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  XVIII. 
  Notes 
  on 
  Lycaena 
  alcon 
  F., 
  as 
  reared 
  in 
  1918-1919. 
  

   By 
  T. 
  A. 
  Chapman, 
  M.D., 
  F.R.S. 
  

  

  [Read 
  November 
  5th, 
  1919.] 
  

  

  Plates 
  XXIII-XXVIII. 
  

  

  My 
  observations 
  on 
  the 
  early 
  stages 
  of 
  Lycaena 
  alcon 
  F., 
  

   in 
  1917-1918, 
  ending 
  with 
  the 
  emergence 
  of 
  a 
  (^ 
  imago 
  on 
  

   Aug. 
  2, 
  1918, 
  are 
  repoi-ted 
  by 
  Monsieur 
  Oberthiir, 
  in 
  the 
  

   16th 
  vohime 
  of 
  the 
  "Etudes 
  de 
  Lepidopterologie 
  Comparee," 
  

   and 
  referred 
  to 
  in 
  the 
  Proceedings 
  of 
  the 
  Entomological 
  

   Society 
  of 
  London, 
  1918, 
  p. 
  civ. 
  

  

  Monsieur 
  Oberthiir 
  sent 
  me 
  larvae 
  of 
  L. 
  alcon 
  again 
  in 
  

   the 
  autuitm 
  of 
  1918, 
  and 
  my 
  observations 
  on 
  these 
  are 
  

   similar 
  to 
  those 
  of 
  the 
  preceding 
  year, 
  but 
  I 
  have 
  added 
  

   an 
  item 
  or 
  two. 
  I 
  have 
  especially 
  secured 
  figures 
  by 
  Mr. 
  

   E. 
  C. 
  Knight 
  of 
  the 
  full-grown 
  larva 
  and 
  pupa 
  (PI. 
  XXIII). 
  

   Mr. 
  Knight's 
  figures 
  are 
  remarkably 
  good, 
  though 
  those 
  of 
  

   the 
  larva 
  do 
  not 
  suggest 
  so 
  strongly, 
  as 
  a 
  close 
  examination 
  of 
  

   the 
  living 
  larva 
  does, 
  that 
  the 
  fat-bodies 
  are 
  really 
  the 
  basis 
  

   of 
  the 
  appearance 
  of 
  the 
  larva 
  and 
  lead 
  to 
  the 
  dorsal 
  vessel 
  

   appearing 
  as 
  a 
  dark 
  line 
  down 
  the 
  back, 
  a 
  line 
  in 
  which 
  

   really 
  nothing 
  is 
  to 
  be 
  seen 
  but 
  the 
  darlaiess 
  due 
  to 
  its 
  

   being 
  overshadowed 
  by 
  the 
  tissues 
  beside 
  it, 
  maldng 
  it 
  

   an 
  unoccupied 
  chasm. 
  It 
  varies 
  in 
  width 
  with 
  the 
  regular 
  

   pulsations, 
  and 
  the 
  figure 
  shows 
  a 
  spot 
  where 
  it 
  is 
  rather 
  

   wider 
  as 
  the 
  pulsation 
  passes 
  along. 
  I 
  also 
  succeeded 
  in 
  

   obtaining 
  the 
  larval 
  skins 
  cast 
  on 
  pupation, 
  and 
  one 
  of 
  

   these, 
  obtained 
  immediately 
  it 
  was 
  cast, 
  is 
  not 
  altogether 
  

   a 
  failure 
  in 
  momiting 
  ; 
  the 
  others 
  were 
  less 
  successful. 
  I 
  

   was 
  very 
  glad 
  to 
  obtain 
  these, 
  as 
  it 
  enables 
  me 
  to 
  show 
  

   photographs 
  proving 
  that 
  the 
  head 
  and 
  prothoracic 
  plate 
  

   of 
  the 
  full-grown 
  larva 
  are 
  identical 
  with 
  those 
  of 
  the 
  small 
  

   third 
  instar 
  larva 
  that 
  is 
  carried 
  into 
  the 
  ants' 
  nests. 
  

   However 
  much 
  any 
  one 
  may 
  be 
  willing 
  to 
  accept 
  my 
  word 
  

   for 
  this 
  most 
  remarkable 
  circumstance 
  in 
  the 
  life-history 
  

   of 
  a 
  Lepidopteron, 
  it 
  is 
  much 
  more 
  satisfactory 
  to 
  have 
  

   actual 
  demonstration 
  submitted. 
  

  

  I 
  had 
  six 
  nests 
  of 
  Myrmica, 
  four 
  of 
  which 
  were 
  M. 
  

  

  TRANS. 
  ENT. 
  SOC. 
  LOND. 
  1919. 
  — 
  PARTS 
  III, 
  IV. 
  (dEC.) 
  

  

  