﻿SKELETON. 
  35 
  

  

  The 
  membrane 
  bones, 
  all 
  paired 
  with 
  the 
  excep- 
  

   tion 
  of 
  the 
  parasphenoid 
  (and 
  in 
  Pelobates 
  the 
  fronto- 
  

   parietal), 
  are 
  the 
  following 
  : 
  — 
  Praemaxillarj, 
  maxillary, 
  

   squamosal, 
  pterygoid, 
  palatine, 
  vomer, 
  parasphenoid, 
  

   nasal 
  (often 
  called 
  prae 
  frontal), 
  and 
  fronto-parietal. 
  

   A 
  small 
  ossification 
  behind 
  the 
  narial 
  opening 
  is 
  the 
  

   turbinal, 
  regarded 
  by 
  some 
  as 
  the 
  true 
  nasal. 
  The 
  

   cranial 
  ossification 
  may 
  be 
  feeble, 
  and 
  a 
  considerable 
  

   portion 
  of 
  the 
  cartilaginous 
  primordial 
  cranium 
  remain 
  

   exposed, 
  — 
  as, 
  for 
  instance, 
  in 
  Bomhinator, 
  which, 
  

   together 
  with 
  Pelodytes, 
  is 
  remarkable 
  for 
  the 
  lack 
  of 
  

   palatine 
  bones 
  ; 
  or 
  it 
  may 
  be 
  extraordinarily 
  developed, 
  

   with 
  superaddition 
  of 
  dermo-ossificatioD, 
  as 
  in 
  Pelo- 
  

   bates, 
  one 
  species 
  of 
  which 
  (P. 
  mdtripes) 
  is 
  distin- 
  

   guished 
  by 
  the 
  expansion 
  of 
  the 
  fronto-parietal 
  and 
  

  

  Fig. 
  13. 
  

  

  Upper 
  view 
  of 
  skull 
  of 
  Pelobates 
  cultripes. 
  

  

  squamosal, 
  which 
  join 
  to 
  form 
  a 
  complete 
  roof 
  over 
  

   the 
  prootic 
  (Fig. 
  13). 
  The 
  genus 
  Pelobates 
  is 
  further 
  

   remarkable 
  in 
  having 
  the 
  fronto-parietal 
  single, 
  

   whilst 
  in 
  all 
  other 
  European 
  genera 
  it 
  is 
  paired, 
  

   and 
  in 
  many 
  species 
  so 
  separated 
  along 
  a 
  portion 
  

   of 
  the 
  median 
  line 
  as 
  to 
  leave 
  the 
  endocranial 
  or 
  

   fronto-parietal 
  fontanelle 
  exposed 
  between 
  the 
  two. 
  

   The 
  nasals 
  may 
  join 
  in 
  the 
  middle 
  line, 
  or 
  be 
  more 
  or 
  

   less 
  widely 
  separated 
  from 
  each 
  other. 
  The 
  upper 
  

   lamina 
  of 
  the 
  ethmoid 
  is 
  usually 
  exposed 
  between 
  the 
  

   fronto-parietals 
  and 
  the 
  nasals, 
  and 
  in 
  Pelobates 
  fuscus 
  

   it 
  is 
  so 
  prolonged 
  forwards 
  as 
  to 
  reappear 
  between 
  

   the 
  nasals 
  and 
  the 
  prsemaxillaries. 
  

  

  