﻿DISTRIBUTION 
  OF 
  FISHES 
  — 
  JOEDAN" 
  361 
  

  

  the 
  islands 
  of 
  the 
  Pacific, 
  seems 
  to 
  have 
  had 
  its 
  origin 
  in 
  India, 
  

   from 
  which 
  region 
  its 
  genera 
  have 
  radiated 
  in 
  every 
  direction. 
  

  

  The 
  cyprinoid 
  division 
  of 
  the 
  equatorial 
  zone 
  forms 
  two 
  districts, 
  

   the 
  Indian 
  and 
  the 
  African. 
  The 
  acyprinoid 
  division 
  includes 
  South 
  

   America, 
  south 
  of 
  Mexico, 
  and 
  all 
  the 
  islands 
  of 
  the 
  tropical 
  Pacific 
  

   lying 
  to 
  the 
  east 
  of 
  " 
  Wallace's 
  Line." 
  This 
  line 
  separates 
  Borneo 
  

   from 
  Celebes 
  and 
  Bali 
  from 
  Lompoe, 
  and 
  marks 
  in 
  the 
  Pacific 
  the 
  

   western 
  limit 
  of 
  cyprinoid 
  fishes, 
  as 
  well 
  as 
  that 
  of 
  monkeys 
  and 
  

   other 
  important 
  groups 
  of 
  land 
  animals. 
  This 
  line, 
  recognized 
  as 
  

   very 
  important 
  in 
  the 
  distribution 
  of 
  land 
  animals, 
  coincides 
  in 
  

   general 
  with 
  the 
  ocean 
  current 
  between 
  Celebes 
  and 
  Papua, 
  which 
  is 
  

   one 
  of 
  the 
  sources 
  of 
  the 
  Kuro-Shiwo. 
  

  

  In 
  Australia, 
  New 
  Zealand, 
  Hawaii, 
  and 
  Polynesia 
  generally, 
  the 
  

   fresh-water 
  fishes 
  are 
  derived 
  from 
  marine 
  types 
  by 
  modification 
  of 
  

   one 
  sort 
  or 
  another. 
  In 
  no 
  case, 
  so 
  far 
  as 
  I 
  know, 
  in 
  any 
  island 
  to 
  

   the 
  eastward 
  of 
  Borneo, 
  is 
  found 
  any 
  species 
  derived 
  from 
  fresh- 
  

   water 
  families 
  of 
  either 
  the 
  eastern 
  or 
  the 
  western 
  continent. 
  Of 
  

   course, 
  minor 
  subdivisions 
  in 
  these 
  districts 
  are 
  formed 
  by 
  the 
  con- 
  

   tour 
  lines 
  of 
  river 
  basins. 
  The 
  fishes 
  of 
  the 
  Nile 
  differ 
  from 
  those 
  

   of 
  the 
  Niger 
  or 
  the 
  Congo, 
  or 
  of 
  the 
  streams 
  of 
  Madagascar 
  or 
  Cape 
  

   Colony, 
  but 
  in 
  all 
  these 
  regions 
  the 
  essential 
  character 
  of 
  the 
  fish 
  

   fauna 
  remains 
  the 
  same. 
  

  

  The 
  third 
  great 
  region, 
  the 
  southern 
  zone, 
  or 
  sub-Antarctic, 
  is 
  

   scantily 
  supplied 
  with 
  fresh-water 
  fishes, 
  and 
  the 
  few 
  it 
  possesses 
  

   are 
  chiefly 
  derived 
  from 
  modifications 
  of 
  the 
  marine 
  fauna 
  of 
  the 
  

   equatorial 
  zone 
  to 
  the 
  north. 
  Three 
  districts 
  are 
  recognized 
  — 
  Tas- 
  

   mania, 
  New 
  Zealand, 
  and 
  Patagonia. 
  

  

  The 
  degree 
  of 
  survival 
  among 
  the 
  marine 
  fishes, 
  from 
  the 
  Miocene 
  

   period 
  on, 
  is 
  fairly 
  well 
  tested 
  in 
  various 
  deposits, 
  but 
  of 
  fresh 
  -water 
  

   forms 
  we 
  have 
  scanty 
  record. 
  The 
  numbers 
  of 
  the 
  species 
  of 
  fishes 
  

   preserved 
  in 
  the 
  strata 
  of 
  dried-up 
  ponds 
  and 
  similar 
  locations 
  is 
  

   very 
  small, 
  and 
  the 
  most 
  that 
  we 
  can 
  say 
  of 
  them 
  is 
  that 
  they 
  belong 
  

   to 
  families 
  still 
  extant, 
  and 
  most 
  of 
  them 
  to 
  genera 
  now 
  extinct 
  but 
  

   closely 
  related 
  to 
  living 
  forms. 
  The 
  hundreds 
  of 
  thousands, 
  or 
  

   millions, 
  of 
  years 
  since 
  the 
  Miocene 
  have 
  given 
  time 
  for 
  incidents 
  

   which 
  change 
  the 
  stress 
  in 
  the 
  lives 
  of 
  animals 
  enough 
  to 
  produce 
  a 
  

   change 
  in 
  generic 
  characters 
  on 
  the 
  part 
  of 
  most 
  of 
  them. 
  Among 
  

   those 
  animals 
  which 
  have 
  the 
  widest 
  range 
  of 
  environment, 
  these 
  

   changes 
  occur 
  most 
  rapidly 
  ; 
  hence 
  fishes 
  of 
  the 
  Miocene 
  differ 
  more 
  

   from 
  their 
  living 
  types 
  than 
  most 
  mollusks 
  do. 
  

  

  Among 
  marine 
  fishes 
  the 
  changes 
  can 
  be 
  most 
  clearly 
  shown 
  be- 
  

   cause 
  the 
  amount 
  of 
  material 
  is 
  vastly 
  greater. 
  The 
  phenomena 
  of 
  

   geminate 
  or 
  twin 
  species 
  occur 
  in 
  all 
  groups. 
  With 
  geographical 
  

   separation, 
  as 
  with 
  geological 
  separation, 
  we 
  find 
  arising 
  forms 
  which 
  

  

  