﻿POTAMOMYA. 
  Panama 
  Shells. 
  519 
  

  

  Length 
  1.98 
  inch 
  j 
  height 
  1,35 
  inch 
  ; 
  breadth 
  .7 
  inch. 
  

  

  Station. 
  — 
  Unknown. 
  

  

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

   1 
  valve 
  only 
  was 
  found. 
  

  

  498. 
  Pandora 
  corniifa. 
  Nov. 
  sp. 
  

  

  Shell 
  elongate, 
  ovate, 
  very 
  inequilateral, 
  the 
  posterior 
  part 
  

   being 
  much 
  longer 
  and 
  higher 
  ; 
  dorsal 
  margin 
  nearly 
  straight^ 
  

   posteriorly 
  sharply 
  rostriform 
  ; 
  posterior 
  margin 
  much 
  exca- 
  

   vated 
  next 
  beneath 
  the 
  rostriform 
  projection; 
  ventral 
  margin 
  

   well 
  rounded 
  : 
  pearl-white 
  : 
  with 
  some 
  unequal 
  striae 
  of 
  growth 
  ; 
  

   right 
  valve 
  with 
  a 
  prominent 
  angle 
  extending 
  from 
  the 
  beak 
  to 
  

   the 
  middle 
  of 
  the 
  sinus 
  of 
  the 
  posterior 
  margin 
  ; 
  left 
  valve 
  with 
  

   a 
  corresponding 
  depressed 
  angle 
  : 
  beaks 
  indistinct 
  ; 
  umbones 
  

   slightly 
  and 
  almost 
  equally 
  convex. 
  

  

  Length 
  .7 
  inch 
  ; 
  height 
  .42 
  inch 
  ; 
  breadth 
  ,11 
  inch. 
  

  

  We 
  adopt 
  the 
  appropriate 
  name 
  suggested 
  by 
  Dr. 
  Gould. 
  

  

  Station. 
  — 
  Unknown. 
  

  

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

  

  Only 
  1 
  specimen 
  was 
  found. 
  

  

  499. 
  Potamomya 
  aequalis. 
  Nov. 
  sp. 
  

  

  Shell 
  subovate, 
  nearly 
  equilateral, 
  slightly 
  inequivalve 
  ; 
  with 
  

   the 
  margin 
  subangulated 
  posteriorly, 
  otherwise 
  well 
  rounded 
  : 
  

   white 
  beneath 
  a 
  pale 
  brown 
  epidermis 
  : 
  with 
  unequal 
  striae 
  of 
  

   growth; 
  posteriorly 
  with 
  an 
  umbonial 
  angle 
  not 
  very 
  promi- 
  

   nent 
  : 
  beaks 
  small 
  : 
  right 
  umbo 
  very 
  prominent, 
  both 
  somewhat 
  

   compressed 
  : 
  tooth 
  rather 
  small 
  ; 
  teeth 
  of 
  the 
  left 
  valve 
  with 
  a 
  

   medial 
  ridge. 
  

  

  Length 
  ,78 
  inch; 
  height 
  .66 
  inch; 
  breadth 
  .42 
  inch. 
  

  

  Station. 
  — 
  In 
  soft 
  impalpable 
  mud, 
  under 
  a 
  mangrove 
  thicket, 
  

   near 
  high 
  water 
  mark, 
  and 
  near 
  the 
  outlet 
  of 
  a 
  small 
  stream, 
  

   with 
  Area 
  tuberculosa. 
  

  

  