﻿102 
  BRITISH 
  LEPIDOPTERA. 
  

  

  stage, 
  and 
  that 
  of 
  Oidaematophorus 
  lithodactyla 
  has 
  it 
  sufficiently 
  

   developed 
  to 
  give 
  the 
  larva 
  quite 
  a 
  second 
  stage 
  appearance. 
  

  

  The 
  gradations 
  and 
  variation 
  exhibited 
  in 
  the 
  secondary 
  hairs, 
  

   tubercles, 
  and 
  warts 
  of 
  Alucitid 
  larvae, 
  has 
  led 
  Chapman 
  to 
  point 
  out 
  

   the 
  following 
  details 
  (in 
  lift.). 
  He 
  remarks: 
  "From 
  the 
  primitive 
  

   primary 
  hair 
  or 
  tubercle, 
  we 
  find 
  all 
  sorts 
  of 
  gradations 
  ; 
  Ave 
  have 
  the 
  

   primary 
  hair 
  with 
  or 
  without 
  a 
  plate, 
  with 
  or 
  without 
  an 
  elevation 
  ; 
  we 
  

   find 
  it 
  accompanied 
  by 
  one 
  or 
  more 
  hairs 
  that 
  are 
  distinctly 
  secondary 
  ; 
  

   we 
  find 
  the 
  primary 
  hair 
  accompanied 
  by 
  one 
  or 
  more 
  that 
  cannot 
  be 
  

   distinguished 
  from 
  it, 
  as 
  well 
  as 
  by 
  undoubted 
  secondary 
  hairs, 
  and 
  

   we 
  find 
  warts 
  and 
  bosses 
  that 
  are 
  quite 
  similar 
  to 
  those 
  of 
  Arctias. 
  

   We 
  further 
  find 
  various 
  modifications 
  of 
  this, 
  such 
  as 
  the 
  hair-carrying 
  

   wart 
  being 
  a 
  more 
  or 
  less 
  globular 
  expansion 
  at 
  the 
  summit 
  of 
  a 
  

   narrow 
  neck. 
  Everything 
  that 
  we 
  have 
  here 
  added 
  to 
  the 
  primary 
  

   hair 
  is 
  'secondary.' 
  Another 
  group 
  of 
  secondary 
  hairs 
  (or 
  tubercles) 
  is 
  

   formed 
  by 
  those 
  that 
  appear 
  to 
  be 
  of 
  precisely 
  the 
  same 
  character 
  as 
  

   the 
  primary 
  ones, 
  occurring 
  at 
  very 
  definite 
  situations, 
  and 
  differing 
  

   from 
  the 
  primary 
  ones 
  only 
  in 
  not 
  being 
  of 
  universal 
  occurrence, 
  but 
  

   nevertheless 
  appearing 
  in 
  species 
  of 
  widely 
  different 
  groups 
  in 
  the 
  same 
  

   situations. 
  Of 
  these, 
  the 
  plumes 
  present 
  several 
  examples, 
  especially 
  

   those 
  on 
  two 
  tubercles 
  posterior 
  to 
  the 
  spiracles 
  on 
  the 
  abdominal 
  

   segments 
  of 
  many 
  species. 
  The 
  third 
  class 
  of 
  secondary 
  hairs 
  are 
  

   those 
  distributed 
  over 
  the 
  general 
  skin-surface, 
  without 
  special 
  

   reference 
  to 
  the 
  tubercles 
  proper, 
  and 
  often, 
  apparently, 
  in 
  quite 
  a 
  

   haphazard 
  and 
  entirely 
  asymmetrical 
  manner." 
  

