﻿230 
  Mr. 
  E. 
  C. 
  L. 
  Perkins 
  on 
  

  

  been 
  utilised 
  previously 
  by 
  Andrena. 
  The 
  sarae 
  author 
  

   records 
  several 
  of 
  our 
  species 
  of 
  Nomada 
  as 
  parasites 
  on 
  

   various 
  larger 
  Halictus, 
  and 
  one, 
  N. 
  fabriciana, 
  as 
  being 
  

   the 
  peculiar 
  parasite 
  of 
  Panvrgus 
  banksianus. 
  Shuckard 
  

   corroborates 
  this, 
  but 
  Smith 
  is 
  certainly 
  wrong 
  in 
  the 
  case 
  

   of 
  Halictus, 
  and 
  in 
  general, 
  when 
  assigning 
  hosts 
  to 
  the 
  

   various 
  Nomadas, 
  appears 
  to 
  have 
  formed 
  his 
  opinion 
  from 
  

   such 
  bees 
  as 
  he 
  saw 
  on 
  the 
  same 
  flowers 
  as 
  the 
  parasites 
  

   or 
  flying 
  about 
  in 
  the 
  same 
  vicinity. 
  

  

  Of 
  N 
  . 
  fabriciana 
  in 
  his 
  first 
  edition 
  he 
  says 
  that 
  it 
  is 
  

   met 
  with 
  on 
  Hampstead 
  Heath 
  " 
  about 
  the 
  end 
  of 
  April 
  

   and 
  during 
  May, 
  and 
  it 
  has 
  also 
  been 
  taken 
  in 
  Yorkshire 
  

   in 
  the 
  month 
  of 
  July." 
  April 
  and 
  May 
  is 
  the 
  normal 
  time 
  

   for 
  this 
  Nomada, 
  and 
  Panurgus 
  is 
  not 
  to 
  be 
  found 
  then. 
  

   In 
  Yorkshire 
  it 
  was 
  probably 
  a 
  late 
  season, 
  when 
  Smith 
  

   found 
  specimens 
  in 
  July, 
  and 
  these 
  belonged 
  to 
  the 
  first 
  

   brood, 
  since 
  he 
  took 
  fresh 
  males 
  of 
  early 
  spring 
  bees 
  at 
  

   the 
  same 
  time 
  (e. 
  g., 
  i^ 
  trimmer 
  ana 
  and 
  cineraria). 
  For 
  these 
  

   reasons 
  one 
  cannot 
  place 
  much 
  faith 
  on 
  Smith's 
  observa- 
  

   tions 
  as 
  a 
  whole, 
  though, 
  of 
  course, 
  in 
  a 
  number 
  of 
  cases 
  

   he 
  is 
  correct. 
  Some 
  records 
  of 
  parasitism 
  given 
  by 
  

   Saunders 
  are 
  also, 
  I 
  believe, 
  incorrect, 
  but 
  it 
  may 
  be 
  

   suspected 
  that 
  these 
  were 
  chiefly 
  taken 
  from 
  Smith's 
  

   works 
  and 
  not 
  due 
  to 
  his 
  own 
  observation. 
  

  

  There 
  are 
  a 
  few 
  well-known 
  Continental 
  species 
  of 
  

   Nomada 
  which 
  attack 
  species 
  of 
  Andrena 
  common 
  in 
  this 
  

   country, 
  but 
  are 
  themselves 
  unknown 
  here. 
  Such 
  are 
  

   N. 
  obscura 
  on 
  A. 
  ruficrus, 
  N. 
  cinnabarina 
  on 
  A. 
  labialis, 
  

   and 
  alboguttata, 
  a 
  large 
  race 
  of 
  baccata, 
  on 
  A, 
  sericea. 
  

   N. 
  rhenana 
  is 
  said 
  to 
  be 
  parasitic 
  on 
  A. 
  afzeliella. 
  

  

  It 
  is, 
  I 
  think, 
  very 
  rare 
  for 
  a 
  species 
  of 
  Nomada, 
  or 
  even 
  

   for 
  a 
  group 
  of 
  closely 
  allied 
  species 
  of 
  this 
  genus, 
  to 
  attack 
  

   Andrenas 
  that 
  are 
  widely 
  separated 
  in 
  structure, 
  and 
  

   consequently 
  the 
  study 
  of 
  their 
  parasitism 
  will 
  help 
  in 
  

   fixing 
  the 
  afiuiities 
  of 
  species 
  and 
  of 
  groups 
  in 
  Andrena. 
  

   Of 
  course 
  this 
  rule 
  is 
  not 
  without 
  exceptions. 
  The 
  rufi- 
  

   cornis 
  group 
  of 
  Nomada 
  is 
  attached 
  to 
  the 
  varians 
  group 
  of 
  

   Andrena, 
  but 
  N. 
  fl.ava 
  and 
  N. 
  bucephalae 
  attack 
  that 
  of 
  

   N. 
  trimmerana, 
  a 
  distinct 
  group, 
  but 
  still 
  clearly 
  allied 
  

   to 
  that 
  of 
  varians. 
  I 
  know 
  no 
  case 
  in 
  our 
  British 
  Nomadas 
  

   where 
  the 
  same 
  species 
  of 
  parasite 
  attacks 
  Andrenas 
  

   belonging 
  to 
  two 
  distinct 
  groups, 
  though, 
  if 
  we 
  accept 
  

   some 
  of 
  Smith's 
  conclusions, 
  such 
  cases 
  would 
  be 
  not 
  

   uncommon 
  and 
  of 
  a 
  most 
  surprising 
  character. 
  

  

  