﻿104 
  BRITISH 
  LEPIDOPTERA. 
  

  

  long, 
  pointed 
  and 
  tapering, 
  finely 
  spiculate 
  along 
  their 
  shafts, 
  whilst 
  

   the 
  secondary 
  hairs 
  are 
  usually 
  short, 
  smooth, 
  and 
  somewhat 
  clubbed 
  

   at 
  their 
  tips, 
  and, 
  as 
  we 
  have 
  noted, 
  they 
  surround 
  the 
  primary 
  

   tubercular 
  setae 
  when 
  the 
  tubercles 
  are 
  modified 
  into 
  wart-like 
  struc- 
  

   tures. 
  In 
  some 
  cases 
  the 
  primary 
  hairs 
  take 
  on 
  the 
  smooth, 
  clubbed 
  

   character, 
  usually 
  supposed 
  to 
  be 
  peculiar 
  to 
  the 
  secondary 
  hairs, 
  and 
  

   are 
  difficult 
  to 
  distinguish 
  therefrom. 
  Apart, 
  however, 
  from 
  the 
  

   primary 
  and 
  secondary 
  hairs 
  arising 
  on, 
  and 
  around, 
  the 
  tubercular 
  

   structures, 
  there 
  are 
  a 
  number 
  of 
  secondary 
  scattered 
  hairs, 
  variable 
  in 
  

   their 
  development, 
  that 
  arise 
  from 
  the 
  general 
  skin 
  -surface, 
  apparently 
  

   quite 
  independently 
  of 
  the 
  tubercles, 
  and 
  more 
  or 
  less 
  irregularly, 
  

   although 
  usually 
  more 
  frequent 
  in 
  those 
  parts 
  that 
  appear 
  to 
  want 
  

   protection, 
  and 
  where 
  there 
  would 
  appear 
  to 
  be 
  a 
  special 
  stimulus 
  to 
  

   their 
  growth. 
  They 
  may 
  thus 
  vary 
  from 
  a 
  few 
  irregular 
  scattered 
  

   hairs 
  to 
  an 
  evenly-distributed 
  coat, 
  occupying 
  the 
  greater 
  part 
  of 
  the 
  

   skin-surface. 
  They 
  would 
  appear 
  to 
  form 
  a 
  somewhat 
  generalised 
  

   feature, 
  for 
  they 
  are 
  found 
  in 
  all 
  the 
  Platyptiliine 
  larva? 
  (except 
  Frederi- 
  

   cina 
  calodactyla=zetterstedtii), 
  whilst 
  only 
  the 
  Merrifieldiid 
  tribe 
  of 
  the 
  

   Alucitines 
  has 
  them, 
  all 
  the 
  other 
  tribes, 
  represented 
  in 
  Britain, 
  on 
  this 
  

   side 
  of 
  the 
  plume 
  stirps, 
  being 
  without 
  them. 
  This 
  character 
  alone 
  (apart 
  

   from 
  other 
  important 
  structural 
  ones) 
  raises 
  Alucita 
  pentad 
  'actyla 
  and 
  

   Porrittia 
  f/alactodactyla 
  far 
  above 
  Wheeleria 
  metjadaetyla 
  (spilod 
  actyla), 
  W. 
  

   niveidactyla 
  (baliodactyla), 
  and 
  Merrijieldia 
  tridactyla, 
  with 
  which 
  they 
  

   have 
  long 
  been 
  generically 
  grouped, 
  the 
  three 
  last-named 
  presenting 
  these 
  

   secondary 
  hairs 
  (although 
  they 
  have 
  almost 
  disappeared 
  in 
  M. 
  tridactyla), 
  

   whilst 
  the 
  others 
  are 
  without 
  them. 
  Chapman 
  further 
  notes 
  (in 
  litt.) 
  

   that, 
  in 
  the 
  Platyptiliine 
  larvae 
  (except 
  that 
  of 
  F. 
  calodactyla 
  which 
  has 
  

   none), 
  the 
  secondary 
  hairs 
  are 
  a 
  kind 
  of 
  glorified 
  skin-points 
  — 
  short, 
  

   conical, 
  without 
  jointed 
  base, 
  and 
  evenly 
  distributed 
  over 
  the 
  whole 
  

   surface 
  ; 
  in 
  nearly 
  all 
  others 
  the 
  secondary 
  hairs 
  are 
  hairs, 
  and 
  have 
  

   limited 
  and 
  special 
  distribution. 
  The 
  Stenoptiliids 
  (as 
  represented 
  by 
  

   Adkinia 
  bipunctidactyla) 
  are 
  the 
  most 
  like 
  Platyptiliids, 
  but 
  the 
  hairs 
  are 
  

   clubbed. 
  It 
  is 
  not 
  surprising 
  that, 
  as 
  soon 
  as 
  these 
  characters 
  were 
  

   recognised, 
  they 
  should 
  be 
  utilised 
  to 
  get 
  a 
  wider 
  view 
  of 
  the 
  relation- 
  

   ship 
  of 
  the 
  Alucitids 
  inter 
  se, 
  than 
  that 
  presented 
  by 
  a 
  study 
  of 
  the 
  

   imagines. 
  Hofmann 
  published 
  (Die 
  deutsch. 
  Pterophorinen, 
  pp. 
  12 
  et 
  

   seq.) 
  a 
  somewhat 
  detailed 
  description 
  of 
  the 
  larval 
  tubercles, 
  but 
  grouped 
  

   the 
  larvae 
  on 
  the 
  superficial 
  character 
  of 
  form 
  into 
  five 
  types, 
  which 
  he 
  

   described 
  as 
  follows 
  : 
  — 
  

  

  1. 
  Larvae 
  of 
  compressed 
  form, 
  short 
  and 
  thick, 
  back 
  little 
  arched, 
  attenuated 
  

   in 
  front 
  and 
  behind, 
  with 
  a 
  small 
  retractile 
  head, 
  and 
  scarcely 
  noticeable 
  lateral 
  

   flange 
  — 
  E 
  uck 
  emidophobus 
  . 
  

  

  2. 
  More 
  elongated 
  form, 
  not 
  unlike 
  certa'n 
  Tortricid 
  larvae 
  - 
  Oxyptilidi. 
  

  

  3. 
  Markedly 
  shortened 
  forms, 
  back 
  strongly 
  arched, 
  resembling 
  certain 
  

   dipterous 
  (Trypeta) 
  larvae— 
  Ad 
  ainidi. 
  

  

  4. 
  Larvae 
  compressed 
  from 
  above 
  downwards, 
  flat, 
  with 
  a 
  strongly 
  developed 
  

   lateral 
  flange 
  ; 
  rests 
  closely 
  appressed 
  to 
  the 
  leaves 
  of 
  the 
  foodplants 
  — 
  Porrittia. 
  

  

  5. 
  Larvae 
  furnished 
  with 
  tall 
  fleshy 
  humps 
  — 
  Agdistides. 
  

  

  He 
  adds 
  (op. 
  tit.) 
  a 
  detailed 
  note 
  on 
  the 
  structure 
  of 
  the 
  skin 
  and 
  its 
  

   armature, 
  distinguishing 
  between 
  the 
  tubercular 
  setae 
  and 
  warts, 
  and 
  

   the 
  hairs 
  on 
  the 
  general 
  body 
  surface. 
  He 
  particularly 
  notes 
  the 
  

   ventral 
  warts, 
  which 
  he 
  says 
  " 
  stand 
  on 
  both 
  sides 
  of 
  the 
  median 
  line 
  

   of 
  the 
  venter 
  only 
  on 
  those 
  segments 
  unfurnished 
  with 
  legs, 
  and 
  are 
  

   very 
  small 
  and 
  simple, 
  rarely 
  double." 
  He 
  further 
  remarks 
  the 
  change 
  

  

  