﻿2 
  BRITISH 
  LEPIDOPTERA. 
  

  

  rare, 
  and, 
  before 
  accepting 
  any 
  general 
  statements 
  to 
  the 
  contrary, 
  

   should 
  require 
  exact 
  data 
  and 
  absolutely 
  reliable 
  evidence. 
  

  

  Sonie 
  thirty 
  years 
  ago 
  it 
  was 
  accepted 
  as 
  an 
  article 
  of 
  entomological 
  

   faith 
  that, 
  even 
  if 
  hybrids 
  of 
  first-crosses 
  were 
  obtained, 
  the 
  hybrids 
  

   were 
  sterile 
  and 
  unable 
  to 
  produce 
  further 
  progeny, 
  yet, 
  at 
  the 
  time, 
  

   few 
  facts 
  could 
  be 
  brought 
  forward 
  in 
  support 
  of 
  the 
  general 
  belief, 
  

   although 
  vague 
  statements 
  like 
  that 
  of 
  House, 
  concerning 
  Smerinthus 
  

   hybr. 
  hybridus 
  (quoted 
  antea, 
  iii., 
  p. 
  449) 
  were 
  freely 
  stated 
  and 
  accepted. 
  

   House 
  asserted 
  that 
  some 
  examples 
  of 
  this 
  hybrid 
  bred 
  by 
  him 
  

   appeared 
  " 
  to 
  be 
  as 
  nearly 
  intermediate 
  between 
  the 
  sexes 
  as 
  

   between 
  the 
  species, 
  and 
  evidently 
  to 
  partake 
  of 
  the 
  nature 
  of 
  both 
  

   sexes," 
  etc., 
  yet 
  one, 
  when 
  examined 
  critically 
  by 
  Westwood, 
  was 
  

   pronounced 
  to 
  be 
  a 
  $ 
  ; 
  certainly 
  those 
  in 
  our 
  own 
  collection 
  (bred 
  by 
  

   Kirk) 
  consist 
  of 
  four 
  $ 
  s 
  and 
  one 
  $ 
  . 
  Pierce, 
  too, 
  examined 
  the 
  

   genitalia 
  of 
  the 
  hybrids 
  bred 
  by 
  Bacot, 
  and 
  found 
  that 
  the 
  apparently 
  

   S 
  specimens 
  possessed 
  distinctly 
  $ 
  organs 
  [antea, 
  iii., 
  p. 
  390). 
  In 
  

   spite 
  of 
  this, 
  experiments 
  on 
  a 
  large 
  scale 
  have 
  shown 
  that 
  the 
  

   impression, 
  on 
  the 
  whole, 
  was 
  a 
  fairly 
  correct 
  one, 
  although 
  it 
  has 
  

   been 
  proved, 
  especially 
  in 
  the 
  case 
  of 
  $ 
  hybrids, 
  to 
  be 
  incorrect 
  in 
  

   many 
  cases. 
  Some 
  of 
  the 
  earliest 
  experiments 
  showing 
  that 
  certain 
  

   hybrids 
  were 
  more 
  or 
  less 
  fertile, 
  inter 
  se, 
  were 
  discounted 
  by 
  the 
  

   superficial 
  criticism 
  that, 
  if 
  the 
  progeny 
  was 
  fertile, 
  then 
  the 
  species 
  

   crossed 
  were 
  not 
  truly 
  distinct 
  specific 
  forms, 
  e.g., 
  Wallace, 
  in 
  1866, 
  

   recorded 
  (Ent. 
  Mo. 
  Mag., 
  ii., 
  p. 
  240) 
  that 
  Philosamia 
  cyntkia 
  and 
  ricini 
  

