﻿Ortmnnn 
  — 
  Magellanian 
  Beds 
  of 
  Piinta 
  Arenas. 
  429 
  

  

  Characterized 
  by 
  the 
  elongate 
  form, 
  and 
  allied 
  by 
  that 
  charac- 
  

   ter 
  to 
  y. 
  landbecki 
  Philippi 
  (p. 
  116, 
  pi. 
  20, 
  f. 
  8), 
  Cretaceous, 
  

   Algarrobo. 
  The 
  present 
  species 
  differs 
  from 
  landbecki 
  by 
  the 
  

   situation 
  of 
  the 
  apex, 
  which 
  is 
  in 
  the 
  latter 
  at 
  f 
  ; 
  the 
  former 
  

   is 
  less 
  swollen, 
  and 
  the 
  area 
  is 
  indistinct. 
  

  

  Cytherea 
  {?) 
  jyseudocrassa 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  upper 
  part. 
  — 
  1 
  right 
  valve. 
  

  

  Shell 
  very 
  thick 
  and 
  very 
  convex, 
  outline 
  almost 
  circular, 
  

   posterior 
  end 
  rounded. 
  Apex 
  at 
  f 
  of 
  the 
  length. 
  Exterior 
  

   surface 
  concentrically 
  striated, 
  but 
  the 
  adhering 
  matrix 
  obscures 
  

   the 
  sculpture. 
  L. 
  62™^^, 
  H. 
  60"^°^, 
  D. 
  25. 
  

  

  The 
  generic 
  position, 
  is 
  doubtful. 
  Posterior 
  tooth 
  of 
  the 
  

   hinge 
  divided. 
  Yentral 
  margin 
  of 
  shell 
  not 
  crenulated. 
  

  

  Characterized 
  by 
  the 
  very 
  thick 
  shell 
  and 
  the 
  almost 
  circular 
  

   outline, 
  Y. 
  crassa 
  Phil. 
  (p. 
  128, 
  pi. 
  21, 
  f. 
  1), 
  from 
  the 
  Pliocene 
  

   Coquimbo 
  beds 
  of 
  Chile, 
  is 
  related, 
  but 
  in 
  our 
  species 
  the 
  trans- 
  

   verse 
  diameter 
  is 
  greater, 
  the 
  hinge 
  is 
  different, 
  and 
  the 
  apex 
  

   is 
  situated 
  differently. 
  Further, 
  Y. 
  altaPhiL 
  (p. 
  116, 
  pi. 
  20, 
  f. 
  3), 
  

   from 
  the 
  Cretaceous 
  of 
  Algarrobo 
  is 
  an 
  allied 
  form, 
  but 
  the 
  

   present 
  species 
  is 
  higher, 
  and 
  rounded 
  posteriorly 
  (not 
  "subro- 
  

   strate 
  ") 
  : 
  Y. 
  alta 
  is 
  more 
  triangular 
  in 
  outline. 
  

  

  Dosinia 
  complanata 
  (Phil.) 
  (Artemis 
  c. 
  Philippi, 
  1. 
  c, 
  p. 
  114, 
  

   pi. 
  15, 
  f. 
  1). 
  , 
  ^ 
  

  

  Magellanian 
  beds, 
  lower 
  part. 
  4 
  left, 
  3 
  right 
  valves, 
  imbed- 
  

   ded 
  in 
  matrix. 
  

  

  I 
  cannot 
  distinguish 
  our 
  specimens 
  from 
  Philippi's 
  species. 
  

  

  This 
  form 
  has 
  been 
  found 
  previously 
  in 
  the 
  Navidad 
  beds 
  

   near 
  Matanzas, 
  Chile. 
  

  

  Glycimeris 
  ihari 
  (Phil.) 
  (Panopsea 
  i, 
  Philippi, 
  1. 
  c, 
  p. 
  167, 
  

   pi. 
  35, 
  f. 
  4). 
  

  

  Magellanian 
  beds, 
  lower 
  part. 
  1 
  double 
  valve, 
  4 
  left 
  and 
  2 
  

   right 
  valves. 
  

  

  Characterized 
  by 
  the 
  elongate 
  outline, 
  arcuate 
  ventral 
  mar- 
  

   gin, 
  narrower 
  posterior 
  end, 
  and 
  situation 
  of 
  apex. 
  

  

  Recorded 
  from 
  Magellanes 
  and 
  Skyring 
  Water. 
  

  

  Glycimeris 
  suhsymmetrica 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  upper 
  part.— 
  1 
  right 
  valve. 
  

  

  Almost 
  identical 
  with 
  G. 
  ibari, 
  but 
  not 
  so 
  much 
  elongated, 
  

   and 
  posterior 
  end 
  not 
  narrowed. 
  Relation 
  of 
  H. 
  to 
  L. 
  = 
  1 
  : 
  1, 
  

   6 
  (in 
  ibari 
  = 
  1 
  : 
  1, 
  8 
  to 
  2, 
  0). 
  

  

  Lutraria 
  undatoides 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  lower 
  part. 
  — 
  1 
  donble 
  valve. 
  

  

  Shell 
  almost 
  elliptic, 
  IJ 
  as 
  long 
  as 
  high. 
  Surface 
  with 
  strong 
  

   and 
  somewhat 
  irregular, 
  undulated 
  concentric 
  folds. 
  Dorsal 
  

   margin 
  almost 
  straight, 
  ventral 
  margin 
  slightly 
  arcuate. 
  Apex 
  

   at 
  ^ 
  of 
  the 
  length, 
  prominent, 
  rather 
  sharp, 
  incurved. 
  Anterior 
  

   and 
  posterior 
  ends 
  evenly 
  rounded 
  off 
  and 
  of 
  the 
  same 
  height. 
  

   L. 
  32'"™, 
  H. 
  21"^"^, 
  apex 
  at 
  11™"^ 
  from 
  anterior 
  end. 
  

  

  