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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  connection 
  it 
  is 
  interesting 
  to 
  note 
  that 
  the 
  wide 
  ranging 
  faiinal 
  units 
  

   of 
  the 
  Paleozoic 
  are 
  very 
  remarkable 
  in 
  the 
  fact 
  that 
  they 
  are 
  made 
  

   up 
  of 
  large 
  numbers 
  of 
  individuals 
  representing 
  relatively 
  few 
  genera 
  

   and 
  species. 
  In 
  western 
  America 
  a 
  certain 
  Ordovician 
  horizon 
  may 
  

   confidently 
  be 
  expected 
  to 
  yield 
  a 
  dozen 
  or 
  so 
  genera 
  of 
  brachiopods 
  

   and 
  corals, 
  in 
  most 
  cases 
  represented 
  by 
  one 
  species 
  each. 
  This 
  small 
  

   group 
  of 
  organisms 
  is 
  found 
  in 
  abundance 
  from 
  the 
  Mexican 
  border 
  

   to 
  central 
  Alaska. 
  Over 
  and 
  above 
  this 
  small 
  number 
  of 
  character- 
  

   istic 
  species 
  additional 
  forms 
  may 
  only 
  be 
  added 
  by 
  diligent 
  search. 
  

   The 
  wide 
  range 
  of 
  the 
  faunule 
  is 
  shown 
  by 
  the 
  fact 
  that 
  the 
  same 
  

   approximate 
  association 
  of 
  identical 
  or 
  nearly 
  allied 
  species 
  is 
  found 
  

   in 
  the 
  Baltic 
  region 
  of 
  Europe, 
  in 
  Baffin 
  Land, 
  Ellesmereland, 
  and 
  

   Burma. 
  Similar 
  small 
  groups 
  of 
  widely 
  distributed 
  organisms 
  are 
  

   found 
  at 
  many 
  other 
  horizons. 
  

  

  Under 
  present 
  oceanic 
  condition,s 
  organisms 
  secreting 
  large 
  amounts 
  

   of 
  lime 
  are 
  most 
  abundant 
  in 
  warm 
  waters 
  and 
  minimal 
  in 
  very 
  cold 
  

   waters. 
  This 
  is 
  perhaps 
  a 
  function 
  of 
  the 
  chemical 
  content 
  of 
  the 
  

   sea 
  water, 
  depending 
  on 
  the 
  amount 
  of 
  carbon 
  dioxide 
  present. 
  Here 
  

   we 
  are 
  at 
  a 
  loss, 
  for 
  who 
  knows 
  the 
  gas 
  content 
  of 
  the 
  ancient 
  seas? 
  

   Even 
  at 
  that, 
  heavy 
  lime 
  secretion 
  is 
  not 
  characteristic 
  of 
  the 
  Paleo- 
  

   zoic 
  organisms 
  as 
  a 
  rule, 
  particularly 
  in 
  the 
  early 
  Paleozoic. 
  Judged 
  

   by 
  such 
  a 
  standard, 
  certainly 
  the 
  mar\'elous 
  asseniblajre 
  of 
  soft-bodied 
  

   invertebrates 
  from 
  the 
  Cambrian 
  shales 
  of 
  British 
  Columbia 
  described 
  

   by 
  Walcott 
  would 
  point 
  rather 
  to 
  cold 
  than 
  warm 
  water 
  conditions. 
  

   In 
  this 
  connection 
  it 
  should 
  be 
  borne 
  in 
  mind 
  that 
  the 
  calcareous 
  alga 
  

   LitJiothamniwni 
  is 
  extraordinarily 
  abundant 
  in 
  the 
  north 
  polar 
  sea, 
  

   where 
  the 
  temperature 
  of 
  the 
  water 
  seldom 
  rise,s 
  above 
  0° 
  C. 
  After 
  

   all 
  we 
  are 
  not 
  seeking 
  to 
  prove 
  freezing 
  temj)eratures 
  for 
  all 
  our 
  

   ancient 
  faunas. 
  Rather 
  the 
  attempt 
  has 
  been 
  made 
  to 
  show 
  no 
  real 
  

   incompatibility 
  between 
  our 
  fossil 
  faunas 
  and 
  a 
  possible 
  temperate 
  

   to 
  cold 
  water 
  habitat. 
  

  

  An 
  argument 
  for 
  warm 
  seas 
  constantly 
  used 
  is 
  the 
  presence 
  of 
  

   coral 
  reefs 
  in 
  the 
  pa.st. 
  These 
  reefs 
  are 
  not 
  impressive 
  at 
  best 
  and 
  

   should 
  be 
  used 
  with 
  caution. 
  Bonney, 
  Yakolew, 
  and 
  others 
  have 
  

   pointed 
  out 
  that 
  there 
  is 
  little 
  real 
  analogy 
  between 
  Paleozoic 
  and 
  

   recent 
  coral 
  reefs. 
  As 
  a 
  rule 
  the 
  most 
  important 
  constituent 
  of 
  the 
  

   Paleozoic 
  reefs 
  is 
  Stromatoporoidea, 
  while 
  next 
  in 
  importance 
  come 
  

   the 
  Tabulata 
  and 
  finally 
  the 
  Tetracoralla. 
  These 
  proportions 
  vary, 
  

   but 
  as 
  an 
  average 
  they 
  probably 
  hold 
  good. 
  Of 
  the 
  three 
  groups 
  the 
  

   Tetracoralla 
  alone 
  may 
  be 
  compared 
  with 
  the 
  reef 
  corals 
  of 
  to-day, 
  

   and 
  even 
  here 
  the 
  kinship 
  is 
  ,so 
  remote 
  that 
  it 
  would 
  be 
  rash 
  indeed 
  

   to 
  insist 
  on 
  similar 
  conditions 
  of 
  life. 
  Rathier, 
  it 
  is 
  better 
  to 
  con- 
  

   sider 
  the 
  bathymetric 
  and 
  temperature 
  ranges 
  of 
  modern 
  corals. 
  We 
  

   have 
  already 
  noted 
  the 
  presence 
  in 
  the 
  freezing 
  waters 
  of 
  McMurdo 
  

   Sound 
  of 
  a 
  cup 
  coral, 
  and 
  we 
  know 
  that 
  similar 
  corals 
  range 
  down 
  

  

  