﻿444 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  easily 
  referable 
  at 
  a 
  glance 
  to 
  their 
  place 
  in 
  the 
  genus. 
  The 
  images 
  ex- 
  

   hibit 
  with 
  shght 
  variations 
  one 
  color 
  pattern, 
  one 
  plan 
  of 
  venation, 
  one 
  

   habitus, 
  and 
  are 
  therefore 
  not 
  easy 
  to 
  distinguish. 
  I 
  give 
  below 
  an 
  arti- 
  

   ficial 
  key 
  to 
  p.id 
  in 
  the 
  recognition 
  of 
  our 
  species, 
  and 
  follow 
  it 
  with 
  a 
  

   synoptic 
  arrangement 
  of 
  the 
  genus, 
  in 
  which 
  is 
  included 
  a 
  statement 
  of 
  

   the 
  more 
  important 
  characters 
  of 
  lesser 
  groups 
  within 
  the 
  genus. 
  For 
  

   all 
  of 
  these 
  I 
  prefer 
  to 
  retain 
  the 
  old 
  generic 
  name 
  Gomphus 
  till 
  more 
  of 
  

   the 
  nymphs 
  are 
  known. 
  

  

  ARTIFICIAL 
  KEY 
  TO 
  IMAGOS 
  

  

  1 
  Face 
  entirely 
  yellow 
  2 
  

  

  Face 
  yellow, 
  transversely 
  banded 
  with 
  black 
  10 
  

  

  Face 
  suffused 
  with 
  brownish 
  black 
  ; 
  large, 
  very 
  elongate 
  species, 
  with 
  a 
  dis- 
  

   tinct 
  anal 
  loop 
  of 
  a 
  single 
  cell, 
  a 
  pair 
  of 
  narrow 
  oblique 
  yellow 
  stripes 
  on 
  

   the 
  dark 
  background 
  of 
  the 
  thoracic 
  dorsum 
  14 
  

  

  2 
  Hind 
  margin 
  of 
  the 
  occiput 
  with 
  a 
  distinct 
  median 
  tooth 
  villosipes 
  

  

  " 
  without 
  " 
  3 
  

  

  -3 
  Tibiae 
  yellow 
  externally 
  4 
  

  

  '' 
  black 
  " 
  7 
  

  

  4 
  Abdominal 
  segments 
  7-9 
  strongly 
  dilated 
  about 
  as 
  wide 
  as 
  the 
  thorax 
  

  

  f 
  ra 
  ternus 
  

   Abdominal 
  segments 
  7-9 
  little 
  dilated, 
  much 
  narrower 
  than 
  the 
  thorax. 
  .. 
  5 
  

  

  5 
  Length 
  under 
  45 
  mm 
  exilis 
  

  

  Length 
  over 
  45 
  mm 
  6 
  

  

  6 
  Superior 
  abdominal 
  appendages 
  of 
  the 
  male 
  with 
  a 
  sharp 
  inferior 
  tooth 
  ; 
  

  

  vulvar 
  lamina 
  of 
  the 
  female 
  composed 
  of 
  two 
  acute 
  triangular 
  lobes, 
  one 
  

  

  fourth 
  as 
  long 
  as 
  the 
  ninth 
  segment 
  spicatus 
  

  

  Superior 
  abdominal 
  appendage 
  of 
  the 
  male 
  with 
  a 
  lovv^ 
  inferior 
  lobe 
  ; 
  vulvar 
  

   lamina 
  of 
  the 
  female 
  composed 
  of 
  two 
  low 
  rounded 
  lobes, 
  and 
  hardly 
  

   longer 
  than 
  one 
  10th 
  of 
  the 
  ninth 
  segment 
  sordid 
  us 
  

  

  7 
  Length 
  under 
  40 
  mm 
  abbreviatus 
  

  

  Length 
  over 
  40 
  mm 
  and 
  under 
  50 
  mm 
  8 
  

  

  Length 
  over 
  50 
  mm 
  9 
  

  

  8 
  Abdominal 
  segments 
  7-9 
  greatly 
  dilated, 
  as 
  wide 
  as 
  the 
  thorax 
  

  

  ventri 
  cosus 
  

   Abdominal 
  segments 
  7-9 
  little 
  dilated, 
  much 
  narrower 
  than 
  the 
  thorax 
  

  

  quadri 
  color 
  

  

  9 
  Dorsum 
  of 
  the 
  10th 
  abdominal 
  segment 
  and 
  the 
  superior 
  appendages 
  

  

  black 
  descriptus 
  

  

  Dorsum 
  of 
  the 
  lOfch 
  abdominal 
  segment 
  and 
  the 
  superior 
  appendages 
  

   yellow 
  furcifer 
  

  

  10 
  Yellow 
  of 
  the 
  thoracic 
  dorsum 
  reduced 
  to 
  two 
  narrow, 
  oblique, 
  isolated, 
  

  

  yellow 
  stripes 
  scudderi 
  

  

  Yellow 
  stripes 
  of 
  the 
  thoracic 
  dorsum 
  broader, 
  not 
  isolated, 
  dilated 
  at 
  

   their 
  anterior 
  ends 
  11 
  

  

  11 
  Side 
  (anterior 
  face) 
  of 
  the 
  hind 
  femora 
  yellow 
  amnicola 
  

  

  Sides 
  of 
  the 
  hind 
  femora 
  black 
  12 
  

  

  