﻿BRITISH 
  LEPIDOPTERA. 
  

  

  Imago. 
  — 
  18mm. 
  -20mm. 
  in 
  expanse. 
  Forewings 
  dark 
  grey 
  or 
  

   whitish-grey 
  with 
  a 
  slight 
  violet 
  tinge 
  in 
  fresh 
  examples, 
  the 
  costal 
  

   half 
  somewhat 
  darker 
  ; 
  the 
  median 
  and 
  apical 
  areas 
  paler 
  ; 
  the 
  inner 
  

   marginal 
  area 
  sometimes 
  tinged 
  with 
  brownish 
  ; 
  speckled 
  with 
  white 
  

   scales 
  between 
  the 
  nervures, 
  also 
  a 
  few 
  scattered 
  black 
  scales 
  ; 
  the 
  

   basal 
  half 
  of 
  costa 
  sometimes 
  faintly 
  dotted 
  with 
  white, 
  the 
  outer 
  half 
  

   of 
  costa 
  with 
  a 
  strongly 
  developed 
  white 
  edging, 
  especially 
  distinct 
  

   towards 
  apex 
  ; 
  a 
  faint 
  brownish 
  dot 
  near 
  centre 
  of 
  disc 
  (sometimes 
  

   absent), 
  another 
  near 
  the 
  lower 
  extremity 
  of 
  fissure, 
  inconspicuous, 
  

   scarcely 
  darker 
  than 
  ground 
  colour 
  ; 
  two, 
  tiny, 
  black, 
  outer-marginal, 
  

   dots 
  towards 
  anal 
  angle 
  of 
  upper 
  lobe, 
  and 
  two 
  on 
  outer 
  margin 
  of 
  lower 
  

   lobe 
  towards 
  apex 
  ; 
  fringes 
  dark 
  grey, 
  whitish 
  in 
  cleft. 
  Hindwings 
  

   dark, 
  glossy, 
  golden-brown 
  in 
  tint; 
  fringes 
  just 
  a 
  little 
  paler 
  than 
  the 
  

   ground 
  colour 
  of 
  the 
  wings, 
  very 
  glossy 
  towards 
  apex 
  of 
  plumules. 
  

  

  Sexual 
  dimorphism. 
  — 
  The 
  $ 
  noticeably 
  larger 
  than 
  the 
  $ 
  , 
  of 
  a 
  

   deeper 
  tone 
  in 
  all 
  its 
  parts, 
  but 
  above 
  all 
  in 
  hindwings, 
  which 
  are 
  

   nearly 
  black 
  (Lambillion). 
  

  

  Variation. 
  — 
  In 
  the 
  more 
  typical 
  British 
  form 
  there 
  is 
  considerable 
  

   minor 
  variation, 
  especially 
  in 
  the 
  amount 
  of 
  black 
  and 
  white 
  scaling 
  on 
  

   the 
  forewings, 
  the 
  depth 
  of 
  the 
  ground 
  colour 
  along 
  the 
  costa, 
  and 
  the 
  

   presence 
  of 
  brown 
  shading 
  along 
  the 
  inner 
  margin, 
  particularly 
  towards 
  

   the 
  base. 
  In 
  some, 
  the 
  black 
  and 
  white 
  scales, 
  running 
  along 
  and 
  

   between 
  the 
  nervures, 
  give 
  a 
  distinct 
  suggestion 
  of 
  delicate 
  longitudinal 
  

   striation, 
  and, 
  in 
  the 
  palest 
  examples, 
  the 
  white 
  scaling 
  is 
  continued 
  

   from 
  the 
  base, 
  through 
  the 
  middle 
  of 
  the 
  wing 
  to 
  the 
  apex, 
  the 
  latter 
  

   sometimes 
  being 
  particularly 
  white. 
  There 
  is 
  also 
  considerable 
  

   variation 
  in 
  the 
  depth 
  of 
  the 
  tint 
  of, 
  and 
  size 
  of, 
  the 
  discal 
  and 
  fissural 
  

