Fortunately, the species seems not difficult to rear from the egg, otherwise specimens in collections would be not only very limited in number, but frequently very indifferent in condition. In colour the moth is whity brown, more or less dusted or clouded with dark grey; except in the darker forms, three irregular black lines on the fore wings, and two on the hind wings, are clearly seen. It flies at dusk in June and July, and sits by day on lichen-covered rocks. The caterpillar is pale ochreous brown, with irregular dark brown lines. It feeds on ling (_Calluna_) and crowberry (_Empetrum_) from September to May; but when eggs are obtained, the caterpillar hatching from them may be kept on chickweed, knotgrass, etc., and the moth be reared the same year. Mr. R. Tait records the finding of ten caterpillars on navelwort (_Cotyledon_) growing among heather in a very sheltered corner among rocks in North Wales, at Easter, 1906. He also notes that moths reared in captivity pair readily. The British localities, all in North Wales, are Aber, Bangor, Barmouth, Bettws-y-coed, Conway, Dolgelly, Lanfairfechan, and Penmaenmawr. THE LEAST CARPET (_Acidalia_ (_Ptychopoda_) _rusticata_). The whitish fore wings of this species (Plate 45, Figs. 3 and 6) are crossed by a blackish central band, and there is a blackish patch at the base of the wings, with an extension along the front margin, almost or quite to the central band; the hind wings have a central dot, and three or four dark grey wavy lines, the space between the first and second darkened, and appearing to be a continuation of the fore wing band. The thick set, pale ochreous-brown, or grey-brown, caterpillar (Plate 48, Fig. 1, drawn from a skin) has three more or less distinct pale lines along the back, and a series of darker diamonds along the central area; head, brown. In the open, its food probably consists of decaying or withered leaves, but when treated in captivity it will eat and thrive upon growing knotgrass, groundsel, dandelion, etc. August to May. Mr. Mera mentions that some caterpillars he reared on dandelion produced moths that were larger in size than most captured specimens. [Illustration] 2 Pl. 44. 1. SMALL GRASS EMERALD: _caterpillar_. 2. LITTLE EMERALD: _caterpillar_. 3, 3a. SMALL EMERALD: _caterpillar, chrysalis and cocoon_. [Illustration] 2 Pl. 45. 1, 4. PURPLE BORDERED GOLD. 2, 5. WEAVER'S WAVE. 3, 6. LEAST CARPET. 7, 10. RUSTY WAVE. 8, 11, 14. SMALL DUSTY WAVE. 9, 12. DOTTED BORDER WAVE. 13. SILKY WAVE. 15, 18. DWARF CREAM WAVE. 16. ISLE OF WIGHT WAVE. 17. SATIN WAVE.