﻿70 
  W. 
  B. 
  IJANDLKS. 
  

  

  asserts 
  that 
  iti 
  addition 
  to 
  the 
  functional 
  kidney 
  which 
  is 
  

   sitnated 
  to 
  the 
  riglit 
  of 
  tlie 
  anus 
  before 
  torsion 
  there 
  is 
  

   present 
  a 
  rudiment 
  of 
  tlie 
  actmil 
  right 
  kidney 
  ]yiui>- 
  to 
  the 
  

   left 
  of 
  the 
  anus 
  before 
  torsion. 
  

  

  This 
  observation, 
  however, 
  as 
  Woodward 
  remarks 
  (45, 
  p. 
  

   260), 
  loses 
  its 
  value 
  when 
  we 
  consider 
  that 
  this 
  so-called 
  

   rudiment 
  of 
  a 
  right 
  kidney 
  is 
  only 
  apparent 
  as 
  a 
  slight 
  out- 
  

   growth 
  of 
  the 
  pericardium 
  which 
  quickly 
  loses 
  its 
  identity 
  

   without 
  ever 
  showing 
  any 
  indication 
  of 
  the 
  character 
  of 
  a 
  

   true 
  kidney. 
  

  

  On 
  the 
  other 
  hand, 
  Perrier 
  (37) 
  seeks 
  to 
  homologise 
  the 
  

   single 
  kidney 
  of 
  the 
  Monotocardia 
  with 
  both 
  kidneys 
  

   of 
  the 
  Diotocardia, 
  comparing 
  the 
  true 
  excretory 
  portion 
  

   with 
  the 
  right 
  kidney 
  and 
  the 
  neph 
  ridial 
  gland 
  with 
  the 
  

   left 
  kidney 
  or 
  papillary 
  sac. 
  Thus 
  he 
  considers 
  that 
  the 
  two 
  

   distinct 
  kidneys 
  of 
  the 
  Diotocardia 
  have 
  been 
  united 
  to 
  form 
  

   the 
  single 
  excretory 
  organ 
  of 
  the 
  Monotocardia. 
  

  

  Woodward 
  also 
  supports 
  this 
  view, 
  and, 
  mentioning 
  that 
  

   through 
  suppi'ession 
  of 
  the 
  right 
  gill 
  the 
  two 
  kidneys 
  of 
  

   the 
  nzygobranchiate 
  Diotocardia 
  approach 
  each 
  other 
  very 
  

   closely, 
  he 
  suggests 
  that 
  in 
  early 
  Monotocardia 
  a 
  connection 
  

   between 
  these 
  two 
  kidneys 
  was 
  formed, 
  thus 
  enabling 
  the 
  

   excretory 
  products 
  of 
  the 
  right 
  kidney 
  to 
  pass 
  through 
  the 
  

   left 
  kidney 
  and 
  so 
  to 
  the 
  exterior, 
  while 
  the 
  right 
  kidney- 
  

   duct, 
  serving 
  for 
  the 
  transmission 
  of 
  the 
  genital 
  products, 
  

   would 
  eventually 
  become 
  comjjletely 
  separated 
  from 
  the 
  

   kidney 
  and 
  function 
  entirely 
  as 
  a 
  genital 
  duct, 
  the 
  glandular 
  

   portion 
  oP 
  the 
  papillary 
  sac 
  then 
  degenerating 
  and 
  remaining 
  

   only 
  as 
  the 
  nephridial 
  or 
  renal 
  ghnid 
  of 
  the 
  Monotocardia. 
  

  

  Haller 
  (21) 
  also 
  maintained 
  the 
  view 
  that 
  the 
  kidney 
  of 
  

   the 
  Monotocardia 
  was 
  the 
  homologue 
  of 
  the 
  right 
  kidney 
  of 
  

   the 
  Diotocardia, 
  aud 
  in 
  Turbo 
  described 
  the 
  presence 
  of 
  a 
  

   connection 
  between 
  the 
  right 
  and 
  left 
  kidneys 
  (21, 
  figs. 
  26, 
  

   28). 
  This 
  observation 
  is, 
  however, 
  erroneous. 
  In 
  Ampul- 
  

   laria 
  Bouvier 
  (7) 
  has 
  described 
  the 
  presence 
  of 
  two 
  kidneys 
  

   which 
  are 
  in 
  communication 
  with 
  one 
  another, 
  one 
  of 
  them 
  

   corresponding 
  to 
  the 
  right 
  and 
  the 
  other 
  to 
  tlie 
  left 
  kidney 
  

  

  