﻿96 
  Dr. 
  G. 
  C. 
  Crampton's 
  Notes 
  on 
  the 
  Ancestry 
  of 
  the 
  

  

  have 
  been 
  more 
  exact 
  to 
  represent 
  these 
  three 
  groups 
  

   as 
  three 
  intersecting 
  spheres 
  rather 
  than 
  as 
  circles 
  drawn 
  

   in 
  one 
  plane 
  ; 
  but 
  the 
  figure 
  in 
  question 
  will 
  serve 
  well 
  

   enough 
  to 
  illustrate 
  the 
  points 
  under 
  discussion. 
  

  

  The 
  circle 
  representing 
  the 
  Ephemerid 
  group 
  has 
  been 
  

   represented 
  as 
  though 
  somewhat 
  lower 
  than 
  that 
  of 
  the 
  

   Plecopteron 
  group, 
  since 
  certain 
  Palaeodictyopteron 
  

   members 
  of 
  the 
  Ephemerid 
  section 
  are 
  somewhat 
  more 
  

   primitive 
  than 
  the 
  lowest 
  representatives 
  of 
  the 
  Plecopteron 
  

   section. 
  On 
  the 
  other 
  hand, 
  some 
  members 
  of 
  the 
  

   Ephemerid 
  group 
  may 
  occupy 
  a 
  position 
  extending 
  up 
  even 
  

   into 
  the 
  territory 
  of 
  the 
  Neuropteron 
  group 
  (as 
  shown 
  in 
  

   the 
  figure), 
  since 
  they 
  have 
  much 
  in 
  common 
  with 
  the 
  

   lowest 
  members 
  of 
  the 
  Neuropteron 
  section. 
  As 
  far 
  as 
  

   the 
  more 
  direct 
  ancestors 
  of 
  the 
  Neuropteron 
  section 
  are 
  

   concerned, 
  however, 
  I 
  would 
  provisionally 
  consider 
  the 
  

   Plecopteron 
  section 
  as 
  more 
  nearly 
  representing 
  their 
  

   immediate 
  ancestors, 
  while 
  the 
  Ephemerid 
  section 
  may 
  

   represent 
  the 
  common 
  stock 
  from 
  which 
  both 
  the 
  Pleco- 
  

   pteron 
  and 
  Neuropteron 
  sections 
  are 
  ultimately 
  to 
  be 
  derived. 
  

   On 
  this 
  account, 
  the 
  circle 
  representing 
  the 
  Plecopteron 
  

   group 
  has 
  been 
  represented 
  as 
  though 
  intermediate 
  between 
  

   the 
  other 
  two, 
  in 
  the 
  figure. 
  

  

  Tillyard, 
  1917 
  (Biology 
  of 
  Dragonflies), 
  emphasises 
  the 
  

   resemblance 
  between 
  the 
  Protascalaphine 
  Neuropteron 
  

   Stilbopteryx 
  and 
  the 
  Odonata, 
  not 
  only, 
  in 
  appearance, 
  but 
  

   even 
  in 
  its 
  mode 
  of 
  flight, 
  etc., 
  and 
  it 
  must 
  be 
  admitted 
  that 
  

   the 
  Neuroptera 
  are 
  in 
  many 
  respects 
  extremely 
  hke 
  the 
  

   Odonata 
  and 
  their 
  alhes, 
  the 
  Ephemerida. 
  Handhrsch, 
  

   1906 
  (Die 
  Fossilen 
  Insekten), 
  has 
  also 
  pointed 
  out 
  the 
  

   marked 
  resemblance 
  of 
  the 
  Neuroptera 
  to 
  certain 
  fossil 
  

   Palaeodictyoptera, 
  so 
  that 
  when 
  one 
  considers 
  the 
  Neuro- 
  

   ptera 
  alone, 
  there 
  is 
  considerable 
  evidence 
  for 
  regarding 
  

   the 
  Ephemerid 
  section 
  (^. 
  e. 
  the 
  Ephemerida, 
  Odonata, 
  

   and 
  Palaeodictyoptera) 
  as 
  more 
  nearly 
  representing 
  the 
  

   ancestral 
  group 
  giving 
  rise 
  to 
  the 
  insects 
  related 
  to 
  the 
  

   Neuroptera. 
  The 
  Psocidae, 
  however, 
  must 
  be 
  considered 
  

   also 
  in 
  such 
  a 
  phylogenetic 
  study, 
  since 
  they 
  also 
  occupy 
  

   a 
  position 
  near 
  the 
  base 
  of 
  the 
  fines 
  of 
  descent 
  of 
  the 
  

   insects 
  related 
  to 
  the 
  Neuroptera, 
  as 
  is 
  shown 
  in 
  Fig. 
  2 
  ; 
  

   and 
  a 
  study 
  of 
  the 
  affinities 
  of 
  the 
  Psocidae 
  is 
  of 
  no 
  less 
  

   importance 
  than 
  those 
  of 
  the 
  Neuroptera, 
  in 
  attempting 
  to 
  

   determine 
  the 
  ancestry 
  of 
  the 
  insects 
  in 
  question. 
  Now 
  the 
  

   Psocidae 
  exhibit 
  undeniable 
  affinities 
  with 
  the 
  Coleoptera. 
  

  

  