﻿AMPHIDESMA. 
  Panama 
  Shells. 
  513 
  

  

  cave, 
  otherwise 
  with 
  all 
  the 
  margins 
  well 
  rounded 
  : 
  purple 
  near 
  

   the 
  beaks, 
  otherwise 
  dingy 
  white 
  : 
  interior 
  similarly 
  colored, 
  

   but 
  with 
  the 
  purple 
  region 
  larger 
  : 
  smooth 
  near 
  the 
  beaks, 
  

   otherwise 
  with 
  fine 
  raised 
  concentric 
  lines, 
  and 
  crowded 
  radiat- 
  

   ing 
  strias, 
  which 
  are 
  mostly 
  microscopic, 
  and 
  which 
  posteriorly 
  

   are 
  divergent 
  and 
  wholly 
  microscopic 
  ; 
  beaks 
  small, 
  prominent 
  : 
  

   umbones 
  convex. 
  

  

  Length 
  .85 
  inch 
  ; 
  height 
  .74 
  inch 
  ; 
  breadth 
  .42 
  inch. 
  

  

  Station. 
  — 
  Unknown. 
  

  

  Habitat 
  — 
  Panama 
  ; 
  C. 
  B. 
  A. 
  ! 
  

   Only 
  1 
  valve 
  was 
  found. 
  

  

  486. 
  Aiuphidesma 
  ellipticiim 
  ? 
  

  

  Synonymy. 
  

  

  Amphidesma 
  elHptiaim 
  Sowb. 
  in 
  Proc. 
  Zool. 
  Soc. 
  Load, 
  

  

  p. 
  200. 
  . 
  - 
  . 
  - 
  Dec. 
  1832. 
  

   Hanley 
  Descr. 
  Catal. 
  p. 
  45. 
  1845? 
  

  

  Station. 
  — 
  Dredged 
  at 
  a 
  depth 
  of 
  9 
  fathoms 
  in 
  sandy 
  mud 
  ; 
  

   Cuming 
  ! 
  Sowerby. 
  

  

  Mabitat. 
  — 
  Monte 
  Christi 
  ; 
  Cuming 
  ! 
  Sowerby. 
  

   West 
  Columbia 
  ; 
  Hanley. 
  

   Panama 
  ; 
  C. 
  B. 
  A. 
  ! 
  

   "We 
  obtained 
  20 
  specimens 
  on 
  the 
  reef 
  at 
  low 
  water 
  mark. 
  

   Most 
  of 
  them 
  are 
  in 
  fine 
  condition, 
  although 
  none 
  were 
  taken 
  

   alive. 
  

  

  487. 
  Amphidesma 
  proximum. 
  Nov. 
  sp. 
  

  

  Shell 
  suborbicular, 
  slightly 
  flesuous, 
  a 
  little 
  inequilateral, 
  

   with 
  the 
  anterior 
  dorsal 
  margin 
  concave, 
  with 
  the 
  posterior 
  

   dorsal 
  margin 
  a 
  little 
  excurved, 
  subtruncated 
  posteriorly, 
  other- 
  

   wise 
  with 
  the 
  margins 
  well 
  rounded 
  : 
  snow 
  white, 
  with 
  a 
  thin 
  

   slate 
  or 
  umber-colored 
  epidermis 
  : 
  centrally 
  and 
  anteriorly 
  with 
  

   very 
  fine 
  rather 
  distant 
  raised 
  lines 
  ; 
  with 
  extremely 
  minute 
  

  

  