﻿The 
  British 
  Species 
  of 
  Andrena 
  and 
  Nomada. 
  267 
  

  

  dilated 
  and 
  so 
  densely 
  clothed 
  that 
  its 
  outline 
  is 
  seen 
  

   with 
  difficulty; 
  (abdomen 
  in 
  both 
  sexes 
  short 
  or 
  sub- 
  

   globose 
  ; 
  legs 
  of 
  (J 
  very 
  incrassate). 
  . 
  . 
  Macropis. 
  

   9. 
  (4) 
  First 
  cubital 
  cell 
  on 
  its 
  lower 
  side 
  notably 
  longer 
  than 
  the 
  

   second 
  (form 
  elongate, 
  abdomen 
  banded; 
  ? 
  with 
  the 
  

   scopae 
  of 
  hind 
  tibiae 
  and 
  metatarsi 
  yeUow 
  and 
  extremely 
  

   long) 
  Dasypoda. 
  

  

  10. 
  (1) 
  Three 
  cubital 
  cells 
  in 
  the 
  front 
  wings. 
  

  

  11. 
  (14) 
  Basal 
  nervure 
  very 
  strongly 
  curved. 
  

  

  (Third 
  antennal 
  joint 
  in 
  ^ 
  very 
  short 
  transverse 
  or 
  nearly 
  

   square 
  in 
  outUne 
  when 
  viewed 
  from 
  in 
  front; 
  $ 
  either 
  

   with 
  a 
  median 
  " 
  rima 
  " 
  on 
  the 
  5th 
  abdominal 
  segment 
  

   or 
  the 
  hind 
  tibiae 
  are 
  spinose 
  and 
  lack 
  a 
  scopa.) 
  

  

  12. 
  (13) 
  $ 
  with 
  well-developed 
  scopa 
  and 
  with 
  long 
  plumose 
  hairs 
  

  

  at 
  the 
  base 
  of 
  the 
  hind 
  femora 
  beneath; 
  c^ 
  genital 
  

   opening 
  distinctly 
  ventral. 
  Halictus. 
  

  

  13. 
  (12) 
  9 
  without 
  scopae, 
  ^ 
  genital 
  opening 
  at 
  the 
  tip 
  of 
  the 
  

  

  abdomen 
  or 
  almost 
  so 
  Sphecodes. 
  

  

  14. 
  (11) 
  Basal 
  nervure 
  oblique, 
  but 
  nearly 
  straight. 
  

  

  15. 
  (16) 
  (^ 
  with 
  the 
  6th 
  ventral 
  abdominal 
  segment 
  widened 
  on 
  

  

  each 
  side 
  at 
  the 
  base 
  with 
  a 
  hairy 
  lobe, 
  which 
  is 
  not 
  

   covered 
  by 
  the 
  deflexed 
  margin 
  of 
  the 
  dorsal 
  segment 
  

   above 
  it; 
  $ 
  without 
  a 
  special 
  sensory 
  groove 
  on 
  the 
  

   upper 
  part 
  of 
  the 
  face 
  along 
  the 
  eye 
  margins; 
  apex 
  

   of 
  hind 
  metatarsus 
  outwardly 
  with 
  a 
  lamella 
  of 
  hairs 
  

   extended 
  over 
  the 
  2nd 
  tarsal 
  joint 
  Cilissa. 
  

  

  16. 
  (15) 
  J 
  with 
  the 
  6th 
  ventral 
  segment 
  not 
  thus 
  modified. 
  $ 
  

  

  with 
  a 
  sensory 
  groove, 
  bearing 
  a 
  dense 
  tomentum, 
  on 
  

   each 
  side 
  of 
  the 
  face 
  above; 
  apex 
  of 
  hind 
  metatarsus 
  

   without 
  the 
  special 
  lamella 
  Andrena. 
  

  

  With 
  regard 
  to 
  Andrena 
  and 
  its 
  allies, 
  I 
  consider 
  that 
  

   in 
  the 
  Andreno-Panurgine 
  group 
  are 
  to 
  be 
  found 
  the 
  most 
  

   primitive 
  types 
  of 
  existing 
  bees, 
  from 
  which 
  have 
  originated 
  

   all 
  other 
  groups. 
  The 
  Prosopidae 
  and 
  Colletidae 
  are 
  de- 
  

   rivatives 
  of 
  this 
  group 
  in 
  one 
  direction, 
  the 
  Anthophoridae 
  

   in 
  another; 
  the 
  two 
  former 
  are 
  not 
  primitive 
  in 
  the 
  form 
  

   of 
  their 
  tongue, 
  but 
  this 
  has 
  become 
  modified 
  for 
  a 
  special 
  

   purpose 
  in 
  all 
  females, 
  and 
  the 
  males 
  of 
  most 
  species 
  have 
  

   inherited 
  this 
  form 
  from 
  the 
  latter. 
  In 
  many 
  Prosopidae 
  

   from 
  the 
  Australian 
  region 
  the 
  tongue 
  in 
  the 
  (^ 
  is 
  pointed 
  

   and 
  may 
  be 
  excessively 
  lengthened, 
  and 
  these 
  represent 
  

   the 
  more 
  primitive 
  members 
  of 
  the 
  family. 
  Our 
  Colletes 
  

   is 
  an 
  extreme 
  form, 
  some 
  exotic 
  genera 
  having 
  a 
  very 
  

  

  