320 LEPIDOPTERA. 



tufts pale smoky-grey ; legs dull white, regularly barred with 

 black ; first pair very strong, and after death extremely stiff 

 at the joints. 



This species bears an extraordinary resemblance to 

 Diphthcra Orion, but is very much more robust, its thorax 

 more squared, its abdomen much stouter; its collar green, 

 while that of D. Orion is black ; and the black edge of its 

 subterminal line disposed in wedges, while in the latter 

 species, it forms a continuous stripe. 



Usually very little variable in the size of the black mark- 

 ings, or the intensity and extent of their white edgings. In 

 colour it unfortunately is unreliable, the green fading very 

 slowly and imperceptibly, but surely, and becoming, in the 

 course of many years, even dull orange. At the same time 

 the white lines fade quite away. In the north of Ireland, in 

 Scotland, and even on Dartmoor, Devon, there is often exten- 

 sion of the black central band of the fore wings, sometimes 

 to a very considerable degree. In the collection of Mr. P. M. 

 Bright is a specimen taken in the New Forest the ground 

 colour of which is a singular greenish-white, with the black 

 markings noi'mal. One taken in Sussex by the Rev. E. N. 

 Bloomfield is pale green, but devoid of black in the markings, 

 which are merely indicated in paler colour. 



On the wing in September and October ; but in the north- 

 east of Scotland it has been taken in plenty at the end of 

 August. It does not hybernate; and its name appears to be 

 somewhat inappropriate, unless it has been given because the 

 moth docs not appear in April. The winter is passed in the 

 egg state. 



Larva stout, naked, somewhat cylindrical, but moderately 

 flattened beneath ; and with the prolegs placed rather wide ; 

 head rounded, greyish-green, inner edge of the lobes margined 

 with black ; body grey-green, or very dusky-brownish green, 

 almost exactly the colour of the outer bark of the oak tree ; 

 dorsal line broad, white, interrupted by a series of very broad 



