128 Mitthejl. d. Münchener Ent. Ver. 1881. 
A. Cephalic bristles.*) 
Vertical bristles, so called from their position on the vertex; 
there are two pairs of them, the inner and the outer one; 
both are inserted more or less behind the upper and inner 
corner of the eye. They are either erect, or the bristles of 
the inner pair are converging, those of the outer diverging. 
These two pairs of bristles are the most persistent of all, 
among the Acalyptrata, although even they disappear in some 
genera. 
Post-vertieal pair of bristles, in the middle of the upper 
part of the oceiput, behind an ideal straight line, connecting 
the vertical bristles of the inner pair. They are generally 
small or absent; large and conspicuous in Zetanocera. 
Ocellar pair‘ of bristles, on the ocellar triangle, they are 
always diverging and pointing forward; — often wanting. 
Fronto-orbital bristles, placed on each side of the front, 
near the orbit, immediately below the vertical bristles, on tlıe 
little stripes which generally vun down from the vertex on 
*) The terminology of the parts of the head is confused and contra- 
dietory in different writers, and for this reason an explanation is necessary. 
Frontal orbit I call the whole interval between the frontal stripe 
and the eye The term is not always appropriate, especially for the Tachi- 
nidae, where that interval occupies the greater part of the front; but I 
prefer to retain it, rather than to change the terminology adopted by Loew, 
in the Monogr. N. Am. Dipt. Vol. I. These parts are the Wangenscheitel- 
platten of Prof. Brauer (Die Zweiflügler des Kais. Mus. in Wien.) and the 
optica frontis of Rob. Desvoidy. When there is no distinct frontal stripe, 
as in some Acalyptrata (for instance the Ephydridae), the dividing line of 
the orbits is merely au ideal one. 
There is no separate term in Loew for the portion of the face, very 
distinet in many Cyclorhapha between the lower part of the frontal fissure 
and the antennal foveae; a stripe which generally contains, in the Calyp- 
trata, a vertical ridge, bearing a row of bristles. We have no other choice 
but to use Robineau Desvoidy’s term facialium (plural facialia), also ad- 
opted by Walker. This piece is very distinet in the Ephydridae, and 
although level here, it is bounded by sutures and often bears a row of hairs. 
Stenhammar calls it epistomatis partes laterales, which is too eumbrous 
for use. 
