﻿jjarasidc 
  on 
  an 
  Octopus. 
  473 
  

  

  tliese 
  proved 
  to 
  be 
  minute 
  copepod.s, 
  attached 
  by 
  their 
  mouth- 
  

   appendages 
  to 
  the 
  skin 
  o£ 
  the 
  octopus, 
  their 
  tail-ends 
  being- 
  

   free. 
  All 
  the 
  specimens 
  found 
  were 
  females, 
  most 
  of 
  them 
  

   with 
  egg-sacs. 
  Tliey 
  appear 
  to 
  belong 
  to 
  a 
  new 
  genus 
  of 
  the 
  

   Harpacticoidea, 
  most 
  nearly 
  allied 
  to 
  the 
  genus 
  Idija, 
  but 
  

   greatly 
  modified 
  for 
  a 
  parasitic 
  life. 
  It 
  may, 
  perhaps, 
  be 
  

   held 
  that 
  a 
  new 
  family 
  should 
  be 
  made 
  for 
  the 
  genus, 
  but 
  

   as 
  all 
  the 
  appendages 
  which 
  have 
  not 
  undergone 
  degeneration 
  

   })ave 
  retained, 
  to 
  a 
  greater 
  or 
  less 
  degree, 
  their 
  /Jj/a-like 
  

   form, 
  I 
  have 
  placed 
  it 
  in 
  the 
  same 
  family 
  as 
  Idija. 
  

  

  The 
  genus 
  and 
  species 
  may 
  be 
  described 
  as 
  follows 
  : 
  — 
  

  

  Family 
  Idyidse. 
  

  

  Genus 
  Cholidya, 
  nov. 
  

  

  An 
  Idyoid, 
  modified 
  for 
  a 
  parasitic 
  life, 
  in 
  which 
  the 
  

   swimming 
  appendages 
  are 
  reduced 
  or 
  absent 
  and 
  thecephalon 
  

   and 
  thorax 
  soft 
  and 
  swollen. 
  Cephalic 
  appendages 
  with 
  the 
  

   same 
  general 
  structure 
  as 
  in 
  the 
  rest 
  of 
  the 
  family. 
  Inner 
  

   ramus 
  of 
  the 
  second 
  antenna 
  very 
  small. 
  Mandible 
  with 
  

   an 
  unbranched 
  palp. 
  First 
  maxilla 
  forming 
  a 
  simple 
  piercer. 
  

   First 
  foot 
  reduced 
  in 
  size, 
  but 
  of 
  the 
  same 
  form 
  as 
  in 
  the 
  

   genus 
  Idi/a. 
  Second 
  foot 
  two-branched, 
  but 
  with 
  its 
  joints 
  

   and 
  setie 
  reduced. 
  Third 
  and 
  fourth 
  feet 
  absent. 
  Fiftli 
  feet 
  

   highly 
  chitinized 
  and 
  ventral 
  in 
  position, 
  coimected 
  by 
  a 
  

   chitinized 
  ventral 
  plate. 
  Abdomen 
  not 
  chitinized 
  and 
  with 
  

   feebly 
  marked 
  segmentation. 
  Egg-sac 
  one, 
  attached. 
  

  

  ChoUdi/a 
  poli/pi, 
  s\). 
  u. 
  

  

  Female 
  (fig. 
  1) 
  length 
  '7S-8 
  mm. 
  Cephalon 
  slightly 
  

   flattened, 
  'i 
  horax 
  globular, 
  swollen, 
  tilled 
  with 
  what 
  appears 
  

   to 
  be 
  undifferentiated 
  food 
  or 
  yolk-material. 
  Abdomen 
  

   tapering 
  from 
  the 
  swollen 
  tlioiax 
  to 
  the 
  small 
  furca. 
  

  

  First 
  antenna 
  (fig. 
  2) 
  six-jointed, 
  the 
  fourth 
  joint 
  bearing 
  

   a 
  short 
  asstiietask 
  ; 
  proportional 
  length 
  of 
  joints, 
  measured 
  

   along 
  the 
  upper 
  margin 
  : 
  — 
  

  

  1 
  2 
  3 
  4 
  5 
  6 
  

  

  10 
  23 
  12 
  8 
  7 
  7 
  

  

  Second 
  antenna 
  (fig. 
  3) 
  with 
  two 
  basal 
  joints; 
  endopodite 
  

   very 
  small, 
  with 
  two 
  terminal 
  seta3 
  ; 
  exopodite 
  two-jointed, 
  

   second 
  joint 
  about 
  half 
  as 
  lung 
  as 
  the 
  first 
  and 
  bearing 
  one 
  

   lateral 
  and 
  four 
  terminal 
  setse. 
  

  

  