﻿490 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  longitudinal 
  band 
  of 
  brown 
  each 
  side 
  of 
  the 
  thorax, 
  rings 
  on 
  femora 
  and 
  

   tibiae, 
  and 
  obscure, 
  interrupted, 
  longitudinal 
  rows 
  of 
  spots 
  on 
  the 
  

   abdomen. 
  Head 
  compact, 
  with 
  eyes 
  very 
  prominent 
  laterally, 
  and 
  the 
  

   front 
  somewhat 
  swollen 
  between 
  the 
  bases 
  of 
  the 
  antennae 
  ; 
  labium 
  with 
  

   its 
  mentum 
  distinctly 
  longer 
  than 
  wide, 
  the 
  median 
  lobe 
  prominent, 
  

   declined, 
  minutely 
  spinulose 
  on 
  its 
  front 
  border, 
  with 
  two 
  stouter 
  spinules 
  

   at 
  the 
  sides 
  of 
  the 
  apical 
  angle; 
  lateral 
  setae 
  seven 
  ; 
  mental 
  setae 
  six 
  to 
  

   nine; 
  movable 
  hook 
  sHghtly 
  incurved, 
  and 
  sharply 
  pointed; 
  teeth 
  crenate, 
  

   spinulose. 
  

  

  Abdomen 
  roof-shaped; 
  segments 
  3-9 
  about 
  equal 
  in 
  length, 
  the 
  loth 
  

   a 
  minute 
  annular 
  segment 
  almost 
  included 
  within 
  the 
  apex 
  of 
  the 
  ninth; 
  

   dorsal 
  hooks 
  on 
  segments 
  2-9, 
  spine-like 
  anteriorly 
  where 
  covered 
  by 
  the 
  

   wings, 
  distinctly 
  cultriform 
  posteriorly; 
  lateral 
  spines 
  on 
  segments 
  8 
  and 
  

  

  9 
  long 
  and 
  broad 
  at 
  base. 
  

  

  Four 
  species 
  are 
  tabulated 
  below: 
  one 
  of 
  these, 
  T. 
  spinosa, 
  has 
  

   not 
  been 
  hitherto 
  recorded 
  from 
  this 
  state. 
  These 
  four 
  were 
  all 
  common 
  

   at 
  Saranac 
  Inn, 
  excepting 
  the 
  typical 
  T. 
  cynosura. 
  So 
  common 
  

   were 
  they, 
  in 
  fact, 
  that 
  I 
  stumbled 
  on 
  two 
  desirable 
  bits 
  of 
  information 
  

   concerning 
  the 
  genus 
  that 
  I 
  should 
  probably 
  have 
  missed 
  had 
  they 
  not 
  

   been 
  very 
  common. 
  The 
  first 
  of 
  these 
  relates 
  to 
  the 
  proportionate 
  

   abundance 
  of 
  the 
  sexes. 
  Males 
  mainly 
  are 
  collected 
  by 
  the 
  ordinary- 
  

   methods 
  ; 
  and 
  for 
  half 
  a 
  century 
  or 
  more 
  students 
  of 
  the 
  group 
  have 
  been 
  

   remarking 
  on 
  the 
  striking 
  preponderance 
  of 
  males 
  in 
  this 
  and 
  other 
  

   genera. 
  I 
  collected 
  on 
  Blueberry 
  island 
  in 
  Little 
  Clear 
  pond 
  in 
  about 
  

  

  10 
  minutes 
  in 
  cast 
  skins 
  of 
  T. 
  spiniger 
  a 
  and 
  T. 
  s 
  e 
  m 
  iaqu 
  ea, 
  

   intermixed, 
  taking 
  them 
  as 
  they 
  came, 
  without 
  any 
  selection 
  whatever. 
  

   These 
  were 
  separated 
  as 
  to 
  species 
  and 
  sexes 
  (the 
  males 
  being 
  easily 
  

   recognized 
  by 
  the 
  indications 
  of 
  the 
  secondary 
  genitalia 
  on 
  the 
  ventral 
  side 
  

   of 
  the 
  second 
  abdominal 
  segment) 
  and 
  counted, 
  with 
  the 
  following 
  results 
  : 
  

   T. 
  spinigera, 
  ^ 
  s 
  22, 
  $S24; 
  T. 
  semiaquea, 
  ^s 
  25, 
  $340, 
  

   in 
  both 
  cases 
  a 
  slight 
  excess 
  of 
  females. 
  I 
  once 
  counted 
  a 
  large 
  number 
  

   of 
  skins 
  ofT. 
  cynosura, 
  and 
  E. 
  princeps 
  taken 
  from 
  Purington 
  

   lake 
  at 
  Galesburg 
  111. 
  I 
  have 
  not 
  the 
  figures 
  resulting 
  from 
  the 
  count, 
  

   but 
  I 
  remember 
  distinctly 
  that 
  there 
  was 
  in 
  each 
  case 
  a 
  slight 
  excess 
  of 
  

   females. 
  The 
  females 
  are 
  more 
  shy 
  and 
  seclusive, 
  and 
  therefore 
  less 
  

   often 
  taken. 
  My 
  breedings 
  have 
  never 
  revealed 
  any 
  material 
  excess 
  in 
  

   numbers 
  of 
  either 
  sex 
  for 
  any 
  species 
  ; 
  and 
  these 
  are 
  certainly 
  more 
  reU- 
  

   able 
  than 
  chance 
  captures 
  in 
  air. 
  

  

  An 
  acquaintance 
  with 
  the 
  eggs 
  of 
  Tetragoneuria 
  was 
  likewise 
  

   almost 
  forced 
  on 
  me. 
  These 
  are 
  laid 
  in 
  strings, 
  attached 
  together 
  in 
  

   masses 
  (as 
  shown 
  in 
  fig. 
  19) 
  and 
  hung 
  on 
  partly 
  submerged 
  twigs 
  at 
  the 
  

   ^surface 
  of 
  the 
  water. 
  These 
  were 
  very 
  common 
  objects 
  about 
  the 
  shores 
  

   *of 
  Little 
  Clear 
  pond. 
  I 
  did 
  not 
  see 
  any 
  of 
  them 
  laid. 
  That 
  they 
  belong 
  

  

  