﻿314 
  W. 
  BLAXLAND 
  BENHAM. 
  

  

  tion, 
  that 
  is, 
  in 
  which 
  a 
  nephridial 
  funnel, 
  if 
  it 
  were 
  present, 
  

   would 
  lie; 
  in 
  other 
  words, 
  the 
  duct 
  does 
  not 
  issue 
  from 
  the 
  

   centre 
  of 
  the 
  funnel 
  as 
  in 
  the 
  sperm-ducts 
  of 
  other 
  Oligo- 
  

   chastes. 
  And 
  I 
  suggest 
  that 
  in 
  this 
  worm 
  we 
  have 
  such 
  a 
  

   composite 
  organ 
  as 
  Goodrich 
  has 
  described 
  in 
  sevei-al 
  of 
  the 
  

   Polychsetes 
  (e. 
  g. 
  Goniada, 
  Phyllodocids, 
  Syllids), 
  and 
  to 
  

   which 
  Lankester 
  gives 
  tlie 
  name 
  " 
  nephromixium." 
  

  

  In 
  connection 
  with 
  the 
  mode 
  of 
  origin 
  of 
  the 
  sperm-duct 
  from 
  

   its 
  ccelomostome, 
  it 
  is 
  ratlier 
  remarkable 
  how 
  little 
  we 
  really 
  

   know 
  ; 
  and 
  it 
  is 
  as 
  well 
  to 
  insist 
  upon 
  this 
  absence 
  of 
  know- 
  

   ledge, 
  and 
  to 
  note 
  precisely 
  how 
  far 
  embryologists 
  have 
  traced 
  

   (a) 
  the 
  development 
  of 
  the 
  genital 
  funnel, 
  and 
  (b) 
  the 
  deve- 
  

   lopment 
  of 
  the 
  duct 
  from 
  this 
  funnel. 
  

  

  Vejdovsky 
  (15) 
  has 
  put 
  on 
  record 
  the 
  general 
  course 
  of 
  the 
  

   history 
  for 
  Chfetogaster, 
  and 
  in 
  less 
  detail 
  for 
  certain 
  other 
  

   genera 
  in 
  which, 
  he 
  says, 
  the 
  same 
  course 
  is 
  followed. 
  The 
  

   genital 
  funnel 
  appears 
  as 
  a 
  thickening 
  of 
  the 
  peritoneal 
  cells 
  

   on 
  the 
  anterior 
  face 
  of 
  the 
  septum, 
  and 
  the 
  genital 
  duct 
  

   grows 
  back 
  from 
  it 
  as 
  a 
  solid 
  cord 
  of 
  cells 
  ; 
  this 
  cord 
  reaches 
  

   the 
  epidermis 
  and 
  becomes 
  hollowed 
  out 
  to 
  form 
  a 
  tube. 
  

  

  In 
  Chtetogaster 
  the 
  nephridinm 
  has 
  no 
  funnel 
  ; 
  but 
  in 
  

   Stylaria 
  lacustris, 
  which 
  he 
  proceeds 
  to 
  describe 
  (p. 
  129), 
  

   he 
  finds 
  that, 
  first 
  of 
  all 
  the 
  nephridium 
  of 
  this 
  segment, 
  VI, 
  

   gradually 
  undergoes 
  a 
  retrogressive 
  metamorphosis, 
  breaking 
  

   up 
  into 
  cells, 
  which 
  separate 
  till 
  nothing 
  but 
  the 
  nephridial 
  

   funnel 
  I'emains 
  on 
  the 
  anterior 
  face 
  of 
  the 
  Septum 
  V/VI. 
  

   This, 
  he 
  says, 
  persists 
  for 
  a 
  long 
  time. 
  His 
  next 
  stage 
  

   figured 
  represents 
  the 
  flat, 
  thick, 
  genital 
  funnel 
  in 
  place 
  of 
  

   the 
  small 
  nephridial 
  funnel. 
  He 
  does 
  not 
  state 
  in 
  so 
  many 
  

   words 
  that 
  the 
  latter 
  goes 
  entirely, 
  and 
  it 
  is 
  possible, 
  in 
  the 
  

   light 
  of 
  Bergh's 
  researches, 
  that 
  it 
  may 
  contribute 
  to 
  the 
  

   formation 
  of 
  the 
  genital 
  funnel. 
  

  

  At 
  any 
  rate, 
  there 
  is 
  apparently 
  no 
  doubt, 
  in 
  spite 
  of 
  what 
  

   Roule 
  later 
  on 
  suggests, 
  that 
  a 
  nephi'idium 
  lies 
  at 
  first 
  in 
  

   the 
  segment, 
  then 
  disappeai's 
  ; 
  that 
  the 
  genital 
  funnel 
  is 
  

   formed 
  from 
  the 
  ccelomic 
  epithelium, 
  and 
  gives 
  rise 
  to 
  the 
  

   genital 
  duct. 
  

  

  