﻿' 
  AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  44/ 
  

  

  Nymph. 
  Abdomen 
  a 
  little 
  wider 
  than 
  the 
  head, 
  the 
  ninth 
  segment 
  

   hardly 
  longer 
  than 
  the 
  eighth 
  ; 
  lateral 
  spines 
  on 
  segments 
  6-9, 
  a 
  well 
  

   marked 
  middorsal 
  impressed 
  line 
  extending 
  to 
  the 
  eighth 
  segment, 
  and 
  

   very 
  minute 
  rudiments 
  of 
  dorsal 
  hooks 
  on 
  segments 
  8 
  and 
  9 
  ; 
  tibial 
  bur- 
  

   rowing 
  hooks 
  large; 
  front 
  border 
  of 
  median 
  lobe 
  of 
  labium 
  straight, 
  

   lateral 
  lobe 
  with 
  its 
  terminal 
  hook 
  bent 
  inward 
  at 
  almost 
  or 
  quite 
  a 
  right 
  

   angle 
  ; 
  apex 
  of 
  abdomen 
  regularly 
  narrowed 
  beyond 
  the 
  middle. 
  

  

  KEY 
  

  

  a) 
  Imago 
  Face 
  entirely 
  yellow; 
  nymph 
  unknown 
  G. 
  ventricosus 
  

  

  aa) 
  Imago 
  Face 
  with 
  narrow 
  black 
  lines 
  on 
  sutures 
  ; 
  sides 
  of 
  hind 
  femora 
  

  

  yellow; 
  nymph 
  unknown 
  G. 
  amnicola 
  

  

  aaa) 
  Imago 
  Face 
  Avith 
  hroad 
  transverse 
  bands 
  of 
  black 
  ; 
  hiud 
  femora 
  black 
  ; 
  

   abdominal 
  segments 
  with 
  basal 
  rings 
  of 
  yellow; 
  nymph 
  with 
  the 
  lateral 
  

   spines 
  of 
  the 
  ninth 
  segment 
  less 
  than 
  half 
  as 
  long 
  as 
  the 
  10th 
  segment 
  

  

  G. 
  scudderi 
  

  

  aaaa) 
  Imago 
  Face 
  with 
  broad 
  transverse 
  bands 
  of 
  black 
  ; 
  hind 
  femora 
  black; 
  

  

  yellow 
  of 
  middle 
  abdominal 
  segments 
  restricted 
  to 
  triangular 
  spots 
  on 
  

  

  the 
  dorsum; 
  nymph 
  with 
  the 
  lateral 
  spines 
  of 
  the 
  ninth 
  segment 
  about 
  

  

  as 
  long 
  as 
  the 
  10th 
  segment 
  G. 
  vastus 
  

  

  Subgenus 
  stylurus 
  

  

  Imago. 
  A 
  single 
  cell 
  between 
  veins 
  Ai 
  and 
  A2 
  at 
  their 
  origin, 
  that 
  cell 
  

   strongly 
  bordered 
  ; 
  abdominal 
  segments 
  7-9 
  not 
  greatly 
  dilated 
  (much 
  

   narrower 
  than 
  the 
  thorax), 
  but 
  considerably 
  elongated; 
  eighth 
  segment 
  

   cut 
  squarely 
  at 
  apex; 
  posterior 
  genital 
  hamule 
  of 
  male 
  strongly 
  directed 
  

   anteriorly; 
  hind 
  femora 
  similar 
  in 
  the 
  two 
  sexes. 
  

  

  Nymph. 
  Abdomen 
  narrower 
  than 
  the 
  head, 
  and 
  greatly 
  elongated; 
  

   tibial 
  burrowing 
  hooks 
  very 
  small 
  ; 
  lateral 
  spines, 
  middorsal 
  suture 
  and 
  

   dorsal 
  hooks 
  of 
  abdomen 
  as 
  in 
  Gomphurus; 
  ninth 
  abdominal 
  seg- 
  

   ment 
  longer 
  than 
  the 
  eighth, 
  sometimes 
  twice 
  as 
  long. 
  

  

  KEY 
  

  

  a) 
  Imago. 
  Ninth 
  abdominal 
  s^egment 
  of 
  imago 
  much 
  shorter 
  than 
  the 
  

   seventh. 
  Nymph 
  with 
  the 
  lateral 
  spines 
  of 
  the 
  ninth 
  abdominal 
  seg- 
  

   ment 
  longer 
  by 
  half 
  than 
  the 
  10th 
  segment 
  G. 
  plagiatus 
  

  

  aa) 
  Imago 
  with 
  segments 
  7 
  and 
  9 
  of 
  abdomen 
  about 
  equal 
  in 
  length. 
  Nymph 
  

   with 
  the 
  lateral 
  spines 
  of 
  the 
  ninth 
  abdominal 
  segment 
  shorter 
  by 
  half 
  

   than 
  the 
  10th 
  segment 
  G. 
  spiniceps 
  

  

  Subgenus 
  arigomphus 
  

   Imago. 
  Two 
  cells 
  between 
  the 
  base 
  of 
  veins 
  Aj 
  and 
  A2 
  at 
  their 
  origin 
  ; 
  

   eighth 
  abdominal 
  segment 
  obhquely 
  cut 
  at 
  apex, 
  longer 
  on 
  the 
  dorsal 
  

   side; 
  hind 
  femora 
  different 
  in 
  the 
  two 
  sexes, 
  in 
  the 
  male 
  hairy, 
  and 
  in 
  

  

  