GEOMETRID.-E—GEOME TRIA . 283 



preserved specimens fade in time, and if in any way damped 

 are liable to do so rapidly, to a dull yellow. 

 On the wing at the end of June and in July. 



Larva thick, very rugose ; head rounded into prominent 

 lobes ; on the front of the second segment is a broad raised 

 dorsal ridge ; on the front of the third another, still broader, 

 produced into an angulated hump ; upon the seventh, eighth, 

 and ninth segments are pairs of pointed dorsal tubercles, or 

 humps, those on the seventh rather pressed together ; very 

 small rugose excrescences on the last three segments ; the 

 whole skin, in fact, varied with ridges and hollows, and 

 having a distinct projecting ridge or fold down each side, 

 beneath the spiracles, and extending to the anal prolegs ; 

 these last are very large and powerful, clasping completely 

 round a twig. Head pinkish-white, the lobes tinged with 

 brown or pinkish-brown ; body soft dull velvety gi-een, or 

 bright green, or yellow-green, with all the little ridges paler, 

 the lateral ridge decidedly so ; the tips of the dorsal tubercles 

 bright light brown or pinkish-brown, and an elongated dorsal 

 blotch on each of the last three segments brighter brown, 

 very broad on the last ; undersurface yellow-green ; legs and 

 ventral prolegs pale purplish-green ; anal prolegs pale pink. 



The infant larva is black, but soon becomes tinged with 

 orange, and with grey or brown ; before hybernating it 

 has assumed almost the exact appearance of a tin}^ brown 

 twig, and appears much shrivelled ; in early spring, while 

 the trees are still bare, it becomes reddish-brown or pur- 

 plish-brown, like the buds and twigs which it then gnaws 

 for food ; as the buds open and allow the young leaves to 

 appear it begins to become green in front, the hinder part 

 remaining brown, like the scales at the back of the opening 

 bud ; as this further opens the larva becomes greener. If 

 upon birch, which opens early, this change takes place in 

 early spring, the green is light and bright and the hinder 

 brown portion brightens ; but if the larva is upon alder, the 



