﻿AND 
  OTHER 
  FAMILIES. 
  107 
  

  

  lobe 
  ; 
  anterior 
  cicatrices 
  confluent 
  ; 
  posterior 
  cicatrices 
  confluent 
  ; 
  dorsal 
  

   cicatrices 
  placed 
  under 
  the 
  cardinal 
  teeth 
  ; 
  cavity 
  of 
  the 
  shell 
  deep 
  : 
  

   cavity 
  of 
  the 
  beaks 
  shallow 
  ; 
  nacre 
  bluish 
  white. 
  

  

  Remarks. 
  — 
  This 
  species 
  most 
  resembles 
  the 
  JHasmodonta 
  marginata 
  

   (Say), 
  but 
  may 
  be 
  distinguished 
  by 
  its 
  more 
  cylindrical 
  form, 
  and 
  its 
  

   want 
  of 
  undulations 
  on 
  the 
  posterior 
  slope. 
  It 
  differs 
  also 
  in 
  the 
  round- 
  

   ness 
  of 
  the 
  umbonial 
  slope, 
  and 
  in 
  the 
  rays. 
  In 
  the 
  marginata 
  the 
  

   rays 
  are 
  more 
  interrupted 
  and 
  scattered, 
  being 
  sometimes 
  quite 
  spotted. 
  

  

  Cyrena 
  rotundata. 
  Plate 
  XVII. 
  fig. 
  51. 
  

  

  Testa 
  rotundatd, 
  sublenticulari, 
  subsequilaterali, 
  transversim 
  rugatd 
  ; 
  clivo 
  pos- 
  

   teriori 
  rugoso 
  ; 
  valvulis 
  crassis 
  ; 
  natibus 
  parvis, 
  acutis, 
  contiguis 
  ; 
  dentibus 
  car- 
  

   dinalibus 
  subbifidis, 
  lateralibus 
  longis, 
  minute 
  serratis, 
  rectisque; 
  margaritd 
  alba 
  

   et 
  purpurea. 
  

  

  Shell 
  round, 
  sublenticular, 
  nearly 
  equilateral, 
  transversely 
  wrinkled, 
  rugose 
  on 
  the 
  

   posterior 
  slope 
  ; 
  valves 
  thick; 
  beaks 
  small, 
  pointed, 
  touching 
  ; 
  cardinal 
  teeth 
  disposed 
  

   to 
  be 
  bifid 
  ; 
  lateral 
  teeth 
  long, 
  straight 
  and 
  minutely 
  serrulate 
  ; 
  nacre 
  white 
  and 
  pinkish. 
  

  

  Hab 
  

  

  My 
  Cabinet. 
  

   Diam. 
  1-5, 
  Length 
  2-9, 
  Breadth 
  3-3 
  inches. 
  

  

  Shell 
  round, 
  sublenticular, 
  nearly 
  equilateral, 
  transversely 
  and 
  rather 
  

   minutely 
  wrinkled, 
  rugose 
  on 
  the 
  posterior 
  slope 
  ; 
  substance 
  of 
  the 
  

   shell 
  thick 
  ; 
  beaks 
  small, 
  pointed, 
  touching 
  ; 
  ligament 
  very 
  short 
  and 
  

   thick 
  ; 
  epidermis 
  yellowish 
  brown 
  before 
  and 
  dark 
  brown 
  behind 
  ; 
  

   anterior 
  slope 
  furnished 
  with 
  a 
  lanceolate 
  mark 
  formed 
  by 
  two 
  curved 
  

   yellow 
  lines, 
  which 
  pass 
  from 
  the 
  beaks 
  to 
  the 
  anterior 
  margin 
  ; 
  pos- 
  

   terior 
  slope 
  rugose, 
  furnished 
  with 
  obsolete 
  oblique 
  folds 
  ; 
  cardinal 
  teeth 
  

   disposed 
  to 
  be 
  bifid; 
  lateral 
  teeth 
  long, 
  straight 
  and 
  very 
  minutely 
  ser- 
  

   rulate 
  ; 
  cicatrices 
  scarcely 
  perceptible 
  ; 
  cavity 
  of 
  the 
  shell 
  rather 
  shallow 
  ; 
  

   cavity 
  of 
  the 
  beaks 
  subangular 
  ; 
  nacre 
  white 
  and 
  pinkish. 
  

  

  Remarks. 
  — 
  This 
  beautiful 
  and 
  fine 
  large 
  species 
  was 
  sent 
  to 
  me 
  

  

  