468 MR. B. F. CUMMINGS ON 
being visible under a strong power without the need of special 
microscopic preparation. The first segment of the antenna, 
though much larger than the succeeding segments, is separated 
from the first segment of the other antenna by a wide space, 
and bears no sort of resemblance to the eccentric form of these 
segments in the male. The cardo is also much larger than the 
cardo in the male, and instead of being practically vertical beside 
the vertical stipes it is at right angles to the latter. The stipes 
is shorter and broader than the same piece in the male, and the 
palpi are so hinged upon it as to point outwards and away from 
the head. 
iv. THe Scent ORGANS OF SERICOSTOMA PERSONATUM. 
More detailed examination of a detached palpus of a male 
reveals the following additional facts. 
The deep brown, comparatively thick chitin of the convex 
outer side ceases abruptly in a transverse line towards the tip 
so as to leave the soft white tip of the palpus (composed of 
thinner chitin of a lighter colour) to fit more easily into the 
base of the antenna. On the inner surface at the base is 
a small lobe with two or three short black bristles at its base 
(text-fig. 6). These bristles in cross-section are seen to be 
fluted. 
In side view the outer margin is very convex, the inner 
margin, which is applied to the head, more or less straight. 
The outer surface is very convex, and the inner surface applied 
to the inner surface of its fellow is concave. But the concavity 
is full of very long silky hairs, which curve up and around in a 
semicircle to protrude near the tip into the hollow in the base 
of the antenne. In the figures only a few of these hairs are 
sketched in. This huge hair-tuft is bounded on the outside by 
a rather pronounced lip, bare except for a row, on the margin, 
of small black bristles, in cross-section seen to be fluted (text- 
fig. 7, FH), and on the inside by a flap (text-fig. 6, FL), which 
projects and keeps the hairs tucked in so that they are prevented 
from straying in an untidy mass on both sides. Further refer- 
ence to this flap is given below. It runs down towards the base 
of the palpus, where it is continuous with the “lip” of the convex 
outer margin. Higher up it carries a fringe of hairs much 
shorter and stouter than the silky hairs of the scent-gland tuft. 
The ends of these hairs are somewhat swollen. The flap ends 
abruptly higher wp so as to leave a channel between it on one 
side and the lip of the palpus opposite on the other side. 
Between these two promontories the long hairs sweep out beyond 
the edge of the palpus, and are sometimes visible as “ fluff” 
projecting from between the two basal antennal segments behind. 
Under the flap is the opening into a large sac which occupies 
the whole of the interior of the palpus from the top to its extreme 
bottom near the stipes. 
