﻿520 
  Panama 
  Shells, 
  CORBULID^. 
  

  

  I 
  Habitat. 
  — 
  Panama 
  ; 
  C. 
  B. 
  A. 
  ! 
  

  

  1 
  specimen 
  was 
  obtained 
  about 
  2 
  2 
  miles 
  east 
  of 
  Panama. 
  

  

  500. 
  Potamomya 
  inflata. 
  Nov. 
  sp. 
  

  

  Sbell 
  ovate, 
  ventricose, 
  inequilateral, 
  moderately 
  inequivalve 
  ; 
  

   posterior 
  margin 
  subtruncated 
  between 
  the 
  extremities 
  of 
  two 
  

   umbonial 
  angles, 
  of 
  wliich 
  the 
  upper 
  one 
  is 
  indistinct 
  ; 
  ventral 
  

   margin 
  moderately 
  excurved; 
  anterior 
  margin 
  abruptly 
  and 
  

   regularly 
  rounded: 
  white 
  beneath 
  a 
  pale 
  brown 
  epidermis: 
  

   with 
  unequal 
  striae 
  of 
  growth: 
  beaks 
  small: 
  umbones 
  very 
  

   prominent, 
  somewhat 
  compressed 
  : 
  teeth 
  small 
  ; 
  tooth 
  of 
  the 
  

   left 
  valve 
  with 
  a 
  medial 
  ridge. 
  

  

  Length 
  .7 
  inch 
  ; 
  height 
  .57 
  inch 
  ; 
  breadth 
  .6 
  inch, 
  

  

  A 
  less 
  ventricose 
  variety 
  has 
  the 
  following 
  dimensions 
  : 
  

  

  Length 
  .6 
  inch 
  ; 
  height 
  .46 
  inch 
  ; 
  breadth 
  .33 
  inch. 
  

  

  Station. 
  — 
  With 
  P. 
  cequalis^ 
  q. 
  v. 
  

  

  5aJ{toi.— 
  Panama 
  ; 
  C. 
  B, 
  A. 
  ! 
  

  

  3 
  specimens 
  were 
  obtained 
  with 
  P. 
  cequnlis. 
  

  

  501. 
  Potamomya 
  trigonalis. 
  Nov. 
  sp. 
  

  

  Shell 
  solid, 
  triangular, 
  moderately 
  inequivalve, 
  subequi- 
  

   lateral 
  ; 
  upper 
  posterior 
  margin 
  moderately 
  excurved, 
  forming 
  

   an 
  angle 
  with 
  the 
  slightly 
  excurved 
  ventral 
  margin 
  ; 
  anteriorly 
  

   with 
  the 
  dorsal 
  margin 
  abruptly 
  and 
  regularly 
  rounded 
  into 
  

   the 
  ventral 
  margin: 
  white 
  beneath 
  a 
  pale 
  brown 
  epidermis: 
  

   with 
  fine 
  striae 
  of 
  growth 
  ^ 
  with 
  a 
  sharp 
  umbonial 
  angle 
  defining 
  

   a 
  posterior 
  area 
  : 
  beaks 
  large 
  and 
  prominent 
  : 
  umbones 
  promi- 
  

   nent, 
  somewhat 
  compressed 
  : 
  teeth 
  large 
  and 
  robust 
  ; 
  tooth 
  of 
  

   the 
  left 
  valve 
  with 
  a 
  medial 
  ridge. 
  

  

  Length 
  .95 
  inch 
  ; 
  height 
  .8 
  inch 
  ; 
  breadth 
  .56 
  inch. 
  

  

  Station. 
  — 
  With 
  P. 
  cequalis, 
  q. 
  v. 
  

  

  Habitat. 
  — 
  Panama 
  ; 
  C. 
  B. 
  A. 
  I 
  

  

  2 
  specimens 
  were 
  obtained. 
  

  

  