﻿MOLLtrSCA. 
  101 
  

  

  umbo. 
  In 
  the 
  left 
  valve, 
  the 
  single 
  lateral 
  tooth 
  on 
  each 
  side 
  is 
  

   elongate, 
  narrow, 
  and 
  erect. 
  Only 
  one 
  cardinal 
  tooth 
  (unless 
  the 
  

   front 
  raised 
  edge 
  of 
  the 
  ligamental 
  fossa 
  be 
  considered 
  a 
  tooth), 
  which 
  

   is 
  elongate, 
  but 
  little 
  raised, 
  situated 
  between 
  the 
  pit 
  and 
  edge 
  of 
  

   the 
  lunule. 
  Muscular 
  scars 
  pj'riform, 
  the 
  front 
  one 
  elongate, 
  the 
  

   posterior 
  more 
  rounded. 
  Pallial 
  sinus 
  extending 
  halfway 
  across 
  the 
  

   valves, 
  sharply 
  rounded 
  at 
  the 
  end. 
  A 
  second 
  sinuation 
  within 
  

   the 
  other, 
  and 
  consequently 
  shorter 
  and 
  less 
  acutely 
  curved, 
  is 
  a 
  

   remarkable 
  feature 
  in 
  both 
  valves 
  of 
  the 
  single 
  perfect 
  shell 
  before 
  

   me 
  ; 
  in 
  a 
  separate 
  valve 
  this 
  is 
  not 
  noticeable, 
  but 
  may 
  have 
  been 
  

   obliterated, 
  as 
  the 
  specimen 
  is 
  somewhat 
  sea-worn. 
  The 
  inner 
  sur- 
  

   face 
  of 
  this 
  species 
  is 
  glossy 
  and 
  radiately 
  substriated, 
  one 
  impres«'ed 
  

   ray 
  from 
  the 
  umbones 
  to 
  the 
  end 
  of 
  the 
  mantle-siniis 
  being 
  especially 
  

   conspicuous. 
  Length 
  36| 
  millim., 
  height 
  24, 
  diameter 
  12, 
  

  

  Hah. 
  Thursday 
  Island, 
  Torres 
  Straits, 
  4-6 
  fms. 
  

  

  This 
  very 
  interesting 
  species 
  bears 
  a 
  rather 
  close 
  relationship 
  

   to 
  Mactra 
  trianr/idans 
  of 
  Lamarck 
  ; 
  it 
  is, 
  however, 
  quite 
  distinct. 
  

   It 
  is 
  a 
  trifle 
  shorter, 
  . 
  less 
  angular, 
  not 
  so 
  strongly 
  concentrically 
  

   costato, 
  has 
  an 
  excavated 
  lunule 
  and 
  a 
  simken 
  area 
  not 
  defined 
  

   by 
  carinate 
  edges, 
  and 
  the 
  dorsal 
  margins 
  not 
  prominent, 
  forming 
  a 
  

   keel 
  on 
  each 
  side 
  ; 
  the 
  umbones 
  as 
  in 
  M. 
  trianr/uJaris. 
  M. 
  aspersa, 
  

   Sowerby, 
  is 
  a 
  more 
  finely 
  sculptured 
  shell, 
  more 
  rounded 
  posteriorly, 
  

   with 
  a 
  shallower 
  lunule 
  and 
  a 
  narrower 
  dorsal 
  area. 
  The 
  pallial 
  

   sinus 
  in 
  the 
  present 
  species 
  reaches 
  halfway 
  across 
  the 
  valve, 
  whilst 
  

   in 
  M. 
  aspersa 
  it 
  has 
  a 
  further 
  extension 
  and 
  lacks 
  the 
  duplex 
  feature 
  

   described 
  previously, 
  

  

  30. 
  Mactrinula 
  angulifera. 
  

  

  Mactra 
  angulifera, 
  Deshayes, 
  Proc. 
  Zool. 
  Soc. 
  1854, 
  p. 
  70; 
  Reeve, 
  

   Conch. 
  Icon. 
  fig. 
  83. 
  

  

  Hah. 
  Island 
  of 
  Ticao, 
  Philippine 
  Islands 
  {Cuming); 
  Port 
  Curtis 
  

   ( 
  Coppinger). 
  

  

  Behind 
  the 
  conspicuous 
  keel 
  which 
  marks 
  off 
  the 
  posterior 
  area, 
  

   about 
  midway 
  between 
  it 
  and 
  the 
  margin, 
  there 
  are 
  one 
  or 
  two 
  

   minor 
  ridges. 
  In 
  the 
  Cumingian 
  collection 
  there 
  is 
  a 
  second 
  

   specimen, 
  somewhat 
  larger 
  than 
  that 
  figured 
  by 
  Reeve, 
  having 
  a 
  

   length 
  of 
  32 
  millim. 
  and 
  a 
  width 
  of 
  47. 
  

  

  31. 
  Cardium 
  reevianum. 
  

  

  Dunker, 
  Novitates 
  Conch, 
  p. 
  2"2, 
  pi. 
  6. 
  figs. 
  Q, 
  7, 
  8. 
  

  

  Hah. 
  Port 
  Darwin, 
  8-12 
  fms., 
  bottom 
  mud 
  and 
  sand 
  (Coppinger) 
  ; 
  

   Port 
  Essington 
  (Mus. 
  Cuming). 
  

  

  Cardium 
  vertehratum, 
  Jonas 
  (Zeitschr. 
  fiir 
  Malak. 
  1844, 
  p. 
  33), 
  

   from 
  West 
  Australia, 
  is 
  apparently 
  closely 
  related 
  to 
  the 
  present 
  species. 
  

  

  32, 
  Cardium 
  hystrix. 
  

  

  Reeve, 
  Conch. 
  Icon. 
  figs. 
  40 
  a, 
  b 
  ; 
  Romer, 
  Conch.-Cab. 
  p, 
  112. 
  

  

  Hah. 
  Corrigidor, 
  Philippines 
  {Cuming) 
  ; 
  Flinders 
  and 
  Clairmont 
  

   Islands, 
  N,E. 
  Australia 
  {Coppinger). 
  

  

  