﻿HYBRIDISATION 
  IN 
  LEPIDOPTERA. 
  19 
  

  

  of 
  S. 
  luctuosa 
  $ 
  X 
  S. 
  sordida 
  2 
  > 
  also 
  from 
  S. 
  viertli 
  J 
  x 
  rustica 
  2 
  > 
  

   and 
  from 
  S. 
  inversa 
  $ 
  xviertli 
  2 
  (Iris, 
  1898, 
  pp. 
  392-7, 
  pi. 
  vi). 
  A 
  

   crossing 
  of 
  sordida 
  $ 
  x 
  luctuosa 
  2 
  produced 
  a 
  few 
  weakly 
  larvae 
  that 
  

   soon 
  died. 
  He 
  describes 
  the 
  hybrids 
  as 
  : 
  

  

  1 
  and 
  2. 
  Spilosoma 
  hybr. 
  crassa, 
  Caradja 
  (stand 
  ftissi 
  S 
  X 
  sordida 
  2) 
  

   and 
  Spilosoma 
  hybr. 
  viertli, 
  Caradja 
  (rustica 
  $ 
  x 
  sordida 
  2). 
  — 
  -Eight 
  

   fruitful 
  pairings 
  of 
  S. 
  hybr. 
  crassa 
  were 
  obtained, 
  the 
  reciprocal 
  

   crossing 
  of 
  sordida 
  $ 
  x 
  stand 
  fussi 
  2 
  being 
  unfruitful. 
  One 
  fruitful 
  pair- 
  

   ing 
  of 
  S. 
  hybr. 
  viertli 
  was 
  also 
  obtained, 
  the 
  reciprocal 
  cross 
  sordida 
  $ 
  x 
  

   rustica 
  2 
  being, 
  however, 
  unfruitful. 
  In 
  each 
  of 
  the 
  broods 
  of 
  both 
  forms 
  

   some 
  12-13 
  per 
  cent, 
  only 
  of 
  the 
  larvae 
  hatched 
  (all 
  the 
  eggs 
  had 
  

   become 
  darker 
  on 
  the 
  6th 
  day, 
  and 
  some 
  progress 
  of 
  larval 
  development 
  

   was 
  observed 
  in 
  the 
  eggs 
  that 
  did 
  not 
  hatch), 
  many 
  other 
  larvae 
  had 
  

   begun 
  to 
  eat 
  through 
  the 
  eggshell, 
  but 
  had 
  not 
  strength 
  to 
  get 
  further. 
  

   Of 
  those 
  that 
  hatched, 
  some 
  25 
  per 
  cent, 
  refused 
  food 
  and 
  died. 
  The 
  

   others 
  were 
  healthy, 
  developed 
  normally, 
  and 
  finally 
  pupated, 
  some 
  

   larvae, 
  however, 
  taking 
  48, 
  others 
  72-76, 
  the 
  majority 
  taking 
  about 
  

   60, 
  days. 
  Altogether 
  12 
  healthy 
  pupae 
  of 
  crassa 
  and 
  114 
  viertli 
  resulted. 
  

   Mismanagement 
  of 
  the 
  pupae 
  ended 
  in 
  only 
  two 
  pairs 
  of 
  imagines 
  of 
  

   crassa, 
  and 
  a 
  few 
  pairs 
  of 
  viertli 
  being 
  reared. 
  These 
  varied 
  considerably, 
  

   and 
  all 
  four 
  examples 
  of 
  crassa, 
  and 
  the 
  seven 
  most 
  diverse 
  specimens 
  

   of 
  viertli, 
  are 
  figured 
  in 
  the 
  Iris, 
  vol. 
  x., 
  pi. 
  ix., 
  figs. 
  1-11. 
  The 
  ovaries 
  

   of 
  the 
  hybrid 
  2 
  s 
  were 
  apparently 
  quite 
  normally 
  developed, 
  and 
  

   one 
  2 
  viertli, 
  paired 
  with 
  a 
  $ 
  rustica, 
  laid 
  193 
  eggs, 
  all 
  of 
  which 
  

   produced 
  healthy 
  larvae(see 
  beata 
  postea. 
  The 
  hybrid 
  larvae 
  of 
  both 
  crassa 
  

