﻿1874.] 
  On 
  the 
  Brain 
  and 
  Skull 
  of 
  Amphioxus 
  lanceolatus. 
  127 
  

  

  Iu 
  the 
  discussion 
  of 
  oceanic 
  phenomena 
  too 
  much 
  attention 
  is 
  usually 
  

   paid 
  to 
  the 
  great 
  currents. 
  When 
  it 
  is 
  wished 
  to 
  study 
  the 
  phenomena 
  

   due 
  to 
  temperature, 
  or 
  to 
  any 
  single 
  cause, 
  the 
  effect 
  of 
  the 
  winds, 
  which 
  

   is 
  seen 
  in 
  its 
  most 
  intense 
  form 
  in 
  the 
  ocean-currents, 
  should 
  be 
  elimi- 
  

   nated 
  as 
  far 
  as 
  possible 
  ; 
  which 
  in 
  this 
  case 
  can 
  only 
  be 
  done 
  by 
  selecting 
  

   comparatively 
  motionless 
  seas, 
  like 
  the 
  one 
  which 
  I 
  have 
  mentioned 
  in 
  

   the 
  North 
  Atlantic*. 
  When 
  the 
  effect 
  of 
  atmospheric 
  climate 
  has 
  been 
  

   studied 
  on 
  the 
  ocean 
  at 
  large, 
  it 
  would 
  then 
  be 
  proper 
  to 
  apply 
  the 
  

   experience 
  gained 
  to 
  the 
  consideration 
  of 
  the 
  more 
  complicated 
  phe- 
  

   nomena 
  of 
  the 
  currents. 
  

  

  I 
  am 
  at 
  present 
  engaged 
  in 
  a 
  detailed 
  consideration 
  of 
  the 
  temperature 
  

   and 
  specific 
  gravity 
  results, 
  principally 
  in 
  the 
  direction 
  above 
  indicated, 
  

   and 
  hope 
  shortly 
  to 
  be 
  able 
  to 
  send 
  it 
  home 
  for 
  publication. 
  

  

  III. 
  u 
  Preliminary 
  Note 
  upon 
  the 
  Brain 
  and 
  Skull 
  of 
  Amphioxus 
  

   lanceolatus" 
  By 
  T. 
  H. 
  Huxley, 
  Sec. 
  R.S. 
  Received 
  De- 
  

   cember 
  17 
  3 
  1874. 
  

  

  The 
  singular 
  little 
  fish 
  Amphioxus 
  lanceolatus 
  has 
  been 
  universally 
  

   regarded 
  as 
  an 
  extremely 
  anomalous 
  member 
  of 
  the 
  Vertebrate 
  series, 
  by 
  

   reason 
  of 
  the 
  supposed 
  absence 
  of 
  renal 
  organs 
  and 
  of 
  any 
  proper 
  

   skull 
  and 
  brain. 
  'On 
  these 
  grounds, 
  chiefly, 
  Agassiz 
  proposed 
  to 
  separate 
  

   it 
  from 
  all 
  other 
  fishes, 
  and 
  Haeckel, 
  going 
  further, 
  made 
  a 
  distinct 
  divi- 
  

   sion 
  of 
  the 
  Vertebrata 
  (^cramYt) 
  for 
  its 
  reception 
  ; 
  while 
  Semper 
  t, 
  in 
  a 
  lately 
  

   published 
  paper, 
  separates 
  it 
  from 
  the 
  Vertebrata 
  altogether. 
  

  

  In 
  a 
  recent 
  communication 
  to 
  the 
  Linnean 
  Society, 
  I 
  have 
  described 
  

   what 
  I 
  believe 
  to 
  be 
  the 
  representative 
  of 
  the 
  ducts 
  of 
  the 
  Wolffian 
  bodies, 
  

   or 
  " 
  primordial 
  kidneys 
  " 
  of 
  the 
  higher 
  Vertebrata, 
  in 
  Amphioxus 
  ; 
  and 
  I 
  

   propose, 
  in 
  this 
  preliminary 
  notice, 
  to 
  point 
  out 
  that 
  although 
  Amphioxus 
  

   has 
  no 
  completely 
  differentiated 
  brain 
  or 
  skull, 
  yet 
  it 
  possesses 
  very 
  well- 
  

   marked 
  and 
  relatively 
  large 
  divisions 
  of 
  the 
  cerebro-spinal 
  nervous 
  axis 
  

   and 
  of 
  the 
  spinal 
  column, 
  which 
  answer 
  to 
  the 
  encephalon 
  and 
  the 
  

   cranium 
  of 
  the 
  higher 
  Vertebrata. 
  

  

  The 
  oral 
  aperture 
  of 
  Amphioxus 
  is 
  large, 
  of 
  a 
  long 
  oval 
  shape, 
  and 
  

  

  * 
  It 
  will 
  be 
  seen 
  that 
  the 
  principle 
  that 
  the 
  depth 
  to 
  which 
  the 
  effect 
  of 
  the 
  sun's 
  

   rays 
  penetrates 
  depends 
  on 
  the 
  yearly 
  range 
  of 
  temperature 
  of 
  the 
  water 
  at 
  the 
  sur- 
  

   face, 
  explains 
  the 
  presence 
  of 
  the 
  large 
  body 
  of 
  comparatively 
  warm 
  water 
  in 
  the 
  North 
  

   Atlantic, 
  the 
  existence 
  of 
  which 
  has 
  been 
  usually 
  ascribed 
  to 
  an 
  assumed 
  reflux 
  or 
  back 
  

   water 
  of 
  the 
  Gulf 
  -stream. 
  The 
  warm 
  water 
  is 
  due 
  to 
  no 
  extraneous 
  cause, 
  but 
  is 
  

   the 
  natural 
  effect 
  of 
  the 
  conditions 
  of 
  climate 
  at 
  the 
  surface 
  ; 
  and 
  the 
  effect 
  of 
  these 
  

   conditions 
  of 
  climate 
  are 
  so 
  apparent 
  in 
  the 
  temperature 
  of 
  the 
  water, 
  just 
  because 
  it 
  

   is 
  free 
  from 
  the 
  influence 
  of 
  oceanic 
  currents 
  and 
  exposed 
  to 
  the 
  effects 
  of 
  climate 
  

   alone. 
  

  

  t 
  " 
  Die 
  Stammverwandtschaft 
  der 
  Wirbelthiere 
  und 
  Wirbellosen," 
  Arbeiten 
  aus 
  dem 
  

   zool.-zootom. 
  Institut 
  in 
  Wiirzburg, 
  Bd. 
  ii. 
  1874, 
  p. 
  42. 
  

  

  l2 
  

  

  