﻿292 
  REPOET 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  general 
  rule 
  can 
  be 
  laid 
  down 
  as 
  to 
  the 
  relative 
  proportions 
  of 
  the 
  epi- 
  

   cranium 
  and 
  of 
  the 
  clj-peus, 
  or 
  of 
  the 
  gular 
  region. 
  

  

  On 
  this 
  account 
  I 
  had 
  at 
  one 
  time 
  decided 
  to 
  split 
  the 
  group 
  into 
  two, 
  

   and 
  to 
  restrict 
  Erichson's 
  Pseudoneuroptera 
  to 
  the 
  Platyptera,^*" 
  and 
  to 
  

   adopt 
  Latreille's 
  term 
  Suhulicornia 
  for 
  the 
  Odonata 
  and 
  Ephemerina 
  

   {SuhuUcornes 
  of 
  Latreille). 
  It 
  may, 
  however, 
  be 
  best, 
  for 
  the 
  sake 
  of 
  

   clearness, 
  to 
  retain 
  Erichson's 
  order 
  Fseudoneuroptera 
  as 
  he 
  indicated 
  

   it, 
  and 
  to 
  dismember 
  it 
  into 
  what 
  may 
  be 
  regarded, 
  provisionally 
  at 
  

   least, 
  as 
  three 
  suborders 
  : 
  

  

  1. 
  Flaiyptera 
  (Termitidse, 
  Embidse, 
  PsOcidse, 
  and 
  Perlid8e:=Oorroden- 
  

   tia 
  and 
  Orthoptera 
  amphibiotica 
  in 
  part). 
  

  

  2. 
  Odonata 
  (Libellulidse). 
  

  

  3. 
  Ephemerina 
  (EphemeridsB). 
  

  

  It 
  is 
  comparatively 
  easy 
  to 
  give 
  well-grounded 
  differential 
  characters 
  

   for 
  these 
  three 
  suborders. 
  They 
  are 
  so 
  distinct 
  that 
  they 
  may 
  perhaps 
  

   hereafter 
  be 
  regarded 
  as 
  entitled 
  to 
  the 
  rank 
  of 
  orders, 
  or 
  the 
  Fseudo- 
  

   neuroptera 
  may 
  be 
  dismembered 
  into 
  the 
  Fseudoneuroptera 
  and 
  Suhuli- 
  

   cornia 
  (Odonata 
  and 
  Ephemerina). 
  

  

  1. 
  Flatyptera. 
  — 
  The 
  body 
  is 
  flattened 
  j 
  the 
  head 
  horizontal. 
  The 
  pro- 
  

   notum 
  is 
  large, 
  broad, 
  and 
  square. 
  The 
  meso- 
  and 
  metanotum 
  are 
  re- 
  

   markable 
  on 
  account 
  of 
  the 
  imperfect 
  differentiation 
  of 
  the 
  scutum 
  and 
  

   scutellum 
  j 
  the 
  latter 
  is 
  indefinite 
  in 
  outline, 
  but 
  very 
  large. 
  The 
  flanks 
  

   (pleurites) 
  are, 
  when 
  long, 
  oblique, 
  or 
  are 
  short. 
  The 
  sternites 
  are 
  usu- 
  

   ally 
  very 
  large 
  and 
  broad. 
  There 
  are 
  often 
  eleven 
  uromeres. 
  

  

  2. 
  Odonata. 
  — 
  While 
  the 
  Odonata 
  and 
  Ephemerina 
  are 
  somewhat 
  alike 
  

   as 
  regards 
  the 
  form 
  and 
  venation 
  of 
  the 
  fore 
  wiugs, 
  in 
  their 
  moutb 
  -parts 
  

   and 
  thorax 
  they 
  are 
  entirely 
  unlike. 
  The 
  Odonata 
  are 
  remarkable 
  for 
  

   the 
  great 
  dorsal 
  (tergal) 
  development 
  of 
  the 
  mesepisterna 
  and 
  the 
  enor- 
  

   mous 
  development 
  of 
  the 
  meso- 
  and 
  metapleurites 
  in 
  general, 
  while 
  

   the 
  notum 
  of 
  the 
  meso- 
  and 
  metathorax, 
  though 
  of 
  the 
  same 
  type 
  as 
  the 
  

   Orthoptera, 
  is 
  minute 
  in 
  size. 
  The 
  prothorax 
  is 
  very 
  small, 
  both 
  dor- 
  

   sally 
  and 
  on 
  th6 
  sides, 
  forming 
  a 
  collar. 
  

  

  The 
  wings 
  are 
  as 
  markedly 
  net- 
  veined 
  as 
  in 
  the 
  Orthoptera, 
  though 
  

   the 
  hinder 
  pair 
  are 
  not 
  folded 
  longitudiually 
  as 
  in 
  that 
  order. 
  The 
  

   Odonata 
  literally 
  live 
  on 
  the 
  wing, 
  and 
  thus 
  the 
  shape 
  of 
  the 
  sclerites 
  

   of 
  the 
  notum 
  of 
  the 
  wing 
  -bearing 
  segments 
  approaches 
  that 
  of 
  the 
  

   Orthoptera, 
  although 
  the 
  prothorax 
  is 
  remarkably 
  small 
  compared 
  with 
  

   that 
  of 
  the 
  Orthoptera, 
  and 
  forbids 
  their 
  union 
  with 
  this 
  order, 
  as 
  was 
  

   done 
  by 
  Gerstacker 
  and 
  other 
  German 
  entomologists. 
  The 
  head 
  of 
  the 
  

   Odonata 
  is 
  remarkable 
  for 
  the 
  enormous 
  size 
  of 
  the 
  eyes 
  and 
  the 
  con- 
  

   sequent 
  great 
  reduction 
  in 
  size 
  of 
  the 
  epicraniuiia, 
  as 
  compared 
  with 
  

   the 
  large 
  epicranium 
  of 
  the 
  Orthoptera. 
  The 
  mouth-parts 
  are 
  like 
  

   those 
  of 
  the 
  Orthoptera, 
  except 
  that 
  the 
  second 
  maxillae 
  form 
  a 
  re- 
  

  

  i''" 
  This 
  name 
  irXarv?, 
  flat, 
  Trrepov, 
  •wing, 
  in 
  allusion 
  to 
  the 
  wings 
  which 
  in 
  the 
  majority 
  (the 
  Psocidao 
  

   folding 
  their 
  wings 
  rather 
  roof-like) 
  fold 
  their 
  wings 
  flat 
  on 
  the 
  back. 
  The 
  Isoti*^«ra 
  of 
  Brull6 
  comprise 
  

   the 
  Termitidso 
  alone. 
  

  

  