﻿428 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  1888 
  Hexagenia 
  sp.? 
  (probably 
  vari 
  a 
  bills 
  and 
  bilineata) 
  Forbes, 
  

   State 
  lab. 
  nat. 
  hist. 
  Bui. 
  3. 
  2: 
  484-85 
  (estimate 
  of 
  the 
  value 
  of 
  Hexa- 
  

   genia 
  larvae 
  as 
  food 
  for 
  fishes, 
  based 
  on 
  the 
  examination 
  of 
  the 
  stomach 
  

   contents 
  of 
  1221 
  fishes, 
  representing 
  87 
  species, 
  63 
  genera, 
  and 
  25 
  fami- 
  

   lies: 
  Hosagenia 
  larvae 
  constitute 
  nearly 
  one 
  tenth 
  of 
  all 
  the 
  food 
  

   taken). 
  Summary 
  in 
  Insect 
  life. 
  1888. 
  1 
  : 
  158-61 
  

  

  This 
  species 
  was 
  much 
  less 
  numerous 
  than 
  the 
  other 
  six 
  whose 
  life 
  his- 
  

   tories 
  are 
  discussed 
  here. 
  It 
  was 
  found 
  only 
  along 
  Little 
  Clear 
  creek. 
  

   An 
  occasional 
  subimago 
  was 
  seen 
  in 
  early 
  morning 
  leaving 
  the 
  water 
  and 
  

   flying 
  weakly 
  to 
  some 
  neighboring 
  tree 
  trunk 
  to 
  rest. 
  A 
  single 
  specimen 
  

   was 
  taken 
  on 
  the 
  outside 
  of 
  a 
  trap 
  lantern 
  in 
  the 
  morning 
  twihght. 
  A 
  

   few 
  were 
  picked 
  from 
  the 
  sides 
  of 
  the 
  hatchery 
  building, 
  where 
  they 
  were 
  

   conspicuous 
  on 
  account 
  of 
  their 
  size. 
  

  

  The 
  nymphs 
  were 
  easily 
  obtained 
  from 
  the 
  bottom 
  of 
  the 
  creek 
  with 
  

   a 
  sieve 
  net. 
  They 
  were 
  obtainable 
  throughout 
  the 
  season, 
  this 
  species 
  not 
  

   having 
  a 
  limited 
  period 
  of 
  emergence, 
  as 
  H. 
  bilineata 
  seems 
  to 
  have. 
  

   Nymphs 
  taken 
  incidentally 
  while 
  collecting, 
  were 
  reared 
  at 
  various 
  times 
  

   from 
  June 
  26 
  to 
  Aug. 
  i. 
  They 
  were 
  associated 
  in 
  the 
  creek 
  bed 
  with 
  

   Ephemera 
  varia, 
  described 
  below, 
  but 
  were 
  very 
  much 
  less 
  num- 
  

   erous. 
  In 
  our 
  breeding 
  cages 
  the 
  subimago 
  emerged 
  one 
  night 
  and 
  

   transformed 
  to 
  the 
  imago 
  the 
  night 
  following. 
  

  

  Nymph. 
  PL 
  16, 
  fig, 
  2, 
  3. 
  Length 
  of 
  body 
  27 
  mm; 
  setae 
  12 
  mm 
  more; 
  

   abdomen 
  of 
  male 
  18, 
  of 
  female 
  21 
  mm 
  ; 
  antenna 
  4.5 
  mm. 
  

  

  Color 
  yellow, 
  with 
  some 
  paler 
  longitudinal 
  markings 
  on 
  the 
  thorax 
  ; 
  a 
  

   series 
  of 
  mushroom-shaped 
  marks 
  on 
  abdominal 
  segments 
  6-9. 
  

  

  Head 
  compressed 
  ; 
  a 
  shelf 
  like 
  prominence 
  above 
  the 
  base 
  of 
  each 
  an- 
  

   tenna, 
  straight 
  on 
  its 
  front 
  border, 
  round 
  on 
  its 
  exterior 
  side; 
  the 
  

   frontal 
  prominence 
  semi-elliptic 
  ; 
  mandibular 
  tusks 
  long, 
  stout, 
  upcurved, 
  

   with 
  a 
  line 
  of 
  hairs 
  on 
  their 
  supero-external 
  margin. 
  

  

  Antennae 
  at 
  base, 
  and 
  the 
  sharp 
  edges 
  of 
  the 
  legs, 
  and 
  the 
  lateral 
  

   margins 
  of 
  the 
  prothorax, 
  densely 
  clothed 
  with 
  long 
  yellowish 
  hairs. 
  

   The 
  antennae 
  are 
  bare 
  at 
  the 
  tips 
  and 
  do 
  not 
  surpass 
  the 
  extended 
  fore 
  

   tarsi. 
  

  

  Legs 
  (pi. 
  16, 
  fig. 
  3) 
  short, 
  stout, 
  twisted, 
  flattened, 
  closely 
  applied 
  to 
  

   the 
  sides 
  of 
  the 
  body, 
  and 
  well 
  adapted 
  for 
  burrowing 
  ; 
  femora 
  and 
  tibiae 
  

   scapulate 
  ; 
  the 
  tibia 
  produced 
  at 
  its 
  apex 
  into 
  a 
  terminal 
  burrowing 
  hook 
  

   and 
  scraper, 
  the 
  edges 
  bearing 
  a 
  stifl"line 
  of 
  hairs 
  ; 
  the 
  hind 
  foot 
  chelate, 
  

   the 
  distal 
  angle 
  of 
  the 
  tibia 
  forming 
  with 
  the 
  opposed 
  tarsus 
  a 
  pincer. 
  

  

  Gills 
  on 
  segments 
  1-7 
  ; 
  gill 
  of 
  the 
  first 
  segment 
  small 
  and 
  shaped 
  like 
  

   a 
  tuning 
  fork 
  ; 
  of 
  the 
  six 
  following 
  segments 
  large, 
  of 
  a 
  rich 
  purplish 
  

   color, 
  two 
  leaved, 
  the 
  leaves 
  similar, 
  lanceolate, 
  and 
  densely 
  fringed 
  with 
  

   minute 
  linear 
  respiratory 
  filaments, 
  which 
  are 
  as 
  long 
  as 
  the 
  greatest 
  

   width 
  of 
  the 
  gill 
  leaf. 
  On 
  the 
  flat 
  side 
  of 
  each 
  gill 
  leaf 
  is 
  a 
  yellow, 
  longi- 
  

   tudinal 
  median 
  line 
  closely 
  bordered 
  on 
  either 
  side 
  by 
  a 
  line 
  of 
  black. 
  All 
  

   the 
  gills 
  are 
  directed 
  over 
  the 
  back, 
  where 
  they 
  are 
  gently 
  waved 
  back 
  

   and 
  forth 
  in 
  intermittent, 
  graceful 
  motion. 
  

  

  One 
  of 
  the 
  largest 
  of 
  our 
  May 
  flies 
  ; 
  generally 
  distributed 
  over 
  the 
  

   United 
  States 
  east 
  of 
  the 
  Rocky 
  mountains. 
  

  

  