﻿6 
  

  

  BRITISH 
  LEPIJDOPTERA. 
  

  

  being 
  too 
  weak 
  to 
  eat 
  its 
  way 
  out 
  of 
  the 
  egg, 
  (2) 
  The 
  eggshell 
  being 
  too 
  

   thick 
  (or 
  otherwise 
  unsuitable) 
  for 
  the 
  jaws 
  of 
  the 
  hybrid 
  larva 
  to 
  

   work 
  on. 
  These 
  are, 
  of 
  course, 
  physical 
  conditions, 
  quite 
  independent 
  

   of 
  the 
  phenomena 
  that 
  one 
  has 
  to 
  consider 
  when 
  the 
  eggs 
  of 
  actual 
  

   hybrids 
  are 
  proved 
  to 
  be 
  sterile, 
  for, 
  in 
  this 
  case, 
  the 
  reasons 
  adduced 
  

   above 
  must 
  be 
  largely 
  inadmissible, 
  and 
  one 
  suspects 
  that 
  actual 
  

   weakness 
  of 
  the 
  embryo 
  is 
  generally 
  the 
  prevailing 
  cause. 
  

  

  Eecent 
  experiments 
  have 
  gone 
  to 
  prove 
  that 
  the 
  extern 
  al 
  repro- 
  

   ductive 
  organs 
  of 
  hybrids 
  are 
  usually 
  perfect 
  in 
  structure, 
  especially 
  

   those 
  of 
  the 
  3 
  s 
  (see 
  antea, 
  vol. 
  iii., 
  p. 
  890), 
  although, 
  compared 
  with 
  

   pure 
  species, 
  there 
  is 
  certainly 
  a 
  great 
  tendency 
  to 
  an 
  admixture 
  of 
  

   imperfectly 
  developed 
  J 
  and 
  2 
  sexual 
  organs 
  internally, 
  producing 
  

   what 
  is 
  known 
  as 
  gynandromorphism, 
  especially 
  in 
  specimens 
  which 
  

   are 
  largely 
  in 
  external 
  structure 
  and 
  appearance 
  2 
  s. 
  Such 
  specimens 
  

   are, 
  of 
  course, 
  alike 
  in 
  true 
  species 
  and 
  hybrids, 
  necessarily 
  sterile. 
  

   We 
  are 
  still, 
  however, 
  much 
  in 
  the 
  dark 
  as 
  to 
  how 
  far 
  the 
  sexual 
  

   organs 
  themselves 
  are 
  functionally 
  impotent, 
  as 
  Darwin 
  avers, 
  when 
  

   perfect 
  in 
  structure, 
  but 
  it 
  is 
  quite 
  clear 
  that 
  they 
  are 
  not 
  so 
  to 
  anything 
  

   like 
  the 
  extent 
  assumed 
  by 
  the 
  older 
  biologists, 
  and 
  that 
  J 
  hybrids 
  are 
  

   frequently, 
  abundantly 
  and 
  freely 
  fertile 
  with 
  2 
  s 
  of 
  either 
  parent 
  species 
  

   e.g., 
  Saturnia 
  'hybr. 
  emiliae* 
  $ 
  X 
  pyri 
  2 
  ; 
  S. 
  hybr. 
  emiliae 
  J 
  X 
  pavonia 
  2 
  

   S. 
  hybr. 
  bornemanni 
  $ 
  x 
  pavonia 
  2 
  ', 
  S. 
  hybr. 
  bornemanni 
  $ 
  x 
  pyri 
  2 
  

   S. 
  hybr. 
  bornemanni 
  ' 
  $ 
  x 
  spini 
  2 
  ', 
  S. 
  hybr. 
  stand 
  fussi 
  $ 
  x 
  pavonia 
  2 
  : 
  

   S. 
  hybr. 
  schau 
  fussi 
  $ 
  x 
  pavonia 
  2 
  ; 
  Anthrocera 
  hybr. 
  Jietcheri 
  3 
  x 
  

   lonicerae 
  2 
  ', 
  A. 
  hyhv. 
  Jietcheri 
  $ 
  x 
  trifolii 
  2 
  ', 
  A. 
  hybr. 
  worthingi 
  $ 
  

   X 
  lonicerae 
  2 
  \ 
  A. 
  hybr. 
  worthingi 
  $ 
  X 
  trifolii 
  2 
  ', 
  A. 
  hybr. 
  complexa 
  

   $ 
  X 
  trifolii 
  2 
  ; 
  Clostera 
  hybr. 
  raesclikei 
  J 
  x 
  anachoreta 
  2 
  \ 
  C. 
  hybr. 
  

