﻿254 
  Transactions. 
  — 
  Zoology, 
  

  

  owing 
  to 
  the 
  transparency 
  of 
  the 
  shell 
  the 
  mucus-gland 
  (testis 
  ?) 
  could 
  

   easily 
  be 
  seen. 
  

  

  Fain. 
  II. 
  Cytheridge. 
  

   Superior 
  antenna 
  five- 
  to 
  seven-jointed, 
  armed 
  with 
  setae 
  or 
  spines 
  ; 
  

   inferior 
  antennae 
  four- 
  to 
  five-jointed, 
  without 
  a 
  brush 
  of 
  setse. 
  Three 
  pairs 
  

   of 
  feet, 
  all 
  very 
  much 
  alike, 
  adapted 
  for 
  walking. 
  Post-abdomen 
  rudimen- 
  

   tary, 
  consisting 
  of 
  two 
  very 
  small 
  lobes. 
  

  

  Genus 
  I. 
  Cythere, 
  Midler. 
  

  

  Shell 
  usually 
  thick 
  and 
  strong, 
  with 
  a 
  more 
  or 
  less 
  rough 
  and 
  uneven 
  

  

  surface, 
  Superior 
  antennae 
  five- 
  to 
  six-jointed, 
  spiniferous 
  ; 
  inferior 
  antennae 
  

  

  four-jointed. 
  Mandibular 
  palpus 
  three- 
  to 
  four-jointed, 
  and 
  furnished 
  with 
  

  

  a 
  tuft 
  of 
  from 
  two 
  to 
  five 
  setfB. 
  Internal 
  lobe 
  of 
  first 
  maxillae 
  well 
  developed. 
  

  

  1, 
  Cythere 
  aira, 
  nov. 
  sp. 
  Figs. 
  A. 
  2 
  and 
  C,l. 
  

  

  Valves 
  subreniform, 
  highest 
  behind 
  the 
  middle, 
  narrowing 
  anteriorly, 
  

   rounded 
  posteriorly 
  ; 
  when 
  viewed 
  from 
  above, 
  narrow-oblong, 
  evenly 
  

   convex, 
  tapering 
  to 
  a 
  subacute 
  apex 
  anteriorly, 
  more 
  obtuse 
  posteriorly. 
  

   Examined 
  under 
  a 
  high 
  power, 
  the 
  shell 
  is 
  seen 
  to 
  be 
  sparsely 
  covered 
  with 
  

   circular 
  translucent 
  spots, 
  which 
  appear 
  black 
  when 
  the 
  animal 
  is 
  witliin. 
  

   Margin 
  fringed 
  with 
  very 
  short 
  close 
  cilia. 
  Colour 
  nearly 
  black, 
  opaque, 
  

   except 
  near 
  the 
  margins. 
  Limbs 
  yellowish. 
  Superior 
  antennae 
  6-jointed, 
  

   last 
  joint 
  small, 
  three 
  preceding 
  subequal 
  in 
  length, 
  setse 
  short 
  ; 
  second 
  

   joint 
  fringed 
  with 
  minute 
  hairs 
  on 
  lower 
  margin. 
  Inferior 
  antennje 
  stout, 
  

   with 
  the 
  last 
  joint 
  very 
  short 
  ; 
  terminal 
  claws 
  short 
  and 
  uneven 
  ; 
  urticatmg 
  

   seta 
  bi- 
  articulate, 
  reaching 
  to 
  the 
  extremity 
  of 
  the 
  antenna. 
  Limbs 
  similar 
  

   in 
  shape, 
  lengthening 
  posteriorly. 
  Length 
  Jg- 
  inch 
  ; 
  height 
  i^^ 
  inch. 
  

  

  Among 
  AlgcB 
  in 
  shallow 
  water, 
  Otago 
  Harbour. 
  

  

  2. 
  Cythere 
  truncata, 
  nov. 
  sp. 
  Fig. 
  C.2 
  a-c. 
  

  

  Valves 
  sub-quadrilateral, 
  highest 
  in 
  front, 
  lower 
  margin 
  slightly 
  hol- 
  

   lowed 
  in 
  the 
  middle, 
  anterior 
  extremity 
  very 
  wide 
  and 
  rounded, 
  middle 
  of 
  

   upper 
  margin 
  falling 
  slightly 
  away 
  ; 
  posterior 
  extremity 
  with 
  its 
  upper 
  half 
  

   hollowed 
  out 
  into 
  a 
  deep 
  oblique 
  notch. 
  When 
  viewed 
  from 
  above, 
  the 
  

   valves 
  are 
  elongate-quadrilateral 
  in 
  outline, 
  obtuse 
  in 
  front, 
  sides 
  nearly 
  

   straight, 
  and 
  about 
  even 
  in 
  width 
  to 
  the 
  posterior 
  angle, 
  where 
  they 
  sud- 
  

   denly 
  faU 
  away 
  to 
  the 
  margin. 
  "Whole 
  anterior 
  margin 
  fringed 
  with 
  broad, 
  

   curved, 
  and 
  flat 
  teeth, 
  the 
  rest 
  all 
  smooth. 
  Surface 
  irregularly 
  pitted 
  and 
  

   grooved, 
  marked 
  with 
  circular 
  dots. 
  Greatest 
  height 
  barely 
  equal 
  to 
  half 
  

   the 
  length. 
  The 
  limbs 
  of 
  the 
  animal 
  are 
  brownish-yellow 
  in 
  colour. 
  Last 
  

   joint 
  of 
  upper 
  antenna 
  only 
  half 
  as 
  long 
  as 
  preceding 
  ; 
  terminal 
  set^e 
  stout. 
  

   Urticating 
  seta 
  of 
  lower 
  antenna 
  short, 
  only 
  reaching 
  to 
  middle 
  of 
  third 
  

   joint, 
  uniarticulate. 
  Mandibular 
  palp 
  bearing 
  three 
  curved 
  and 
  pectinately 
  

  

  