HYDROCAMPID^E—HYDROCAMPA. 295 



edged with a golden-brown stripe ; cilia white. Female 

 similar, often rather larger. 



Undersides of all the wings white, with the markings of 

 the upper side accurately repeated, though in a fainter tint 

 of colour. Body and legs white. 



Usually very constant in its delicate colour and lovely 

 markings, but liable distinctly to local races. In the fens of 

 Norfolk, and sometimes occupying most restricted areas in 

 these fens, specimens are found having all the markings less 

 distinct, sometimes all present but faint, or only partially 

 present, or only in single or double lines instead of stripes, 

 and decreasing in distinctness till some of the specimens are 

 pure silky white, wholly destitute of markings. 



In Ireland a somewhat similar race is found, but in it the 

 discal and central spots of the fore wings, and a fine brown 

 line along their hind margins remain usually quite visible as 

 the other markings disappear ; and every intermediate shade 

 of distinctions or obliteration occurs, till at Lough Oughter, 

 Co. Cavan, the purely white form again appears. When the 

 partially obliterated form was first found, it was mistaken 

 for the allied (non-British) species, H. rivulalis. 



On the wing from the end of June till August — apparently 

 in a single generation. 



Larva seven-eighths of an inch long ; rather slender, 

 tapering from the thii-d segment to the head and from the 

 tenth to the anal extremity ; head small, flattened, and 

 tapering towards the mouth, translucent pale brown, the 

 lobes marked with a reticulation of darker brown, and a 

 similar streak in the middle of each, mouth blackish-brown, 

 ocelli large and black ; segmental divisions and sub-divisions 

 moderately well defined; the skin a little puckered aud 

 dimpled along the sides ; dorsal plate yelloM-, or olive- 

 yellow, sometimes with a few freckles, and a thin transverse 

 streak of brown along the hind margin ; rest of the body 

 deep bright yellow, or olive-yellow, so translucent as to show 



