﻿EXTERNAL 
  CHARACTEflS. 
  11 
  

  

  pupil 
  appears 
  nearly 
  round, 
  or 
  straight 
  when 
  the 
  

   subtriangular 
  form 
  obtains 
  (Fig. 
  2, 
  a). 
  In 
  some 
  

   specimens 
  of 
  Bomhinator 
  the 
  upper 
  border 
  is 
  even 
  

   emarginate, 
  so 
  as 
  to 
  produce 
  the 
  shape 
  of 
  a 
  heart 
  ; 
  and 
  

   when 
  extremely 
  contracted 
  the 
  pupil 
  divides 
  into 
  

   three 
  branches, 
  affecting 
  the 
  shape 
  of 
  a 
  Y 
  (Fig. 
  2, 
  a) 
  

   This 
  type 
  of 
  pupil 
  approaches 
  the 
  vertical, 
  and 
  in 
  

   some 
  specimens 
  of 
  Discoglossus 
  the 
  much-contracted 
  

   pupil 
  is 
  in 
  fact 
  a 
  little 
  deeper 
  than 
  broad. 
  In 
  Alijtes, 
  

   Felodytes, 
  and 
  Pelobates 
  (Fig. 
  2, 
  b, 
  c) 
  we 
  find 
  a 
  regular 
  

   cat's 
  pupil, 
  vertically 
  elliptical 
  or 
  club-shaped, 
  linear 
  

   when 
  fully 
  contracted. 
  

  

  The 
  tymijanum, 
  or 
  drum 
  of 
  the 
  ear, 
  is 
  absent 
  in 
  

   Bomhinator 
  and 
  Pelobates. 
  When 
  present 
  it 
  may 
  be 
  

   concealed 
  under 
  the 
  skin, 
  as 
  in 
  some 
  specimens 
  of 
  

   Discoglossus, 
  Felodytes, 
  and 
  Bufo 
  vulgaris, 
  or 
  appear 
  

   on 
  the 
  temple 
  behind 
  the 
  eye 
  as 
  a 
  round 
  or 
  oval 
  disk 
  

   covered 
  with 
  thin 
  skin 
  (Fig. 
  1, 
  a, 
  p. 
  9). 
  

  

  The 
  mouth 
  is 
  large, 
  and 
  cleft 
  to 
  beyond 
  the 
  eyes. 
  

   The 
  jaws 
  are 
  edentulous 
  in 
  Bufo 
  ; 
  the 
  upper 
  is 
  armed 
  

   with 
  numerous 
  closely-set 
  teeth 
  in 
  the 
  other 
  genera 
  — 
  

   ten 
  to 
  fifteen 
  in 
  each 
  prsemaxillary, 
  forty 
  to 
  fifty 
  in 
  

   each 
  maxillary. 
  The 
  teeth 
  have 
  sharply-pointed, 
  

   slightly-hooked 
  crowns 
  with 
  long 
  shafts 
  applied 
  to 
  

   the 
  inner 
  side 
  of 
  the 
  prsemaxillary 
  and 
  maxillary 
  

   bones. 
  The 
  palate 
  (Fig. 
  3, 
  p. 
  12) 
  is 
  pierced 
  by 
  two 
  

   pairs 
  of 
  orifices, 
  the 
  choanm, 
  or 
  inner 
  openings 
  of 
  the 
  

   nostrils 
  anteriorly, 
  and 
  the 
  openings 
  of 
  the 
  Eusta- 
  

   chian 
  or 
  auditory 
  tubes, 
  situated 
  near 
  the 
  commis- 
  

   sures 
  of 
  the 
  jaws; 
  the 
  Eustachian 
  tubes 
  are 
  extremely 
  

   fine, 
  or 
  sometimes 
  even 
  indistinct, 
  in 
  Bomhinator. 
  In 
  

   all 
  the 
  genera 
  except 
  Bufo 
  there 
  are 
  two 
  groups 
  or 
  

   series 
  of 
  teeth, 
  each 
  implanted 
  on 
  an 
  eminence 
  of 
  the 
  

   vomerine 
  bones 
  ; 
  these 
  vomerine 
  teeth 
  are 
  situated 
  

   between 
  or 
  behind 
  the 
  choanse, 
  as 
  shown 
  on 
  p. 
  12, 
  

   Fig. 
  3, 
  A, 
  0, 
  D. 
  

  

  The 
  tongue, 
  thick 
  and 
  papillose, 
  flat, 
  is 
  attached 
  in 
  

   front 
  and 
  in 
  the 
  middle, 
  and 
  the 
  posterior 
  portion, 
  by 
  

   being 
  bent 
  over 
  and 
  rapidly 
  thrust 
  out 
  of 
  the 
  mouth, 
  

  

  