ACIDALIA IMMUTATA. 119 
paler than the ground colour, below which comes 
another dusky line, darkest on its upper edge and 
fading off below. 
The larva described above resembles in structure 
and colouring those of Acidalia fumata, A. promutata, 
and A. wnitaria, except that the two last are longer; 
and it is altogether different from the type furnished 
by the shorter, stiff, and flattish larvee of A. subsericeata, 
A. wncanata, A. aversata, A. nornata, and A. osseata. 
(John Hellins, H.M.M., August, 1864, I, 72.) 
The egg of A. unmutata is of a long cylindrical shape, 
flat at one end, more conical at the other, strongly 
ribbed, with transverse reticulation; colour pale buff, 
speckled with strawberry-pink. (J. Hellins, July, 
1868; E.M.M., September, 1868, V, 97.) 
On the 21st of July, 1870, I received afew eggs (or 
rather larvae, as the eggs had hatched on the way) of 
Acidaha immutata from the Rev. J. Hellins, of Exeter ; 
and subsequently the Rev. H. N. Bloomfield, of Guest- 
ling, near Hastings, sent me a further supply of eggs. 
The young larvee fed until the autumn on Polygonum 
aviculare, when they began to hybernate, having 
attained a length of half an inch, and being of average 
thicknessin proportion. Head alittle broader than the 
second segment, rather flattened and slightly notched 
on the crown; body of nearly uniform width, but 
tapering very slightly anteriorly ; skin very finely, but 
almost inconspicuously, ribbed transversely ; ground 
colour pale olive-brown; head brown, marbled with 
grey ; medio-dorsal stripe very indistinct ; on the 
anterior segments it 1s composed of a very fine double 
line, darker than the ground colour; these lines con- 
join and become darker and more conspicuous poste- 
riorly, forming a distinct black stripe on the tenth, 
eleventh, and twelfth segments; there are also four 
square black marks at equal distances apart on the 
dorsal surface, each of which is divided into two equal 
parts by the medio-dorsal line; the subdorsal lines 
are brownish-grey, and the spiracular lines grey; 
