﻿34 
  ON 
  THE 
  NAIADES, 
  

  

  plicated; 
  cardinal 
  teeth 
  double 
  in 
  both 
  valves; 
  lateral 
  teeth 
  straight; 
  nacre 
  splendidly 
  

   pearly, 
  slightly 
  salmon 
  coloured, 
  and 
  beautifully 
  iridescent. 
  

  

  Hab. 
  China. 
  Mrs 
  Murchison. 
  

  

  My 
  Cabinet. 
  

   Diam. 
  *7, 
  Length 
  -8, 
  Breadth 
  1-9 
  inches. 
  

  

  Shell 
  narrow-elliptical, 
  transverse, 
  inequilateral, 
  angular 
  behind, 
  and 
  

   slightly 
  emarginate 
  at 
  basal 
  margin 
  ; 
  substance 
  of 
  the 
  shell 
  rather 
  thin 
  ; 
  

   beaks 
  and 
  unibones 
  beautifully 
  plicated 
  ; 
  umbonial 
  slope 
  subcarinate 
  

   and 
  rough 
  with 
  the 
  angles 
  of 
  the 
  folds 
  ; 
  posterior 
  slope 
  finely 
  plicate 
  : 
  

   ligament 
  yellow 
  and 
  narrow; 
  epidermis 
  dark 
  green; 
  cardinal 
  teeth 
  

   double 
  in 
  both 
  valves; 
  lateral 
  teeth 
  straight 
  ; 
  anterior 
  cicatrices 
  distinct; 
  

   posterior 
  cicatrices 
  confluent; 
  dorsal 
  cicatrices 
  in 
  the 
  centre 
  of 
  the 
  

   cavity 
  of 
  the 
  beaks 
  ; 
  cavity 
  of 
  the 
  beaks 
  shallow 
  ; 
  nacre 
  rich, 
  and 
  splen- 
  

   didly 
  pearly, 
  slightly 
  salmon 
  coloured, 
  and 
  beautifully 
  iridescent. 
  

  

  Remarks.— 
  This 
  splendid 
  species 
  I 
  owe 
  to 
  the 
  great 
  kindness 
  of 
  

   Mrs 
  Murchison, 
  the 
  wife 
  of 
  the 
  present 
  learned 
  president 
  of 
  the 
  Geo- 
  

   logical 
  Society 
  of 
  London. 
  Among 
  many 
  fine 
  and 
  rare 
  shells 
  received 
  

   from 
  her 
  I 
  found 
  this, 
  which 
  appears 
  not 
  to 
  have 
  been 
  before 
  de- 
  

   scribed. 
  It 
  perhaps 
  most 
  resembles 
  the 
  U. 
  cceruleus 
  (nobis), 
  particu- 
  

   larly 
  in 
  the 
  outline 
  : 
  it 
  is, 
  however, 
  rather 
  more 
  transverse. 
  It 
  diners 
  

   greatly 
  from 
  the 
  cceruleus 
  in 
  the 
  number 
  and 
  size 
  of 
  the 
  folds. 
  These, 
  

   behind 
  the 
  umbonial 
  slope, 
  are 
  parallel 
  to 
  the 
  ligament 
  ; 
  while 
  those 
  on 
  

   the 
  anterior 
  margin 
  are 
  oblique. 
  The 
  acute 
  angles 
  formed 
  by 
  the 
  

   folds 
  on 
  the 
  umbonial 
  slope 
  are 
  very 
  remarkable. 
  The 
  inferior 
  part 
  

   of 
  the 
  shell 
  is 
  free 
  from 
  folds 
  : 
  this 
  may 
  not, 
  however, 
  prove 
  a 
  constant 
  

   character. 
  Its 
  nacre 
  is 
  without 
  exception 
  finer 
  than 
  any 
  I 
  have 
  ever 
  

   seen, 
  and 
  rich 
  beyond 
  description. 
  The 
  folds 
  being 
  visible 
  from 
  the 
  

   interior, 
  add 
  greatly 
  to 
  its 
  lustre.* 
  

  

  * 
  Since 
  writing 
  these 
  remarks 
  I 
  have 
  seen 
  several 
  specimens 
  of 
  this 
  shell 
  in 
  Europe. 
  At 
  

   the 
  Jardin 
  des 
  Plantes, 
  Monsieur 
  de 
  Blainville 
  showed 
  me 
  two 
  or 
  three 
  specimens 
  recently 
  

   received, 
  and 
  not 
  yet 
  placed 
  in 
  the 
  cabinet. 
  He 
  considered 
  the 
  shell 
  undescribed, 
  until 
  I 
  

   mentioned 
  the 
  name 
  I 
  had 
  given 
  it. 
  

  

  