﻿AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  

  

  491 
  

  

  to 
  Tetragoneuriais, 
  therefore, 
  an 
  inference 
  : 
  it 
  is 
  sufficiently 
  justi- 
  

   fied 
  by 
  the 
  following 
  considerations. 
  

  

  i) 
  Tetragoneuria 
  was 
  the 
  only 
  libellulid 
  sufficiently 
  common 
  at 
  

   the 
  pond 
  to 
  have 
  produced 
  the 
  enormous 
  number 
  of 
  eggs 
  observed 
  there. 
  

   I 
  think 
  one 
  might 
  easily 
  have 
  filled 
  a 
  barrel 
  with 
  the 
  clusters 
  that 
  could 
  

   have 
  been 
  picked 
  up 
  at 
  the 
  surface 
  of 
  this 
  pond 
  : 
  the 
  cluster 
  shown 
  in 
  

   the 
  figure 
  (which 
  was 
  smaller 
  than 
  the 
  average) 
  contained 
  about 
  1 
  10,000 
  

   eggs 
  (counted 
  in 
  part, 
  and 
  estimated), 
  and 
  with 
  its 
  enveloping 
  gelatin 
  

  

  Fig. 
  19 
  Eggs 
  of 
  Tetragoneuria 
  hung 
  on 
  submerged 
  twigs 
  near 
  surface 
  of 
  the 
  water 
  

  

  would 
  have 
  about 
  filled 
  a 
  half 
  pint 
  measure. 
  These 
  clusters 
  are 
  doubtless 
  

   the 
  work 
  of 
  a 
  number 
  of 
  females 
  ; 
  the 
  separate 
  strings 
  are 
  often 
  indicated 
  

   by 
  the 
  ends 
  left 
  hanging 
  free. 
  These 
  are 
  undoubtedly 
  libelluHd 
  eggs 
  : 
  none 
  

   of 
  our 
  larger 
  Libellulinae 
  lay 
  their 
  eggs 
  in 
  strings; 
  nor 
  do 
  the 
  smaller 
  

   Cordulinae, 
  but 
  the 
  European 
  genus 
  E 
  p 
  i 
  t 
  h 
  e 
  c 
  a 
  , 
  not 
  distantly 
  related 
  

   to 
  Tetragoneuria, 
  does 
  so. 
  

  

  No 
  other 
  Cordulinae 
  were 
  common 
  at 
  this 
  pond. 
  I 
  did 
  not 
  get 
  more 
  

   than 
  a 
  single 
  nymph 
  or 
  imago 
  of 
  any 
  other 
  save 
  Cordulia 
  shurt- 
  

   leffi, 
  and 
  of 
  that 
  less 
  than 
  a 
  dozen 
  in 
  all, 
  there. 
  But 
  Tetragoneurias 
  

   were 
  abundant 
  above 
  all 
  that 
  I 
  have 
  ever 
  seen 
  elsewhere. 
  They 
  were 
  

   scattered 
  all 
  about 
  the 
  margin 
  excepting, 
  perhaps, 
  the 
  bare 
  shores 
  of 
  part 
  

   of 
  the 
  north 
  side, 
  and 
  were 
  apparently 
  rather 
  uniformly 
  distributed. 
  I 
  

   counted 
  the 
  number 
  of 
  cast 
  skins 
  of 
  Tetragoneuria, 
  without 
  regard 
  

   to 
  species, 
  clinging 
  to 
  the 
  thin 
  grass 
  tussocks 
  and 
  fallen 
  twigs 
  along 
  the 
  

   water's 
  edge 
  for 
  a 
  distance 
  of 
  several 
  rods 
  at 
  two 
  places 
  : 
  at 
  the 
  north 
  

  

  