﻿THE 
  DISTRIBUTION 
  OF 
  FRESH-WATER 
  FISHES 
  

  

  By 
  David 
  Stare 
  Jordan 
  

  

  [With 
  2 
  plates] 
  

  

  The 
  phrase 
  " 
  Distribution 
  of 
  fishes 
  " 
  (as 
  witli 
  distribution 
  of 
  other 
  

   organisms) 
  involves 
  two 
  separate 
  but 
  closely 
  related 
  problems: 
  First, 
  

   tlie 
  actual 
  facts 
  in 
  regard 
  to 
  the 
  presence 
  in 
  the 
  various 
  waters 
  of 
  

   certain 
  species 
  which 
  constitute 
  the 
  fish 
  fauna; 
  second, 
  the 
  problem 
  

   for 
  each 
  species, 
  of 
  how 
  did 
  it 
  get 
  there. 
  For 
  every 
  kind 
  of 
  fish 
  had 
  

   its 
  origin 
  somewhere, 
  and 
  for 
  the 
  most 
  part 
  not 
  in 
  any 
  stream 
  it 
  now 
  

   inhabits. 
  For 
  each 
  different 
  fish 
  fauna 
  is 
  very 
  old 
  in 
  the 
  temperate 
  

   zones, 
  mostly 
  dating 
  back 
  to 
  the 
  last 
  glacial 
  period, 
  and 
  to 
  the 
  read- 
  

   justment 
  of 
  conditions 
  which 
  followed 
  the 
  expansion 
  and 
  the 
  reces- 
  

   sion 
  of 
  the 
  ice. 
  

  

  The 
  science 
  of 
  zoogeography 
  deals 
  with 
  both 
  series 
  of 
  problems, 
  

   the 
  actual 
  location 
  of 
  different 
  species 
  on 
  the 
  surface 
  of 
  the 
  earth, 
  

   and 
  the 
  laws 
  or 
  relations 
  of 
  cause 
  and 
  effect 
  by 
  which 
  their 
  location 
  

   is 
  determined. 
  

  

  In 
  physical 
  geography 
  we 
  may 
  prepare 
  maps 
  of 
  the 
  earth 
  or 
  of 
  any 
  

   part 
  of 
  it, 
  these 
  bringing 
  to 
  prominence 
  the 
  physical 
  features 
  of 
  its 
  

   surface. 
  Such 
  maps 
  show 
  here 
  a 
  sea, 
  there 
  a 
  plateau, 
  here 
  a 
  moun- 
  

   tain 
  chain, 
  there 
  a 
  desert, 
  a 
  prairie, 
  a 
  peninsula, 
  or 
  an 
  island. 
  In 
  

   political 
  geography 
  the 
  maps 
  show 
  the 
  physical 
  features 
  of 
  the 
  earth 
  

   as 
  related 
  to 
  the 
  people 
  who 
  inhabit 
  them 
  and 
  the 
  states 
  or 
  powers 
  

   which 
  receive 
  or 
  claim 
  their 
  allegiance. 
  In 
  zoogeography 
  the 
  realms 
  

   of 
  the 
  earth 
  are 
  considered 
  in 
  relation 
  to 
  the 
  species 
  or 
  tribes 
  of 
  

   animals 
  which 
  inhabit 
  them. 
  Thus 
  series 
  of 
  maps 
  could 
  be 
  drawn 
  

   representing 
  those 
  parts 
  of 
  North 
  America 
  in 
  which 
  catfishes 
  or 
  

   trout 
  or 
  sunfishes 
  are 
  found 
  in 
  the 
  streams. 
  In 
  like 
  manner 
  the 
  

   distribution 
  of 
  any 
  particular 
  fish 
  as 
  the 
  muskallonge 
  or 
  the 
  yellow 
  

   perch 
  could 
  be 
  shown 
  on 
  the 
  map. 
  The 
  details 
  of 
  such 
  a 
  map 
  are 
  

   very 
  instructive, 
  and 
  their 
  consideration 
  at 
  once 
  raises 
  a 
  series 
  of 
  

   questions 
  as 
  to 
  the 
  cause 
  behind 
  each 
  fact. 
  In 
  science 
  it 
  must 
  be 
  

   supposed 
  that 
  no 
  fact 
  is 
  arbitrary 
  or 
  meaningless. 
  The 
  word 
  " 
  dis- 
  

   continuous 
  " 
  has 
  only 
  a 
  relative 
  meaning, 
  if 
  any, 
  in 
  biology. 
  In 
  the 
  

   case 
  of 
  fishes 
  the 
  details 
  of 
  the 
  method 
  of 
  diffusion 
  of 
  species 
  afford 
  

   matters 
  of 
  deep 
  interest. 
  

  

  1 
  This 
  article 
  Is 
  based 
  in 
  large 
  part 
  on 
  earlier 
  ones 
  of 
  the 
  author 
  on 
  the 
  same 
  subject, 
  

   in 
  Science 
  Sketches, 
  18S7 
  and 
  1896, 
  and 
  one 
  in 
  Fishes, 
  1925. 
  

  

  355 
  

  

  