﻿coo 
  PltOCEEDINC.S 
  OF 
  THE 
  XATIOXAl. 
  MUSEUM. 
  v..l.xx 
  

  

  15. 
  The 
  widest 
  gap 
  in 
  the 
  chain 
  is 
  that 
  between 
  Saniav 
  and 
  Luzon. 
  

   No 
  final 
  conclusions 
  can 
  be 
  reached 
  as 
  to 
  the 
  precise 
  relationship 
  of 
  the 
  

   islands 
  in 
  this 
  chain, 
  however, 
  until 
  the 
  highland 
  avilaunae 
  of 
  the 
  

   southern 
  islands 
  are 
  better 
  known. 
  

  

  I 
  have 
  not 
  sufficient 
  fanilHarity 
  with 
  the 
  birds 
  of 
  the 
  larger 
  land 
  

   masses 
  adjacent 
  to 
  the 
  Philipi)ines 
  to 
  intelligently 
  discuss 
  the 
  relation- 
  

   ships 
  of 
  the 
  Philippine 
  birds 
  as 
  a 
  whole, 
  and, 
  leaving 
  this 
  interesting 
  

   (luestion 
  to 
  wiser 
  heads 
  than 
  mine, 
  I 
  ])ass 
  to 
  the 
  consideration 
  of 
  some 
  of 
  

   the 
  more 
  general 
  problems 
  of 
  distribution 
  ami 
  devel()i)ment 
  raised 
  by 
  

   the 
  known 
  distribution 
  of 
  the 
  birds 
  within 
  the 
  limits 
  of 
  the 
  archipelago. 
  

  

  STEERE'S 
  LA\V 
  OF 
  DISTRIBUTION. 
  

  

  While 
  the 
  question 
  of 
  the 
  relationships 
  between 
  the 
  birds 
  of 
  tlie 
  

   various 
  islands 
  is 
  not 
  without 
  its 
  interest, 
  other 
  and 
  more 
  important 
  

   jiroblems, 
  which 
  can 
  not 
  be 
  so 
  readily 
  disposed 
  of, 
  are 
  presented 
  by 
  the 
  

   facts 
  of 
  distribution 
  of 
  the 
  resident 
  birds. 
  So 
  far 
  as 
  J 
  know, 
  Steere 
  

   has 
  been 
  the 
  only 
  one 
  to 
  attempt 
  to 
  discuss 
  these 
  more 
  general 
  (pies- 
  

   tions 
  on 
  the 
  strength 
  of 
  the 
  data 
  furnished 
  by 
  Philippine 
  species. 
  

  

  In 
  his 
  pajier 
  on 
  '^ 
  The 
  Distribution 
  of 
  Genera 
  and 
  Species 
  of 
  Xon- 
  

   migratorj' 
  Land 
  Birds 
  in 
  the 
  Philippines" 
  he 
  makes 
  a 
  somewhat 
  

   detailed 
  examination 
  of 
  the 
  birds 
  obtained 
  by 
  the 
  Steere 
  expedition, 
  

   as 
  the 
  result 
  of 
  which 
  he 
  arrives 
  at 
  the 
  conclusion 
  that 
  " 
  the 
  genus 
  is 
  

   represented 
  by 
  but 
  a 
  single 
  species 
  in 
  a 
  place," 
  He 
  believes 
  that 
  

   Philippine 
  species 
  and 
  varieties 
  are 
  geographical 
  or 
  local 
  groups 
  de- 
  

   pending 
  on 
  local 
  causes 
  for 
  their 
  existence, 
  and 
  that 
  they 
  show 
  isolation 
  

   to 
  be 
  the 
  first 
  and 
  necessary 
  step 
  in 
  the 
  formation 
  of 
  species. 
  It 
  is 
  

   evident 
  that 
  when 
  he 
  speaks 
  of 
  isolation 
  he 
  refers 
  to 
  geographical 
  isola- 
  

   tion, 
  for 
  in 
  describing 
  tlie 
  species 
  which 
  he 
  holds 
  confirm 
  his 
  law 
  he 
  

   says: 
  "In 
  o'J 
  genera, 
  with 
  15.) 
  species, 
  each 
  genus 
  is 
  represented 
  in 
  

   the 
  Philippines 
  by 
  two 
  or 
  more 
  species, 
  each 
  of 
  which 
  exists 
  in 
  a 
  lim- 
  

   ited 
  area 
  of 
  its 
  own, 
  sharply 
  separated 
  by 
  sea 
  channels 
  from 
  the 
  

   similar 
  areas 
  occupied 
  by 
  the 
  other 
  species 
  of 
  the 
  same 
  genus." 
  

  

  In 
  the 
  paragraph 
  which 
  precedes 
  the 
  one 
  in 
  which 
  he 
  states 
  his 
  law 
  

   he 
  says 
  that 
  "there 
  results 
  115 
  genera 
  out 
  of 
  150, 
  and 
  302 
  species 
  out 
  

   of 
  .'U2, 
  or 
  29 
  from 
  every 
  30 
  of 
  the 
  genera, 
  and 
  over 
  30 
  from 
  every 
  31 
  

   of 
  the 
  species, 
  so 
  distributed 
  in 
  the 
  islands 
  that 
  no 
  two 
  species 
  nearly 
  

   enough 
  allied 
  to 
  be 
  put 
  in 
  the 
  same 
  section 
  or 
  subgenus 
  are 
  found 
  

   existing 
  in 
  the 
  same 
  island." 
  This 
  statement, 
  as 
  well 
  as 
  the 
  one 
  above 
  

   quoted, 
  shows 
  that 
  by 
  "place" 
  he 
  means 
  island. 
  

  

  Steere 
  contined 
  himself 
  to 
  an 
  examination 
  of 
  his 
  own 
  birds 
  and 
  those 
  

   collected 
  by 
  Moseley, 
  Bourns, 
  and 
  myself 
  in 
  1887-88, 
  in 
  the 
  belief 
  that 
  

   "these 
  collections, 
  while 
  not 
  com])rising 
  all 
  species 
  known 
  from 
  the 
  

   islands, 
  are 
  so 
  nearly 
  complete 
  that 
  any 
  just 
  conclusions 
  drawn 
  from 
  

   them 
  nuist 
  be 
  accepted 
  as 
  truth, 
  which 
  further 
  exploration 
  will 
  only 
  

   strengthen." 
  

  

  lie 
  divides 
  the 
  genera 
  discussed 
  into 
  five 
  lists, 
  A, 
  B, 
  0, 
  1), 
  and 
  E, 
  

  

  