﻿SOME 
  NEW 
  SPECII5S 
  OF 
  THE 
  GENUS 
  PHKEODRILUS. 
  273 
  

  

  second 
  form 
  {h) 
  appear 
  to 
  be 
  rather 
  shorter 
  thau 
  the 
  former. 
  

   In 
  several 
  segments, 
  however, 
  towards 
  the 
  hinder 
  part 
  of 
  the 
  

   worm, 
  both 
  the 
  chietEe 
  have 
  a 
  tooth. 
  There 
  seem 
  to 
  be 
  no 
  

   " 
  reserve 
  " 
  cha3ts3. 
  Of 
  the 
  two 
  forms, 
  the 
  simpler 
  (a) 
  is 
  the 
  

   more 
  ventral 
  of 
  the 
  two, 
  while 
  occasionally 
  in 
  the 
  posterior 
  

   half 
  of 
  the 
  worm 
  one 
  of 
  the 
  cha3ta3 
  may 
  be 
  absent. 
  

   These 
  ventral 
  chastas 
  measure 
  0075 
  mm. 
  in 
  length; 
  

   they 
  are 
  smaller 
  than 
  in 
  P. 
  kerguelenensis. 
  In 
  the 
  

   character 
  of 
  the 
  clueta; 
  this 
  species 
  resembles 
  the 
  South 
  

   American 
  species 
  (" 
  Hesperodrilus 
  "), 
  rather 
  than 
  the 
  

   Kergueleu 
  or 
  New 
  Zealand 
  species. 
  The 
  ventral 
  chsette 
  are 
  

   absent 
  in 
  Segments 
  XII 
  and 
  XIII 
  ; 
  in 
  the 
  latter 
  they 
  

   are 
  replaced, 
  however, 
  by 
  special 
  copulatory 
  bristles 
  

   (fig. 
  3), 
  to 
  which 
  reference 
  is 
  made 
  below. 
  

  

  The 
  clitellum 
  encircles 
  the 
  posterior 
  part 
  of 
  Segment 
  XII 
  

   and 
  the 
  whole 
  of 
  Segment 
  XIII; 
  its 
  margins 
  in 
  sexually 
  

   mature 
  individuals 
  are 
  well 
  defined 
  ; 
  anteriorly 
  it 
  ceases 
  

   at 
  about 
  the 
  level 
  of 
  the 
  male 
  genital 
  pores 
  (PI. 
  13, 
  fig. 
  4). 
  

   In 
  whole 
  specimens, 
  viewed 
  by 
  transmitted 
  light, 
  this 
  

   region 
  appears 
  blackish, 
  and 
  the 
  epidermis 
  is 
  at 
  least 
  twice 
  

   the 
  thickness 
  of 
  that 
  layer 
  in 
  the 
  neighbouring 
  regions. 
  

  

  The 
  male 
  pores 
  are 
  on 
  the 
  twelfth 
  segment, 
  close 
  to 
  its 
  

   hinder 
  margin, 
  in 
  line 
  with 
  the 
  ventral 
  chcetse. 
  

  

  The 
  oviducal 
  pores 
  are 
  immediately 
  behind 
  them 
  on 
  the 
  

   boundary 
  between 
  the 
  Segments 
  XII 
  and 
  XIII. 
  

  

  The 
  spermathecal 
  pores 
  are 
  in 
  Segment 
  XIII, 
  in 
  front 
  

   of 
  the 
  line 
  of 
  ventral 
  chsetse. 
  

  

  Thus, 
  the 
  three 
  pores 
  are 
  unusually 
  close 
  together 
  : 
  and 
  

   the 
  body 
  of 
  the 
  preserved 
  worm 
  is 
  nearly 
  always 
  abruptly 
  

   bent 
  at 
  the 
  thirteenth 
  segment. 
  

  

  Internal 
  Anatomy. 
  

  

  The 
  alimentary 
  canal 
  presents 
  no 
  noteworthy 
  features; 
  the 
  

   buccal 
  region 
  is 
  very 
  short 
  ; 
  and 
  the 
  pharynx 
  occupies 
  part 
  of 
  

   Segment 
  II 
  and 
  the 
  whole 
  of 
  Segment 
  III. 
  Its 
  roof 
  is 
  pouched, 
  

   and 
  the 
  musculatui'e 
  is 
  but 
  feeble. 
  It 
  is 
  remarkable 
  that 
  in 
  

  

  