   difjicilis 
  $ 
  X 
  curtula 
  2 
  ', 
  C. 
  hybr. 
  facilis 
  $ 
  X 
  anachoreta 
  2 
  . 
  Female 
  

   hybrids, 
  too, 
  are 
  occasionally 
  fertile 
  when 
  crossed 
  with 
  a 
  $ 
  of 
  one 
  of 
  

   the 
  parent 
  species, 
  e.g., 
  Spilosoma 
  hybr. 
  viertli 
  2 
  X 
  mendica 
  $ 
  ; 
  S. 
  hybr. 
  

   liilaris 
  2 
  X 
  mendica 
  $ 
  ; 
  Antheraea 
  hybr. 
  perny-yama 
  2 
  X 
  pernyi 
  $ 
  ; 
  

   Anthrocera 
  hybr. 
  Jietcheri 
  2 
  X 
  lonicerae 
  $ 
  ; 
  A. 
  hybr. 
  jietcheri 
  2 
  X 
  

   trifolii 
  g 
  ; 
  A. 
  hybr. 
  worthingi 
  2 
  X 
  lonicerae 
  g 
  ; 
  A. 
  hybr. 
  complexa 
  2 
  

   X 
  lonicerae 
  $ 
  ; 
  Saturnia 
  hybr. 
  schau 
  fussi 
  2 
  X 
  pavonia 
  g 
  ; 
  Tephrosia 
  

   hybr. 
  ridingi-sufusa 
  2 
  X 
  crepuscularia 
  $ 
  , 
  and 
  this 
  may 
  be 
  so 
  even 
  when 
  

   the 
  hybrids 
  are 
  not 
  apparently 
  fertile 
  inter 
  se. 
  On 
  the 
  other 
  hand, 
  

   some 
  hybrids 
  are 
  fertile 
  inter 
  se, 
  e.g., 
  Anthrocera 
  hybr. 
  worthingi; 
  A. 
  

   Irybr. 
  jietcheri 
  ; 
  Philosamia 
  hybr. 
  uallacei 
  ; 
  Saturnia 
  hybr. 
  schau 
  fussi 
  ; 
  

   Clostera 
  hybr. 
  prima 
  ; 
  C. 
  hybr. 
  inversa 
  ; 
  Tephrosia 
  hybr. 
  ridingi 
  : 
  T. 
  

   hybr. 
  ridingi- 
  suffusa 
  ; 
  Spilosoma 
  hybr. 
  seileri 
  : 
  S. 
  hybr. 
  hilaris. 
  

  

  Very 
  few 
  $ 
  s 
  and 
  $ 
  s 
  of 
  related 
  hybrids 
  have 
  been 
  crossed, 
  but 
  

   Anthrocera 
  hybr. 
  worthingi 
  and 
  A. 
  hybr. 
  Jietcheri 
  and 
  Tephrosia 
  hybr. 
  

   bacoti-sufusa 
  and 
  T. 
  hybr. 
  ridingi-sufusa, 
  are 
  quite 
  fertile 
  inter 
  se, 
  and 
  

   Saturnia 
  hybr. 
  bornemanni 
  $ 
  x 
  hybr. 
  schaufussi 
  2 
  has 
  been 
  successfully 
  

   reared 
  to 
  the 
  imaginal 
  state, 
  all 
  of 
  which 
  goes 
  to 
  prove 
  that 
  hybrids 
  are 
  

   not 
  necessarily, 
  and 
  by 
  the 
  mere 
  fact 
  of 
  their 
  being 
  hybrids, 
  sterile, 
  but 
  

   that 
  2 
  hybrids 
  appear 
  to 
  be 
  much 
  more 
  frequently 
  functionally 
  impotent 
  

   than 
  $ 
  s. 
  Eecent 
  evidence 
  bearing 
  on 
  the 
  subject 
  goes 
  far 
  to 
  suggest 
  

   that 
  the 
  sterility 
  of 
  first 
  crosses, 
  and 
  hybrids 
  of 
  allied 
  species, 
  is 
  due 
  

  

  * 
  We 
  are 
  inclined 
  to 
  disagree 
  with 
  this 
  form 
  of 
  nomenclature, 
  adopted 
  first 
  by 
  

   Standfuss 
  and 
  other 
  entomologists, 
  since 
  it 
  tends 
  to 
  obscure 
  the 
  ancestry 
  of 
  the 
  

   forms 
  dealt 
  with, 
  and 
  so, 
  to 
  make 
  the 
  names 
  intelligible, 
  we 
  have 
  added 
  a 
  complete 
  

   list 
  of 
  the 
  hybrids 
  mentioned, 
  with 
  their 
  parentage, 
  at 
  the 
  end 
  of 
  this 
  chapter. 
  

  

  