   ( 
  = 
  lunula), 
  although 
  differing 
  remarkably 
  in 
  all 
  their 
  stages, 
  feeding 
  

   on 
  very 
  different 
  plants, 
  and 
  natives 
  of 
  different 
  countries, 
  would 
  

   hybridise 
  freely, 
  the 
  hybrids 
  being 
  not 
  only 
  fertile 
  among 
  themselves, 
  

   but 
  also 
  with 
  either 
  of 
  their 
  original 
  parents. 
  Watson, 
  repeating 
  

   the 
  facts 
  of 
  the 
  fertility 
  of 
  hybrid 
  P. 
  cynthia 
  and 
  P. 
  lunula 
  (ricini), 
  

   asserts 
  (Entom., 
  xxvi., 
  p. 
  174) 
  that 
  lunula 
  ( 
  = 
  ricini) 
  "is 
  merely 
  the 
  

   Burmese 
  local 
  polyvoltine, 
  or 
  many-brooded, 
  variety 
  of 
  the 
  common 
  

   cynthia," 
  thus 
  reducing 
  lunula 
  (ricini) 
  to 
  varietal 
  rank, 
  and 
  follows 
  this 
  

   up 
  with 
  the 
  extreme 
  statement 
  that 
  " 
  it 
  is 
  quite 
  the 
  rule 
  for 
  hybrids 
  to 
  

   be 
  infertile," 
  that 
  he 
  " 
  only 
  knew 
  of 
  one 
  hybrid 
  moth 
  depositing 
  ova," 
  

   and 
  that 
  he 
  " 
  very 
  much 
  doubted 
  that 
  these, 
  if 
  fertilised, 
  could 
  produce 
  

   larva?." 
  Watson 
  would 
  evidently, 
  from 
  his 
  further 
  statements 
  (op. 
  cit., 
  

   p. 
  173), 
  make 
  the 
  fact 
  of 
  a 
  2 
  hybrid 
  moth 
  producing 
  ova, 
  and 
  a 
  $ 
  

   hybrid 
  spermatozoa, 
  the 
  sole 
  test 
  of 
  distinctness 
  in 
  the 
  parent 
  species. 
  

   If 
  " 
  the 
  absence 
  or 
  presence 
  of 
  eggs 
  in 
  ? 
  hybrids 
  conclusively 
  proved," 
  

   as 
  he 
  says 
  they 
  should, 
  " 
  the 
  bona 
  ricks 
  of 
  the 
  parents 
  to 
  rank 
  as 
  

   species 
  or 
  varieties," 
  we 
  should 
  by 
  this 
  time 
  find 
  it 
  necessary 
  to 
  

   reduce 
  Philosamia 
  cynthia 
  and 
  P. 
  lunula, 
  Saturnia 
  pavonia, 
  S. 
  spini 
  

   and 
  S. 
  pyri, 
  Clostera 
  piyra, 
  C. 
  curtula 
  and 
  C. 
  anachoreta, 
  Anthrocera 
  

   lonicerae 
  and 
  A. 
  trifolii, 
  Tephrosia 
  crepuscularia 
  and 
  T. 
  bistortata, 
  &c, 
  

   to 
  varietal 
  rank, 
  which 
  might 
  not 
  meet 
  with 
  general 
  approval. 
  

  

  The 
  older 
  naturalists 
  considered 
  that 
  hybrids 
  had 
  been 
  specially 
  

   endowed 
  with 
  sterility 
  in 
  order 
  to 
  prevent 
  their 
  confusion, 
  and 
  it 
  is 
  

   clear 
  to 
  the 
  most 
  casual 
  observer 
  that, 
  had 
  the 
  various 
  species 
  been 
  

   able 
  to 
  cross 
  freely, 
  they 
  could 
  not 
  maintain 
  their 
  distinctness, 
  especially 
  

   when 
  several 
  close 
  allies 
  are 
  localised 
  in 
  a 
  restricted 
  space. 
  The 
  failure 
  

   of 
  such 
  species 
  to 
  cross 
  is, 
  however, 
  dependent 
  on 
  many 
  things, 
  of 
  which 
  

   actual 
  inability 
  to 
  pair 
  is 
  probably 
  rarely, 
  if 
  ever, 
  the 
  most 
  important, 
  

   for 
  there 
  are 
  occasional 
  records 
  of 
  pairing 
  not 
  only 
  between 
  closely 
  

  

  