﻿CROMBKUGGHIA 
  DISTANS. 
  453 
  

  

  almost 
  identical 
  in 
  these 
  respects. 
  The 
  different 
  form 
  of 
  the 
  abdomina, 
  

   however, 
  distinguishes 
  the 
  sexes 
  at 
  a 
  glance. 
  

  

  Variation.— 
  The 
  British 
  specimens 
  in 
  our 
  possession 
  vary 
  consider- 
  

   ably 
  in 
  size, 
  colour, 
  and 
  extent 
  and 
  intensity 
  of 
  markings. 
  In 
  size 
  the 
  

   limits 
  of 
  variation 
  fall 
  between 
  14 
  • 
  7mm. 
  and 
  2Q- 
  3mm. 
  In 
  colour 
  there 
  are 
  

   two 
  very 
  distinct 
  forms 
  readily 
  noticeable,one 
  a 
  bright 
  rusty-brown 
  (almost 
  

   of 
  the 
  tint 
  of 
  the 
  brightest 
  $ 
  Marasmarcha 
  lunaedactyla) 
  , 
  the 
  other 
  of 
  

   a 
  much 
  greyer 
  tint 
  (inclining 
  to 
  a 
  greyish-fawn, 
  with 
  a 
  tinge 
  of 
  fuscous 
  

   in 
  it). 
  These 
  represent 
  the 
  two 
  forms 
  known 
  in 
  this 
  country, 
  

   respectively, 
  as 
  distans 
  and 
  laetus 
  (though 
  not 
  apparently 
  so 
  described 
  

   by 
  Zeller), 
  and 
  are 
  generally 
  supposed 
  to 
  represent 
  seasonal 
  di- 
  

   morphism, 
  the 
  early 
  brood 
  being 
  composed 
  of 
  the 
  brighter, 
  and 
  

   the 
  later 
  brood 
  the 
  greyer, 
  specimens. 
  In 
  our 
  experience 
  this 
  

   appears 
  to 
  be 
  only 
  partly 
  true, 
  but 
  it 
  has 
  proved 
  impossible 
  to 
  get 
  

   specimens 
  with 
  full 
  data 
  of 
  the 
  two 
  broods 
  from 
  the 
  same 
  locality 
  in 
  

   the 
  same 
  year, 
  and, 
  at 
  Deal, 
  where 
  we 
  know 
  the 
  species 
  best, 
  the 
  greyer 
  

   form 
  has 
  appeared 
  on 
  the 
  wing, 
  in 
  different 
  seasons, 
  from 
  the 
  end 
  of 
  

   June 
  to 
  mid-August, 
  all 
  possibly 
  belonging 
  to 
  the 
  second 
  brood 
  of 
  

   different 
  years. 
  Our 
  brightest 
  examples 
  come 
  from 
  the 
  Dover 
  district, 
  

   but 
  the 
  month 
  of 
  capture 
  is 
  not 
  given. 
  Whether 
  the 
  variation 
  is 
  not 
  

   more 
  largely 
  a 
  matter 
  of 
  habitat 
  than 
  season 
  (first 
  or 
  second 
  brood) 
  must 
  

   still 
  be 
  considered, 
  therefore, 
  an 
  open 
  question, 
  but 
  we 
  suspect 
  that 
  it 
  is. 
  

   Besides 
  these, 
  however, 
  there 
  is 
  a 
  very 
  pale 
  ochreous 
  form, 
  a 
  modifica- 
  

   tion 
  of 
  the 
  brightest 
  brown 
  forms. 
  The 
  markings 
  vary 
  from 
  clear 
  

   white 
  to 
  a 
  dingy 
  ochreous, 
  and 
  sometimes 
  approach 
  almost 
  complete 
  

   obsolescence. 
  This 
  tendency 
  to 
  failure 
  is 
  particularly 
  noticeable 
  in 
  the 
  

   markings 
  connected 
  with 
  the 
  apex 
  of 
  the 
  wing, 
  and 
  in 
  the 
  outer 
  lobal 
  

