﻿NO. 
  1950. 
  CRUSTACEAN 
  PARASITES 
  OF 
  FISH 
  AND 
  CRABS— 
  WILSON. 
  241 
  

  

  In 
  connection 
  with 
  tliis 
  species 
  the 
  author 
  had 
  an 
  unusual 
  and 
  

   very 
  interesting 
  experience. 
  When 
  first 
  obtained 
  none 
  of 
  the 
  females 
  

   had 
  any 
  portion 
  of 
  their 
  egg-strings, 
  but 
  two 
  of 
  them 
  extruded 
  their 
  

   eggs 
  while 
  being 
  examined 
  under 
  the 
  microscope. 
  

  

  The 
  conditions 
  were 
  artificial, 
  to 
  be 
  sure, 
  and 
  yet 
  the 
  method 
  was 
  

   suggestive 
  and 
  well 
  worth 
  recording. 
  The 
  two 
  females 
  writhed 
  

   convulsively 
  for 
  some 
  time, 
  contracting 
  the 
  longitudinal 
  body 
  mus- 
  

   cles 
  with 
  especial 
  violence. 
  So 
  vigorous 
  were 
  these 
  convulsions 
  

   that 
  at 
  first 
  it 
  was 
  supposed 
  some 
  chemical 
  had 
  gotten 
  into 
  the 
  sea 
  

   water 
  in 
  the 
  watch 
  glass, 
  but 
  this 
  was 
  afterwards 
  conclusively 
  dis- 
  

   proved. 
  The 
  cement 
  glands 
  were 
  the 
  first 
  to 
  respond, 
  and 
  they 
  

   poured 
  out 
  enough 
  of 
  their 
  secretion 
  to 
  form 
  a 
  pair 
  of 
  empty 
  cases 
  

   the 
  full 
  length 
  of 
  the 
  completed 
  egg-strings. 
  These 
  were 
  narrow, 
  

   hollow, 
  elastic, 
  and 
  tapered 
  to 
  a 
  sharp 
  point 
  at 
  their 
  tips. 
  Into 
  

   these 
  the 
  eggs 
  were 
  forced, 
  one 
  at 
  a 
  time, 
  each 
  egg 
  requiring 
  severe 
  

   contraction 
  to 
  force 
  it 
  through 
  the 
  external 
  opening 
  of 
  the 
  oviduct. 
  

   As 
  it 
  issued 
  into 
  the 
  external 
  case 
  it 
  distended 
  the 
  latter 
  consider- 
  

   ably, 
  thereby 
  proving 
  it 
  to 
  be 
  elastic.- 
  The 
  first 
  egg 
  remained 
  close 
  

   to 
  the 
  genital 
  segment 
  until 
  it 
  was 
  pushed 
  along 
  by 
  the 
  extrusion 
  of 
  

   the 
  second 
  one, 
  and 
  this 
  by 
  the 
  third, 
  and 
  so 
  on. 
  The 
  tip 
  of 
  the 
  

   case 
  remained 
  all 
  the 
  while 
  much 
  narrower 
  than 
  the 
  part 
  filled 
  by 
  

   the 
  eggs, 
  and 
  was 
  sharply 
  pointed 
  untU 
  finally 
  the 
  first 
  egg 
  was 
  

   pushed 
  back 
  into 
  it 
  and 
  rounded 
  it 
  out 
  into 
  its 
  usual 
  form. 
  

  

  So 
  far 
  as 
  known 
  the 
  extrusion 
  of 
  the 
  egg 
  cases 
  has 
  never 
  before 
  

   been 
  witnessed 
  among 
  the 
  Dichelestiidse, 
  and 
  from 
  it 
  we 
  may 
  deduce 
  

   the 
  following 
  : 
  

  

  1. 
  The 
  cement 
  substance 
  which 
  forms 
  the 
  external 
  case 
  is 
  not 
  

   extruded 
  piecemeal 
  along 
  with 
  each 
  egg, 
  but 
  the 
  full 
  amount 
  neces- 
  

   sary 
  to 
  form 
  the 
  case 
  is 
  pushed 
  out 
  before 
  any 
  egg 
  is 
  laid, 
  and 
  has 
  a 
  

   chance 
  to 
  stiffen 
  somewhat 
  in 
  contact 
  with 
  the 
  sea 
  water 
  before 
  the 
  

   first 
  egg 
  enters 
  it. 
  

  

  2. 
  The 
  bag 
  thus 
  formed 
  previous 
  to 
  the 
  issuance 
  of 
  the 
  eggs 
  is 
  not 
  

   smooth; 
  each 
  muscular 
  contraction 
  seems 
  to 
  push 
  out 
  a 
  certain 
  

   amount 
  of 
  the 
  substance, 
  approximately 
  enough 
  to 
  cover 
  one 
  egg, 
  

   and 
  between 
  these 
  successive 
  portions 
  the 
  bag 
  is 
  slightly 
  constricted, 
  

   making 
  it 
  appear 
  segmented. 
  

  

  3. 
  The 
  bag 
  is 
  but 
  little 
  more 
  than 
  half 
  the 
  diameter 
  of 
  the 
  eggs 
  

   and 
  tapers 
  to 
  a 
  sharp 
  point 
  at 
  its 
  tip; 
  hence 
  it 
  must 
  stretch 
  as 
  the 
  

   eggs 
  are 
  pushed 
  into 
  it. 
  At 
  first 
  it 
  appears 
  to 
  be 
  quite 
  elastic, 
  but 
  

   loses 
  this 
  quality 
  ydih 
  every 
  successive 
  stretching 
  and 
  soon 
  remains 
  

   distended 
  so 
  that 
  the 
  eggs 
  slip 
  along 
  through 
  it 
  easily. 
  

  

  4. 
  Each 
  egg 
  remains 
  close 
  to 
  the 
  body 
  until 
  pushed 
  backward 
  by 
  

   the 
  issuance 
  of 
  the 
  next 
  one, 
  the 
  tip 
  of 
  the 
  bag 
  hanging 
  loosely 
  like 
  

   the 
  finger 
  of 
  a 
  glove 
  that 
  is 
  being 
  put 
  on 
  for 
  the 
  first 
  time. 
  

  

  69077°— 
  Proc.N.M.vol.44— 
  13 
  16 
  

  

  