
importance. The most complete complement (excluding the occasional haphazard 
supernumerary) is 1 + 3 ia setae and is found in the great majority of Goniinae. 
The presutural intra-alar is most often absent in the other subfamilies but is 
present, for example, in Voriini and Campylochetini (which have a I + 3 2a 
complement like most Goniinae) and sometimes elsewhere. Many Phasiinae 
and a few Tachininae have two strong posterior intra-alars that are widely 
spaced with the anterior one close to the transverse suture, e.g. Leucostoma, 
Cylindromyia, Zita, Leverella; this arrangement of two post ia is fundamentally 
different from that found in forms normally possessing three but occasionally 
lacking the anterior one (in which case the two remaining post ia stand near 
each other and the front one is remote from the transverse suture). A few 
forms completely lack intra-alar setae (e.g. some Phasiini and Ormiini) or they 
may be missing in isolated specimens of species normally possessing at least 
one. In Cylindromyia the anterior one of the two post ia is enormously strong 
and stands out of alignment with the hind one and unusually close to the 
pre-alar seta. 
last section of Cu,. The part of vein Cu, between its junction with m-cu and its 
apex at the wing margin. 
lateral scutellar setae. One or more pairs of marginal scutellar setae standing 
between the basal and subapical or apical pairs (Text-fig. 5). 
These setae are frequently absent, and when present are usually weaker than 
the basals and subapicals. 

