﻿F. 
  C. 
  Case 
  — 
  Foramina 
  perforating, 
  etc. 
  321 
  

  

  Art. 
  XXX. 
  — 
  On 
  the 
  Foramina 
  perforating 
  the 
  Cranial 
  

   Region 
  of 
  a 
  Permian 
  Reptile 
  and 
  on 
  a 
  Cast 
  of 
  its 
  Brain 
  

   Cavity; 
  by 
  E. 
  C. 
  Case. 
  

  

  During 
  the 
  spring 
  of 
  1896 
  the 
  author 
  collected 
  from 
  the 
  

   Middle 
  Permian 
  of 
  Texas 
  the 
  nearly 
  complete 
  skeleton 
  of 
  a 
  

   reptile 
  (Dimetrodon 
  incisivus 
  Cope) 
  belonging 
  to 
  the 
  Pelyco- 
  

   saurian 
  group 
  of 
  Cope's 
  order 
  Theromora. 
  It 
  has 
  recently 
  

   been 
  shown* 
  that 
  the 
  order 
  Theromora, 
  has 
  no 
  existence 
  and 
  

   that 
  the 
  Pelycosauria 
  are 
  merely 
  specialized 
  Rhyncocephalians 
  

   closely 
  allied 
  to 
  Palceohatteria. 
  

  

  The 
  cranial 
  region 
  in 
  the 
  specimen 
  is 
  especially 
  well 
  pre- 
  

   served 
  and 
  permits 
  a 
  close 
  study 
  of 
  the 
  different 
  foramina. 
  

   The 
  bones 
  are 
  all 
  in 
  their 
  natural 
  relations 
  and 
  nearly 
  free 
  

   from 
  distortion, 
  so 
  that 
  the 
  brain 
  cavity 
  when 
  freed 
  from 
  its 
  

   enclosed 
  matrix 
  showed 
  its 
  natural 
  form. 
  The 
  occipital 
  region 
  

   closely 
  resembles 
  that 
  of 
  Sphamodon. 
  The 
  condyle 
  is 
  formed 
  

   by 
  the 
  exoccipitals 
  and 
  basioccipital. 
  The 
  exoccipitals 
  meet 
  in 
  

   the 
  median 
  line 
  above, 
  excluding 
  the 
  supraoccipital 
  from 
  any 
  

   part 
  in 
  the 
  foramen 
  magnum. 
  Laterally 
  they 
  join 
  the 
  

   expanded 
  proximal 
  ends 
  of 
  the 
  paroccipitals. 
  The 
  supraocci- 
  

   pital 
  is 
  a 
  triangular 
  plate 
  inclined 
  forward 
  as 
  it 
  ascends 
  and 
  

   joining 
  by 
  the 
  base 
  of 
  the 
  triangle 
  the 
  parietals 
  above. 
  Lat- 
  

   erally 
  it 
  joins 
  the 
  paroccipitals 
  and 
  inferiorly 
  the 
  exoccipitals. 
  

   The 
  paroccipitals 
  are 
  expanded 
  proximally, 
  joining 
  the 
  supra- 
  

   occipital 
  and 
  exoccipitals. 
  Distally 
  they 
  are 
  elongated 
  out- 
  

   wards, 
  backwards 
  and 
  downwards 
  and 
  join 
  the 
  greatly 
  

   flattened 
  quadrates. 
  The 
  lower 
  edge 
  of 
  the 
  proximal 
  end 
  is 
  

   marked 
  by 
  a 
  notch 
  which, 
  in 
  union 
  with 
  similar 
  notches 
  in 
  the 
  

   basioccipital 
  and 
  petrosal 
  form 
  the 
  fenestra 
  ovalis. 
  The 
  paroc- 
  

   cipitals 
  remained 
  free 
  during 
  life 
  or 
  until 
  advanced 
  age. 
  This 
  

   feature 
  is 
  found 
  only 
  in 
  turtles 
  and 
  the 
  young 
  /Sphwnodon. 
  It 
  

   has 
  been 
  noticed 
  in 
  young 
  lizards 
  before 
  leaving 
  the 
  egg.f 
  

   The 
  basioccipital 
  forms 
  the 
  lower 
  portion 
  of 
  the 
  condyle 
  and 
  

   lies 
  between 
  the 
  exoccipitals 
  and 
  paroccipitals. 
  The 
  lower 
  

   surface 
  is 
  trough-like 
  for 
  its 
  posterior 
  half 
  and 
  supported 
  a 
  pos- 
  

   terior 
  extension 
  of 
  the 
  basisphenoid. 
  Laterally 
  a 
  slight 
  notch 
  

   forms 
  the 
  inner 
  wall 
  of 
  the 
  fenestra 
  ovalis. 
  Anterior 
  to 
  the 
  

   horizontal, 
  trough-like 
  portion 
  the 
  inferior 
  surface 
  rises 
  

   sharply 
  ; 
  the 
  angle 
  thus 
  formed 
  is 
  marked 
  by 
  a 
  large 
  foramen 
  

   through 
  which 
  the 
  hypophysis 
  passes 
  into 
  the 
  interior 
  of 
  the 
  

  

  * 
  Baur 
  and 
  Case 
  : 
  On 
  the 
  Morphology 
  of 
  the 
  Skull 
  of 
  the 
  Pelycosauria, 
  and 
  

   the 
  Origin 
  of 
  the 
  Mammalia, 
  Anat. 
  Anz., 
  xiii, 
  Nr. 
  4 
  and 
  5, 
  1897. 
  

  

  f 
  Siebenrock, 
  F. 
  : 
  Das 
  Skelet 
  der 
  Lacerta 
  Simonyi 
  Steind. 
  und 
  der 
  Lacertiden 
  

   familie 
  iiberhaupt 
  ; 
  Sitzunbenchten 
  der 
  kaiserl. 
  Akademie 
  der 
  Wissenschaften 
  in 
  

   Wien. 
  Mathm. 
  Naturwiss. 
  Classe., 
  ciii, 
  Abth. 
  1, 
  April, 
  1894. 
  

  

  