﻿90 
  

  

  INTRODUCTION. 
  

  

  eye 
  and 
  perforates 
  the 
  lower 
  eyelid 
  ; 
  the 
  intestine 
  

   shortens 
  ; 
  the 
  anal 
  tube 
  ceases 
  to 
  function, 
  and 
  dis- 
  

   appears 
  with 
  the 
  last 
  vestiges 
  of 
  the 
  caudal 
  crest, 
  

   which 
  had 
  become 
  detached 
  from 
  the 
  vent; 
  and 
  the 
  

   young 
  frog, 
  usually 
  still 
  bearing 
  a 
  stumpy 
  tail, 
  leaves 
  

   the 
  water. 
  The 
  metamorphosis 
  is 
  completed. 
  

  

  The 
  skull 
  and 
  its 
  appendages 
  also 
  undergo 
  very 
  

   important 
  changes. 
  The 
  cranium 
  in 
  the 
  tadpole 
  is 
  a 
  

   large 
  undivided 
  cartilage 
  with 
  narial 
  openings 
  and 
  

   large 
  suborbital 
  fenestrae. 
  The 
  suspensorium 
  of 
  the 
  

   lower 
  jaw 
  is 
  extremely 
  elongate, 
  and 
  sends 
  up 
  a 
  

   strong 
  process, 
  connected 
  with 
  the 
  cranium 
  by 
  a 
  

   bridge, 
  in 
  front 
  of 
  the 
  eye. 
  The 
  prssmaxillaries 
  are 
  

  

  Fig. 
  37. 
  

  

  jjro 
  

  

  PP 
  Tva 
  

  

  OX)- 
  

  

  pro. 
  

  

  vlO 
  

  

  eo~ 
  

  

  SIC 
  

  

  A. 
  Skull 
  of 
  full-grown 
  tadpole 
  of 
  Pelohates 
  fuscus. 
  B. 
  The 
  same 
  

   at 
  the 
  end 
  of 
  tlie 
  metamorpliosis, 
  after 
  the 
  loss 
  of 
  the 
  horny 
  

   beak. 
  chij. 
  Oeratohyal 
  cartilage, 
  eo. 
  Exoccipital. 
  fp. 
  Fronto- 
  

   parietal. 
  II. 
  Lower 
  labial 
  cartilage, 
  me. 
  Mandibular 
  (Mecke- 
  

   lian) 
  cartilage, 
  na. 
  Nasal 
  processes 
  of 
  cbondrocranium. 
  po. 
  

   Prseorbital 
  process, 
  pro. 
  Prootic. 
  su. 
  Suspensorium 
  (palato- 
  

   quadrate). 
  ul. 
  Upper 
  labial 
  cartilage. 
  

  

  represented 
  by 
  a 
  single 
  or 
  paired 
  cartilage, 
  the 
  upper 
  

   labial, 
  loosely 
  attached 
  to 
  the 
  diverging 
  anterior 
  pro- 
  

   cesses 
  of 
  the 
  cranium, 
  which 
  supports 
  the 
  upper 
  horny 
  

   beak; 
  and 
  to 
  this 
  corresponds 
  a 
  pair 
  of 
  cartilages, 
  

   the 
  lower 
  labials, 
  ultimately 
  the 
  mento-Meckelian 
  or 
  

   symphysial 
  bones, 
  supporting 
  the 
  lower 
  beak 
  and 
  

   attached 
  to 
  the 
  short 
  mandibular 
  or 
  Meckelian 
  

   cartilage. 
  In 
  the 
  transformation 
  of 
  the 
  mouth 
  this 
  

   mandibular 
  cartilage 
  acquires 
  a 
  greater 
  length, 
  and 
  

   the 
  suspensorium 
  becomes 
  reduced 
  in 
  proportion 
  and 
  

   shifted 
  backwards. 
  

  

  