﻿AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  

  

  479 
  

  

  long, 
  reaching 
  the 
  sixth 
  abdominal 
  segment 
  when 
  the 
  nymph 
  is 
  grown 
  ; 
  

   lateral 
  spines 
  are 
  present 
  on 
  abdominal 
  segments 
  8 
  and 
  9, 
  but 
  the 
  dorsal 
  

   hooks 
  are 
  very 
  variable, 
  and 
  often 
  wanting. 
  

  

  Of 
  the 
  three 
  subfamiHes 
  characterized 
  below, 
  the 
  first 
  one 
  is 
  here 
  

   newly 
  set 
  apart; 
  the 
  other 
  two 
  are 
  so 
  closely 
  alHed 
  that 
  no 
  single 
  abso- 
  

  

  Fig. 
  18 
  Bases 
  of 
  wings 
  of 
  Leucorhinia 
  glacialis 
  Hagen. 
  Ccosta; 
  Scsubcosta; 
  ij 
  radius 
  

   JK" 
  media; 
  Cm 
  cubitus; 
  4 
  anal 
  vein; 
  ar 
  arculus; 
  ttriaagle; 
  «' 
  subtriangle 
  ; 
  s 
  supra 
  triangle 
  ; 
  a 
  anal 
  

   loop 
  

  

  lately 
  distinctive 
  character 
  has 
  yet 
  been 
  found 
  that 
  will 
  separate 
  all 
  the 
  

   imagos. 
  A 
  combination 
  of 
  characters 
  seems 
  to 
  be 
  necessary 
  for 
  dis- 
  

   tinguishing 
  both 
  imagos 
  and 
  nymphs: 
  a 
  combination 
  is 
  therefore 
  used 
  in 
  

   the 
  following 
  tables. 
  

  

  KEY 
  TO 
  SUBFAMILIES 
  

  

  Imagos 
  

   a 
  The 
  triangle 
  of 
  the 
  hind 
  wing 
  placed 
  considerably 
  beyond 
  the 
  arculus; 
  the 
  

   anal 
  loop 
  well 
  developed, 
  and 
  hardly 
  longer 
  than 
  broad; 
  with 
  more 
  than 
  

  

  two 
  cubito-anal 
  cross 
  veins 
  Macromiinae 
  

  

  aa 
  The 
  triangle 
  of 
  the 
  hind 
  wing 
  (fig. 
  18) 
  retracted 
  to 
  the 
  level 
  of 
  the 
  arculus, 
  

   or 
  even 
  passing 
  it 
  a 
  little 
  sometimes; 
  the 
  anal 
  loop, 
  greatly 
  elongated 
  

   (except 
  in 
  Nannothemis) 
  and 
  becoming 
  foot-shaped; 
  one 
  or 
  two 
  

   cubito-anal 
  cross 
  veins. 
  

  

  