﻿100 
  COLLECTIONS 
  FROM 
  MELAjnESIi.. 
  

  

  and 
  bifid, 
  and 
  two 
  in 
  the 
  left, 
  of 
  which 
  the 
  anterior 
  is 
  the 
  larger 
  and 
  

   bifid. 
  A 
  single 
  lateral 
  tooth 
  occurs 
  in 
  the 
  right 
  valve 
  on 
  each 
  side 
  

   not 
  far 
  from 
  the 
  cardinals, 
  with 
  a 
  groove 
  between 
  them 
  and 
  the 
  

   margin. 
  Left 
  valve 
  with 
  a 
  slight 
  tooth-like 
  projection 
  on 
  the 
  mar- 
  

   gin 
  on 
  each 
  side 
  fitting 
  into 
  the 
  grooves 
  in 
  the 
  other 
  valve. 
  The 
  

   paUial 
  sinus 
  is 
  large 
  and 
  deep. 
  Internal 
  cartilage 
  minute, 
  narrow, 
  

   oblique, 
  posterior 
  to 
  the 
  cardinal 
  teeth. 
  External 
  ligament 
  small. 
  

   The 
  largest 
  specimen 
  measures 
  13 
  millim. 
  by 
  9g. 
  T. 
  alba 
  of 
  Wood 
  

   is 
  somewhat 
  like 
  this 
  species, 
  but 
  is 
  more 
  acute 
  posteriorly, 
  the 
  

   detail 
  of 
  its 
  dentition 
  is 
  different, 
  and 
  the 
  cartilage 
  larger. 
  

  

  27. 
  Mactra 
  eximia. 
  

   {Deshayes) 
  ; 
  Reeve, 
  Conch. 
  Icon. 
  fig. 
  31 
  (rayed 
  variety). 
  

  

  Hah. 
  Port 
  Denison, 
  Queensland 
  ( 
  Coj^pmr/er) 
  ; 
  Port 
  Curtis, 
  More- 
  

   ton 
  Bay 
  {coU. 
  Gaming) 
  ; 
  JN".E. 
  coast 
  of 
  Australia 
  {Brit. 
  Mus.). 
  

  

  There 
  are 
  altogether 
  eight 
  specimens 
  of 
  this 
  species 
  in 
  the 
  Museum, 
  

   three 
  of 
  them 
  being 
  ornamented 
  with 
  numerous 
  reddish 
  rays, 
  and 
  

   the 
  remaining 
  five 
  uniformly 
  white 
  beneath 
  the 
  greyish 
  and 
  yellowish 
  

   epidermis. 
  

  

  28. 
  Mactra 
  producta, 
  var. 
  

  

  Spisula 
  producta, 
  Anyas, 
  Proc. 
  Zool. 
  Soc. 
  1867, 
  p. 
  900, 
  pi. 
  44. 
  tig. 
  7. 
  

  

  Hab. 
  Port 
  Jackson 
  (Angas 
  and 
  Coppinger). 
  

  

  The 
  three 
  shells 
  dredged 
  by 
  Dr. 
  Coppinger 
  are 
  probably 
  a 
  variety 
  

   of 
  this 
  species. 
  They 
  are 
  all 
  small, 
  apparently 
  immature, 
  and 
  difter 
  

   from 
  the 
  types 
  presented 
  to 
  the 
  Museum 
  by 
  Mr. 
  Angas 
  in 
  being 
  

   less 
  produced 
  posteriorly. 
  They 
  are 
  proportionally 
  longer 
  from 
  the 
  

   umbones 
  to 
  the 
  ventral 
  margin, 
  which 
  exhibits 
  a 
  very 
  faint 
  incurva- 
  

   tion 
  near 
  the 
  hinder 
  extremity, 
  and 
  the 
  posterior 
  dorsal 
  slope 
  is 
  a 
  

   trifle 
  more 
  arcuate. 
  

  

  29. 
  Mactra 
  (Oxyperas) 
  coppingeri. 
  (Plate 
  VII. 
  figs. 
  D-D 
  2.) 
  

  

  Shell 
  transversely 
  elongate, 
  triangular, 
  a 
  little 
  inequilateral, 
  

   rather 
  compressed, 
  thinnish, 
  narrowly 
  gaping 
  posteriorly, 
  smooth 
  

   towards 
  the 
  beaks, 
  concentrically 
  plicately 
  ridged 
  elsewhere, 
  white, 
  

   covered 
  with 
  a 
  pale 
  yellowish 
  epidermis, 
  spotted 
  somewhat 
  sparsely 
  

   throughout 
  with 
  brownish 
  dots, 
  and 
  ornamented 
  on 
  the 
  dorsal 
  areas 
  

   with 
  cross 
  lines 
  of 
  a 
  deeper 
  brown, 
  and 
  with 
  a 
  large 
  patch 
  of 
  the 
  

   same 
  colour 
  on 
  the 
  hinder 
  slope 
  of 
  each 
  valve. 
  Umbones 
  moderately 
  

   acute, 
  not 
  large, 
  inclining 
  towards 
  and 
  situated 
  a 
  trifle 
  in 
  advance 
  

   of 
  the 
  centre. 
  Lunule 
  sunken, 
  not 
  circumscribed 
  by 
  acute 
  edges, 
  

   extending 
  more 
  than 
  halfway 
  down 
  the 
  anterior 
  slope. 
  Posterior 
  

   area 
  as 
  deep 
  as 
  the 
  lunule 
  and 
  a 
  trifle 
  longer, 
  smoothish, 
  not 
  much 
  

   afi^ected 
  by 
  the 
  terminations 
  of 
  the 
  concentric 
  ridges. 
  Two 
  lateral 
  

   teeth 
  on 
  each 
  side 
  in 
  the 
  right 
  valve, 
  separated 
  by 
  a 
  deep 
  groove 
  

   quite 
  approximated 
  to 
  the 
  cardinal 
  teeth 
  in 
  front 
  and 
  the 
  cartilage- 
  

   pit 
  behind. 
  The 
  latter 
  is 
  large, 
  deep, 
  and 
  located 
  posterior 
  to 
  the 
  

   beak. 
  The 
  cardinal 
  tooth 
  is 
  small, 
  insignificant, 
  bounds 
  the 
  ligament, 
  

   and 
  has 
  a 
  cross 
  piece 
  above 
  it 
  immediately 
  beneath 
  the 
  apex 
  of 
  the 
  

  

  