  

  With 
  regard 
  to 
  the 
  character 
  of 
  the 
  primary 
  tubercles 
  (i, 
  ii, 
  iii, 
  

   iv, 
  v 
  and 
  vii) 
  it 
  is 
  to 
  be 
  noted 
  that 
  they 
  vary 
  from 
  simple 
  single- 
  

   haired 
  chitinous 
  buttons 
  to 
  complicated 
  warts. 
  Above 
  the 
  spiracles 
  

   are 
  three 
  primary 
  tubercles 
  on 
  each 
  side, 
  which 
  are 
  called 
  i, 
  ii 
  

   and 
  iii, 
  and 
  there 
  are 
  also 
  two 
  minute 
  points 
  which 
  are 
  probably 
  of 
  

   as 
  generalised 
  a 
  character 
  as 
  are 
  the 
  primary 
  tubercles, 
  a 
  very 
  minute 
  

   one, 
  close 
  to, 
  and 
  in 
  front 
  of, 
  the 
  spiracle, 
  which 
  may 
  be 
  called 
  A, 
  and 
  

   another, 
  very 
  minute, 
  in 
  front 
  of 
  ii, 
  which 
  may 
  be 
  called 
  ; 
  i 
  and 
  ii 
  

   are, 
  as 
  usual, 
  situated 
  as 
  anterior 
  and 
  posterior 
  trapezoidals, 
  i 
  nearer 
  tne 
  

   central 
  line 
  ; 
  iii 
  is 
  supraspiracular. 
  The 
  position 
  of 
  the 
  primaries 
  iv 
  and 
  

   v, 
  is 
  below 
  the 
  spiracle, 
  where 
  they 
  are 
  placed 
  not 
  only 
  pretty 
  close 
  to- 
  

   gether, 
  but 
  usually 
  on 
  the 
  same 
  plate 
  or 
  forming 
  a 
  conjoined 
  wart. 
  In 
  

   the 
  Agdistid 
  larva 
  they 
  are 
  rather 
  more 
  widely 
  apart, 
  nearly 
  at 
  a 
  level, 
  

   with 
  a 
  distinct 
  tendency 
  in 
  some 
  species 
  for 
  the 
  posterior, 
  iv, 
  to 
  be 
  the 
  

   higher, 
  whilst 
  in 
  the 
  Alucitid 
  larvae 
  the 
  anterior, 
  v, 
  is 
  always 
  above 
  

   the 
  posterior 
  iv 
  (at 
  an 
  angle 
  one 
  to 
  the 
  other 
  of 
  about 
  45° 
  to 
  the 
  larval 
  

   resting-place). 
  Besides 
  these 
  are 
  vi 
  (appearing 
  after 
  the 
  first 
  moult, 
  

   and 
  not 
  a 
  primary 
  tubercle) 
  and 
  vii, 
  below 
  each 
  other, 
  and 
  beneath 
  

   iv 
  + 
  v, 
  and 
  there 
  are, 
  besides, 
  one 
  (or 
  two) 
  other 
  accessory, 
  post- 
  

   spiracular 
  groups 
  — 
  B 
  x 
  and 
  B 
  2 
  *, 
  towards 
  the 
  back 
  of 
  each 
  abdominal 
  

   segment. 
  The 
  addition 
  of 
  extra 
  hairs 
  to 
  the 
  primary 
  tubercles 
  change 
  

   them, 
  in 
  many 
  species, 
  into 
  highly-specialised 
  tubercular 
  warts, 
  and 
  

   there 
  appears 
  in 
  the 
  larval 
  tubercular 
  structure 
  of 
  the 
  Alucitids 
  to 
  be 
  

   every 
  intermediate 
  stage 
  in 
  these 
  tubercles 
  between 
  a 
  single-haired 
  

   tubercle 
  and 
  a 
  very 
  complicated 
  many-haired 
  wart. 
  The 
  only 
  sub- 
  

   primary 
  tubercle 
  present, 
  on 
  the 
  abdominal 
  segments, 
  is 
  vi 
  ; 
  this 
  is 
  

  

  * 
  Dyar's 
  iiia 
  and 
  iiib 
  (infra). 
  

  

  