﻿NO. 
  1950. 
  CRUSTACEAN 
  PARASITES 
  OF 
  FISH 
  AND 
  CRABS— 
  WILSON. 
  269 
  

  

  In 
  view 
  of 
  these 
  statements 
  it 
  will 
  be 
  of 
  special 
  interest 
  to 
  record 
  

   the 
  discovery 
  of 
  a 
  new 
  species 
  of 
  Cypridina, 
  parasitic 
  upon 
  the 
  gills 
  

   of 
  several 
  kinds 
  of 
  fish. 
  

  

  That 
  the 
  presence 
  of 
  these 
  ostracods 
  on 
  the 
  fishes' 
  gills 
  was 
  not 
  

   accidental 
  is 
  abundantly 
  proven 
  by 
  the 
  following 
  considerations: 
  

   First 
  there 
  were 
  too 
  many 
  of 
  them; 
  one 
  or 
  two 
  or 
  half 
  a 
  dozen 
  might 
  

   be 
  washed 
  on 
  to 
  the 
  gills 
  of 
  a 
  fish 
  accidentally, 
  but 
  not 
  40 
  or 
  50. 
  

   Again 
  they 
  were 
  arranged 
  altogether 
  too 
  regularly; 
  in 
  the 
  space 
  be- 
  

   tween 
  the 
  bases 
  of 
  two 
  adjacent 
  filaments 
  and 
  in 
  contact 
  with 
  the 
  gill 
  

   arch, 
  there 
  was 
  always 
  a 
  single 
  ostracod, 
  its 
  long 
  diameter 
  at 
  right 
  

   angles 
  to 
  the 
  gill 
  arch, 
  so 
  that 
  its 
  anterior 
  end 
  projected 
  slightly 
  on 
  one 
  

   side 
  between 
  the 
  filaments, 
  and 
  its 
  posterior 
  end 
  on 
  the 
  other 
  side. 
  

  

  Furthermore 
  the 
  tissues 
  of 
  each 
  filament 
  where 
  they 
  came 
  in 
  con- 
  

   tact 
  with 
  the 
  shell 
  of 
  the 
  ostracod, 
  were 
  hollowed 
  out 
  in 
  the 
  center 
  

   and 
  slightly 
  raised 
  around 
  the 
  edges, 
  thus 
  forming 
  a 
  sort 
  of 
  pocket, 
  

   which 
  held 
  the 
  ostracod 
  securely 
  in 
  place 
  so 
  that 
  it 
  could 
  be 
  removed 
  

   only 
  ^\•ith 
  a 
  paii' 
  of 
  forceps. 
  This 
  of 
  course 
  is 
  absolute 
  proof 
  that 
  

   the 
  ostracod 
  was 
  not 
  washed 
  in 
  temporarily, 
  but 
  that 
  it 
  had 
  remained 
  

   in 
  position 
  long 
  enough 
  to 
  produce 
  this 
  eftect 
  on 
  the 
  tissues. 
  In 
  

   view 
  of 
  such 
  conditions 
  these 
  ostracods 
  may 
  fairly 
  be 
  called 
  parasitic. 
  

   While 
  it 
  is 
  impossible 
  to 
  see 
  how 
  they 
  can 
  draw 
  any 
  blood 
  from 
  the 
  

   fish's 
  gills, 
  3^et 
  they 
  certainly 
  share 
  the 
  oxygenated 
  water 
  with 
  which 
  

   the 
  fish 
  keeps 
  its 
  gills 
  supplied, 
  and 
  they 
  get 
  their 
  food 
  in 
  some 
  way 
  

   while 
  there. 
  For 
  food 
  they 
  may 
  devour 
  anything 
  that 
  the 
  water 
  

   contains 
  and 
  brings 
  to 
  them, 
  they 
  may 
  eat 
  scraps 
  of 
  the 
  fish's 
  food 
  

   that 
  come 
  their 
  way, 
  or 
  they 
  may 
  feed 
  on 
  the 
  slime 
  with 
  which 
  the 
  

   fish's 
  gills 
  are 
  covered. 
  It 
  is 
  impossible 
  to 
  determine 
  at 
  present 
  

   just 
  what 
  does 
  constitute 
  their 
  diet. 
  

  

  CYPRIDINA 
  PARASITICA, 
  new 
  species. 
  

   Plate 
  53. 
  

  

  Host 
  and 
  record 
  of 
  specimens. 
  — 
  Five 
  lots 
  of 
  this 
  ostracod 
  were 
  ob- 
  

   tained 
  in 
  all; 
  two 
  of 
  these 
  were 
  taken 
  from 
  the 
  gills 
  of 
  two 
  hammer- 
  

   head 
  sharks, 
  SpTiyrna 
  zygsena, 
  on 
  July 
  9, 
  and 
  include 
  about 
  50 
  speci- 
  

   mens 
  each. 
  They 
  have 
  received 
  the 
  numbers 
  43581 
  and 
  43586, 
  

   U.S.N.M., 
  and 
  become 
  paratypes 
  of 
  the 
  new 
  species. 
  The 
  third 
  lot 
  

   contains 
  a 
  single 
  specimen 
  found 
  on 
  the 
  gills 
  of 
  Epinephelus 
  adscen- 
  

   sionis, 
  August 
  9, 
  and 
  is 
  numbered 
  43599, 
  U.S.N.M. 
  

  

  The 
  fourth 
  lot 
  contains 
  three 
  specimens 
  taken 
  from 
  the 
  gills 
  of 
  

   a 
  jack, 
  Caranx 
  crysos, 
  August 
  1, 
  and 
  is 
  numbered 
  43604, 
  U.S.N.M. 
  

   The 
  fifth 
  lot 
  contains 
  12 
  specimens 
  and 
  was 
  obtained 
  from 
  the 
  nasal 
  

   tubes 
  of 
  the 
  hammer-head 
  shark 
  on 
  June 
  17, 
  and 
  is 
  numbered 
  

   43603, 
  U.S.N.M. 
  

  

  Type-specimen. 
  — 
  Male, 
  Cat. 
  No. 
  43508, 
  U.S.N.M., 
  from 
  one 
  of 
  the 
  

   hammer-head 
  sharks. 
  

  

  