﻿Diptera, 
  Hemiptera 
  and 
  Insects 
  related 
  to 
  Neuroptera. 
  109 
  

  

  I 
  have 
  even 
  found 
  a 
  genital 
  structure 
  in 
  the 
  males 
  of 
  the 
  

   TipuUd 
  Pachyrhina 
  macrophallus 
  described 
  by 
  Dietz, 
  1918 
  

   (Trans. 
  Amer. 
  Ent. 
  See, 
  44, 
  p. 
  105), 
  strongly 
  suggestive 
  

   of 
  the 
  coiled 
  spring-hke 
  structure 
  in 
  the 
  genitaha 
  of 
  males 
  

   of 
  Bittacus. 
  The 
  resemblance 
  between 
  the 
  genitalia 
  of 
  

   the 
  males 
  of 
  both 
  groups 
  has 
  been 
  pointed 
  out 
  in 
  a 
  paper 
  

   pubhshed 
  in 
  Psyche, 
  1918, 
  vol. 
  25, 
  p. 
  55, 
  and 
  the 
  evolution 
  

   of 
  the 
  head 
  types 
  in 
  Neuroptera, 
  Mecoptera 
  and 
  Diptera 
  

   has 
  been 
  traced 
  in 
  a 
  paper 
  published 
  in 
  the 
  Annals 
  Ent. 
  

   Soc. 
  America; 
  1918, 
  vol. 
  10, 
  p. 
  337. 
  As 
  was 
  pointed 
  out 
  

   in 
  the 
  paper 
  on 
  the 
  evolution 
  of 
  the 
  head 
  types 
  in 
  Diptera, 
  

   etc., 
  the 
  Trichoptera 
  have 
  retained 
  certain 
  features 
  sug- 
  

   gestive 
  of 
  the 
  ancestors 
  of 
  the 
  Diptera 
  (and 
  Packard, 
  1883, 
  

   derives 
  the 
  Diptera 
  from 
  them) 
  ; 
  but 
  this 
  may 
  possibly 
  

   be 
  explained 
  as 
  the 
  result 
  of 
  the 
  relationship 
  of 
  both 
  

   Diptera 
  and 
  Trichoptera 
  to 
  the 
  Mecoptera, 
  since 
  the 
  

   Diptera 
  and 
  Trichoptera 
  were 
  in 
  all 
  probability 
  descended 
  

   from 
  ancestors 
  not 
  unlike 
  the 
  Mecoptera 
  (or 
  from 
  the 
  

   Neuroptera-like 
  ancestors 
  of 
  the 
  Mecoptera). 
  Similarly, 
  

   since 
  the 
  Lepidoptera 
  were 
  descended 
  from 
  ancestors 
  

   resembhng 
  those 
  of 
  the 
  Trichoptera 
  and 
  Mecoptera, 
  they 
  

   therefore 
  might 
  also 
  carry 
  over 
  certain 
  characters 
  in 
  common 
  

   with 
  the 
  Diptera, 
  which 
  are 
  derived 
  from 
  a 
  similar 
  ancestry. 
  

   I 
  would 
  thus 
  account 
  for 
  the 
  resemblances 
  of 
  the 
  Lepido- 
  

   ptera, 
  Trichoptera, 
  Hymenoptera, 
  etc., 
  to 
  the 
  Diptera, 
  as 
  

   the 
  result 
  of 
  their 
  common 
  or 
  mutual 
  relationship 
  to 
  the 
  

   Mecoptera 
  (or 
  the 
  Neuropteroid 
  ancestors 
  of 
  the 
  Mecoptera). 
  

   If 
  it 
  should 
  prove 
  to 
  be 
  the 
  case 
  that 
  the 
  Homoptera 
  (and 
  

   Hemiptera) 
  are 
  more 
  closely 
  related 
  to 
  the 
  Mecoptera 
  and 
  

   other 
  Neuropteroid 
  insects 
  than 
  to 
  the 
  Psocidae 
  and 
  their 
  

   allies, 
  the 
  shght 
  resemblance 
  of 
  the 
  Hemiptera 
  to 
  the 
  

   Diptera 
  might 
  in 
  the 
  same 
  way 
  be 
  explained 
  as 
  the 
  result 
  

   of 
  their 
  mutual 
  relationship 
  to 
  the 
  Mecoptera. 
  At 
  present, 
  

   however, 
  I 
  do 
  not 
  think 
  that 
  the 
  Homoptera 
  are 
  very 
  

   closely 
  related 
  to 
  the 
  Diptera, 
  while 
  the 
  Lepidoptera 
  do 
  

   show 
  some 
  unmistakable 
  resemblances 
  to 
  the 
  Diptexa, 
  as 
  

   is 
  also 
  the 
  case 
  with 
  the 
  Trichoptera, 
  and 
  to 
  some 
  extent, 
  

   the 
  Hymenoptera 
  also. 
  

  

  Whether 
  the 
  ancestors 
  of 
  the 
  Diptera 
  would 
  have 
  been 
  

   placed 
  in 
  the 
  order 
  Mecoptera 
  by 
  systematists, 
  or 
  whether 
  

   they 
  were 
  Neuroptera-hke 
  forms 
  giving 
  rise 
  to 
  both 
  the 
  

   Dipteron 
  and 
  Mecopteron 
  lines 
  of 
  descent, 
  I 
  cannot 
  say 
  ; 
  

   but 
  it 
  is 
  quite 
  evident 
  that 
  the 
  Mecopteron 
  line 
  of 
  descent 
  

   has 
  paralleled 
  that 
  of 
  the 
  Diptera 
  more 
  closely 
  and 
  for 
  a 
  

  

  