﻿478 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  This 
  is 
  a 
  common 
  species 
  about 
  the 
  upland 
  spring 
  bogs 
  near 
  Ithaca 
  

   and 
  McLean 
  N. 
  Y. 
  I 
  have 
  collected 
  the 
  nymphs 
  by 
  hundreds 
  from 
  

   the 
  brownish 
  vegetable 
  debris 
  of 
  the 
  puny 
  streams 
  trickhng 
  through 
  such 
  

   places. 
  

  

  The 
  nymph 
  differs 
  from 
  the 
  preceding 
  species 
  in 
  being 
  a 
  trifle 
  smaller, 
  

   and 
  considerably 
  less 
  hairy; 
  the 
  lateral 
  margins 
  of 
  segments 
  8 
  and 
  9 
  of 
  

   abdomen 
  are 
  thin 
  and 
  sharp 
  and 
  bear 
  sharp 
  triangular 
  spines; 
  the 
  labium 
  

   is 
  less 
  widened 
  just 
  before 
  the 
  bases 
  of 
  the 
  lateral 
  lobes 
  ; 
  the 
  median 
  lobe 
  

   is 
  less 
  produced, 
  more 
  deeply 
  notched 
  in 
  the 
  middle, 
  and 
  the 
  two 
  lobes 
  

   separated 
  by 
  this 
  median 
  notch 
  are 
  again 
  cleft 
  by 
  a 
  lesser 
  notch. 
  

  

  Possibly 
  these 
  differences 
  in 
  median 
  lobe 
  of 
  labium 
  and 
  in 
  lateral 
  

   margins 
  of 
  abdominal 
  segments 
  8 
  and 
  9 
  may 
  prove 
  constant 
  for 
  the 
  sub- 
  

   genera 
  Z 
  o 
  r 
  a 
  e 
  n 
  a 
  and 
  Cordulegaster. 
  

  

  Skimmers 
  

   This 
  family 
  is 
  a 
  host, 
  and 
  includes 
  many 
  of 
  the 
  commonest 
  of 
  our 
  

   species. 
  Most 
  of 
  them 
  are 
  of 
  well 
  sustained 
  flight, 
  and 
  are 
  seen 
  con- 
  

   tinually 
  hovering 
  over 
  the 
  sur- 
  

   face 
  of 
  still 
  water, 
  or 
  are 
  met 
  

   with 
  on 
  the 
  uplands 
  while 
  for- 
  

   aging. 
  The 
  females 
  do 
  not 
  

   insert 
  their 
  eggs 
  into 
  the 
  tis- 
  

   sues 
  of 
  plants, 
  but 
  drop 
  them 
  

   loosely 
  into 
  the 
  water, 
  or 
  hang 
  

   them 
  in 
  strings 
  about 
  plant 
  

   stems 
  at 
  the 
  surface 
  of 
  the 
  

   water. 
  

  

  The 
  nymphs 
  are 
  sprawlers 
  

   on 
  the 
  bottom, 
  mainly 
  in 
  shal- 
  

   low 
  water, 
  or 
  clamberers 
  over 
  

   fallen 
  plant 
  stems, 
  and 
  are 
  

   protectively 
  colored. 
  They 
  

   agree 
  in 
  the 
  following 
  char- 
  

   acters 
  : 
  the 
  labium 
  (fig. 
  17) 
  

   is 
  masklike, 
  spoon-shaped, 
  

   with 
  raptorial 
  setae, 
  and 
  with 
  

  

  Fig. 
  17 
  Diagram 
  of 
  the 
  Libellulid 
  nymph 
  labium 
  (Peri- 
  . 
  , 
  , 
  , 
  , 
  j 
  

   themis 
  domltia). 
  Sm 
  submentum; 
  m 
  mentum; 
  its 
  lateral 
  lobe 
  tOOthed 
  OU 
  itS 
  

   ms 
  mental 
  setae 
  ; 
  ml 
  median 
  lobe 
  ; 
  II 
  lateral 
  lobes 
  ; 
  Is 
  late- 
  

   ral 
  setae 
  ; 
  t 
  teeth 
  ; 
  /i 
  movable 
  hook 
  distal 
  margin; 
  the 
  antennae 
  

  

  are 
  seven-jointed, 
  and 
  setiform; 
  the 
  tarsi 
  are 
  three 
  -jointed, 
  with 
  the 
  third 
  

   joint 
  never 
  as 
  long 
  as 
  the 
  two 
  basal 
  ones 
  together; 
  the 
  wing 
  cases 
  are 
  

  

  