﻿The 
  British 
  Species 
  of 
  Andrena 
  and 
  Nomada. 
  265 
  

  

  SYSTEMATIC. 
  

  

  Position 
  of 
  Andrena 
  and 
  Nomada 
  amongst 
  British 
  

   Bees. 
  

  

  Andrena 
  and 
  Nomada 
  are 
  both 
  very 
  distinct 
  genera, 
  the 
  latter 
  

   indeed 
  is 
  so 
  peculiar 
  in 
  appearance 
  and 
  structure 
  that 
  it 
  has 
  been 
  

   entirely 
  misplaced 
  by 
  some 
  Hymenopterists. 
  Their 
  position 
  

   amongst 
  our 
  bees 
  may 
  be 
  briefly 
  shown 
  as 
  follows 
  : 
  — 
  

  

  1. 
  (2) 
  Hind 
  tibiae 
  without 
  calcaria 
  at 
  the 
  apex. 
  . 
  . 
  . 
  Apidae. 
  

  

  2. 
  (1) 
  Hind 
  tibiae 
  with 
  calcaria. 
  

  

  3. 
  (4) 
  First 
  cubital 
  cell 
  divided 
  transversely 
  by 
  a 
  vein 
  or 
  streak. 
  

  

  Bombidae. 
  

  

  4. 
  (.3) 
  First 
  cubital 
  cell 
  not 
  divided. 
  

  

  5. 
  (6) 
  Labrum 
  long, 
  reflexed 
  in 
  repose, 
  the 
  mandibles 
  closed 
  

  

  over 
  it, 
  so 
  that 
  at 
  most 
  a 
  Little 
  of 
  the 
  base 
  is 
  exposed. 
  

  

  Megachilidae. 
  

   (i. 
  (5) 
  Labrum 
  not 
  thus 
  concealed, 
  the 
  mandibles 
  closing 
  round 
  

   its 
  apical 
  margin. 
  

  

  7. 
  (10) 
  Labrum 
  large 
  and 
  without 
  a 
  specialised 
  glabrous 
  area 
  or 
  

  

  raised 
  tubercle 
  on 
  its 
  basal 
  portion, 
  often 
  nearly 
  evenly 
  

   punctured 
  or 
  pubescent 
  over 
  its 
  whole 
  surface. 
  

  

  8. 
  (9) 
  Species 
  nearly 
  glabrous 
  to 
  the 
  naked 
  eye 
  and 
  without 
  

  

  conspicuous 
  pubescent 
  bands 
  (often 
  metallic); 
  abdomen 
  

   without 
  a 
  definite 
  pygidial 
  area. 
  . 
  . 
  . 
  Ceratinidae. 
  

  

  9. 
  (8) 
  The 
  nearly 
  glabrous 
  species 
  have 
  a 
  definite 
  pygidial 
  area 
  

  

  in 
  both 
  sexes; 
  many 
  are 
  well-clothed 
  and 
  have 
  con- 
  

   spicuous 
  pubescent 
  bands 
  Anthophoridae. 
  

  

  10. 
  (7) 
  Labrum 
  often 
  small, 
  or 
  with 
  a 
  special 
  glabrous 
  area 
  or 
  

  

  raised 
  tubercle 
  at 
  the 
  base 
  ; 
  sometimes 
  it 
  is 
  concealed 
  

   beneath 
  a 
  dense 
  regular 
  fringe 
  of 
  special 
  hairs 
  springing 
  

   from 
  the 
  apical 
  margin 
  of 
  the 
  clypeus. 
  

  

  11. 
  (12) 
  Tongue 
  acute 
  at 
  the 
  tip 
  Andrenidae 
  

  

  (inch 
  Panurgidae 
  of 
  some 
  authors). 
  

  

  12. 
  (11) 
  Tongue 
  blunt 
  or 
  emarginate 
  at 
  the 
  tip 
  (except 
  in 
  males 
  

  

  of 
  some 
  exotic 
  forms). 
  

  

  13. 
  (14) 
  Three 
  cubital 
  cells 
  in 
  front 
  wings; 
  hind 
  tibiae 
  with 
  a 
  

  

  scopa 
  Colletidae. 
  

  

  14. 
  (13) 
  Two 
  submarginal 
  cells 
  in 
  front 
  wings; 
  hind 
  tibiae 
  without 
  

  

  a 
  scopa 
  Prosopidae. 
  

  

  Anthophoridae. 
  

   1. 
  (6) 
  Face 
  of 
  ^ 
  yellow 
  or 
  with 
  yellow 
  markings 
  and 
  the 
  tooth 
  

   on 
  the 
  tarsal 
  claws 
  always 
  long 
  and 
  sharp; 
  $ 
  with 
  

   well-developed 
  scopae 
  on 
  the 
  hind 
  legs. 
  

  

  