﻿Misce 
  Uaneous. 
  1 
  ~> 
  5 
  

  

  has 
  reached 
  a 
  considerable 
  size. 
  Morphologically 
  both 
  forms 
  of 
  

   metamorphosis 
  are 
  identical 
  ; 
  but 
  while 
  certain 
  structures, 
  as, 
  for 
  

   instance, 
  parts 
  of 
  the 
  calcareous 
  framework 
  of 
  the 
  pluteus, 
  are 
  recog- 
  

   nizable, 
  a 
  nomadic 
  pluteus 
  is 
  never 
  formed 
  in 
  this 
  genus. 
  

  

  In 
  collecting 
  adult 
  Amphiuraus 
  in 
  order 
  to 
  discover 
  new 
  stages 
  

   in 
  the 
  development 
  of 
  the 
  young 
  my 
  attention 
  was 
  often 
  attracted 
  

   to 
  certain 
  adults 
  of 
  this 
  genus 
  in 
  which 
  a 
  portion 
  of 
  the 
  upper 
  

   (aboral) 
  surface 
  of 
  the 
  body 
  has 
  a 
  reddish 
  colour, 
  while 
  in 
  most 
  

   specimens 
  the 
  body 
  is 
  chocolate-brown. 
  This 
  coloration 
  was 
  noticed 
  

   to 
  be 
  ordinarily 
  limited 
  to 
  a 
  marginal 
  region 
  of 
  the 
  body 
  just 
  be- 
  

   tween 
  the 
  radial 
  shields. 
  

  

  It 
  was 
  invariably 
  found, 
  when 
  those 
  adult 
  AmpJiiuroe 
  with 
  red- 
  

   dish 
  coloration 
  on 
  the 
  aboral 
  surface 
  of 
  the 
  body 
  were 
  dissected, 
  

   that 
  young 
  were 
  absent 
  from 
  the 
  brood-sacs. 
  It 
  was, 
  moreover, 
  

   almost 
  invariably 
  found 
  that 
  in 
  these 
  adults 
  the 
  ovary 
  had 
  suffered 
  

   a 
  change 
  and 
  had 
  degenerated 
  into 
  an 
  amorphous 
  mass 
  in 
  which 
  

   ova 
  were 
  not 
  recognizable. 
  In 
  the 
  brood-sacs 
  of 
  such, 
  instead 
  of 
  

   young 
  Amphiura 
  there 
  were 
  found 
  small 
  packets 
  of 
  pink-coloured 
  

   ova, 
  which, 
  when 
  seen 
  through 
  the 
  wall 
  of 
  the 
  body, 
  impart 
  the 
  

   reddish 
  colour 
  to 
  the 
  aboral 
  body-wall. 
  In 
  addition 
  to 
  these 
  packets 
  

   of 
  ova 
  it 
  was 
  likewise 
  found 
  that 
  t 
  lie 
  brood- 
  cavities 
  of 
  many 
  of 
  the 
  

   specimens 
  thus 
  abnormally 
  coloured 
  harboured 
  a 
  small 
  Crustacean. 
  

   In 
  an 
  examination 
  of 
  the 
  pinkish 
  clusters 
  of 
  ova 
  in 
  the 
  brood-sac 
  

   of 
  the 
  Amphiura 
  it 
  was 
  discovered 
  that 
  they 
  are 
  in 
  all 
  conditions 
  

   of 
  growth 
  from 
  the 
  first 
  stages 
  of 
  segmentation 
  into 
  a 
  well-formed 
  

   Nauplius. 
  Young 
  Crustaceans 
  free 
  from 
  the 
  packet 
  of 
  ova 
  were 
  

   also 
  found 
  in 
  great 
  numbers 
  in 
  the 
  brood-sacs. 
  These 
  adults 
  were 
  

   identified 
  as 
  belonging 
  to 
  the 
  group 
  of 
  Crustacea 
  called 
  the 
  Cope- 
  

   poda. 
  

  

  An 
  interpretation 
  of 
  the 
  above 
  facts 
  seems 
  to 
  be 
  that 
  we 
  have 
  

   here 
  a 
  strange 
  instance 
  of 
  parasitism. 
  It 
  is 
  also 
  thought 
  to 
  be 
  

   unique 
  among 
  the 
  Echinoderms. 
  Although 
  many 
  genera 
  of 
  para- 
  

   sitic 
  Copepods 
  are 
  known, 
  I 
  am 
  not 
  familiar 
  with 
  recorded 
  instances 
  

   where 
  these 
  parasitic 
  Crustaceans 
  enter 
  the 
  brood-sac 
  of 
  an 
  Am- 
  

   phiura 
  and 
  destroy 
  the 
  virility 
  of 
  its 
  host 
  for 
  the 
  good 
  of 
  its 
  own 
  

   offspring. 
  Many 
  instances 
  of 
  Crustacean 
  parasites 
  castrating 
  other 
  

   Crustaceans 
  have 
  been 
  recorded 
  by 
  Giard 
  ; 
  but 
  in 
  these 
  cases 
  it 
  has 
  

   not 
  been 
  shown 
  that 
  the 
  castration 
  of 
  the 
  host 
  is 
  a 
  direct 
  benefit 
  to 
  

   the 
  offspring 
  of 
  the 
  parasite 
  itself. 
  In 
  Amphiura, 
  however, 
  we 
  

   have 
  a 
  condition 
  where 
  we 
  can 
  legitimately 
  conclude 
  that 
  the 
  

   amorphous 
  condition 
  of 
  the 
  ovary 
  of 
  the 
  Amphiura 
  is 
  the 
  direct 
  

   result 
  of 
  the 
  presence 
  of 
  the 
  mother 
  Crustacean 
  in 
  the 
  brood-cavity 
  

   of 
  the 
  Amphiura. 
  We 
  may 
  suppose 
  that 
  the 
  parent 
  of 
  the 
  Crusta- 
  

   cean 
  made 
  her 
  way 
  through 
  the 
  genital 
  slits 
  of 
  the 
  Echinoderm 
  into 
  

   the 
  brood-sacs, 
  and 
  there 
  spayed 
  the 
  Amphiura. 
  Packets 
  of 
  the 
  

   ova 
  were 
  left 
  in 
  the 
  brood-sacs 
  to 
  develop. 
  With 
  the 
  destruc- 
  

   tion 
  of 
  the 
  possibility 
  of 
  offspring 
  in 
  Amphiura 
  within 
  her 
  own 
  

   brood-sacs 
  the 
  future 
  life 
  of 
  the 
  young 
  Crustacea 
  was 
  assured, 
  and 
  

  

  