﻿74 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  nearly 
  bare 
  setae 
  25 
  mm 
  long, 
  and 
  brown 
  fore 
  legs 
  whose 
  tarsi 
  are 
  

   9 
  mm 
  long 
  The 
  enlarged 
  and 
  smoothly 
  rounded 
  eyes 
  of 
  the 
  male 
  

   just 
  meet 
  each 
  other 
  above 
  the 
  head. 
  The 
  face 
  is 
  black, 
  with 
  the 
  

   vertical 
  nasal 
  carina 
  yellow, 
  and 
  also 
  a 
  spot 
  behind 
  the 
  ocelli 
  and 
  

   between 
  the 
  compound 
  eyes. 
  Otherwise 
  the 
  coloration 
  is 
  as 
  in 
  the 
  

   female. 
  The 
  segments 
  of 
  the 
  fore 
  tarsus 
  of 
  the 
  male 
  are 
  of 
  nearly 
  

   equal 
  length, 
  the 
  5th 
  being 
  perhaps 
  a 
  trifle 
  shorter 
  than 
  the 
  others 
  : 
  

   in 
  middle 
  and 
  hind 
  tarsi, 
  the 
  four 
  basal 
  segments 
  are 
  of 
  approxi- 
  

   mately 
  equal 
  length, 
  while 
  the 
  5th 
  is 
  as 
  long 
  as 
  any 
  two 
  other 
  seg- 
  

   ments. 
  Unlike 
  the 
  female, 
  which 
  has 
  blunt 
  and 
  flabellate 
  claws 
  on 
  

   the 
  fore 
  tarsi, 
  those 
  of 
  the 
  male 
  are 
  on 
  all 
  tarsi 
  sharply 
  hooked 
  

   and 
  similar. 
  In 
  several 
  of 
  the 
  specimens 
  the 
  radial 
  sector 
  of 
  the 
  

   hind 
  wing 
  has 
  its 
  second 
  forks 
  less 
  equal 
  than 
  in 
  the 
  female 
  

   described 
  above, 
  the 
  lower 
  fork 
  being 
  deeper 
  than 
  the 
  upper. 
  

  

  The 
  appendages 
  of 
  the 
  male 
  abdoimen 
  are 
  strongly 
  chitinized, 
  the 
  

   forceps 
  base 
  is 
  longer 
  than 
  the 
  9th 
  segment, 
  widened 
  distally, 
  

   broadly 
  truncated 
  on 
  each 
  hind 
  angle 
  to 
  receive 
  the 
  much 
  narrower 
  

   base 
  of 
  the 
  forceps, 
  and 
  angularly 
  excavate 
  on 
  the 
  wrinkled 
  but 
  

   strongly- 
  chitinized 
  hind 
  margin 
  in 
  a 
  broadly 
  triangular 
  rear 
  notch. 
  

   The 
  forceps 
  limbs 
  are 
  long 
  and 
  strongly 
  divaricate 
  and 
  conspic- 
  

   uous. 
  Each 
  consists 
  of 
  four 
  segments, 
  of 
  which 
  the 
  first, 
  third 
  and 
  

   fourth 
  are 
  short 
  and 
  of 
  about 
  equal 
  length 
  and 
  are 
  together 
  about 
  

   equal 
  in 
  length 
  to 
  the 
  second 
  segment. 
  The 
  apical 
  half 
  of 
  the 
  for- 
  

   ceps 
  is 
  transversely 
  wrinkled, 
  and 
  it 
  is 
  wholly 
  dark 
  brown 
  in 
  color. 
  

  

  After 
  studying 
  the 
  male 
  I 
  conclude 
  that 
  the 
  features 
  which 
  

   chiefly 
  distinguish 
  this 
  genus 
  from 
  Siphlurus 
  are 
  in 
  both 
  sexes 
  the 
  

   onisciform 
  abdomen, 
  and 
  the 
  midventral 
  thoracic 
  spines. 
  

  

  While 
  the 
  foregoing 
  is 
  passing 
  through 
  the 
  printer's 
  hands 
  an- 
  

   other 
  species 
  of 
  Mayfly 
  of 
  the 
  genus 
  Potamanthus 
  has 
  been 
  sent 
  

   me 
  by 
  Dr 
  Felt, 
  collected 
  on 
  June 
  29, 
  1909 
  at 
  Schenectady. 
  It 
  is 
  

   larger 
  than 
  P. 
  d 
  i 
  a 
  p 
  h 
  a 
  n 
  u 
  s 
  , 
  described 
  in 
  the 
  report 
  of 
  the 
  State 
  

   Entomologist 
  for 
  1907 
  [p. 
  193-94, 
  and 
  pi. 
  10, 
  fig. 
  5], 
  and 
  is 
  readily 
  

   distinguished 
  therefrom 
  by 
  the 
  abbreviated 
  middle 
  caudal 
  seta 
  and 
  

   by 
  the 
  form 
  of 
  the 
  appendages 
  in 
  the 
  male. 
  . 
  

  

  Potamanthus 
  inequalis 
  sp. 
  nov. 
  

  

  Length 
  of 
  body 
  11 
  mm, 
  of 
  fore 
  leg 
  about 
  10 
  mm, 
  of 
  lateral 
  setae 
  

   26 
  mm, 
  of 
  middle 
  seta 
  15 
  mm, 
  expanse 
  of 
  wings 
  24 
  mm. 
  Color 
  

   white, 
  with 
  fuscous 
  head, 
  pale 
  yellowish 
  thorax 
  and 
  translucent 
  

   white 
  abdomen. 
  Legs 
  white 
  except 
  the 
  slightly 
  infuscated 
  tips 
  of 
  

  

  