Very similar to the last species, but generally smaller, and the ground colour has usually less brown in it; the chief character, however, by which it may be distinguished, is the broader and clearer white wedge-shaped mark between veins one and two on the fore wings. Reference to the figures of each species on Plate 28 will show this at once. The eggs are greenish white, and the full-grown caterpillar is purplish brown on the back merging into violet on the sides; there is a broad yellow stripe along the spiracle area; the head is violet, faintly marked with black. A noticeable feature of this caterpillar is its varnished appearance. It feeds on birch in June and July, and sometimes in September and October. The early stages are figured on Plate 29, Figs. 3, 3a, and 3b. The species has a somewhat similar distribution to that mentioned for the preceding, but it seems to be commoner in the North of England and in Scotland than elsewhere in the British Isles. THE PEBBLE PROMINENT (_Notodonta ziczac_). This moth varies in the colour of the fore wings from pale ochreous brown to a darker brown tinged with reddish; the usual pale greyish patch in the middle of the costal area is {71} sometimes obliterated by a suffusion of the darker colour; the dark-brown first and second lines are often only visible towards the front edge of the wings; a blackish lunule or crescent forms, in conjunction with the strongly curved outer line, the outline of the characteristic pebble-like mark on the apical area of the wings; a pale saw-edged line, which is inwardly shaded with dusky and intersected by black streaks on the veins, traverses the pebble mark, but in the lighter coloured specimens this line is not traceable. The female has browner hind wings than the male. The moth is depicted on Plate 31, Fig. 2; and the early stages on Plate 30, Figs. 1, 1a, and 1b. The caterpillar, when full grown, is pale ochreous grey, sometimes tinged with pink or purplish brown, or with yellowish, and especially on the hind rings; a yellow stripe along the back is edged here and there with brownish; the diffuse dusky line along the area of the black margined spiracles is edged with yellowish. It is occasionally found on poplar, but sallows and willow are the more usual food plants, and it feeds upon these in June and July and again in August and September. The reddish brown chrysalis is enclosed in an earthen cocoon just under the surface of the ground at the roots of tree or bush upon which the caterpillar fed. The moth emerges in May and June from chrysalides of the previous year, and in August as a second generation. Three broods in the year have been obtained in confinement, but this is probably exceptional.