Hybridising T. bistortata and T. crepuscularia. 21 
29 
3g 
bt 49 
252 329 
2f 1¢ 
48 f 529 
These two females are very small, and 
would belong to the preceding set, but for 
the remarkable development (1) of the square 
spot about two-thirds towards the apex of the 
forewing and placed between the submarginal 
and marginal lines; (2) of the transverse 
bands, which suggest strongly a superficial 
likeness to 7’. consonaria, Hb. [See further 
notes on this form in Bacot’s inbred series 
from Batch VI (p. 32).] 
Bred June 18th, June 21st and June 24th. 
I am scarcely able to distinguish these from 
typical 7’. crepuscularia, they are rather more 
suffused, and hence tend to approach the set 
following. 
These are remarkable. The ground colour 
is pale, but with much fuscous suffusion ; 
strongly marked transverse lines, tending to 
form bands by shading within the basal and 
outside the median lines. They are totally 
unlike the southern 7’, bistortata ab. abietaria 
(the male parent) and 7’. bistortata ab. conson- 
aria (the summer brood); superficially the 
paler ones are not very unlike 7’. crepuscularia 
(the York form). On the other hand, they 
are quite inseparable from Perthshire 7’. bzs- 
tortata, which is a very specialised form of 
the species. They are much larger and 
broader winged insects than one ever obtains 
among 7’. bistortata ab. consonaria. 
Uniformly suffused and practically ab. 
delamerensis. 'The males are darker (blackish- 
fuscous) than the females, with stronger 
transverse lines and a more or less clearly 
defined subterminal line; the females are 
uniform, grey-black in colour, with ill-defined 
markings, and here and there small irregular 
patches of the typical pale coloration. 
The forewings approaching ab. delamerensis, 
the hindwings more or less typical; probably 
nearer delamerensis than any other form. 
2 pup# remained unemerged on November 
10th, 1897. 
