﻿108 
  COLLECTIONS 
  FROM 
  MELANESIA, 
  

  

  This 
  so-called 
  species, 
  also 
  C. 
  donacina, 
  Lamarck, 
  0. 
  ciimmgii, 
  A. 
  

   Adams, 
  0. 
  castanea, 
  Reeve, 
  C. 
  errones, 
  Reeve, 
  and 
  O. 
  decipiens, 
  

   Reeve, 
  I 
  believe 
  to 
  be 
  mere 
  variations 
  of 
  one 
  and 
  the 
  same 
  form, 
  

   namely 
  C. 
  Jcimpcola, 
  Lamarck, 
  The 
  composition 
  of 
  the 
  hinge 
  is 
  the 
  

   same 
  in 
  all, 
  and 
  the 
  peculiar 
  colouring 
  of 
  the 
  interior 
  is 
  similar 
  (vide 
  

   Reeve, 
  fig. 
  16, 
  and 
  Delessert, 
  pi, 
  iv. 
  fig, 
  1 
  b). 
  The 
  variation 
  in 
  form 
  

   is 
  partly 
  due 
  to 
  age 
  ; 
  for 
  instance, 
  a 
  young 
  0. 
  decipiens 
  has 
  the 
  form 
  

   of 
  donacina, 
  and 
  it 
  is 
  only 
  towards 
  maturity 
  that 
  the 
  posterior 
  end 
  

   becomes 
  markedly 
  produced 
  ; 
  and 
  the 
  same 
  observation 
  applies 
  to 
  G. 
  

   errones. 
  The 
  amount 
  of 
  concentric 
  ribbing 
  is 
  not 
  constant 
  ; 
  but 
  all 
  

   intermediate 
  forms 
  are 
  met 
  with, 
  from 
  0. 
  castanea 
  and 
  C. 
  donacina 
  

   (type), 
  which 
  have 
  least, 
  to 
  0. 
  pidchra, 
  which 
  has 
  most, 
  being 
  cos- 
  

   tate 
  throughout, 
  except 
  at 
  the 
  posterior 
  extremity. 
  The 
  pallial 
  line 
  

   in 
  every 
  specimen 
  examined 
  does 
  not 
  appear 
  to 
  be 
  parallel 
  with 
  the 
  

   margin 
  of 
  the 
  valve, 
  but 
  becomes 
  gradually 
  more 
  remote 
  anteriorly, 
  

   the 
  space 
  between 
  it 
  and 
  the 
  margin 
  being 
  radiately 
  shallowly 
  

   subsulcate, 
  seen 
  better 
  in 
  some 
  lights 
  than 
  others. 
  The 
  epidermis 
  

   scarcely 
  varies 
  at 
  all 
  : 
  in 
  some 
  examples 
  it 
  appears 
  to 
  have 
  lost 
  the 
  

   dull 
  bloom 
  which 
  covers 
  others 
  ; 
  but 
  this 
  defect 
  is 
  the 
  result 
  of 
  fric- 
  

   tion, 
  for 
  a 
  dull 
  specimen 
  in 
  perfect 
  condition 
  is 
  easily 
  rendered 
  

   glossy 
  by 
  merely 
  being 
  rubbed 
  with 
  a 
  wet 
  cloth, 
  the 
  bloom 
  disap- 
  

   pearing 
  as 
  it 
  does 
  from 
  fruit 
  under 
  similar 
  circumstances. 
  Judging 
  

   from 
  the 
  specimens 
  in 
  the 
  British 
  Museum 
  with 
  reliable 
  localities 
  

   attached 
  to 
  them, 
  it 
  appears 
  that 
  the 
  species 
  ranges 
  from 
  Queensland 
  

   on 
  the 
  east 
  side 
  of 
  Australia, 
  along 
  the 
  north 
  coast 
  to 
  Swan 
  River 
  on 
  

   the 
  west, 
  I 
  find 
  a 
  specimen 
  of 
  the 
  variety 
  cmningii 
  from 
  Port 
  

   Curtis 
  and 
  another 
  from 
  Sandy 
  Cape 
  on 
  the 
  north-east 
  coast 
  ; 
  var. 
  

   ptdcJira 
  from 
  Port 
  Essington; 
  vars. 
  decipiens 
  and 
  castanea 
  from 
  

   Swan 
  River. 
  

  

  50. 
  Modiola, 
  sp. 
  

   Hah. 
  Port 
  Molle. 
  

  

  A 
  single 
  distorted 
  specimen 
  only 
  is 
  before 
  me, 
  remarkably 
  like 
  

   the 
  European 
  M. 
  barbata. 
  

  

  51. 
  Modiola 
  glaberrima. 
  

  

  Dunher 
  ; 
  Reeve, 
  Conch. 
  Icon. 
  fig. 
  48. 
  

   Hcd). 
  Sydney 
  {Dunher) 
  ; 
  Port 
  Jackson 
  (Coppinger 
  and 
  Angus). 
  

  

  52. 
  Modiolaria 
  miranda. 
  (Plate 
  VII. 
  fig. 
  N.) 
  

  

  Shell 
  transversely 
  elongate, 
  highest 
  at 
  the 
  middle, 
  of 
  pale 
  greenish 
  

   tint, 
  varied 
  with 
  a 
  few 
  indistinct 
  light 
  reddish 
  irregular 
  markings, 
  

   not 
  glossy, 
  rather 
  strongly 
  radiately 
  ridged 
  at 
  both 
  ends 
  and 
  very 
  

   finely 
  on 
  the 
  central 
  portion 
  of 
  the 
  valves. 
  Whole 
  surface 
  concen- 
  

   trically 
  striated, 
  producing 
  a 
  subgranose 
  appearance 
  upon 
  the 
  cos- 
  

   tulse 
  ; 
  the 
  anterior 
  are 
  about 
  ten 
  in 
  number, 
  the 
  posterior 
  about 
  

  

  