But  the  most  remarkable  features  connected  with  the  Pierinw  are  their  gregarious  and
migratory  habits.  Of  the  first  peculiarity  we  have  many  independent  records  from  different
parts  of  the  world,  a  few  only  of  which  can  here  be  recapitulated.  In  South  Africa  Mr.  Trimen
bears  witness  that  "the  habits  of  the  species  of  this  division  are  often  gi-egarious  or  pseudo-
gregarious,  as  considerable  numbers  of  one  kind  are  often  found  about  some  favourite  spot  or
attractive  flowers ;  and  little  clusters  of  some  species  of  '  Whites '  may  frequently  be  seen
congregated  on  the  damp  mud  at  the  margins  of  pools  or  brooks."  ||  This  was  strongly
witnessed  in  South-west  Celebes  by  M.  C.  Piepers,  and  well  described  by  that  entertaining
entomologist.  When  travelling  in  that  region, — to  use  his  own  words, — "my  companion
suddenly  exclaimed,  as  we  were  crossing  a  nearly  dry  brook,  '  Oh,  look  what  a  beautiful
flower ! '  And  on  looking  where  he  pointed  I  saw  in  the  bed  of  the  stream,  amongst  the  damp
gi'avel,  a  beautiful  orange-coloured  flower  with  a  white  centre,  about  ten  centimetres  in
diameter.  The  strangeness  of  the  occurrence  led  me  to  step  nearer  in  order  to  observe  it  more
closely,  when  what  did  I  see  ? — the  flower  consisted  of  two  concentric  rings  of  butterflies
{CaUidnjas  scfiUa,  Linn.),  which  had  closed  their  wings  (which  are  yellow,  and  orange  beneath),
and  were  busily  sucking  up  the  moisture  from  the  damp  sand,  and  thus  represented  in  the
most  closely  deceptive  manner  the  petals  of  a  flower.  They  surrounded  five  of  another  white
species  of  Pieris  similarly  occupied,  which  thus  seemed  to  form  the  white  centre  of  the  flower.
