﻿474 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  a 
  hidden 
  labium 
  springs 
  from 
  the 
  sand 
  with 
  a 
  mighty 
  sweep 
  and 
  

   clutches 
  it. 
  I 
  fed 
  to 
  a 
  nymph 
  of 
  Cordulegaster 
  diastatops 
  

   14 
  full 
  grown 
  nymphs 
  of 
  C 
  ap 
  nia 
  in 
  rapid 
  succession, 
  which 
  should 
  

   represent 
  a 
  bulk 
  about 
  equal 
  to 
  that 
  of 
  the 
  nymph 
  that 
  ate 
  them. 
  It 
  ate 
  

   a 
  dozen 
  quickly, 
  the 
  last 
  two 
  more 
  slowly 
  : 
  it 
  had 
  been 
  without 
  food 
  sev- 
  

   eral 
  weeks. 
  Nymphs 
  of 
  the 
  species 
  described 
  below 
  as 
  C. 
  maculatus 
  

   supposition, 
  at 
  Saranac 
  Inn, 
  captured 
  and 
  ate 
  young 
  brook 
  trout 
  as 
  long 
  

   as 
  themselves, 
  when 
  placed 
  in 
  their 
  cage. 
  So 
  eager 
  were 
  they, 
  they 
  

   would 
  rise 
  partly 
  from 
  the 
  sand 
  on 
  approach 
  of 
  a 
  trout. 
  Like 
  the 
  

   nymplis 
  of 
  the 
  Aeschninae, 
  they 
  seem 
  to 
  have 
  a 
  decided 
  preference 
  for 
  

   big 
  game, 
  if 
  one 
  may 
  judge 
  by 
  the 
  strenuous 
  efforts 
  they 
  put 
  forth 
  when 
  

   something 
  at 
  the 
  limit 
  of 
  their 
  capacity 
  for 
  capturing 
  approaches. 
  

   Our 
  species 
  belong 
  to 
  a 
  single 
  genus. 
  

  

  CORDULEGASTER 
  Lcach 
  

  

  Of 
  the 
  seven 
  species 
  occurring 
  north 
  of 
  Mexico 
  six 
  are 
  found 
  in 
  the 
  

   eastern 
  United 
  States, 
  and 
  of 
  these 
  six, 
  five 
  are 
  likely 
  to 
  be 
  found 
  in 
  New 
  

   York 
  state 
  when 
  careful 
  collecting 
  is 
  done 
  for 
  them. 
  But 
  two 
  of 
  these, 
  

   C. 
  erroneus 
  (from 
  Keene 
  valley) 
  and 
  C. 
  diastatops, 
  are 
  on 
  rec- 
  

   ord 
  from 
  the 
  state 
  ; 
  a 
  third, 
  C. 
  maculatus 
  is 
  recorded 
  below 
  from 
  

   Saranac 
  Inn. 
  

  

  Images 
  of 
  the 
  six 
  species 
  of 
  the 
  eastern 
  United 
  States 
  may 
  be 
  sepa- 
  

   rated 
  by 
  the 
  following 
  table 
  : 
  

   a 
  Eyes 
  not 
  contiguous; 
  the 
  proximal 
  inferior 
  tooth 
  of 
  the 
  superior 
  abdominal 
  

   appendage 
  of 
  the 
  male 
  almost 
  completely 
  incased 
  within 
  the 
  10th 
  segment 
  

   (subgenus 
  Z 
  o 
  r 
  a 
  e 
  n 
  a 
  ) 
  

  

  & 
  Abdomen 
  with 
  yellow 
  lateral 
  spots; 
  stigma 
  brown 
  diastatops 
  

  

  && 
  Abdomen 
  with 
  yellow 
  half 
  rings 
  ; 
  stigma 
  yellow 
  sayi 
  

  

  aa 
  Eyes 
  contiguous; 
  proximal 
  inferior 
  tooth 
  of 
  superior 
  appendage 
  of 
  male 
  

   more 
  or 
  less 
  completely 
  exposed 
  

   & 
  Two 
  cublto-anal 
  cross 
  veins 
  before 
  the 
  triangles; 
  triangle 
  open, 
  or 
  divided 
  

   Ipy 
  a 
  single 
  cross 
  vein 
  ; 
  stigma 
  moderate 
  (subgenus 
  Cordulegaster) 
  

  

  c 
  Abdomen 
  with 
  >ellow 
  lateral 
  spots 
  , 
  maculatus 
  

  

  CO 
  Abdomen 
  with 
  yellow 
  half 
  rings 
  erroneus 
  

  

  M 
  Usually 
  three 
  cubito-anal 
  cross 
  veins 
  before 
  the 
  triangle; 
  triangle 
  often 
  

   divided 
  by 
  more 
  than 
  one 
  cross 
  vein 
  ; 
  stigma 
  very 
  long 
  (subgenus 
  

   Taeniogaster) 
  

  

  d 
  Abdomen 
  with 
  lateral 
  yellow 
  spots 
  (southern) 
  fasciatus 
  

  

  dd 
  Abdomen 
  with 
  a 
  middorsal 
  line 
  of 
  spots 
  obliquns 
  

  

  ARTIFICIAL 
  KEY 
  TO 
  THE 
  SAME 
  SPECIES 
  

  

  a 
  Abdomen 
  with 
  a 
  middorsal 
  line 
  of 
  spots 
  obliquus 
  

  

  aa 
  Abdomen 
  with 
  yellow 
  half 
  rings 
  on 
  the 
  segments 
  

  

  & 
  Face 
  yellow 
  , 
  sayi 
  

  

  