﻿SOME 
  NEW 
  SPECIES 
  OF 
  THE 
  GENUS 
  PHBEODEILUS. 
  295 
  

  

  r. 
  VI. 
  Radiating 
  muscle-fibres 
  traversing 
  the 
  cavity 
  of 
  tlie 
  atrial 
  sac. 
  s. 
  Septum. 
  

   s.d. 
  Sperm-duct, 
  splh. 
  Aperture 
  of 
  spermatheca, 
  t. 
  m. 
  Retractor 
  muscles 
  of 
  

   penial 
  sac. 
  r. 
  Ventral 
  cliselse. 
  .r. 
  Point 
  of 
  union 
  of 
  sperm-duct 
  and 
  spermi- 
  

   ducal 
  gland, 
  y. 
  Folding 
  of 
  atrial 
  epithelium 
  at 
  the 
  penis, 
  z. 
  Transverse 
  

   fold 
  of 
  the 
  epithelium 
  of 
  the 
  penial 
  sac. 
  ^J 
  Male 
  pore. 
  ? 
  Orifice 
  of 
  oviduct. 
  

  

  Figs. 
  1 
  fo 
  10 
  illustrate 
  the 
  anatomy 
  of 
  Phreodrilus 
  lacustris, 
  n. 
  sp. 
  

   Fig. 
  11 
  refers 
  to 
  P. 
  mauiensis, 
  n. 
  sp. 
  

   Figs. 
  12 
  to 
  28 
  refer 
  to 
  P. 
  beddardi, 
  n. 
  sp. 
  

  

  Fig. 
  1. 
  — 
  Side 
  view 
  of 
  anterior 
  extremity 
  of 
  P. 
  lacustris. 
  x 
  40, 
  camera. 
  

   Note 
  the 
  conical 
  form 
  of 
  prostomium, 
  the 
  absence 
  of 
  dorsal 
  chsetse 
  on 
  Seg- 
  

   ment 
  II 
  and 
  the 
  annulation 
  of 
  the 
  segments. 
  

  

  Fig. 
  2. 
  — 
  The 
  two 
  ventral 
  chaetse 
  of 
  a 
  bundle. 
  X 
  G40. 
  («) 
  The 
  simple 
  

   form 
  ; 
  {b) 
  the 
  toothed 
  one. 
  

  

  Fig. 
  3. 
  — 
  The 
  spermathecal 
  pore 
  and 
  copulatory 
  chajtse 
  of 
  Segment 
  XIII, 
  as 
  

   seen 
  in 
  a 
  transparent 
  specimen. 
  

  

  Fig. 
  4. 
  — 
  Ventral 
  view 
  of 
  Segments 
  X 
  to 
  XIV, 
  to 
  show 
  the 
  clitellum 
  and 
  

   genital 
  pores; 
  the 
  former 
  is 
  shaded. 
  Ou 
  the 
  right 
  side 
  of 
  the 
  fiuure 
  the 
  

   penis 
  {p.) 
  is 
  represented 
  as 
  being 
  protruded 
  from 
  the 
  male 
  pore 
  [^). 
  The 
  

   ventral 
  cliaetge 
  are 
  absent 
  in 
  XII, 
  XIII, 
  but 
  in 
  latter 
  are 
  replaced 
  by 
  copulatory 
  

   chsetae 
  {cp.). 
  $ 
  oviducal 
  pore, 
  spt/i 
  Spermathecal 
  pore. 
  

  

  Fig. 
  5. 
  — 
  View 
  of 
  the 
  entire 
  male 
  efferent 
  apparatus, 
  constructed 
  from 
  

   sketches 
  of 
  the 
  opaque 
  and 
  transparent 
  preparations 
  of 
  the 
  isolated 
  organ. 
  

   The 
  apex 
  of 
  the 
  spermiducal 
  gland 
  {gl.) 
  is 
  slightly 
  shifted 
  from 
  its 
  true 
  

   position 
  near 
  the 
  septum, 
  so 
  as 
  to 
  exhibit 
  more 
  clearly 
  the 
  course 
  of 
  the 
  

   sperm-duct 
  {s. 
  d.) 
  ; 
  the 
  union 
  of 
  the 
  two 
  is 
  indicated 
  at 
  x. 
  The 
  wall 
  of 
  the 
  

   penial 
  sac 
  {p. 
  s.) 
  is 
  represented 
  as 
  being 
  transparent, 
  allowing 
  the 
  penis 
  {p.) 
  

   to 
  be 
  seen 
  ; 
  the 
  sac 
  is 
  still 
  attached 
  to 
  the 
  body-wall 
  at 
  the 
  male 
  aperture. 
  

  

  Fig. 
  6. 
  — 
  A 
  somewhat 
  diagrammatic 
  representation 
  of 
  the 
  penial 
  sac, 
  etc., 
  

   founded 
  on 
  the 
  study 
  of 
  the 
  organ 
  mounted 
  in 
  glycerine. 
  In 
  the 
  upper 
  part 
  

   of 
  the 
  sac 
  the 
  circular 
  coat 
  of 
  muscles 
  {m.) 
  is 
  in 
  focus 
  ; 
  in 
  the 
  middle 
  of 
  the 
  

   sac 
  the 
  bases 
  of 
  the 
  epithelial 
  cells 
  {e.) 
  are 
  shown 
  ; 
  while 
  lower 
  down 
  the 
  wall 
  

   is 
  in 
  optical 
  section, 
  so 
  that 
  the 
  cavity 
  {ps.) 
  is 
  in 
  view, 
  as 
  well 
  as 
  the 
  external 
  

   ej)ithelium 
  of 
  the 
  penis 
  itself. 
  The 
  terminal 
  region 
  of 
  the 
  penis 
  is 
  seen 
  in 
  

   optical 
  median 
  section, 
  which 
  brings 
  into 
  view 
  the 
  lumen 
  of 
  the 
  distal 
  part 
  of 
  

   the 
  atrium, 
  which 
  opens 
  near 
  the 
  tip 
  of 
  the 
  penis 
  at 
  o. 
  p. 
  

  

  Fig. 
  7. 
  — 
  A 
  median 
  longitudinal 
  section 
  along 
  the 
  penis 
  and 
  its 
  sac, 
  drawn 
  

   as 
  carefully 
  as 
  possible 
  under 
  Leitz, 
  oil 
  immersion, 
  -^^. 
  The 
  spermiducal 
  

   gland 
  {gl.) 
  is 
  seen 
  to 
  change 
  its 
  character 
  as 
  it 
  narrows 
  to 
  form 
  the 
  neck 
  («.), 
  

   into 
  which 
  the 
  sperm-duct 
  opens 
  (see 
  fig. 
  5). 
  This 
  neck 
  is 
  continued 
  through 
  

   the 
  penis, 
  and 
  corresponds 
  to 
  the 
  atrium 
  of 
  some 
  other 
  species. 
  The 
  longi- 
  

  

  