﻿Copepoda 
  from 
  the 
  Falkland 
  Islands, 
  377 
  

  

  their 
  appearances 
  have 
  at 
  times 
  been 
  frequently 
  noticed, 
  

   and 
  a 
  considerable 
  time 
  may 
  elapse 
  ere 
  they 
  are 
  again 
  met 
  

   with. 
  

  

  The 
  form 
  recorded 
  by 
  Dr. 
  Giesbrecht 
  in 
  his 
  account 
  of 
  

   the 
  Copepoda 
  collected 
  by 
  the 
  Belgian 
  Antarctic 
  Expedition, 
  

   already 
  referred 
  to, 
  was 
  obtained 
  in 
  a 
  plankton 
  sample 
  from 
  

   475 
  metres, 
  taken 
  in 
  lat. 
  69° 
  54' 
  S., 
  long. 
  82° 
  49' 
  W. 
  ; 
  only 
  

   a 
  single 
  specimen 
  was 
  observed. 
  This 
  specimen 
  was 
  a 
  male 
  

   and 
  is 
  smaller 
  than 
  those 
  from 
  the 
  Falkland 
  Islands, 
  which 
  

   appear 
  to 
  be 
  all 
  females 
  * 
  ; 
  but 
  although, 
  as 
  previously 
  stated^ 
  

   there 
  is 
  a 
  certain 
  resemblance 
  between 
  the 
  male 
  described 
  by 
  

   Dr. 
  Giesbrecht 
  and 
  those 
  from 
  the 
  Falklands, 
  I 
  am 
  unable^ 
  

   from 
  the 
  differences 
  observed, 
  to 
  regard 
  them 
  as 
  the 
  male 
  

   and 
  female 
  of 
  the 
  same 
  species. 
  

  

  Caligoida. 
  

   Genus 
  Caligus, 
  O. 
  F. 
  Miiller, 
  1785. 
  

  

  Caligus 
  tliynni, 
  Dana. 
  (PI. 
  XVI. 
  figs. 
  13, 
  14.) 
  

  

  A 
  single 
  specimen 
  of 
  a 
  Caligus, 
  which 
  appears 
  to 
  be 
  the 
  

   male 
  of 
  C. 
  thynni, 
  Dana, 
  was 
  captured 
  at 
  Roy 
  Cove, 
  Falkland 
  

   Islands, 
  in 
  3 
  fathoms 
  water, 
  in 
  December 
  1909. 
  The 
  speci- 
  

   men 
  measures 
  scarcely 
  3 
  mm. 
  from 
  the 
  forehead 
  to 
  the 
  end 
  

   of 
  the 
  caudal 
  rami, 
  and 
  is 
  therefore 
  considerably 
  smaller 
  

   than 
  the 
  females 
  of 
  that 
  species 
  are 
  said 
  to 
  be. 
  The 
  males 
  

   and 
  females 
  of 
  these 
  fish-parasites, 
  however, 
  frequently 
  

   differ 
  more 
  or 
  less 
  from 
  each 
  other, 
  not 
  only 
  in 
  size, 
  but 
  also 
  

   in 
  their 
  general 
  appearance. 
  Unless, 
  therefore, 
  both 
  sexes 
  

   are 
  available 
  for 
  examination, 
  there 
  may 
  be 
  some 
  diflSculty 
  

   in 
  determining 
  accurately 
  the 
  species 
  they 
  belong 
  to. 
  

   Figure 
  13 
  represents 
  the 
  general 
  form 
  of 
  the 
  specimen 
  seen 
  

   from 
  the 
  dorsal 
  aspect, 
  and 
  figure 
  14 
  one 
  of 
  the 
  fourth 
  pair 
  

   of 
  legs. 
  It 
  would 
  appear, 
  from 
  records 
  previously 
  published, 
  

   that 
  the 
  male 
  of 
  C. 
  thytmi, 
  like 
  that 
  of 
  C. 
  rapax 
  in 
  our 
  own 
  

   seas, 
  is 
  able 
  to 
  lead 
  at 
  times 
  the 
  life 
  of 
  a 
  "free 
  swimmer'^; 
  

   hence 
  its 
  occurrence 
  in 
  tow-net 
  gatherings 
  with 
  other 
  pelagic 
  

   organisms. 
  

  

  * 
  In 
  this 
  group 
  the, 
  males 
  are 
  almost 
  iuvariablj' 
  smaller 
  than 
  the 
  

   females. 
  

  

  