﻿DEVELOPMENT 
  AND 
  METAMORPHOSIS. 
  

  

  89 
  

  

  front 
  of 
  them 
  a 
  small 
  cleft, 
  out 
  of 
  whicli 
  the 
  gill- 
  

   filaments 
  of 
  the 
  branchial 
  arches 
  in 
  process 
  of 
  dis- 
  

   appearance 
  may 
  often 
  be 
  seen 
  projecting 
  (Fig. 
  35). 
  

  

  Fig. 
  35 
  

  

  Alytes 
  obstetricans, 
  towards 
  the 
  end 
  of 
  the 
  larval 
  stage, 
  

   showing 
  the 
  gills 
  (br) 
  protruding 
  through 
  the 
  cleft 
  in 
  

   front 
  of 
  the 
  arm, 
  and 
  the 
  median 
  spiraculum 
  (sp). 
  

  

  Then 
  only 
  the 
  caudal 
  crests 
  become 
  reduced 
  and 
  the 
  

   tail 
  gradually 
  absorbed; 
  the 
  gill-arches 
  entirely 
  dis- 
  

   appear 
  ; 
  the 
  lungs, 
  which 
  had 
  co-existed 
  as 
  accessory 
  

   respiratory 
  and 
  hydrostatic 
  organs, 
  assume 
  alone 
  (or, 
  

   rather, 
  together 
  with 
  the 
  skin) 
  the 
  respiratory 
  func- 
  

  

  FiG. 
  36. 
  

  

  ---"NV 
  

  

  DeYelo-pment 
  of 
  Discoglossus 
  pictiis, 
  x 
  1^. 
  

  

  tions 
  ; 
  the 
  horny 
  armature 
  of 
  the 
  mouth 
  and 
  lips 
  is 
  

   shed 
  in 
  pieces 
  ; 
  the 
  lips 
  are 
  absorbed 
  and 
  the 
  buccal 
  

   cleft 
  extends 
  ; 
  the 
  eyes 
  become 
  free 
  and 
  acquire 
  move- 
  

   able 
  lids 
  ; 
  the 
  lachrymal 
  canal 
  is 
  shifted 
  towards 
  the 
  

  

  