﻿117 
  

  

  divided 
  in 
  the 
  median 
  line; 
  each 
  lateral 
  part 
  has 
  in 
  front 
  

   an 
  articulation 
  to 
  which 
  the 
  hooks 
  are 
  connected, 
  one 
  on 
  

   each 
  part 
  (Fig. 
  13); 
  the 
  two 
  lateral 
  parts 
  of 
  the 
  skeleton 
  

   are 
  mutually 
  connected 
  by 
  an 
  arched, 
  transverse 
  rod 
  which 
  

   is 
  placed 
  on 
  the 
  spot 
  where 
  the 
  plate 
  present 
  in 
  the 
  first 
  

   stage 
  was 
  placed. 
  Most 
  species 
  are 
  amphipneustic, 
  but 
  

   some 
  (Panzeria 
  rudis 
  and 
  Ocyptera 
  brassicaria) 
  are 
  meta- 
  

   pneustic. 
  The 
  anterior 
  spiracles 
  are 
  elongated 
  and 
  generally 
  

   divided 
  into 
  two 
  knobs 
  (Fig. 
  14) 
  which 
  may 
  soraetimes 
  

   fViviania 
  cinerea 
  Fig. 
  37) 
  be 
  very 
  small. 
  The 
  larva 
  of 
  

   Carcelia 
  gnava 
  has 
  in 
  this 
  stage 
  a 
  larger 
  number 
  of 
  knobs 
  

   on 
  the 
  anterior 
  spiracles 
  (Fig. 
  29). 
  The 
  posterior 
  spiracles 
  

   resemble 
  those 
  in 
  the 
  first 
  stage, 
  thus 
  having 
  only 
  two 
  

   knobs, 
  but 
  the 
  knobs 
  are 
  somewhat 
  larger, 
  sometimes 
  sinuous 
  

   (Ocyptera 
  brassicaria 
  Fig. 
  42), 
  and 
  sometimes 
  partly 
  con- 
  

   fluent 
  (SleinieUa 
  callida 
  Fig. 
  26). 
  

  

  Third 
  stage. 
  The 
  anterior 
  part 
  of 
  the 
  pharyngeal 
  

   skeleton 
  is 
  connected 
  with 
  the 
  posterior 
  part 
  by 
  an 
  articu- 
  

   lation 
  (Fig. 
  16). 
  All 
  larvæ, 
  except 
  those 
  of 
  Ocyptera 
  brassi- 
  

   caria, 
  are 
  amphipneustic. 
  The 
  anterior 
  spiracles 
  are 
  large 
  

   and 
  generally 
  richly 
  branched 
  (Fig. 
  22). 
  The 
  posterior 
  

   spiracles 
  are 
  surrounded 
  by 
  a 
  chitinous 
  border 
  generally 
  

   dividing 
  the 
  spiracle 
  into 
  areas 
  (Fig. 
  49). 
  Each 
  spiracle 
  

   has 
  three 
  respiratory 
  areas 
  at 
  least. 
  

  

  In 
  the 
  larvæ 
  examined 
  the 
  armature 
  of 
  spines 
  is 
  present 
  

   on 
  the 
  front 
  and 
  hind 
  margins 
  of 
  the 
  segments. 
  The 
  spines 
  

   on 
  the 
  front 
  margins 
  are 
  largest 
  on 
  the 
  anterior 
  segments 
  

   and 
  decrease 
  in 
  size 
  behind. 
  The 
  spines 
  on 
  the 
  hind 
  

   margins 
  are 
  generally 
  not 
  found 
  on 
  the 
  anterior 
  segments, 
  

   but 
  appear 
  on 
  the 
  third 
  or 
  fourth 
  segment 
  and 
  increase 
  in 
  

   size 
  behind. 
  All 
  the 
  spines 
  on 
  the 
  front 
  margins 
  point 
  

   backAvards, 
  and 
  all 
  those 
  on 
  the 
  hind 
  margins 
  point 
  for- 
  

   wards 
  (Fig. 
  48). 
  The 
  last 
  segment 
  has 
  a 
  girdle 
  of 
  spines 
  

   directed 
  forwards. 
  In 
  the 
  first 
  stage 
  some 
  single, 
  very 
  large 
  

  

  