﻿428 
  Ortmann 
  — 
  Magellanian 
  Beds 
  of 
  Punta 
  Arenas. 
  

  

  Agreeing 
  well 
  with 
  Philippi's 
  figure. 
  Characterized 
  by 
  the 
  

   radial 
  folds, 
  which 
  in 
  our 
  specimens 
  — 
  although 
  they 
  are 
  much 
  

   water-worn— 
  are 
  well 
  exhibited. 
  In 
  all 
  the 
  other 
  Patagonian 
  

   oysters 
  these 
  radial 
  folds 
  are 
  only 
  faintly 
  or 
  not 
  at 
  all 
  developed. 
  

  

  Recorded 
  by 
  Philippi 
  from 
  the 
  Straits 
  of 
  Magellan. 
  

  

  Cardita 
  elegantoides 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  upper 
  part. 
  — 
  3 
  isolated 
  right 
  valves, 
  2 
  

   valves 
  imbedded 
  in 
  the 
  matrix. 
  

  

  Shell 
  somewhat 
  rounded, 
  slightly 
  inclined, 
  with 
  19 
  radial 
  ribs^ 
  

   which 
  are 
  rounded, 
  about 
  as 
  broad 
  as 
  the 
  intervening 
  furrows, 
  

   and 
  nodulose. 
  Lunula 
  small, 
  oblong. 
  L. 
  16™'^, 
  H. 
  14°^'°. 
  

  

  This 
  species 
  comes 
  very 
  near 
  in 
  outline 
  to 
  C. 
  elegans 
  Lmck. 
  

   (see: 
  Wood, 
  Eoc. 
  Biv. 
  Engl. 
  1, 
  1861, 
  p. 
  146, 
  pi. 
  22, 
  f. 
  16) 
  from 
  

   the 
  upper 
  Eocene 
  of 
  England 
  and 
  France. 
  Also 
  the 
  number 
  

   of 
  ribs 
  agrees 
  closely 
  (17-20 
  in 
  elegans) 
  : 
  but 
  there 
  is 
  a 
  broader 
  

   interspace 
  between 
  the 
  ribs 
  in 
  C. 
  elegans, 
  and 
  the 
  ribs 
  them- 
  

   selves 
  are 
  thinner 
  and 
  more 
  nodulous. 
  — 
  C. 
  volckmanni 
  Philippi 
  

   (1. 
  c, 
  p. 
  173, 
  pi. 
  37, 
  f. 
  4) 
  from 
  Tubul 
  (:Navidad 
  beds) 
  is 
  also 
  

   closely 
  related, 
  but 
  has 
  only 
  15 
  ribs. 
  

  

  Yeiius 
  difflcilis 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  upper 
  part. 
  — 
  1 
  left 
  and 
  2 
  right 
  valves. 
  — 
  

   Lower 
  part 
  (horizon 
  II). 
  — 
  2 
  double 
  valves 
  and 
  2 
  left 
  valves. 
  

  

  Shell 
  thick, 
  oblique, 
  inflated, 
  posteriorly 
  a 
  little 
  narrowed, 
  

   apex 
  situated 
  in 
  advance 
  of 
  or 
  at 
  \ 
  of 
  the 
  length. 
  Area 
  long, 
  

   occupying 
  almost 
  the 
  whole 
  of 
  the 
  posterior 
  dorsal 
  margin 
  of 
  

   the 
  shell. 
  Lunula 
  oval, 
  flat, 
  exterior 
  surface 
  with 
  close 
  and 
  

   regular 
  concentric 
  furrows, 
  and 
  with 
  some 
  concentric 
  lines 
  of 
  

   growth 
  (remains 
  of 
  ventral 
  margins), 
  the 
  latter 
  more 
  crowded 
  

   near 
  the 
  lower 
  margin, 
  and 
  irregular. 
  Concentric 
  furrows 
  

   sharp, 
  not 
  interrupted, 
  h; 
  — 
  V'^ 
  distant 
  from 
  each 
  other. 
  Length 
  

   of 
  a 
  large 
  valve 
  : 
  75'''"^, 
  height 
  64"""', 
  transverse 
  diameter 
  (of 
  

   half 
  shell) 
  18""\ 
  Apex 
  situated 
  at 
  16°^'" 
  from 
  anterior 
  end. 
  

  

  Comes 
  very 
  near 
  to 
  Y. 
  subsulcata 
  Philippi 
  (p. 
  115, 
  pi. 
  17, 
  f. 
  7), 
  

   from 
  the 
  Cretaceous 
  of 
  Algarrobo, 
  but 
  in 
  the 
  latter 
  species 
  the 
  

   concentric 
  furrows 
  do 
  not 
  extend 
  all 
  over 
  the 
  surface, 
  but 
  are 
  

   interrupted 
  in 
  the 
  middle. 
  

   Venus 
  arenosa 
  spec. 
  nov. 
  

  

  Magellanian 
  beds, 
  upper 
  part. 
  — 
  3 
  right 
  valves. 
  

  

  Shell 
  transversely 
  elliptical, 
  moderately 
  swollen. 
  Posterior 
  

   end 
  hardly 
  narrower 
  than 
  the 
  anterior. 
  Apex 
  situated 
  at 
  ca. 
  \ 
  

   of 
  the 
  length. 
  Area 
  indistinct, 
  shorter 
  than 
  the 
  posterior 
  part 
  

   of 
  the 
  dorsal 
  margin. 
  Nymphae 
  f-f 
  as 
  long 
  as 
  the 
  area. 
  Lun- 
  

   ula 
  indistinct. 
  Exterior 
  surface 
  with 
  strong 
  concentric 
  lines 
  of 
  

   growth, 
  which 
  have 
  between 
  them 
  finer 
  concentric 
  striae 
  

   (obliterated 
  in 
  our 
  specimens 
  on 
  account 
  of 
  the 
  closely 
  adhering 
  

   matrix). 
  L. 
  60"^"\ 
  H. 
  44'"'", 
  D. 
  (half 
  shell) 
  15"^'^\ 
  ' 
  All 
  three 
  

   specimens 
  show 
  the 
  hinge 
  teeth 
  of 
  a 
  true 
  Venus. 
  

  

  