﻿AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  42/ 
  

  

  them 
  well. 
  They 
  cling 
  closely 
  to 
  twigs, 
  bark, 
  etc., 
  and 
  will 
  allow 
  them- 
  

   selves 
  to 
  be 
  lifted 
  from 
  the 
  water 
  without 
  stirring. 
  

  

  Nymph. 
  Length 
  5.5 
  mm; 
  setae 
  3.4 
  mm 
  additional; 
  abdomen 
  

   2.5 
  mm; 
  antenna 
  2.3 
  mm. 
  

  

  Body 
  stout, 
  with 
  thick 
  thorax, 
  and 
  short 
  and 
  rapidly 
  tapering 
  ab- 
  

   domen. 
  

  

  Color 
  pale 
  brownish, 
  darker 
  above, 
  obscured 
  by 
  adherent 
  silt, 
  by 
  

   diatoms, 
  vorticellae, 
  hydras, 
  and 
  other 
  adherent 
  organisms. 
  

  

  Abdomen 
  with 
  large 
  and 
  sharp, 
  flat 
  teeth, 
  made 
  by 
  the 
  projecting, 
  

   posterolateral 
  angles 
  of 
  the 
  third 
  to 
  the 
  ninth 
  segments, 
  largest 
  on 
  

   segment 
  7, 
  smallest 
  on 
  segment 
  3. 
  

  

  Gills 
  present 
  on 
  segments 
  1-6 
  ; 
  on 
  segment 
  i 
  minute 
  rudiments 
  ; 
  on 
  

   segment 
  2 
  thick, 
  elytroid, 
  covering 
  the 
  functional 
  gills, 
  squarish, 
  the 
  distal 
  

   and 
  external 
  angles 
  rounded, 
  the 
  basal-internal 
  angle 
  square; 
  there 
  is 
  on 
  

   the 
  anterior 
  face 
  a 
  piliferous 
  carina, 
  regularly 
  arcuate, 
  near 
  the 
  external 
  

   margin, 
  extending 
  from 
  the 
  outer 
  basal 
  to 
  the 
  inner 
  distal 
  angle. 
  The 
  

   gills 
  on 
  segments 
  ;^-6 
  diminish 
  in 
  size 
  posteriorly 
  ; 
  they 
  have 
  the 
  shape 
  

   of 
  the 
  hind 
  wing 
  of 
  a 
  pierid 
  butterfly, 
  and 
  bear 
  a 
  long 
  dense 
  peripheral 
  

   fringe 
  of 
  respiratory 
  filaments. 
  These 
  filaments 
  are 
  unilaterally 
  several 
  

   times 
  branched 
  on 
  the 
  anterior 
  side, 
  and 
  are 
  so 
  closely 
  crowded 
  that 
  they 
  

   overlap 
  in 
  regular 
  series 
  around 
  the 
  margin 
  of 
  the 
  gill 
  leaf. 
  They 
  are 
  

   longest 
  at 
  the 
  distal 
  end, 
  where 
  they 
  exceed 
  the 
  length 
  of 
  the 
  gill 
  leaf 
  

   itself. 
  

  

  Setae 
  slender, 
  thinly 
  fringed 
  along 
  both 
  margins, 
  the 
  middle 
  one 
  appar- 
  

   ently 
  a 
  little 
  shorter 
  in 
  the 
  males, 
  a 
  little 
  longer 
  in 
  the 
  females 
  than 
  the 
  

   other 
  two. 
  

  

  Hexagenia 
  variabilis 
  Eaton 
  

  

  1843-45 
  Palingenia 
  limbata 
  Pictet, 
  Hist. 
  nat. 
  Neur. 
  v. 
  2 
  (Ephera.) 
  p. 
  146, 
  

   pi. 
  12 
  (the 
  original 
  description: 
  this 
  was 
  Serville's 
  name 
  for 
  another 
  

   species) 
  

  

  1853 
  Palingenia 
  limbata 
  Walker, 
  List 
  neur. 
  ins. 
  Brit. 
  mus. 
  3 
  : 
  548 
  

  

  1861 
  Palingenia 
  bilineata 
  Hagen, 
  Synopsis 
  Neur. 
  N. 
  Am. 
  p. 
  41 
  (a 
  full 
  

  

  description) 
  

  

  1862 
  Palingenia 
  limbata 
  Walsh, 
  Acad. 
  nat. 
  sci. 
  Phil. 
  Proc, 
  p. 
  373 
  

  

  1863 
  Palingenia 
  limbata 
  Hagen, 
  Ent. 
  soc. 
  Phi! 
  . 
  Proc. 
  2 
  : 
  176 
  

  

  1863 
  Palingenia 
  limbata 
  Walsh, 
  Ent. 
  soc. 
  Phil. 
  Proc. 
  2:197-99 
  (makes 
  

   the 
  species 
  the 
  type 
  of 
  his 
  new 
  genus 
  Hexagenia) 
  

  

  1868 
  Hexagenia 
  limbata 
  Eaton, 
  Ent. 
  mo. 
  mag. 
  5 
  : 
  85 
  

  

  1871 
  He 
  X 
  ag 
  e 
  n 
  i 
  a 
  limbata 
  Eaton, 
  Ent. 
  soc. 
  Lond. 
  Trans, 
  p. 
  65, 
  pi. 
  1, 
  

   fig. 
  7, 
  and 
  pi. 
  4, 
  fig. 
  3 
  and 
  3a 
  (description 
  in 
  Latin) 
  

  

  3885 
  Hexageni 
  a 
  variab 
  i 
  1 
  i 
  s 
  Eaton, 
  Linn. 
  soc. 
  Lond. 
  Trans. 
  (2) 
  3 
  : 
  55, 
  

   pi. 
  7, 
  fig. 
  lie 
  

  

  1890 
  Hexagenia 
  variabilis 
  Hagen, 
  Stett. 
  ent. 
  zeit. 
  51:11-13 
  (dis- 
  

   tinguishes 
  this 
  species 
  from 
  bilineata 
  Say 
  by 
  the 
  form 
  of 
  the 
  forceps 
  

   of 
  the 
  male) 
  

  

  1892 
  Hexagenia 
  limbata 
  Banks, 
  Am. 
  ent. 
  soc. 
  Trans. 
  19: 
  345 
  (listed) 
  

  

  