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 Euploea, 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.

IDEA AGELIA.
PLATE X. Fig. 1.

Pap. Idea, Linn. Fabr. Cramer, Pl. 193, fig. 1, A, B, and pl. 362, fig. D.—Donovan’s Insects of India.

Varying in size from upwards of six inches across the wings to nearly four and a half. The surface is of a greyish white, with the nervures and posterior border black; the latter sinuated internally, and divided by a series of large spots of a whitish colour, and generally an oval shape; between each of the nervures, and beyond the middle of the wing, is a longitudinal black stripe: the primary wings are moreover marked rather before the middle with four irregular black spots, the anterior one on the costa, the other three forming an abbreviated arched band. The under side does not differ materially from the upper, but the black stripes are rather broader, and there is a large irregular patch in the discoidal cell. The body is whitish with a black line along the back, the thorax having two black central lines and two short transverse ones at their extremity: the breast is marked with oblique black lines, and a row of dusky points runs along each side of the abdomen: antennÆ black.

The insect is a native of Java, Amboina, and other Asiatic islands.

IDEA DAOS.
PLATE X. Fig. 2.

Boisd. Spec. gen. Pl. 24, fig. 3.

This delicate and handsome species is much the smallest, the expansion of the wings not being quite four inches. The ground colour is dusky white, with two remote rows of rounded spots, another at the extremity of the discoidal cell, and several smaller ones on the costa beyond the middle. The abdomen is entirely whitish, the thorax with two connivent black rays on the back and numerous black spots anteriorly: antennÆ black.

It is said by Dr. Boisduval, to whose excellent work we are indebted for a knowledge of it, to be a native of Borneo.