In its typical form (Plate 107, Figs. 10, 11) this white species has three dark-grey almost parallel cross lines on the fore wings and two on the hind wings. The first or the second of these lines on the fore wings may be absent, occasionally both may be missing and the third very faint. Not infrequently in undersized bred specimens the first line approaches the second line either throughout its length or near the inner margin, and more rarely the two are united; in most of such aberrations the tips of the fore wings are rather more rounded than in typical specimens, and these are referable to ab. _rotundaria_, Haworth (Round-winged Wave). I have over a dozen examples of this form, all of which were reared from caterpillars which had been kept on short rations when nearly mature; in some, the outer margin of the fore wings is distinctly rounded, but in others it is much the same as in the larger typical form, and one of these is shown on Plate 107, Fig. 12. The ground colour occasionally assumes a greyish tint, and sometimes this is tinged with pink; more rarely the general colour is leaden grey. [Illustration] 2 Pl. 106. 1. BARRED RED: _caterpillar_. 2, 2a. BARRED UMBER: _egg_, _natural size and enlarged, and caterpillar_. 3. LIGHT EMERALD: _eggs_, _natural size and enlarged_. [Illustration] 2 Pl. 107. 1-3. CLOUDED BORDER. 4, 5. SCORCHED CARPET. 6. SLOE CARPET. 7, 8. CLOUDED SILVER. 9. WHITE-PINION SPOTTED. 10-12. COMMON WHITE WAVE. 13, 14. COMMON WAVE. {267} The caterpillar, of which there are two broods, one in July and another in September, feeds on birch, alder, sallow, etc. It is purplish brown, spotted with white above, and greenish below on the first three rings. There is also a green form with purplish brown marks on the back. (Plate 105, Fig. 3, from a coloured drawing by Mr. A. Sich.) The moth is out in May, June, and August, and is generally common throughout the greater part of the British Isles. Abroad, the range extends to East Siberia and Amurland. COMMON WAVE (_Cabera exanthemata_). Somewhat similar to the last species, but sprinkled with ochreous grey; the fore wings have three greyish cross lines, the first two less regular than those of _pusaria_, and the outer one distinctly curved; variation in the lines is pretty much the same as in _pusaria_ and its small form ab. _rotundaria_. Of the form showing the first and second lines more or less confluent, I have seven examples reared from collected caterpillars; six are undersized, but the other is of quite ordinary size (ab. _approximata_, Haworth); another specimen, also bred, is thinly {268} powdered with ochreous grey, and the lines are very indistinct. The more usual forms are shown on Plate 107, Figs. 13, 14.