   spots, 
  as 
  well 
  as 
  the 
  shade 
  above 
  the 
  latter, 
  all 
  these 
  markings 
  being 
  

   in 
  some 
  quite 
  distinct, 
  in 
  others 
  practically 
  obsolete 
  ; 
  the 
  presence 
  or 
  

   absence 
  of 
  a 
  tiny, 
  dark, 
  longitudinal 
  mark 
  in 
  the 
  upper 
  lobe 
  of 
  forewings 
  

   reminds 
  one 
  also 
  of 
  the 
  similar 
  mark 
  in 
  A. 
  bipunctidactyla, 
  whilst 
  the 
  

   black 
  dots 
  on 
  the 
  outer 
  margin 
  of 
  the 
  same 
  lobe 
  towards 
  the 
  base, 
  

   occasionally 
  have 
  the 
  normal 
  two, 
  extended 
  into 
  a 
  series 
  of 
  three 
  or 
  

   four, 
  the 
  extra 
  ones 
  very 
  faint, 
  whilst 
  those 
  on 
  the 
  outer 
  margin, 
  

   towards 
  the 
  apex 
  of 
  the 
  lower 
  lobe, 
  also 
  vary 
  much 
  in 
  distinctness. 
  

   Compared 
  with 
  a 
  long 
  series 
  from 
  Canterbury, 
  of 
  distinctly 
  purplish 
  

   hue, 
  with 
  a 
  tendency 
  to 
  brownish 
  on 
  the 
  inner 
  margin, 
  the 
  examples 
  

   from 
  Cuxton 
  are 
  particularly 
  whitish, 
  so 
  much 
  so 
  that 
  the 
  forewings 
  

   could 
  be 
  described 
  as 
  whitish, 
  with 
  the 
  costal 
  area 
  narrowly 
  fuscous- 
  

   tinted, 
  the 
  discal 
  and 
  fissural 
  spots 
  faintly 
  fuscous, 
  the 
  front 
  lobe 
  of 
  

   forewings 
  also 
  faintly 
  fuscous, 
  with 
  a 
  white 
  oblique 
  line 
  crossing 
  it 
  at 
  

   some 
  little 
  distance 
  from 
  the 
  outer 
  margin 
  ; 
  the 
  characteristic 
  sprinkling 
  

   of 
  darker 
  scales 
  almost 
  entirely 
  absent 
  ; 
  the 
  fringes 
  pale 
  grey, 
  inclined 
  

   to 
  whitish 
  basally 
  ; 
  the 
  hindwings 
  pale 
  brownish 
  in 
  tint, 
  with 
  grey 
  

   fringes 
  = 
  var. 
  pallida, 
  n. 
  var. 
  We 
  should 
  be 
  inclined 
  to 
  call 
  the 
  dark 
  

   Duponchelian 
  type 
  rare 
  in 
  Britain. 
  We 
  have 
  an 
  example, 
  bred 
  by 
  

   Whittle 
  from 
  Shoeburyness 
  larvae, 
  in 
  which 
  the 
  inner-marginal 
  half 
  of 
  the 
  

   forewing 
  is 
  particularly 
  brown, 
  and 
  the 
  costa 
  and 
  the 
  lobes 
  of 
  the 
  fore- 
  

   wings 
  particularly 
  blackish, 
  with 
  very 
  little 
  white 
  scaling 
  in 
  the 
  median 
  

   area, 
  and 
  practically 
  none 
  in 
  the 
  lobes, 
  where, 
  however, 
  there 
  is 
  a 
  

   distinct 
  sprinkling 
  of 
  black 
  scales, 
  only 
  the 
  extreme 
  apex 
  of 
  the 
  front 
  

   lobe 
  being 
  somewhat 
  paler. 
  Another 
  example 
  from 
  there 
  is 
  strongly 
  

   marked 
  with 
  scattered 
  white 
  scales, 
  throughout 
  the 
  median 
  and 
  lobal 
  

  

  