﻿ORIGIN 
  OF 
  A 
  METAMORPHOSIS 
  IN 
  INSECTS. 
  299 
  

  

  larvae. 
  Brauer's 
  figures 
  show 
  a 
  pair 
  of 
  abdomiual, 
  two-jointed 
  feet 
  to 
  

   ^acli 
  of 
  the 
  niue 
  abdominal 
  segments, 
  while 
  just 
  as 
  in 
  Lepidopterous 
  

   larvae 
  and 
  in 
  that 
  of 
  Panorpa 
  there 
  is 
  a 
  pair 
  of 
  pro 
  thoracic 
  spiracles, 
  

   none 
  on 
  the 
  mesothoracic 
  or 
  metathoracic 
  segments, 
  and 
  there 
  are 
  nine 
  

   pairs 
  of 
  abdominal 
  spiracles 
  according 
  to 
  Brauer's 
  figure, 
  or 
  one 
  more 
  

   pair 
  than 
  in 
  Lepidopterous 
  larvae. 
  

  

  The 
  fact 
  that 
  there 
  are 
  in 
  the 
  larval 
  Panorpidae 
  collectively 
  a 
  pair 
  of 
  feet 
  

   to 
  each 
  abdominal 
  segment 
  (the 
  terminal 
  segment 
  in 
  Panorpa 
  bearing 
  

   what 
  are 
  evidently 
  homologues 
  of 
  the 
  anal 
  proplegs 
  of 
  caterpillars) 
  is 
  

   of 
  much 
  significance 
  when 
  we 
  bear 
  in 
  mind 
  that 
  while 
  no 
  caterpillars 
  are 
  

   known 
  to 
  have 
  more 
  than 
  five 
  pairs 
  of 
  abdominal 
  or 
  proplegs, 
  some 
  of 
  

   the 
  segments 
  bearing 
  none, 
  yet 
  the 
  embryos, 
  as 
  shown 
  by 
  Kowalevsky, 
  

   have 
  temporary 
  embryonic 
  indications 
  of 
  legs, 
  a 
  pair 
  to 
  each 
  segment 
  

   (uromere); 
  it 
  is 
  a 
  significant 
  fact 
  that 
  the 
  cruciform 
  larvae 
  of 
  the 
  Panor- 
  

   pidae 
  actually 
  have 
  two-jointed 
  legs 
  to 
  each 
  abdominal 
  segment, 
  the 
  

   penultimate 
  segment 
  in 
  Bifctacus 
  bearing 
  such 
  legs, 
  and 
  the 
  terminal 
  seg- 
  

   ment 
  bearing 
  leg-like 
  processes 
  in 
  Panorpa. 
  The 
  origin 
  of 
  the 
  Lepi- 
  

   doptera 
  from 
  the 
  same 
  stem-form 
  as 
  the 
  Panorpidae 
  thus 
  seems 
  a 
  rea- 
  

   sonable 
  hypothesis. 
  

  

  In 
  the 
  metamorphosis 
  of 
  Mantispa, 
  as 
  Brauer 
  has 
  shown, 
  there 
  is 
  a 
  

   hypermetamorphosis, 
  i. 
  e., 
  two 
  larval 
  stages. 
  The 
  first 
  stage 
  is 
  Gampodea- 
  

   form 
  5 
  but 
  the 
  second 
  is 
  sub-eruciform. 
  The 
  transformations 
  of 
  Mantispa 
  

   appear 
  to 
  give 
  us 
  the 
  key 
  to 
  the 
  mode 
  in 
  which 
  a 
  metamorphosis 
  was- 
  

   brought 
  about. 
  The 
  larva, 
  born 
  a 
  Oampodea-like 
  form, 
  active, 
  with 
  large, 
  

   long, 
  four-jointed 
  feet, 
  living 
  a 
  sedentary 
  life 
  in 
  the 
  egg-sac 
  of 
  a 
  spider, 
  be- 
  

   fore 
  the 
  first 
  molt 
  loses 
  the 
  use 
  of 
  its 
  feet, 
  while 
  the 
  antennae 
  are 
  partly 
  

   aborted. 
  The 
  fully 
  grown 
  larva 
  is 
  round-bodied, 
  with 
  small, 
  caterpillar- 
  

   like 
  feet 
  and 
  a 
  small, 
  round 
  head. 
  Its 
  external 
  appendages 
  retrograding 
  

   and 
  retarded, 
  acceleration 
  of 
  growth 
  goes 
  on 
  within, 
  and 
  thus 
  the 
  pupal 
  

   form 
  is 
  perfected 
  while 
  the 
  larva 
  is 
  full-fed 
  and 
  quiescent; 
  hence 
  as 
  a 
  

   result 
  the 
  pupal 
  stage 
  became 
  a 
  quiescent 
  one, 
  and 
  by 
  inheritance 
  it 
  grad- 
  

   ually 
  became 
  a 
  permanent 
  habit 
  characteristic 
  oT 
  Il^europtera, 
  all 
  of 
  which 
  

   have 
  a 
  comi)lete 
  metamorphosis, 
  and 
  hence 
  inherited 
  by 
  all 
  the 
  orders 
  of 
  

   metabolic 
  insects 
  which 
  probably 
  originated 
  from 
  Neuroptera- 
  like 
  forms, 
  

   and 
  the 
  imago 
  represents 
  a 
  highly 
  accelerated 
  stage. 
  

  

  When 
  we 
  consider 
  the 
  images 
  or 
  adult 
  iTeuroptera 
  : 
  the 
  small, 
  collar- 
  

   like 
  prothorax, 
  the 
  spherical, 
  concentrated 
  thorax 
  as 
  a 
  whole, 
  and 
  the 
  

   cylindrical 
  abdomen, 
  are 
  features 
  which 
  give 
  them 
  a 
  comparatively 
  spe- 
  

   cialized 
  and 
  modern 
  aspect. 
  Without 
  doubt 
  the 
  INeuropterous 
  labium 
  

   (Plate 
  LIIl) 
  is 
  a 
  secondary 
  product 
  compared 
  with 
  that 
  of 
  the 
  Orthoptera 
  

   or 
  the 
  Platyptera, 
  where 
  it 
  is 
  deeply 
  cleft 
  (Plate 
  XXVII.) 
  It 
  will 
  be 
  re- 
  

   membered 
  that 
  in 
  the 
  embryo 
  of 
  all 
  insects 
  the 
  labium 
  or 
  second 
  maxillae 
  

   originates 
  like 
  the 
  first 
  pair. 
  ' 
  

  

  Origin 
  of 
  the 
  Goleoi^tera. 
  — 
  Although 
  the 
  beetles 
  are 
  a 
  remarkably 
  

   homogeneous 
  and 
  well 
  circumscribed 
  order, 
  there 
  are 
  certain 
  larval 
  

   forms 
  and 
  life-histories 
  which 
  point 
  out 
  with 
  a 
  tolerable 
  degree 
  of 
  cer- 
  

  

  