The eggs are pale olive green tending to brownish, and all that I have seen have been laid in irregular lines on leaves, or {85} on the sides of a chip box. The caterpillar is greyish, with some short hairs and black dots; the back is broadly marked with yellow, and there is a yellow stripe, with black dots on it, low down on the sides; rings four and eleven have each a raised black spot; head blackish. Feeds from June to September, on dwarf sallow (_Salix repens_), and also on young plants of aspen. Like other caterpillars of this genus, it hides by day in a packet of leaves spun together. There are certainly two broods, if not more, in the year. The moth emerges in May, and more irregularly in July or August, and October. Except when attracted to a light, the moth is rarely seen, but in fens, marshes, and boggy places generally, the caterpillars may often be obtained in numbers almost throughout the United Kingdom. Its distribution abroad embraces Northern and Central Europe, with extension into Northern Spain and Italy; Bulgaria, South-east Russia, and Armenia. THYATIRIDÆ. The nine British species next to be considered belong to the old family Cymatophoridæ, but as the name _Cymatophora_, as indicated by Hübner in the "Tentamen" (1816), is now generically used by authors for some species of Geometridæ; and as Hübner's _Verzeichniss_ generic names will have to be used for the species previously included in _Cymatophora_, Tr., the term Thyatiridæ has here been adopted for this family--the Polyplocidæ of Meyrick and others. THE BUFF ARCHES (_Habrosyne derasa_). This pretty species (Plate 36, Figs. 1, 2) is well distributed over the greater part of England and not at all uncommon in the more sylvan districts of the southern counties. It occurs in Wales but has only once been recorded from Scotland. In {86} Ireland it is found in almost every well-wooded locality, but is not generally common. The moth hides among the foliage of the bramble and also creeps under the withered leaves on the ground. It comes freely to sugar, and is often the earliest to attend the banquet, but is rather skittish at first and should be given time to settle down. The fore wings are pale olive grey with two whitish streaks across them, the first oblique approaching the second towards the inner margin; the space between the streaks is clouded with brownish buff and there is a whitish cloud on the costal area, and some strongly waved cross lines before the second streak.