﻿94 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  98 
  

  

  entire 
  length 
  of 
  tbe 
  Irons. 
  The 
  upper 
  half 
  of 
  the 
  frons 
  may 
  be 
  retic- 
  

   ulate, 
  punctate, 
  striate, 
  without 
  sculpture, 
  or 
  it 
  may 
  be 
  reticulate 
  

   and 
  punctate, 
  the 
  clearness 
  and 
  depth 
  of 
  the 
  markings 
  different 
  in 
  

   various 
  species. 
  

  

  The 
  mesonotum 
  may 
  have 
  a 
  fine 
  sculpture, 
  in 
  which 
  case 
  it 
  is 
  usu- 
  

   ally 
  more 
  or 
  less 
  distinctly 
  scaly-reticulate, 
  sometimes 
  more 
  or 
  less 
  

   wrinkled 
  anteriorly, 
  or 
  it 
  may 
  have 
  a 
  much 
  coarser 
  sculpture, 
  in 
  

   which 
  case 
  it 
  is 
  punctate 
  or 
  variously 
  wrinkled, 
  not 
  usually 
  distinctly 
  

   reticulate. 
  The 
  parapsidal 
  grooves 
  may 
  be 
  complete 
  or 
  nearly 
  com- 
  

   plete 
  whether 
  the 
  general 
  sm'face 
  sculpture 
  is 
  fine 
  or 
  coarse, 
  but 
  they 
  

   are 
  usually 
  shorter 
  in 
  those 
  species 
  with 
  fine 
  m-esonotal 
  sculpture. 
  

   When 
  the 
  sculpture 
  is 
  strong 
  the 
  parapsidal 
  grooves 
  are 
  often 
  traced 
  

   only 
  with 
  difficulty. 
  It 
  is 
  sometimes 
  difficult 
  to 
  make 
  sure 
  that 
  the 
  

   groove 
  one 
  is 
  trying 
  to 
  follow 
  is 
  not 
  just 
  one 
  of 
  many 
  furrows 
  in 
  a 
  

   much 
  wrinkled 
  surface. 
  Wrinkles 
  posteriorly 
  on 
  the 
  mesonotum 
  

   appear 
  always 
  to 
  run 
  longitudinally; 
  those 
  situated 
  anteriorly 
  are 
  

   apparently 
  always 
  directed 
  transversely. 
  

  

  The 
  shape 
  and 
  sculpture 
  of 
  the 
  first, 
  second, 
  and 
  third 
  tergites 
  

   present 
  many 
  characters 
  of 
  value 
  in 
  separating 
  species 
  and 
  groups 
  of 
  

   species. 
  The 
  petiole 
  varies, 
  in 
  different 
  species, 
  from 
  broadly 
  trans- 
  

   verse 
  to 
  distinctly 
  longer 
  than 
  wide 
  (measured 
  across 
  base). 
  The 
  

   dorsal 
  surface 
  is 
  always 
  traversed 
  by 
  longitudinal 
  ridges 
  separated 
  by 
  

   more 
  or 
  less 
  profound 
  grooves. 
  In 
  the 
  majority 
  of 
  the 
  Nearctic 
  

   species 
  these 
  ridges 
  extend 
  the 
  entire 
  length 
  of 
  the 
  segment 
  or 
  nearly 
  

   so. 
  Several 
  species, 
  however, 
  have 
  the 
  ridges 
  very 
  short, 
  present 
  

   only 
  across 
  the 
  middle. 
  In 
  the 
  female 
  the 
  petiole 
  may 
  be 
  protuberant 
  

   anteriorly, 
  the 
  longitudinal 
  ridges 
  not 
  present 
  on 
  the 
  swoUen 
  portion. 
  

   A 
  trough-shaped 
  depression 
  sometimes 
  crosses 
  the 
  petiole, 
  the 
  ridges 
  

   traversing 
  it. 
  In 
  several 
  species 
  the 
  anterior 
  margin 
  is 
  narrowly 
  

   reflexed. 
  

  

  The 
  second 
  tergite 
  is 
  always, 
  as 
  far 
  as 
  the 
  author 
  knows, 
  wider 
  

   (measured 
  across 
  base) 
  than 
  long, 
  but 
  the 
  proportions 
  are 
  somewhat 
  

   different 
  in 
  the 
  various 
  species. 
  Like 
  the 
  petiole 
  this 
  segment 
  is 
  

   traversed 
  by 
  longitudinal 
  ridges, 
  or 
  by 
  deep 
  grooves 
  with 
  the 
  upper 
  

   edges 
  of 
  the 
  intervening 
  ridges 
  on 
  a 
  level 
  with 
  the 
  general 
  surface. 
  

   Usually 
  the 
  ridges 
  are 
  longest 
  medially, 
  becoming 
  progressively 
  

   shorter 
  as 
  they 
  approach 
  the 
  lateral 
  margins. 
  A 
  few 
  species 
  have 
  aU 
  

   the 
  ridges 
  equally 
  long, 
  their 
  termini 
  forming 
  a 
  straight 
  line 
  parallel 
  

   with 
  the 
  posterior 
  margin. 
  In 
  some 
  species 
  with 
  shorter 
  lateral 
  ridges 
  

   the 
  second 
  tergite 
  is 
  reticulate 
  toward 
  the 
  sides. 
  

  

  Unlike 
  the 
  petiole 
  and 
  the 
  second 
  tergite 
  the 
  third 
  tergite 
  has 
  no 
  

   set 
  form 
  of 
  sculpture. 
  The 
  surface 
  may 
  be 
  partly 
  or 
  entirely 
  striate, 
  

   partly 
  or 
  entirely 
  reticulate 
  with 
  the 
  enclosed 
  areas 
  varying 
  in 
  size 
  

   and 
  the 
  impressions 
  varying 
  in 
  depth, 
  or 
  punctate, 
  the 
  pits 
  varying 
  in 
  

  

  