The above genus is of very limited extent, comprehending only four
species. They are, however, somewhat remarkable insects, both on
account of their size, and the manner in which their colours are
distributed. The wings are slightly transparent and of a greyish white,
with black stripes running along all the nervures, and occasionally
forming blotches on the surface. The nearest approach to this mode
of colouring among other tribes is presented by certain species of
Euplœa, and particularly by _Pap. dissimilis_, which on this account,
has been termed the Idea-likeness butterfly. The most conspicuous of
its generic characters are the slenderness of the antennæ, which are
so slightly thickened towards the apex as to appear nearly filiform,
and the elongated oval form of the wings: in other respects Idea nearly
conforms to the genera with which it is associated. The palpi have the
terminal joint minute and conical, the second long and thickest in the
middle, the radical one net half its length. The tarsal division of
the anterior legs is dilated, and furnished with two or three unequal
spines.
[Illustration: