﻿PLATYPTILIA 
  ISODACTYLUS. 
  18B 
  

  

  tribe 
  Platyptiliidi, 
  and, 
  in 
  addition, 
  the 
  genus 
  Eucnemidophorus. 
  We 
  

   have 
  already 
  dealt 
  with 
  calodactyla, 
  Schiff., 
  Hb., 
  and 
  petradactyla, 
  Hb., 
  

   under 
  Fredericina 
  (antea, 
  pp. 
  161-2), 
  and 
  of 
  the 
  remainder 
  of 
  the 
  original 
  

   species 
  in 
  this 
  heterotypical 
  genus, 
  we 
  have 
  ochrodactyla, 
  Hb., 
  the 
  type 
  

   of 
  Gillmeria, 
  rhododactyla, 
  Schiff., 
  the 
  type 
  of 
  Eucnemidophorus, 
  and 
  

   megadactyla, 
  Hb. 
  [—gonodactijla, 
  Schiff.), 
  which 
  we 
  named 
  as 
  the 
  type 
  

   of 
  Platyptilia 
  (Ent. 
  Record, 
  xvii., 
  p. 
  37). 
  Whether 
  isodactylus, 
  Zell., 
  

   is 
  really 
  congeneric 
  with 
  gonodactyla, 
  Schiff., 
  and 
  farfarella, 
  Zell., 
  we 
  

   are 
  not 
  prepared 
  to 
  say, 
  but 
  at 
  present 
  we 
  know 
  too 
  little 
  of 
  their 
  early 
  

   stages 
  to 
  separate 
  them 
  under 
  distinct 
  genera. 
  The 
  egg 
  is 
  more 
  or 
  

   less 
  cylindrical 
  according 
  to 
  the 
  Platyptiliid 
  type, 
  they 
  are 
  laid 
  

   externally, 
  but 
  the 
  larva 
  at 
  once 
  becomes 
  a 
  miner 
  and 
  remains 
  so 
  all 
  

   its 
  life. 
  The 
  typical 
  pupation 
  habit 
  of 
  P. 
  isodactylus 
  in 
  the 
  second 
  

   brood, 
  is 
  similar 
  to 
  that 
  of 
  Fredericina, 
  i.e., 
  pupation 
  takes 
  place 
  

   internally 
  in 
  the 
  stem 
  of 
  the 
  foodplant, 
  whilst, 
  in 
  the 
  first 
  brood, 
  the 
  

   larva 
  leaves 
  its 
  burrow 
  and 
  pupates 
  in 
  a 
  cocoon 
  outside. 
  The 
  

   larva 
  of 
  P. 
  gonodactyla 
  usually 
  emerges 
  from 
  its 
  feedincr-mines 
  and 
  

   makes 
  a 
  puparium 
  among 
  the 
  pappus 
  of 
  the 
  Tussilago 
  seedheads 
  (in 
  

   the 
  first 
  brood), 
  or 
  in 
  a 
  cocoon 
  on 
  the 
  undersurface 
  of 
  a 
  leaf 
  (in 
  the 
  

   second 
  brood). 
  Occasionally 
  it 
  appears 
  to 
  pupate 
  quite 
  exposed, 
  as 
  is 
  

   the 
  case 
  with 
  (lillmeria. 
  The 
  two 
  British 
  species, 
  gonodactyla 
  and 
  

   isodactyhts, 
  are 
  double-brooded. 
  

  

  The 
  following 
  is 
  our 
  diagnosis 
  of 
  the 
  restricted 
  genus 
  : 
  — 
  

  

  Imago. 
  — 
  Frontal 
  tuft 
  short 
  ; 
  palpi 
  with 
  the 
  terminal 
  joint 
  rather 
  short, 
  

   porrected 
  ; 
  the 
  frontal 
  tuft 
  and 
  palpi 
  about 
  as 
  long 
  as 
  the 
  head 
  ; 
  the 
  black 
  scales 
  

   on 
  the 
  third 
  plumule 
  of 
  hindwings 
  markedly 
  collected 
  in 
  a 
  small 
  patch 
  near 
  

   the 
  centre 
  ; 
  the 
  costal 
  triangle 
  of 
  forewings 
  usually 
  well-defined 
  ; 
  one 
  lobal 
  trans- 
  

   verse 
  line 
  or 
  band. 
  

  

  Pupa. 
  — 
  The 
  nose-spine 
  shorter, 
  0*25mm. 
  (than 
  in 
  Gillmeria, 
  O-Smm.), 
  less- 
  

   well-developed, 
  and 
  not 
  so 
  prominent; 
  the 
  dorsal 
  line 
  with 
  a 
  curved 
  ventral 
  sweep 
  ;. 
  

   the 
  posterior 
  border 
  of 
  abdominal 
  segments 
  with 
  spinous 
  ridge 
  (marked 
  in 
  isodac- 
  

   tylus, 
  evanescent 
  in 
  gonodactyla) 
  ; 
  the 
  cremastral 
  hooks 
  in 
  forward 
  part 
  of 
  cremaster 
  

   obsolete, 
  the 
  hairs 
  almost 
  evanescent; 
  the 
  wing-markings 
  rather 
  different 
  (difficult 
  

   to 
  define) 
  from 
  those 
  in 
  Gillmeria 
  ; 
  the 
  dorsal 
  ridges 
  distinct 
  ^but 
  rather 
  less, 
  

   prominent 
  than 
  in 
  Gillmeria). 
  

  

  Lahva. 
  — 
  Form, 
  outline 
  and 
  colouring 
  much 
  as 
  in 
  Gillmeria 
  and 
  Fredericina 
  ; 
  

   skin-hairs 
  (or 
  skin-points) 
  present 
  (in 
  Fredericina 
  absent) 
  ; 
  confined 
  to 
  definite 
  

   areas, 
  other 
  parts 
  bare 
  (in 
  Gillmeria 
  completely 
  covered) 
  ; 
  the 
  skin-hairs 
  dark 
  (those 
  

   of 
  Gillmeria 
  alternately 
  dark 
  and 
  colourless) 
  ; 
  hooks 
  of 
  prolegs 
  (8-10) 
  fewer 
  than 
  in 
  

   Gillmeria 
  ; 
  the 
  basal 
  or 
  attached 
  end 
  of 
  hooks, 
  oblique, 
  produced 
  and 
  narrow 
  ; 
  the 
  

   column 
  rather 
  shorter 
  than 
  in 
  Gillmeria 
  ; 
  the 
  head, 
  dorsal 
  plates 
  and 
  legs 
  black 
  ; 
  

   mesothoracic 
  and 
  metathoracic 
  seta) 
  paired 
  (four 
  pairs 
  on 
  each 
  side 
  of 
  segment 
  ), 
  each 
  

   pair 
  on 
  the 
  same 
  plate 
  (rather 
  less 
  markedly 
  in 
  isodactylus 
  than 
  gonodactyla) 
  r 
  

   these 
  pairs 
  at 
  a 
  good 
  distance 
  from 
  each 
  other 
  ; 
  the 
  sette 
  of 
  i 
  and 
  ii 
  rather 
  more 
  

   trapezoidal 
  than 
  in 
  Gillmeria, 
  still 
  almost 
  transverse; 
  plates 
  on 
  8th 
  and 
  9th 
  

   abdominal 
  segments 
  present 
  (absent 
  in 
  Gillmeria). 
  

  

  Platyptilia 
  isodactylus, 
  Zeller. 
  

   Synonymy. 
  — 
  Species: 
  Isodactylus, 
  Zell., 
  "Linn. 
  Ent.," 
  vi., 
  p. 
  328(1852) 
  ; 
  Stphs.. 
  

   "List," 
  p. 
  174 
  (1854); 
  Sta., 
  " 
  Man., 
  "ii 
  M 
  p. 
  440(1859); 
  Dbldy., 
  "Syn. 
  List," 
  2nd 
  ed., 
  

   p. 
  36 
  (1859) 
  ; 
  Jord., 
  » 
  Ent. 
  Mo. 
  Mag.," 
  vi., 
  p. 
  121 
  (1869); 
  Barr. 
  and 
  Buckl., 
  " 
  Ent. 
  

   Mo. 
  Mag.," 
  viii., 
  p. 
  153 
  (1871) 
  ; 
  Hein. 
  and 
  Wooke, 
  " 
  Sohmett. 
  Deutsch.," 
  iii.. 
  pt, 
  2, 
  

   p. 
  786(1877); 
  Leech, 
  "Brit. 
  Pyr.," 
  p. 
  52 
  (1886) 
  ; 
  Tutt. 
  " 
  Young 
  Nat.," 
  \.. 
  p. 
  L63 
  

   (1889); 
  xi., 
  p. 
  79 
  (1890) 
  ; 
  "Pter. 
  Brit.," 
  p. 
  35 
  (1895); 
  Porrt., 
  - 
  Buokl. 
  Law.." 
  i\.. 
  

   p. 
  348, 
  pi. 
  olxiii., 
  fig. 
  4 
  (1901); 
  Barr., 
  «« 
  Lep. 
  Brit. 
  Isles." 
  ix., 
  p. 
  330, 
  pi. 
  413, 
  ties. 
  

   4-4c 
  (1904). 
  Monodactyla/Haw, 
  "Lep. 
  Brit.," 
  p. 
  476 
  (1811); 
  Snell., 
  •• 
  DeVlind, 
  

   Ned.," 
  ii., 
  2, 
  p. 
  L018 
  (1882). 
  Monodactylus, 
  Staphs., 
  " 
  Cat.." 
  ii., 
  p. 
  229 
  (1829) 
  : 
  

  

  * 
  We 
  at 
  first 
  suspected 
  that 
  this 
  should 
  be 
  considered 
  a 
  purely 
  literary 
  name. 
  

   i.e., 
  not 
  described 
  from 
  actual 
  specimens, 
  but 
  OOpied 
  from 
  existent 
  descriptions, 
  when. 
  

  

  