The head is bilobed, having a deep notch on the crown, and of a dull black colour, covered with black warts, each emitting a white hair. The ground colour of the body is deep velvety black, and densely sprinkled with pearl-white warts, each emitting a fine white hair, some being of considerable length, and the majority slightly curved. Down the centre of the back is a series of rich deep rust-red shield-like markings, which commences on the third segment and terminates on the eleventh segment. In the centre of the anal segment is a shining black dorsal disc, much resembling the head; the legs are black and shining, and the four pairs of prolegs are rust colour, with a polished band above the feet, and the anal pair are black with pale reddish feet. The caterpillars feed on sallow, willow, birch, and elm. They cover the leaves of their food-plant with a silken web and live thereon in companies, and do not separate until about to prepare for the chrysalis state. The chrysalis. The dorsal half of the head and wing points are black, and the ventral half orange. Some of the points on the body are tipped with orange. The whole surface is finely and irregularly furrowed and granulated. The ground colour is pale buff, covered with fine fuscous reticulations. The entire surface is clothed with a whitish-powdery substance, giving a pale lilac or pinkish bloom to the chrysalis, which, however, is easily rubbed off, the chrysalis then assuming a brownish hue. Our figure of the chrysalis is after Holland. Mr. Frohawk, who had female butterflies living under observation for about three months, states that eggs were laid in April, May, and June. Caterpillars from the first batch of 192 eggs hatched early in May, nineteen days after they were laid. These were full grown by June 20, and entered the chrysalis state soon after. The butterflies from these commenced to emerge about the middle of July. He says: "Both sallow and willow are equally suitable food for the larvæ, and birch is readily eaten, even when willow has formed the sole food until the last stage; they will feed on elm. Nettle was not appreciated, and not touched by them during the last two or three stages."