﻿324 
  E. 
  C. 
  Case 
  — 
  Foramina 
  perforating 
  the 
  

  

  The 
  fenestra 
  ovalis, 
  fig. 
  3, 
  F. 
  (9., 
  is 
  a 
  single 
  opening 
  leading 
  

   by 
  a 
  very 
  short 
  canal 
  directly 
  into 
  the 
  brain 
  cavity, 
  a 
  character 
  

   found 
  in 
  fishes 
  and 
  the 
  amphibian 
  Menopoma 
  and 
  existing 
  

   imperfectly 
  in 
  some 
  recent 
  reptilia, 
  as 
  the 
  turtles. 
  The 
  same 
  

   thing 
  is 
  described 
  by 
  Cope 
  as 
  existing 
  in 
  another 
  Permian 
  

   reptile, 
  from 
  the 
  same 
  horizon 
  as 
  the 
  present 
  specimen, 
  but 
  

   belonging 
  to 
  a 
  separate 
  family, 
  the 
  Diadectidce, 
  and 
  his 
  order 
  

   Cotylosauria* 
  . 
  

  

  The 
  foramina 
  for 
  the 
  seventh 
  (facial) 
  pair 
  of 
  nerves 
  appear 
  

   on 
  the 
  outer 
  surface 
  of 
  the 
  petrosal 
  just 
  anterior 
  to 
  the 
  fenestra 
  

   ovalis, 
  fig. 
  3, 
  7. 
  They 
  are 
  located 
  relatively 
  a 
  little 
  further 
  back 
  

   than 
  in 
  Sphoenodon. 
  On 
  the 
  inner 
  face 
  of 
  the 
  same 
  bone 
  the 
  

   foramina 
  appear 
  at 
  the 
  side 
  of 
  the 
  base 
  of 
  the 
  brain 
  cavity 
  a 
  

   little 
  anterior 
  to 
  their 
  external 
  opening. 
  They 
  are 
  located 
  

   just 
  anterior 
  to 
  a 
  slight 
  ridge 
  which 
  defines 
  the 
  limits 
  of 
  the 
  

   tympanic 
  cavity. 
  In 
  Sphcenodon 
  this 
  is 
  about 
  the 
  point 
  of 
  

   location 
  of 
  a 
  foramen 
  common 
  to 
  the 
  seventh 
  and 
  eighth 
  

   nerves, 
  which, 
  however, 
  almost 
  immediately 
  divides, 
  the 
  pos- 
  

   terior 
  branch 
  penetrating 
  the 
  inner 
  wall 
  of 
  the 
  tympanic 
  

   cavity 
  and 
  leading 
  the 
  auditory 
  nerve 
  to 
  the 
  inner 
  ear. 
  

  

  The 
  foramen 
  for 
  the 
  fifth 
  (trigeminus) 
  nerve 
  is 
  completed 
  

   from 
  the 
  incisura 
  otosphenoidea 
  by 
  the 
  membranous 
  wall 
  of 
  

   the 
  anterior 
  portion 
  of 
  the 
  brain 
  case, 
  as 
  in 
  Sphamodon 
  and 
  

   many 
  lizards. 
  Fig. 
  3, 
  5. 
  

  

  The 
  deep 
  pit 
  excavating 
  the 
  lower 
  surface 
  of 
  the 
  basisjDhe- 
  

   noid 
  is 
  in 
  all 
  probability 
  the 
  lower 
  opening 
  of 
  the 
  eustachian 
  

   tubes. 
  In 
  most 
  reptilian 
  forms 
  the 
  tubes 
  pass 
  into 
  the 
  pharynx 
  

   in 
  the 
  neighborhood 
  of 
  the 
  basioccipital-basisphenoid 
  suture 
  

   and 
  anterior 
  to 
  the 
  fenestra 
  ovalis. 
  In 
  the 
  crocodilia 
  and 
  the 
  

   aglossal 
  batrachians 
  they 
  have 
  a 
  common 
  opening 
  into 
  the 
  

   mouth. 
  In 
  the 
  present 
  form 
  the 
  tubes 
  probably 
  penetrated 
  

   the 
  large 
  mass 
  of 
  cartilage 
  covering 
  the 
  otic 
  region 
  and 
  the 
  

   posterior 
  end 
  of 
  the 
  basisphenoid 
  and 
  found 
  a 
  common 
  open- 
  

   ing 
  in 
  the 
  deep 
  pit 
  described. 
  It 
  is 
  difficult 
  to 
  imagine 
  the 
  

   use 
  of 
  such 
  an 
  extensive 
  cavity 
  in 
  the 
  basisphenoid, 
  but 
  in 
  the 
  

   Teleosauria 
  an 
  equally 
  large 
  cavity 
  is 
  found 
  roofed 
  over 
  with 
  

   bone. 
  Anterior 
  to 
  this 
  pit 
  two 
  foramina, 
  fig. 
  2, 
  I. 
  C, 
  penetrate 
  

   the 
  lower 
  surface 
  of 
  the 
  basisphenoid 
  bone 
  and 
  on 
  its 
  upper 
  

   surface 
  a 
  large 
  foramen 
  appears 
  just 
  posterior 
  to 
  the 
  origin 
  of 
  

   the 
  presphenoid 
  rostrum. 
  Through 
  the 
  pair 
  on 
  the 
  lower 
  sur- 
  

   face 
  the 
  internal 
  carotid 
  arteries 
  enter 
  the 
  bone 
  and 
  through 
  

   the 
  upper 
  it 
  gains 
  access 
  to 
  the 
  brain 
  cavity 
  by 
  way 
  of 
  the 
  

   pituatary 
  fossa. 
  On 
  either 
  side 
  of 
  the 
  single 
  foramen 
  a 
  pair 
  of 
  

   small 
  foramina 
  carry 
  branches 
  of 
  the 
  internal 
  carotid. 
  All 
  of 
  

  

  * 
  Cope, 
  E. 
  D. 
  : 
  On 
  the 
  Structure 
  of 
  the 
  Brain 
  and 
  Auditory 
  Apparatus 
  of 
  a 
  

   Theromorphous 
  Reptile 
  of 
  the 
  Permian 
  Epoch, 
  Proc. 
  Am. 
  Phil. 
  Soc, 
  vol. 
  xxiii, 
  

   1885. 
  

  

  

  