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  ANNUAL 
  REPOET 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  Connected 
  perhaps 
  with 
  changes 
  due 
  to 
  glacial 
  influences 
  is 
  the 
  

   presence 
  in 
  the 
  deep 
  waters 
  of 
  the 
  Great 
  Lakes 
  of 
  certain 
  marine 
  

   types,® 
  as 
  shown 
  by 
  Prof. 
  Sidney 
  I. 
  Smith 
  and 
  others. 
  One 
  of 
  these 
  

   is 
  a 
  genus 
  of 
  fishes,^ 
  of 
  which 
  the 
  nearest 
  allies 
  now 
  inhabit 
  the 
  

   Arctic 
  Seas. 
  In 
  his 
  review 
  of 
  the 
  fish 
  fauna 
  of 
  Finland,^ 
  Prof. 
  A, 
  J. 
  

   Malmgren 
  finds 
  a 
  number 
  of 
  Arctic 
  species 
  in 
  the 
  waters 
  of 
  Finland 
  

   which 
  are 
  not 
  found 
  either 
  in 
  the 
  North 
  Sea 
  or 
  in 
  the 
  southern 
  por- 
  

   tions 
  of 
  the 
  Baltic. 
  These 
  fishes 
  are 
  said 
  to 
  " 
  agree 
  with 
  their 
  ' 
  fore- 
  

   fathers 
  ' 
  in 
  the 
  glacial 
  ocean 
  in 
  every 
  point, 
  but 
  remain 
  compara- 
  

   tively 
  smaller, 
  leaner, 
  almost 
  starved." 
  Professor 
  Loven^ 
  also 
  has 
  

   shown 
  that 
  numerous 
  small 
  animals 
  of 
  marine 
  origin 
  are 
  found 
  in 
  

   the 
  deep 
  lakes 
  of 
  Sweden 
  and 
  Finland 
  as 
  well 
  as 
  in 
  the 
  Gulf 
  of 
  

   Bothnia. 
  These 
  anomalies 
  of 
  distribution 
  are 
  expained 
  bj^ 
  Loven 
  

   and 
  Malmgren 
  on 
  the 
  supposition 
  of 
  the 
  former 
  continuity 
  of 
  the 
  

   Baltic 
  through 
  the 
  Gulf 
  of 
  Bothnia 
  with 
  the 
  glacial 
  ocean. 
  During 
  

   the 
  second 
  half 
  of 
  the 
  glacial 
  period, 
  according 
  to 
  Loven 
  — 
  

  

  The 
  greater 
  part 
  of 
  Finland 
  and 
  of 
  the 
  middle 
  of 
  Sweden 
  was 
  submerged, 
  and 
  

   the 
  Baltic 
  was 
  a 
  great 
  gulf 
  of 
  the 
  glacial 
  ocean, 
  and 
  not 
  connected 
  with 
  the 
  

   German 
  ocean. 
  By 
  the 
  gradual 
  elevation 
  of 
  the 
  Scandinavian 
  Continent, 
  the 
  

   Baltic 
  became 
  disconnected 
  from 
  the 
  glacial 
  ocean 
  and 
  the 
  Great 
  Lakes 
  

   separated 
  from 
  the 
  Baltic. 
  In 
  consequence 
  of 
  the 
  gradual 
  change 
  of 
  the 
  salt 
  

   water 
  into 
  fresh, 
  the 
  marine 
  fauna 
  became 
  gradually 
  extinct, 
  with 
  the 
  excep- 
  

   tion 
  of 
  the 
  glacial 
  forms 
  mentioned 
  above. 
  

  

  It 
  is 
  possible 
  that 
  the 
  presence 
  of 
  marine 
  types 
  in 
  our 
  Great 
  Lakes 
  

   is 
  to 
  be 
  regarded 
  as 
  due 
  to 
  some 
  depression 
  of 
  the 
  land 
  which 
  would 
  

   connect 
  their 
  waters 
  with 
  those 
  of 
  the 
  Gulf 
  of 
  St. 
  Lawrence. 
  On 
  

   this 
  point, 
  however, 
  our 
  data 
  are 
  still 
  incomplete. 
  

  

  To 
  certain 
  species 
  of 
  upland 
  or 
  mountain 
  fishes 
  the 
  depression 
  of 
  

   the 
  Mississippi 
  Basin 
  itself 
  forms 
  a 
  barrier 
  which 
  can 
  not 
  be 
  passed. 
  

   The 
  black-spotted 
  trout,^° 
  very 
  closely 
  related 
  species 
  of 
  whicii 
  

   abound 
  in 
  all 
  waters 
  of 
  northern 
  Asia, 
  Europe, 
  and 
  western 
  North 
  

   America, 
  has 
  noAvhere 
  crossed 
  the 
  basin 
  of 
  the 
  Mississippi, 
  although 
  

   one 
  of 
  its 
  species 
  finds 
  no 
  difficulty 
  in 
  passing 
  Bering 
  Strait. 
  The 
  

   trout 
  and 
  whitefish 
  of 
  the 
  Rocky 
  Mountain 
  region 
  are 
  all 
  species 
  

   different 
  from 
  those 
  of 
  the 
  Great 
  Lakes 
  or 
  the 
  streams 
  of 
  the 
  Alle- 
  

   gheny 
  system. 
  To 
  the 
  grayling, 
  the 
  trout, 
  the 
  whitefish, 
  the 
  pike, 
  

   and 
  to 
  Arctic 
  and 
  sub-Arctic 
  species 
  generally, 
  Bering 
  Strait 
  has 
  

   evidently 
  proved 
  no 
  serious 
  obstacle 
  to 
  diffusion; 
  and 
  it 
  is 
  not 
  

  

  " 
  Species 
  of 
  Mysis 
  and 
  other 
  genera 
  of 
  Crustaceans, 
  similar 
  to 
  species 
  described 
  by 
  

   Sars 
  and 
  others, 
  in 
  lakes 
  of 
  Sweden 
  and 
  Finland. 
  

  

  ^ 
  TrigJopsis 
  thompsonl 
  Girard, 
  a 
  near 
  ally 
  of 
  the 
  marine 
  sp. 
  Oncocottus 
  quadricor- 
  

   nis 
  L. 
  

  

  8 
  Kritisk 
  Ofvorsigt 
  af 
  Finlands 
  Fisk-Fauna, 
  Helsingfors, 
  3 
  863. 
  

  

  » 
  See 
  Giinther, 
  Zoological 
  Record 
  for 
  1864, 
  p. 
  137. 
  

  

  1" 
  Salmo 
  trutta 
  or 
  fario 
  L., 
  in 
  Europe 
  ; 
  Salmo 
  labrax 
  Pallas, 
  etc., 
  in 
  Asia 
  ; 
  Salmo 
  irideus 
  

   Gibbons 
  in 
  streams 
  of 
  the 
  Pacific 
  coast 
  ; 
  many 
  derivatives 
  of 
  Salmo 
  clarki 
  Richardson, 
  

   throughout 
  the 
  Rocky 
  Mountain 
  Range 
  to 
  the 
  Mexican 
  boundary, 
  and 
  the 
  headwaters 
  

   of 
  the 
  Kansas, 
  Platte, 
  and 
  Missouri. 
  

  

  