   and 
  viertli 
  copy 
  the 
  larvae 
  of 
  sordida 
  accurately 
  in 
  the 
  arrangement 
  of 
  the 
  

   markings, 
  but 
  are 
  more 
  brightly 
  coloured 
  ; 
  in 
  the 
  last 
  instar, 
  however, 
  

   they 
  differed 
  greatly 
  from 
  sordida, 
  some 
  having 
  fox-red 
  hairs 
  like 
  mendica 
  

   larvae, 
  the 
  majority, 
  however, 
  had 
  hairs 
  of 
  dark 
  brown, 
  or 
  brown-grey 
  

   tint 
  ; 
  in 
  all, 
  the 
  light, 
  yellowish-bordered, 
  longitudinal 
  stripes 
  (dorsal 
  

   and 
  lateral) 
  were 
  as 
  sharply 
  marked 
  as 
  in 
  sordida, 
  the 
  last 
  segments 
  

   being 
  reddish-yellow 
  laterally, 
  these 
  last 
  two 
  characters 
  being 
  character- 
  

   istic 
  of 
  the 
  hybrid 
  larvae. 
  In 
  their 
  broad 
  characters, 
  the 
  hybrid 
  larvae 
  

   are 
  much 
  nearer 
  sordida, 
  although 
  in 
  their 
  last 
  skin 
  some 
  more 
  

   nearly 
  approach 
  mendica. 
  

  

  3. 
  Spilosoma 
  hybr. 
  beata, 
  Caradja 
  (rustica 
  g 
  x 
  viertli 
  2 
  ) 
  (Iris, 
  

   1898, 
  pi. 
  vi., 
  figs. 
  7-9). 
  — 
  Rustica 
  blood 
  is 
  prevalent 
  over 
  that 
  of 
  sordida 
  

   as 
  3:1. 
  The 
  so 
  rdida 
  -characters 
  transmitted 
  are 
  — 
  the 
  somewhat 
  

   elongate 
  form 
  of 
  the 
  wings, 
  the 
  faint 
  yellowish-grey 
  ground 
  colour 
  of 
  

   wings, 
  even 
  in 
  2 
  > 
  the 
  tendency 
  to 
  a 
  row 
  of 
  spots 
  commencing 
  at 
  apex, 
  

   the 
  black-spotted 
  fringe 
  of 
  forewings, 
  and, 
  in 
  the 
  2 
  > 
  the 
  dark 
  longi- 
  

   tudinal 
  stripes. 
  [Further 
  crossings 
  could 
  not 
  be 
  effected. 
  

  

  4. 
  Spilosoma 
  hybr. 
  hilaris, 
  Caradja 
  (inversa* 
  $ 
  x 
  riertli 
  2 
  ) 
  (Iris, 
  

   1898, 
  pi. 
  vi., 
  figs. 
  10-11). 
  — 
  The 
  facies 
  of 
  sordida 
  is 
  not 
  very 
  evident 
  

   (except 
  in 
  the 
  stronger 
  spotting 
  of 
  wings 
  in 
  A 
  ), 
  while 
  the 
  influence 
  of 
  

   standfussi, 
  seen 
  in 
  the 
  marked 
  darkening 
  of 
  A 
  , 
  is 
  unmistakable. 
  The 
  

   $ 
  tint 
  is 
  similar 
  to 
  that 
  of 
  palest 
  standfussi 
  2 
  *< 
  whilst 
  the 
  ? 
  is 
  

   similar 
  to 
  the 
  inversa 
  2 
  figured 
  by 
  Caradja, 
  except 
  that 
  the 
  black 
  

   marginal 
  spots 
  of 
  hindwings 
  are 
  much 
  more 
  clearly 
  marked. 
  The 
  

   form 
  was 
  inbred, 
  each 
  crossing 
  being 
  fertile, 
  those 
  of 
  rustica 
  S 
  \ 
  

  

  * 
  The 
  form 
  inversa 
  is 
  a 
  mongrel 
  of 
  two 
  mendica 
  \-.\cc*. 
  viz., 
  3 
  rustica 
  x 
  

   (rustica 
  \ 
  mendica). 
  

  

  