﻿DESIGNATION 
  OF 
  " 
  PERMANENT 
  BREEDING-GROUNDS." 
  57 
  

  

  outer 
  line, 
  showing 
  the 
  utmost 
  extent 
  of 
  its 
  presence 
  in 
  the 
  condition 
  of 
  

  

  bands 
  of 
  winged 
  insects 
  beyond 
  the 
  region 
  where 
  the 
  species 
  may 
  live 
  

   and 
  propagate, 
  or, 
  in 
  other 
  words, 
  the 
  extreme 
  boundary 
  of 
  its 
  flights. 
  

  

  Our 
  investigations, 
  made 
  independently 
  of 
  a 
  knowledge 
  of 
  Koppen's 
  

   conclusions, 
  led 
  to 
  a 
  somewhat 
  similar 
  result. 
  We 
  found 
  it 
  necessary, 
  

   in 
  order 
  to 
  express 
  the 
  relations 
  of 
  C. 
  spretus 
  to 
  the 
  various 
  parts 
  of 
  the 
  

   area 
  over 
  which 
  it 
  roams, 
  to 
  designate 
  an 
  inner 
  or 
  central 
  region 
  as 
  its 
  

   " 
  permanent 
  breeding-grounds," 
  and 
  an 
  outer 
  circumscribing 
  belt 
  as 
  the 
  

   u 
  temporary 
  region," 
  corresponding 
  with 
  Koppen's 
  first 
  and 
  second 
  

   divisions. 
  Its 
  incapability 
  of 
  continuing 
  its 
  existence 
  in 
  this 
  temporary 
  

   region 
  is 
  so 
  marked 
  that 
  we 
  have 
  attempted 
  to 
  designate 
  an 
  interme- 
  

   diate 
  area 
  showing 
  the 
  limits 
  of 
  the 
  oscillations 
  of 
  the 
  permanent 
  breed- 
  

   ing-grounds. 
  But 
  this, 
  in 
  the 
  opinion 
  of 
  the 
  writer 
  of 
  this 
  chapter, 
  is 
  

   too 
  indefinite 
  to 
  be 
  of 
  any 
  real 
  value, 
  an 
  opinion 
  which 
  it 
  is 
  proper 
  for 
  

   me 
  to 
  state 
  is 
  not 
  fully 
  concurred 
  in 
  by 
  all 
  the 
  members 
  of 
  the 
  Commis- 
  

   sion. 
  Our 
  investigations 
  of 
  this 
  species 
  have 
  brought 
  to 
  light 
  no 
  facts 
  

   to 
  warrant 
  us 
  in 
  designating 
  an 
  outer 
  belt 
  corresponding 
  with 
  Koppen's 
  

   third 
  area, 
  as 
  its 
  flights 
  do 
  not 
  extend 
  into 
  any 
  sections, 
  so 
  far 
  as 
  ascer- 
  

   tained, 
  where 
  it 
  may 
  not 
  produce 
  at 
  least 
  one 
  resulting 
  brood. 
  

  

  It 
  is 
  necessary 
  for 
  us 
  to 
  call 
  attention 
  here 
  to 
  the 
  fact 
  that 
  this 
  ar- 
  

   rangement 
  does 
  not 
  include 
  all 
  of 
  the 
  relations 
  of 
  migratory 
  species 
  to 
  

   the 
  regions 
  they 
  are 
  found 
  inhabiting. 
  For 
  example, 
  a 
  species 
  may 
  not 
  

   be 
  essentially 
  migratory 
  and 
  hence 
  may 
  be 
  found 
  to 
  possess 
  this 
  char- 
  

   acter 
  in 
  one 
  district 
  where 
  the 
  conditions 
  are 
  favorable 
  whde 
  in 
  another 
  

   section 
  it 
  may 
  be 
  truly 
  sedentary. 
  Such 
  appears 
  to 
  be 
  the 
  case 
  with 
  A. 
  

   americanum, 
  which 
  in 
  the 
  southern 
  half 
  of 
  the 
  United 
  States 
  is 
  sedentary, 
  

   while 
  in 
  Yucatan 
  and 
  other 
  parts 
  of 
  Central 
  America 
  it 
  is 
  said 
  to 
  be 
  

   migratory. 
  If 
  P. 
  cinerascens 
  is 
  ever 
  truly 
  migratory, 
  of 
  which 
  we 
  have 
  

   some 
  doubt 
  notwithstanding 
  the 
  affirmative 
  evidence 
  on 
  this 
  point, 
  then 
  

   it 
  forms 
  a 
  second 
  example, 
  as 
  we 
  are 
  informed 
  by 
  Selys-Longchamps 
  

   that 
  it 
  is 
  sedentary 
  in 
  Belgium 
  and 
  other 
  parts 
  of 
  Europe. 
  153 
  How 
  far 
  

   this 
  characteristic 
  applies 
  to 
  other 
  locusts 
  of 
  the 
  Eastern 
  Continent 
  we 
  

   are 
  unable 
  to 
  state, 
  as 
  the 
  attention 
  of 
  European 
  entomologists 
  does 
  not 
  

   appear 
  to 
  have 
  been 
  specially 
  directed 
  to 
  this 
  point. 
  

  

  As 
  will 
  be 
  seen 
  hereafter, 
  the 
  evidence 
  obtained 
  by 
  the 
  Commission 
  

   in 
  reference 
  to 
  our 
  Bocky 
  Mountain 
  locust 
  shows 
  it 
  to 
  be 
  essentially 
  

   migratory. 
  The 
  same 
  also 
  appears 
  to 
  be 
  true 
  of 
  A. 
  peregrinum 
  and 
  P. 
  

   migrator 
  ius. 
  

  

  We 
  may 
  as 
  well 
  remark 
  here, 
  in 
  order 
  that 
  our 
  arguments 
  and 
  con- 
  

   clusions 
  may 
  be 
  the 
  better 
  understood, 
  that 
  we 
  do 
  not 
  include 
  in 
  the 
  

   category 
  of 
  k 
  < 
  migratory 
  locusts" 
  or 
  of 
  " 
  locusts 
  " 
  in 
  the 
  true 
  sense, 
  those 
  

   Acridians 
  which 
  occasionally, 
  through 
  the 
  influence 
  of 
  climatic 
  condi- 
  

   tions, 
  are 
  greatly 
  developed 
  and 
  even 
  induced 
  to 
  migrate 
  for 
  short 
  dis- 
  

   tances. 
  

  

  As 
  the 
  native 
  home 
  of 
  an 
  essentially 
  migratory 
  species 
  must 
  be 
  a 
  

  

  153 
  Compt. 
  Rend. 
  Soc. 
  Ent. 
  Belg.. 
  1871-3, 
  xxiv. 
  

  

  