﻿220 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.98 
  

  

  la. 
  Least 
  depth 
  of 
  caudal 
  peduncle 
  1.5 
  to 
  1.8, 
  usually 
  1.6 
  or 
  1.7 
  in 
  its 
  length, 
  which 
  

   is 
  contained 
  1.1 
  to 
  1.4, 
  usually 
  1.2 
  or 
  1.3 
  times 
  in 
  the 
  head. 
  Head 
  3.0 
  to 
  3.3 
  

   in 
  standard 
  length. 
  Interoribital 
  1.6 
  to 
  2.0, 
  usually 
  1.7 
  to 
  1.9 
  in 
  length 
  of 
  

   caudal 
  peduncle. 
  Pectoral 
  rays 
  16 
  to 
  20, 
  usually 
  18 
  or 
  19. 
  Scales 
  in 
  34 
  to 
  

   37, 
  usually 
  35 
  or 
  36 
  transverse 
  rows 
  Fundulus 
  grandis 
  grandis 
  

  

  1&. 
  Least 
  depth 
  of 
  caudal 
  peduncle 
  1.1 
  to 
  1.4, 
  usually 
  1.2 
  or 
  1.3 
  in 
  its 
  length, 
  which 
  

   is 
  contained 
  1.3 
  to 
  1.6, 
  usually 
  1.4 
  or 
  1.5 
  times 
  in 
  the 
  head. 
  Head 
  2.7 
  to 
  3.0 
  

   in 
  standard 
  length. 
  Interorbital 
  1.4 
  to 
  1.6, 
  usually 
  1.5 
  or 
  1.6 
  in 
  length 
  of 
  

   caudal 
  peduncle. 
  Pectoral 
  rays 
  16 
  to 
  18, 
  usually 
  17. 
  Scales 
  in 
  32 
  or 
  33 
  

   transverse 
  rows 
  Fundulus 
  grandis 
  saguanus 
  

  

  The 
  close 
  relationship 
  between 
  Fundulus 
  grandis 
  grandis 
  and 
  F. 
  

   grandis 
  saguanus 
  is 
  shown 
  by 
  a 
  critical 
  comparative 
  study 
  of 
  both 
  

   forms. 
  They 
  more 
  or 
  less 
  overlap 
  in 
  the 
  distinguishing 
  characters 
  

   given 
  in 
  the 
  above 
  key, 
  except 
  for 
  the 
  transverse 
  rows 
  of 
  scales, 
  but 
  

   table 
  1 
  indicates 
  that 
  more 
  adequate 
  material 
  of 
  saguanus 
  will 
  show 
  

   overlap 
  also 
  in 
  this 
  character. 
  For 
  these 
  reasons 
  I 
  think 
  it 
  best 
  to 
  con- 
  

   sider 
  saguanus 
  as 
  only 
  subspecifically 
  distinct 
  from 
  grandis, 
  rather 
  

   than 
  to 
  assign 
  it 
  full 
  specific 
  rank. 
  Both 
  forms 
  have 
  apparently 
  the 
  

   same 
  habits 
  and 
  inhabit 
  calm, 
  shallow, 
  coastal 
  waters. 
  

  

  In 
  comparing 
  the 
  new 
  subspecies 
  with 
  specimens 
  of 
  F. 
  grandis 
  

   grandis 
  from 
  several 
  localities 
  (Florida 
  Keys 
  to 
  Texas) 
  along 
  its 
  range, 
  

   it 
  was 
  found 
  that 
  grandis 
  exhibits 
  a 
  number 
  of 
  variations 
  of 
  geo- 
  

   graphical 
  significance. 
  This 
  subspecies 
  may 
  be 
  shown 
  to 
  be 
  a 
  complex 
  

   of 
  local 
  races 
  if 
  subjected 
  to 
  a 
  critical 
  study 
  of 
  variation 
  throughout 
  

   its 
  range. 
  The 
  Cuban 
  subspecies, 
  saguanus, 
  is 
  most 
  closely 
  related 
  to 
  

   the 
  race 
  of 
  grandis 
  occurring 
  in 
  the 
  Florida 
  Keys. 
  

  

  The 
  common 
  ancestry 
  of 
  Fundulus 
  grandis 
  grandis 
  and 
  F. 
  grandis 
  

   saguanus 
  is 
  well 
  established 
  by 
  their 
  close 
  relationship 
  and 
  vicarious 
  

   distribution, 
  and 
  by 
  their 
  similar 
  habits 
  and 
  habitat. 
  These 
  facts, 
  

   correlated 
  with 
  the 
  paleogeography 
  of 
  the 
  region 
  comprising 
  southern 
  

   Florida 
  and 
  north-central 
  Cuba, 
  suggest 
  that 
  the 
  ancestors 
  of 
  saguanus 
  

   probably 
  migrated 
  to 
  Cuba 
  from 
  southern 
  Florida, 
  via 
  Cay 
  Sal 
  Bank, 
  

   during 
  the 
  Pleistocene. 
  

  

  Such 
  a 
  migration 
  would 
  not 
  be 
  difficult 
  to 
  conceive 
  even 
  during 
  re- 
  

   cent 
  times, 
  since 
  the 
  width 
  of 
  the 
  Strait 
  of 
  Florida 
  between 
  the 
  

   Keys 
  and 
  Cay 
  Sal 
  Bank 
  (about 
  50 
  nautical 
  miles) 
  and 
  that 
  of 
  Nicholas 
  

   Channel 
  between 
  Cay 
  Sal 
  Bank 
  and 
  Cuba 
  (about 
  20 
  nautical 
  miles) 
  

   is 
  not 
  very 
  great. 
  In 
  my 
  opinion, 
  it 
  would 
  not 
  be 
  impossible 
  for 
  

   such 
  a 
  fish 
  as 
  Fu/ndulus 
  to 
  cross 
  these 
  relatively 
  narrow 
  channels. 
  But 
  

   the 
  fact 
  that 
  the 
  populations 
  of 
  the 
  Florida 
  Keys 
  and 
  Cuba 
  have 
  dif- 
  

   ferentiated, 
  at 
  least 
  subspecifically, 
  indicates 
  that 
  such 
  an 
  exchange 
  of 
  

   individuals 
  is 
  not 
  actually 
  taking 
  place 
  between 
  the 
  two 
  regions. 
  

   Much 
  better 
  conditions 
  for 
  this 
  migration, 
  however, 
  existed 
  during 
  the 
  

   Pleistocene 
  when 
  the 
  level 
  of 
  the 
  ocean 
  was 
  much 
  lower, 
  caused 
  by 
  

   waters 
  impounded 
  as 
  ice 
  on 
  the 
  poles. 
  According 
  to 
  Daly 
  (1934, 
  p. 
  

  

  