﻿The 
  British 
  Species 
  of 
  Andrena 
  and 
  Nomada. 
  271 
  

  

  In 
  the 
  males 
  the 
  abundance 
  of 
  hairs 
  often 
  interferes 
  with 
  

   a 
  view 
  of 
  the 
  area, 
  and 
  the 
  following 
  characters 
  are 
  very 
  

   useful. 
  

  

  The 
  clypeus 
  is 
  never 
  white 
  or 
  yellow, 
  the 
  mandibles 
  

   when 
  closed 
  always 
  lie 
  the 
  one 
  on 
  the 
  other, 
  the 
  tips 
  not 
  

   forming 
  a 
  cross, 
  the 
  third 
  antennal 
  joint 
  (so 
  far 
  as 
  British 
  

   species 
  are 
  concerned) 
  is 
  always 
  short, 
  just 
  equal 
  to 
  or 
  

   sometimes 
  a 
  little 
  shorter, 
  but 
  never 
  at 
  all 
  longer 
  than 
  the 
  

   4th. 
  In 
  the 
  (^ 
  genital 
  armature 
  the 
  inner 
  angles 
  of 
  the 
  

   lobes 
  of 
  the 
  stipites 
  are 
  always 
  greatly 
  and 
  acutely 
  pro- 
  

   duced, 
  forming 
  strong 
  divergent 
  spines. 
  Comparatively 
  

   few 
  of 
  our 
  Andrenas 
  have 
  antennal 
  characters 
  as 
  above, 
  

   the 
  3rd 
  joint 
  being 
  usually 
  at 
  least 
  slightly 
  longer 
  than 
  

   the 
  4th. 
  

  

  The 
  females 
  have 
  the 
  floccus 
  of 
  the 
  hind 
  trochanters 
  

   perfect, 
  and 
  the 
  abdomen 
  never 
  bears 
  a 
  special 
  adornment 
  

   of 
  dense, 
  short, 
  white 
  hairs 
  on 
  the 
  apices 
  of 
  thei 
  inter- 
  

   mediate 
  segments 
  forming 
  conspicuous 
  bands 
  or 
  lateral 
  

   streaks. 
  Except 
  in 
  A. 
  albicans, 
  the 
  inner 
  calcar 
  of 
  the 
  

   hind 
  tibiae 
  is 
  unusually 
  long 
  and 
  curved 
  and 
  distinctive 
  

   in 
  appearance 
  accordingly. 
  

  

  Group 
  of 
  A. 
  FLAVIPES 
  (fulvicrus). 
  

  

  The 
  two 
  species 
  flavipes 
  and 
  gravida 
  (fa^ciata) 
  might 
  

   perhaps 
  be 
  included 
  in 
  the 
  group 
  of 
  nigroaenea, 
  but 
  the 
  

   appearance 
  of 
  the 
  females 
  is 
  very 
  distinct. 
  Short 
  decum- 
  

   bent 
  white 
  (or 
  almost 
  white) 
  hairs 
  form 
  3 
  dense 
  and 
  

   complete 
  pale 
  abdominal 
  bands, 
  covering 
  the 
  apical 
  

   impressions 
  on 
  the 
  2nd, 
  3rd 
  and 
  4th 
  segments. 
  When 
  

   these 
  bands 
  are 
  abraded 
  the 
  impressions 
  exhibit 
  a 
  very 
  

   dense 
  and 
  fine 
  distinct 
  puncturation, 
  and 
  this 
  combined 
  

   with 
  the 
  clear 
  and 
  copious 
  or 
  dense 
  puncturation 
  of 
  the 
  

   basal 
  segment, 
  renders 
  old 
  and 
  worn 
  examples 
  not 
  less 
  

   easily 
  determinable 
  than 
  fresh 
  ones. 
  The 
  surface 
  of 
  the 
  

   abdomen 
  is 
  practically 
  glabrous 
  apart 
  from 
  these 
  bands. 
  

   The 
  scopae 
  are 
  red 
  or 
  yellow 
  and 
  the 
  appressed 
  hairs 
  of 
  

   the 
  5th 
  abdominal 
  segment 
  black 
  or 
  dark 
  fuscous. 
  The, 
  

   floccus 
  is 
  imperfect, 
  the 
  hairs 
  of 
  the 
  basal 
  part 
  of 
  the 
  

   trochanter 
  conspicuously 
  different 
  from 
  the 
  apical 
  ones. 
  

   The 
  pygidial 
  area 
  is 
  flat, 
  without 
  a 
  raised 
  median 
  tri- 
  

   angular 
  portion. 
  

  

  The 
  males 
  are 
  often 
  less 
  distinct 
  in 
  appearance, 
  but 
  are 
  

   easily 
  known 
  by 
  the 
  definite 
  minute 
  sculpture 
  on 
  a 
  large 
  

  

  