﻿364 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  The 
  first 
  discussion 
  of 
  the 
  dispersion 
  of 
  fiesh-water 
  fishes 
  in 
  

   America 
  was 
  begun 
  in 
  1850 
  in 
  Professor 
  Agassiz's 
  volume 
  on 
  Lake 
  

   Superior. 
  In 
  his 
  later 
  paper 
  ^ 
  (1854), 
  on 
  the 
  fishes 
  of 
  the 
  Tennessee 
  

   River, 
  he 
  outlines 
  certain 
  questions 
  to 
  be 
  answered. 
  The 
  river 
  rising 
  

   in 
  the 
  mountains 
  of 
  Virginia 
  and 
  North 
  Carolina 
  (latitude 
  37°) 
  as 
  

   the 
  Holston, 
  Clinch, 
  and 
  French 
  Broad, 
  flows 
  rather 
  swiftly 
  south- 
  

   westerly 
  to 
  northern 
  Alabama 
  (latitude 
  34° 
  25'), 
  thence 
  north- 
  

   westerly 
  to 
  the 
  Ohio, 
  which 
  it 
  enters 
  in 
  the 
  same 
  latitude 
  (37°) 
  as 
  

   its 
  source, 
  but 
  naturally 
  at 
  a 
  much 
  lower 
  elevation. 
  Are 
  the 
  fishes 
  

   of 
  the 
  Tennessee 
  the 
  same 
  throughout 
  its 
  extent? 
  If 
  so, 
  water 
  com- 
  

   munication 
  is 
  the 
  chief 
  factor 
  in 
  their 
  general 
  distribution. 
  Again, 
  

   are 
  the 
  differences 
  mainly 
  controlled 
  by 
  the 
  elevation? 
  Or 
  is 
  their 
  

   presence 
  due 
  to 
  climatic 
  differences? 
  

  

  In 
  the 
  extensive 
  collections 
  in 
  the 
  Tennessee 
  Basin 
  made 
  by 
  the 
  

   writer 
  and 
  his 
  associates 
  we 
  find 
  ample 
  evidence 
  of 
  the 
  effects 
  of 
  

   each 
  of 
  these 
  factors. 
  Open 
  communication 
  for 
  a 
  long 
  period 
  is 
  

   the 
  most 
  vital, 
  especially 
  with 
  large 
  or 
  free-swimming 
  fishes. 
  For 
  

   the 
  smaller 
  fishes, 
  darters, 
  minnows, 
  etc., 
  isolation 
  with 
  segregation 
  

   gives 
  rise 
  to 
  numerous 
  geminate 
  or 
  twin 
  forms, 
  in 
  the 
  Allegheny 
  

   iMountains 
  on 
  the 
  one 
  hand 
  and 
  the 
  Ozarks 
  on 
  the 
  other, 
  the 
  iMis- 
  

   sissippi 
  River 
  serving 
  as 
  an 
  obstacle 
  to 
  their 
  dispersion 
  rather 
  than, 
  

   as 
  with 
  the 
  large 
  fishes, 
  being 
  the 
  chief 
  vehicle 
  of 
  distribution. 
  

   The 
  difference 
  in 
  species 
  in 
  the 
  south 
  bend 
  of 
  the 
  river 
  brings 
  in 
  a 
  

   few 
  species 
  of 
  warmer 
  waters, 
  contrasting 
  with 
  those 
  of 
  the 
  mountain 
  

   waters 
  of 
  the 
  French 
  Broad. 
  

  

  In 
  an 
  excellent 
  memoir 
  on 
  the 
  fishes 
  of 
  the 
  Allegheny 
  region 
  

   (1868), 
  Prof. 
  Edward 
  D. 
  Cope 
  has 
  some 
  pertinent 
  suggestions: 
  

  

  As 
  most 
  fresh-Avater 
  fishes 
  perish 
  in 
  salt 
  water, 
  our 
  present 
  river 
  

   faunas 
  date 
  from 
  the 
  last 
  submergence, 
  as 
  also 
  from 
  the 
  last 
  period 
  

   of 
  glacial 
  cold. 
  The 
  latter 
  condition 
  would 
  drive 
  species 
  it 
  did 
  not 
  

   destroy 
  to 
  the 
  low 
  waters 
  along 
  the 
  coast. 
  Cope 
  concludes 
  that 
  " 
  the 
  

   distribution 
  of 
  fresh-water 
  fishes 
  is 
  governed 
  by 
  laws 
  similar 
  to 
  

   those 
  controlling 
  other 
  terrestrials, 
  in 
  spite 
  of 
  the 
  seemingly 
  con- 
  

   fined 
  nature 
  of 
  their 
  habitat." 
  This 
  is 
  doubtless 
  true, 
  in 
  general, 
  

   although 
  in 
  very 
  many 
  cases, 
  each 
  different 
  river 
  basin 
  possesses 
  

   species, 
  geminate 
  to 
  those 
  in 
  the 
  next 
  basin, 
  but 
  not 
  quite 
  identical, 
  

   the 
  difference 
  being 
  due 
  to 
  failure 
  for 
  long 
  periods 
  to 
  interbreed 
  

   with 
  the 
  mass 
  of 
  the 
  parent 
  species. 
  But 
  in 
  many 
  cases 
  the 
  fishes 
  

   of 
  these 
  basins 
  are 
  identical- 
  In 
  one 
  case, 
  which 
  is 
  probably 
  typical 
  

   of 
  many, 
  river 
  fishes 
  were 
  found 
  to 
  enter 
  the 
  sea 
  at 
  times 
  of 
  high 
  

   water, 
  apparently 
  returning 
  to 
  some 
  other 
  stream 
  emptying 
  in 
  the 
  

   same 
  neighborhood. 
  The 
  apparent 
  interchange 
  was 
  plainly 
  seen 
  by 
  

   the 
  writer 
  in 
  the 
  rivers 
  of 
  Escambia 
  and 
  Perdido 
  of 
  western 
  Florida. 
  

  

  3 
  " 
  On 
  fishes 
  from 
  Tennessee 
  River, 
  Alabama." 
  American 
  Journal 
  of 
  Science 
  and 
  Arts, 
  

   2a 
  series, 
  XVII, 
  1854, 
  p. 
  76. 
  

  

  