1924 ] 
The Biology of Trichopoda pennipes Fob. 
59 
by Walton the ‘‘facial plate.” The tentorial thickenings (tt) 
arising at each side near the oral margin and running upward 
nearly to the insertion of the antennae, are easily seen, lying 
just within the facial or vibrissal ridges, which are not pro- 
nounced. The vertex (v) is all that portion of the head, viewed 
is the ocellar triangle, bearing on its raised surface three ocelli 
(oc). From the region of the ocelli to the frontal suture runs a 
median broad velvety-black band or “vitta” (mv), which is 
demarked from the rest of the vertex only by its color, which 
strongly contrasts with the golden-yellow tomentum of the 
lateral portions of the vertex. The genae (ge) are those portions 
of the vertex lying below the ends of the frontal suture, and 
between the oral margin and the eyes. Their color is silvery- 
gray, which shades into the gold of the rest of the vertex above, 
and into the brownish-yellow of the fronto-clypeus. 
Viewed from the side the head is quadrate in shape. The 
postgenae (pge) are those regions behind the genae and extending 
backward and upward along the curve of the compound eyes 
to a point midway between the oral margin and the ocellar 
triangle. The occiput is designated as that portion of the caudal 
aspect of the head extending from a line drawn midway across 
the occipital foramen upward to the vertex. The edge of this 
area can be seen from the side (ocp). 
Chcetotaxy of the Head, On either side of the median vitta 
is a row of frontal bristles (fb) which, since they bend inward 
across the vitta, may be called “transfrontals.’’^ 
On the ocellar triangle, just behind the anterior ocellus, lie 
the great ocellar pair (ob), while behind these, and passing 
between the two lateral ocelli, follow three or more pairs of 
“lesser ocellar” bristles, which in T. pennipes are very small. 
^Here is one instance of the confusion of terms mentioned at the beginning 
of this paper. The area bearing the frontal bristles, although it has been 
called the “front” by taxonomists, is morphologically not the front at all, 
but the vertex. The true front, which lies below the antennae and is fused 
with the clypeus, also bears a double row of macrochaetae which, to one not a 
specialist, might readily be mistaken for the frontal bristles. The writer does 
not recommend here any reconciliation between the terms of the morpho- 
logists and the usage of the taxonomists, but merely wishes to point out the 
true relation of parts. To his mind, any attempt to modify the terminology 
other than by concerted action among taxonomic workers and morphologists 
would only result in “confusion worse confounded.” 
