92 LEPIDOPTERA. 



occasionally becomes so pronounced that fore and hind wings 

 are black, with cue broad white stripe. In Sutherlandshire 

 some speciiueus have all the broken black markings joined 

 into transverse black bands in regular succession. -Mr. 

 A. F. Grifliths has one from this district in which the usual 

 black sub-marginal stripe is replaced by a series of longi- 

 tudinal dashes running inward and totally altering the 

 pattern of markings. In the West of Ireland there appears 

 to be greater local diversity than here ; among specimens 

 obtained at Killarney by ^Mr. C. A. Watts, I found some of 

 the normal southern form, others leaning toward that found 

 on the hills and in the north ; one with the central group of 

 blotches broken up into dots, and another with the hind 

 wings almost spotless, the markings only faintly indicated 

 by brownish clouds. I think, however, that the majority of 

 Irish examples are of the typical race. 



In sub-polar regions, outside the British Isles, still more 

 extreme forms are found. That from Iceland, known as 

 thulearia, but probably only a race of the present species, is 

 almost covered with obscure brown and black suffused mark- 

 ings ; while forms from the northern districts of North 

 America are wonderfully blackened. 



On the wing in .May and June, and in the North in July. 



Larva short, stout, tapering to each extremity, trans- 

 versely wrinkled, sides puckered ; skin shining ; on the 

 second segment is a black horny dorsal plate. Colour dark 

 brown; subdorsal lines ochreous, indistinct; spiracular line 

 composed of a series of ochreous blotches ; head very dark 

 brown, or black ; jirnligs and anal segment pale reddish or 

 yellowish-brown; on the ventral surface is a row of ochreous 

 spots. (C. Fenn.) 



July, August, sometimes till September or even October 

 in the North ; on birch and sweet gale ; according to Ilof- 

 mann also u])on sallow and Vaccinhim idi;/inoxum ; feeding 

 singly on terminal shoots, of which it unites the older leaves 