   line, 
  these 
  markings 
  being 
  very 
  conspicuous 
  in 
  some 
  examples, 
  whilst, 
  

   in 
  other 
  specimens, 
  at 
  the 
  other 
  extreme, 
  they 
  are 
  practically 
  obsolete, 
  

   and, 
  to 
  a 
  less 
  extent, 
  the 
  failure 
  also 
  frequently 
  shows 
  in 
  the 
  lower 
  

   half 
  of 
  the 
  inner 
  lobal 
  line. 
  There 
  is, 
  too, 
  considerable 
  difference 
  in 
  

   the 
  number 
  of 
  white 
  points 
  on 
  the 
  costa, 
  and 
  on 
  the 
  disc 
  of 
  the 
  fore- 
  

   wing, 
  whilst 
  the 
  colour 
  of 
  the 
  hindwings, 
  usually 
  bright 
  coppery-brown, 
  

   is, 
  in 
  the 
  greyest 
  examples, 
  often 
  of 
  a 
  black-grey 
  tint, 
  tending 
  to 
  

   darken 
  the 
  general 
  appearance. 
  In 
  the 
  fringes, 
  the 
  scaling 
  of 
  the 
  

   cleft 
  of 
  the 
  forewings 
  is 
  worthy 
  of 
  examination, 
  the 
  number 
  of 
  short 
  

   biack 
  scales, 
  and 
  the 
  amount 
  of 
  development 
  of 
  the 
  pale 
  sections, 
  where 
  

   the 
  lobal 
  lines 
  cross, 
  varying 
  considerably 
  ; 
  there 
  are 
  also 
  some 
  little 
  

   differences 
  exhibited 
  in 
  the 
  fringes 
  of 
  the 
  inner 
  margin. 
  The 
  scale- 
  

   tuft 
  is 
  entirely 
  different 
  in 
  position 
  from 
  that 
  of 
  the 
  other 
  British 
  

   Oxyptilids, 
  is 
  very 
  small 
  and 
  inconspicuous, 
  and 
  the 
  scales 
  forming 
  it 
  

   are 
  rather 
  readily 
  lost 
  ; 
  the 
  number 
  of 
  black 
  scales 
  on 
  either 
  side 
  of 
  

   the 
  scale-tuft, 
  along 
  the 
  margin 
  of 
  the 
  plumule, 
  varies 
  considerably. 
  

   Zeller's 
  colour 
  description 
  of 
  distans 
  is 
  " 
  luteo-fuscescentes," 
  and 
  

   the 
  dark 
  dirty-brown 
  tint 
  usually 
  connected 
  in 
  our 
  entomological 
  

   literature 
  with 
  the 
  term 
  "fuscous," 
  precludes 
  the 
  usual 
  assumption 
  

   that 
  our 
  brightest 
  brown 
  form 
  of 
  this 
  species 
  is 
  really 
  distans. 
  

   Accepting 
  this 
  as 
  a 
  basis 
  of 
  grouping, 
  our 
  own 
  inclination 
  is 
  to 
  group 
  

   the 
  specimens 
  we 
  get 
  in 
  Britain 
  as 
  follows 
  : 
  

  

  1. 
  Bright 
  rusty-brown 
  with 
  white 
  markings 
  =ab, 
  brunnescens, 
  n. 
  ab. 
  

  

  la. 
  Bright 
  rusty-brown 
  with 
  ochreous 
  markings 
  ab. 
  ochrea-brtmnescens^ 
  n. 
  ab. 
  

  

  lb. 
  Bright 
  rusty-brown 
  with 
  obsolete 
  markings 
  ab. 
  obsoleta-brtmnescens, 
  n. 
  ab. 
  

  

  '2a. 
  Pale 
  ochreous, 
  or 
  greyish-orbivous. 
  with 
  white 
  markings 
  ab. 
  intermedia. 
  

   n.ab. 
  

  

  