﻿528 
  On 
  new 
  Mollusca 
  from 
  Peru 
  and 
  Argentina. 
  

  

  cbocolate 
  bands 
  of 
  irregular 
  width 
  ; 
  whorls 
  A^, 
  almost 
  planu- 
  

   late 
  above, 
  then 
  shouldered 
  and 
  rounded 
  below, 
  the 
  last 
  

   descending 
  considerably 
  in 
  front 
  and 
  rather 
  elongated 
  towards 
  

   the 
  base, 
  smooth 
  ; 
  suture 
  impressed, 
  painted 
  bulow 
  with 
  a 
  

   very 
  broad, 
  whitish-grey, 
  spiral 
  band 
  ; 
  umbilicus 
  funnel- 
  

   shaped, 
  deep; 
  columella 
  margin 
  acute, 
  almost 
  erect, 
  descending 
  

   in 
  a 
  curve 
  ; 
  labrum 
  acute, 
  slightly 
  dilated 
  below 
  ; 
  aperture 
  

   elongately 
  ovate; 
  interior 
  of 
  shell 
  livid 
  greyish 
  brown, 
  shading 
  

   to 
  chocolate. 
  

  

  Alt. 
  52, 
  diam. 
  maj. 
  42*5, 
  diam. 
  miii. 
  36 
  mm. 
  

  

  Aperture 
  : 
  alt. 
  39, 
  diam. 
  22 
  mm. 
  

  

  Hab. 
  Contamano, 
  Rio 
  Ucayali, 
  Eastern 
  Peru. 
  

  

  Corhicula 
  berinejoensis, 
  sp. 
  n. 
  

  

  Shell 
  subtrigonal, 
  whitish 
  cream-colour, 
  almost 
  smootli, 
  

   marked 
  only 
  with 
  very 
  fine 
  concentric 
  strise; 
  dorsal 
  margin 
  

   arched 
  ; 
  ventral 
  margin 
  gently 
  curved 
  ; 
  anterior 
  side 
  rounded 
  ; 
  

   posterior 
  side 
  rather 
  abruptly 
  descending, 
  angled 
  below 
  ; 
  

   right 
  valve 
  bearing 
  a 
  very 
  oblique, 
  marginal 
  anterior 
  and 
  

   two 
  short, 
  solid, 
  posterior 
  cardinal 
  teeth 
  and 
  two 
  curved 
  

   serrated 
  laterals 
  on 
  either 
  side 
  ; 
  left 
  valve 
  bearing 
  two 
  solid 
  

   and 
  divergent 
  anterior 
  and 
  a 
  very 
  oblique, 
  slightly 
  curved 
  

   and 
  elongated, 
  well-developed 
  posterior 
  cardinal 
  tooth, 
  and 
  a 
  

   coarsely 
  serrated 
  curved 
  lateral 
  on 
  either 
  side. 
  

  

  Long. 
  9, 
  lat. 
  9*25 
  mm. 
  

  

  Nab. 
  Rio 
  Bermejo, 
  a 
  tributary 
  of 
  the 
  Rio 
  Ohaco, 
  N. 
  Argen- 
  

   tina 
  (Clark). 
  

  

  Corbicula 
  approximans, 
  sp. 
  n. 
  

  

  Shell 
  differing 
  from 
  C. 
  bermejoensis, 
  Preston, 
  in 
  its 
  much 
  

   more 
  ovate 
  form, 
  it 
  being 
  much 
  more 
  laterally 
  produced 
  on 
  

   either 
  side, 
  but 
  especially 
  anteriorly, 
  than 
  in 
  that 
  species; 
  

   it 
  is 
  also 
  much 
  more 
  coarsely 
  concentrically 
  striate, 
  and 
  the 
  

   cardinal 
  teeth 
  are 
  weaker, 
  chiefly 
  in 
  the 
  right 
  valve. 
  

  

  Long. 
  10 
  (nearly), 
  hit. 
  11 
  (nearly) 
  mm. 
  

  

  Hah, 
  Rio 
  Bermejo, 
  a 
  tributary 
  of 
  the 
  Chaco, 
  N. 
  Argentina 
  

   {Clark). 
  

  

  