﻿Mr. 
  R, 
  C. 
  L. 
  Perkins 
  on 
  Andrena 
  and 
  Nomada. 
  219 
  

  

  many 
  species, 
  wliich 
  in 
  a 
  more 
  favourable 
  district 
  would 
  be 
  

   considered 
  very 
  commonplace. 
  

  

  The 
  habit 
  of 
  forming 
  " 
  colonies," 
  that 
  is 
  for 
  great 
  numbers 
  

   of 
  individuals 
  of 
  a 
  species 
  to 
  form 
  their 
  burrows 
  side 
  by 
  

   side, 
  often 
  so 
  close 
  together 
  as 
  almost 
  to 
  touch 
  one 
  another, 
  

   is 
  very 
  marked 
  in 
  some 
  species 
  of 
  Andrena, 
  while 
  others 
  

   rarely 
  or 
  never 
  do 
  so. 
  Thus 
  one 
  may 
  sometimes 
  see 
  hun- 
  

   dreds 
  of 
  burrows 
  of 
  such 
  species 
  as 
  A 
  . 
  humilis 
  * 
  or 
  ^ 
  . 
  sericea 
  

   {albicrus) 
  in 
  a 
  square 
  yard 
  or 
  two 
  of 
  surface, 
  while 
  species 
  

   like 
  A. 
  trimmerana, 
  nitida, 
  albicans 
  and 
  others 
  rarely 
  or 
  

   never 
  form 
  these 
  compact 
  colonies. 
  Some 
  species, 
  e.g., 
  A. 
  

   cineraria, 
  sometimes 
  form 
  dense 
  colonies, 
  but 
  at 
  other 
  times 
  

   their 
  burrows 
  are 
  scattered 
  singly 
  or 
  two 
  or 
  three 
  together 
  

   over 
  a 
  large 
  acreage 
  of 
  land. 
  In 
  such 
  cases 
  it 
  is 
  probable 
  

   that 
  in 
  the 
  one 
  instance 
  the 
  soil 
  and 
  other 
  conditions 
  are 
  

   pretty 
  much 
  the 
  same 
  over 
  the 
  whole 
  area 
  occupied, 
  and 
  in 
  

   the 
  other 
  that 
  a 
  limited 
  spot 
  affords 
  conditions 
  pre-emin- 
  

   ently 
  favourable, 
  as 
  compared 
  with 
  the 
  surrounding 
  country. 
  

   I 
  suspect 
  the 
  colonising 
  is 
  due 
  sometimes 
  to 
  a 
  natural 
  

   sociability 
  of 
  the 
  species 
  or 
  a 
  reluctance 
  to 
  depart 
  from 
  their 
  

   .immediate 
  birthplace, 
  for 
  we 
  have 
  seen 
  a 
  colony 
  with 
  few 
  

   individuals 
  — 
  probably 
  it 
  had 
  originally 
  been 
  started 
  by 
  a 
  

   single 
  female 
  — 
  ^increase 
  in 
  size 
  and 
  become 
  permanently 
  a 
  

   large 
  one, 
  subject 
  only 
  to 
  increase 
  or 
  decrease 
  as 
  the 
  seasons 
  

   were 
  favourable 
  or 
  otherwise. 
  Some 
  of 
  these 
  colonies 
  

   persist 
  for 
  many 
  years. 
  V. 
  R. 
  Perkins, 
  in 
  his 
  list 
  of 
  the 
  bees 
  

   of 
  Wotton-under-Edge, 
  Gloucestershire, 
  records 
  the 
  dis- 
  

   covery 
  of 
  a 
  colony 
  of 
  A. 
  humilis 
  in 
  1876, 
  from 
  which 
  he 
  

   collected 
  the 
  species 
  again 
  in 
  1882, 
  1887 
  and 
  1891 
  . 
  I 
  myself 
  

   collected 
  from 
  this 
  colony 
  in 
  1886, 
  1887 
  and 
  1890, 
  and 
  

   observed 
  it 
  to 
  be 
  still 
  present 
  in 
  1907 
  and 
  1914. 
  As 
  no 
  other 
  

   colony 
  of 
  this 
  bee 
  has 
  ever 
  been 
  observed 
  in 
  the 
  district, 
  

   we 
  may 
  assume 
  that 
  this 
  one 
  has 
  maintained 
  its 
  hold 
  for 
  

   nearly 
  forty 
  years 
  at 
  least, 
  and 
  might 
  conceivably 
  have 
  

   existed 
  for 
  centuries. 
  Some 
  colonies 
  are 
  of 
  such 
  vast 
  extent 
  

   as 
  to 
  produce 
  almost 
  incredible 
  numbers 
  of 
  individuals. 
  

   Thus 
  those 
  of 
  such 
  species 
  as 
  A. 
  humilis 
  and 
  A. 
  sericea 
  

   sometimes 
  extend 
  in 
  favourable 
  situations, 
  with 
  breaks 
  

   perhaps 
  at 
  intervals, 
  for 
  hundreds 
  of 
  yards. 
  Smith 
  remarks 
  

   of 
  the 
  first 
  named 
  that 
  in 
  a 
  pathway 
  at 
  Hawley 
  Green, 
  

  

  * 
  The 
  changes 
  in 
  nomenclature 
  adopted 
  in 
  this 
  paper 
  will 
  be 
  

   found 
  on 
  p. 
  269, 
  the 
  names 
  used 
  in 
  recent 
  British 
  works 
  and 
  cata- 
  

   logues 
  being 
  added 
  in 
  brackets. 
  

  

  