﻿Nervous 
  System 
  of 
  Ceratodus 
  Forsteri. 
  165 
  

  

  internal 
  branch 
  ; 
  at 
  the 
  anterior 
  border 
  of 
  the 
  temporalis 
  

   muscle 
  both 
  these 
  give 
  off 
  twigs 
  to 
  the 
  floor 
  of 
  the 
  orbit 
  ; 
  the 
  

   external 
  branch 
  then 
  goes 
  forward 
  over 
  the 
  membranous 
  bag 
  

   which 
  is 
  situated 
  above 
  the 
  side 
  of 
  the 
  mouth. 
  This 
  bag 
  has 
  

   no 
  communication 
  with 
  the 
  olfactory 
  vestibule, 
  on 
  the 
  outside 
  

   of 
  which 
  it 
  is 
  placed, 
  but 
  opens 
  externally 
  behind 
  the 
  angle 
  

   of 
  the 
  mouth 
  through 
  a 
  special 
  aperture. 
  The 
  nerve 
  ulti- 
  

   mately 
  divides 
  into 
  two 
  branches, 
  each 
  of 
  which 
  gives 
  off 
  

   terminal 
  filaments 
  in 
  a 
  fan-like 
  manner, 
  which 
  are 
  distributed 
  

   to 
  the 
  deep 
  side 
  of 
  the 
  upper 
  lip, 
  external 
  to 
  the 
  termination 
  

   of 
  the 
  ophthalmic 
  branch. 
  

  

  The 
  internal 
  division 
  takes 
  a 
  turn 
  inward 
  and 
  divides 
  into 
  

   two 
  branches 
  ; 
  the 
  first 
  goes 
  directly 
  downward 
  and 
  enters 
  the 
  

   upper 
  border 
  of 
  the 
  mandible, 
  in 
  front 
  of 
  the 
  origin 
  of 
  the 
  

   temporalis 
  muscle 
  ; 
  the 
  second, 
  which 
  may 
  be 
  looked 
  upon 
  

   as 
  the 
  palatine 
  nerve, 
  passing 
  beneath 
  the 
  ophthalmic, 
  plunges 
  

   downward 
  immediately 
  in 
  front 
  of 
  the 
  pterygopalatine 
  bone, 
  

   and 
  is 
  distributed 
  to 
  the 
  pad 
  of 
  mucous 
  membrane 
  situated 
  on 
  

   the 
  roof 
  of 
  the 
  mouth. 
  

  

  Sixth 
  pair. 
  — 
  The 
  abducens 
  was 
  not 
  found 
  in 
  any 
  of 
  these 
  

   specimens. 
  

  

  Seventh 
  pair 
  (P\. 
  VIII. 
  fig. 
  1, 
  n.7.). 
  — 
  The 
  facial 
  arises 
  imme- 
  

   diately 
  ventrad 
  of 
  the 
  origin 
  of 
  the 
  posterior 
  root 
  of 
  the 
  trifacial; 
  

   it 
  has 
  a 
  single 
  root, 
  which 
  does 
  not 
  join 
  either 
  the 
  fifth 
  in 
  front 
  or 
  

   the 
  acusticus 
  behind, 
  as 
  is 
  the 
  case 
  in 
  Protopterus 
  *, 
  in 
  which 
  

   also, 
  according 
  to 
  Fulliquet, 
  it 
  has 
  tworoots, 
  but 
  passes 
  directly 
  

   outward 
  through 
  the 
  mass 
  of 
  cartilage 
  on 
  the 
  outer 
  side 
  of 
  the 
  

   ear-capsule, 
  which 
  is 
  probably 
  the 
  petrosal 
  ; 
  it 
  terminates 
  by 
  

   being 
  distributed 
  to 
  the 
  integument 
  outside 
  and 
  in 
  front 
  of 
  

   the 
  branchial 
  chamber 
  ; 
  close 
  to 
  its 
  origin 
  it 
  gives 
  off 
  from 
  

   its 
  under 
  surface 
  a 
  branch 
  which 
  plunges 
  down 
  in 
  the 
  carti- 
  

   lage 
  at 
  the 
  base 
  of 
  the 
  skull 
  and 
  divides 
  into 
  a 
  pair 
  of 
  trunks 
  — 
  

   one, 
  passing 
  forward 
  through 
  the 
  base 
  of 
  the 
  skull 
  beneath 
  

   the 
  brain, 
  eventually 
  supplies 
  the 
  anterior 
  part 
  of 
  the 
  roof 
  of 
  

   the 
  mouth, 
  inside 
  and 
  between 
  the 
  olfactory 
  sacs 
  ; 
  the 
  other 
  

   passes 
  back 
  and 
  supplies 
  the 
  middle 
  and 
  outer 
  part 
  of 
  the 
  

   anterior 
  wall 
  of 
  the 
  branchial 
  chamber. 
  

  

  Eighth 
  pair 
  (PI. 
  VIII. 
  fig. 
  1, 
  n. 
  8). 
  — 
  The 
  acusticus 
  arises 
  

   by 
  one 
  root 
  behind 
  and 
  beneath 
  the 
  trifacial, 
  in 
  close 
  contact 
  

   with 
  the 
  origin 
  of 
  the 
  facial 
  ; 
  its 
  root 
  emerges 
  obliquely. 
  At 
  

   its 
  origin 
  the 
  anterior 
  margin 
  is 
  slightly 
  higher 
  on 
  the 
  left 
  

   side 
  and 
  slightly 
  lower 
  on 
  the 
  right 
  than 
  that 
  of 
  the 
  facial 
  ; 
  

   but 
  its 
  posterior 
  margin 
  is 
  on 
  the 
  same 
  level 
  on 
  both 
  sides. 
  

   There 
  is 
  no 
  accessory 
  acusticus 
  to 
  be 
  found 
  here 
  as 
  is 
  the 
  case 
  

   in 
  Protopterus. 
  This 
  nerve 
  divides 
  into 
  two 
  main 
  trunks, 
  

   * 
  Wiedersheirn, 
  /. 
  c. 
  p. 
  7-5, 
  fig. 
  10. 
  

  

  