﻿272 
  W. 
  BT-AXT;AND 
  BENHAM. 
  

  

  male 
  efferent 
  apparatus 
  that 
  does 
  not 
  exist 
  in 
  the 
  South 
  

   American 
  nor 
  in 
  the 
  Kerguelen 
  species, 
  and 
  one 
  is 
  tempted 
  

   to 
  regard 
  the 
  existence 
  of 
  this 
  "atrial 
  sac" 
  as 
  diagnostic 
  of 
  

   the 
  genus 
  as 
  originally 
  formulated, 
  but 
  the 
  intermixture 
  

   presented 
  by 
  other 
  characters 
  is 
  so 
  involved 
  that 
  it 
  seems 
  

   better 
  to 
  adopt 
  Michaelsen's 
  view 
  and 
  place 
  them 
  all 
  in 
  the 
  

   single 
  genus 
  Phreodrilus. 
  

  

  The 
  new 
  species 
  described 
  in 
  the 
  present 
  contribution 
  are 
  

   (a) 
  P. 
  lacnstris, 
  (b) 
  P. 
  beddardi, 
  and 
  (c) 
  P. 
  mauiensis. 
  

  

  Phreodrilus 
  lacustris, 
  n. 
  sp. 
  

  

  A 
  small 
  thin 
  worm, 
  usually 
  much 
  coiled 
  in 
  its 
  preserved 
  

   state. 
  One 
  individual 
  when 
  stretched 
  measured 
  20 
  mm., 
  with 
  

   a 
  diameter 
  of 
  ^ 
  mm., 
  or 
  even 
  less. 
  'J'his 
  individual 
  consists 
  

   of 
  seventy-five 
  segments. 
  

  

  The 
  prostomium 
  is 
  prolobic, 
  short, 
  and 
  conical 
  (PI. 
  13, 
  

   fig. 
  1) 
  . 
  Segments 
  I 
  to 
  VII 
  are 
  very 
  short 
  and 
  distinctly 
  biannu- 
  

   late 
  ; 
  the 
  following 
  segments 
  are 
  longer, 
  and 
  the 
  annulation 
  

   less 
  evident. 
  A 
  " 
  lateral 
  line 
  " 
  is 
  very 
  well 
  marked 
  in 
  the 
  

   stained 
  entire 
  individual. 
  

  

  Cha3ta3. 
  — 
  The 
  dorsal 
  bristles 
  are 
  solitary, 
  very 
  delicate, 
  

   and 
  simply 
  capilliform 
  ; 
  they 
  are 
  not 
  very 
  long, 
  measuring 
  

   O'l 
  mm., 
  and 
  project 
  for 
  a 
  distance 
  equal 
  to 
  about 
  one 
  quai'ter 
  

   to 
  one 
  third 
  the 
  height 
  of 
  body, 
  and 
  are 
  scai-cely 
  as 
  long 
  as 
  

   half 
  a 
  segment. 
  They 
  commence 
  on 
  the 
  third 
  segment, 
  as 
  

   seems 
  to 
  be 
  the 
  typical 
  arrangement 
  in 
  the 
  genus. 
  Here 
  and 
  

   there 
  1 
  noted 
  a 
  couple 
  of 
  dorsal 
  chastoe, 
  but 
  the 
  second 
  is 
  

   quite 
  short. 
  The 
  ventral 
  bristles 
  are 
  in 
  couples, 
  and 
  the 
  two 
  

   differ 
  in 
  size 
  and 
  in 
  the 
  character 
  of 
  the 
  free 
  end, 
  thousrh 
  

   the 
  differences 
  may 
  readily 
  escape 
  observation. 
  Both 
  are 
  

   sigmoid, 
  with 
  a 
  nodal 
  swelling 
  and 
  the 
  free 
  end 
  sharply 
  

   curved 
  (fig. 
  2) 
  ; 
  but 
  whereas 
  in 
  one 
  bristle 
  of 
  each 
  couple 
  (a) 
  

   this 
  end 
  is 
  a 
  simple 
  hook, 
  in 
  the 
  other 
  (5) 
  there 
  is 
  a 
  minute 
  

   tooth 
  on 
  the 
  convex 
  curvature 
  of 
  this 
  hook-like 
  tip 
  ; 
  in 
  some 
  

   cases 
  the 
  tooth 
  is 
  absent 
  and 
  a 
  mere 
  difference 
  in 
  the 
  refrin- 
  

   geucy 
  of 
  this 
  margin 
  suggests 
  a 
  tooth. 
  The 
  chsetge 
  of 
  this 
  

  

  