VII. COSTAL FOLD OF IIESPEBIDAE 
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are bordered with lustrous, straw-coloured scales. A third fringe of 
scales of the same colour, hut thinner and longer, is inserted along the 
common chord, entirely covering the folded part of the wing. The length 
of the scales of this third fringe equals or slightly exceeds the width of the 
fold ; they are longest in the middle of the chord (1*5-2 mm.) where they 
are furthest from the arc; they all have a long, narrow blade, which in 
some is gradually widened, fan-like, into a narrow triangle, with its apex 
more or less dentate (Fig. 3 a) ; others (Fig. 3 5) are filiform, terminating 
in an oval lamina, or in a narrow, apically rounded ribband. The scales 
which bound the area covered by the fold (Fig. 4) are of very varied shape, 
but mostly oval or claviform : nearly all have a dark terminal spot, full of 
opaque granules, separated from the rest of the scale by a transparent 
aureola. These dark spots are sometimes very small, reduced to a mere 
dot, but sometimes occupy the whole width of the scale: they are not 
always exactly terminal, being sometimes displaced to one side : rarely two 
spots are to be seen on the same scale. The aureola which surrounds the 
spots is usually circular, but is sometimes less regular in shape. 
The longitudinal striae which cover the scales pass over the aureola 
also, but become confused and indistinct on the dark spots. The opacity 
and granulation of the dark spots are characters frequently met with in 
scent-scales, and since the apices of the scales with dark spots are covered 
by the free margin of the fold, it appears not improbable that they are 
odoriferous. Thus these scales may discharge at the same time two very 
different functions, the basal part serving to close the fold, the apical acting 
as a scent-organ. 
On removing the scales from the straight line which, cutting longi¬ 
tudinally through the fold, separates the recurved part from the rest of the 
wing, it is seen that the space between these scales and the folded part of 
wing is covered with a dark grey powder, composed chiefly of separate par¬ 
ticles (Fig. 5 a ), measuring about 0*016-0*025 mm. long by 0*004 mm. broad; 
their sides, generally parallel—more rarely converging towards one end— 
are transparent, yellowish, and usually traversed by a more or less dark 
and opaque longitudinal line. Between these particles are others (Fig. 5 &), 
joined end to end by very fine, short threads, like more or less distinctly 
jointed hairs (Figs. 5 c, d). 
The origin of the powder which fills the cavity of the costal fold is 
revealed by these articulated hairs, for it is composed of their fragments. 
Finally, to complete the description of the scales found in the costal fold 
of Telegonus midas , I may mention certain narrow scales, about 0*6 mm. 
long by 0*016 mm. broad, which I found in the cavity of the fold, without 
being able to ascertain exactly where they were inserted. 
Telegonus (?), undetermined species from S. Bento (PI. F, Figs. 6-9).— 
This species, of which I was only able to secure one specimen, much worn, 
but with the costal fold well preserved, is remarkable both for the extent 
of this fold, which occupies nearly three-fifths of the costal margin (Fig. 6), 
2 T 
