THE GENUS ACRONYCTA AND ITS ALLIES. 225 



ground colour, which are of a similar character and disposition 

 to those described under venosa ; and the minute dotting, with 

 hair points is the same. The larva varies little except in colour 

 of hairs and in trilling details of markings, but its general 

 aspect varies immensely according to how much it is fed up 

 and according to its attitude. The front view, when a full-fed 

 larva is drawn up in sulks is very bizarre, the head being sur- 

 mounted by two white triangles pointing up to the brown and 

 black hair tufts. 



It happens however, that, I met with, last year (i88g) at 

 Llandudno, a remarkable variety of the full-grown larva. The 

 ground colour was a light salmon with some darker marblings, 

 the lateral line white, interrupted by the salmon-coloured sub- 

 spiracular tubercle, some dark marks between the dorsal yellow 

 dashes and subdorsal white marks. The spiracles white on a 

 dark mark extending forward to the next incision. The hairs 

 reddish salmon, the head black, with large lateral area reddish, 

 and clypeus reddish with black centre. This larva produced a 

 moth of the ordinary form — whether this was a rare example 

 approaching an albino form, or whether the pale limestone of 

 the Orme's Head, on which it was basking, has developed a 

 local race of this coloration, I do not know. 



The number of moults in Acronycta is five, but a number of 

 the species do, upon occasion, reach the last skin in four 

 moults, omitting the fifth skin ; and where, as in rnmicis, that 

 skin has a special distinctive marking or coloration, or arrange- 

 ment of the hairs, these larvae never exhibit that particular 

 phase. In rnmicis this is by no means uncommon, most broods 

 presenting some examples of it. I have also noted it in 

 menyanthidis, auricouia, Icporina, and aceris, and have no doubt 

 it occurs, if more rarely, in all the others. This variation has 

 no relation to sex. When I first met with it, I thought that it 

 probably represented an attempt to press forward and get in 

 another brood, to become double-brooded, but this also I found 

 not to be the case, nor was there any difference in size in the 

 full-grown larvai or imagines. It seems to be a spontaneous 

 variation, whose meaning and use have yet to be discovered. 

 It is an interesting circumstance to note, in connection with 

 this, that abii alone has four moults as the normal number, and 

 that, in rare instances, it moults five times like the others. 

 The light which these instances throw on the sudden change 

 of the larval form and colouring, in moulting from the fourth 

 to the last skin, must be more fully dealt with under that species. 



