134 Mittheil. d. Münchener Ent. Ver, 1881. 
Pleura. Mesopleural (2), sternopleural (1), pteropleural (1, 
very small). 
Seutellum (4). 
This is the usual type of cbaetotaxy in the genus Tiry- 
peta in the wider sense; in describing therefore that of any 
given species, it will suffice to say: chaetotaxy normal and to 
indicate the differences. Instead of two fronto-orbital bristles, 
there is sometimes only one; instead of three lower fronto- B 
orbital bristles, there are often only two; in some cases there 
are three dorso-central pairs of bristles, the third being in 
front of the suture (Loew, Die Europ. Bohrfliegen, p.5); the scu- 
tellum has sometimes only two bristles, sometimes as many as six. 
If we compare the above formula with the chaetotaxy of 
the asiatic Trypetid P£ilona v. d. W., we perceive at once | 
important differences, which lead us to the conclusion that the | 
genus, although a Trypetid, cannot be referred to Z’rypeta in 
the wider sense of Meigen and Loew. Ptilona (at least a 
species from the Philippine Islands, which I have before me, 
and which seems closely allied to P. brevieornis v. d. W.), 
has no ocellar bristles; only one fronto-orbital, inserted very 
low down, a little above a single fronto-orbital of the lower 
row. On the thorax: I, no praesutural, III, only one pair of 
praescutellar bristles. The rest is normal. I hold the absence 
of the praesutural bristle (T) as the more important and de- 
cisive character. 
Some african species of Dacus, according to Loew, have 
no dorso-central bristles at all (The asiatic Dacus, which I 
can compare have one praescutellar pair). 
Loew (]. c.) describes the lateral bristles of the thoracie 
dorsum as forming two rows on each side; I believe that we 
gain a much clearer view of them when we consider separately, 
those of the dorso-humeral and of the dorso-alar region. As 
soon as I adopted this mode of grouping, I became aware of 
the importance of the praesutural bristle (IT), as characteristic 
of a true Trypeta, and of a bristle behind the suture (II), 
which oecurs in the section Ortalina, but is wanting in the 
other sections of the Ortalidae, 
