﻿164 
  Mr. 
  A. 
  Sanders 
  on 
  the 
  

  

  bodies 
  ; 
  the 
  anterior 
  is 
  the 
  largest 
  ; 
  on 
  it 
  the 
  gasserian 
  gan- 
  

   glion 
  is 
  developed, 
  after 
  passing 
  through 
  which 
  it 
  joins 
  the 
  

   posterior 
  root, 
  which 
  arises 
  a 
  short 
  distance 
  behind 
  the 
  ante- 
  

   rior 
  root, 
  and 
  immediately 
  divides 
  into 
  two 
  branches, 
  which 
  

   join 
  the 
  anterior 
  root 
  just 
  beyond 
  the 
  ganglion. 
  

  

  The 
  branches 
  of 
  the 
  trifacial 
  in 
  Ceratodus 
  do 
  not 
  exactly 
  

   correspond 
  to 
  those 
  of 
  this 
  nerve 
  in 
  Mammalia, 
  but 
  seem 
  to 
  

   be 
  more 
  generalized, 
  and 
  the 
  distribution 
  of 
  the 
  various 
  

   trunks 
  appears 
  to 
  be 
  interchanged 
  to 
  some 
  extent. 
  

  

  The 
  first 
  branch, 
  which 
  may 
  be 
  looked 
  upon 
  as 
  the 
  ophthal- 
  

   mic, 
  is 
  given 
  off 
  from 
  the 
  anterior 
  root 
  before 
  its 
  junction 
  with 
  

   the 
  two 
  branches 
  of 
  the 
  posterior 
  root. 
  It 
  passes 
  out 
  of 
  the 
  

   skull 
  through 
  a 
  special 
  foramen 
  into 
  a 
  fossa, 
  which 
  is 
  occu- 
  

   pied 
  by 
  the 
  temporal 
  muscle 
  and 
  which 
  is 
  not 
  divided 
  from 
  

   the 
  orbit 
  ; 
  it 
  passes 
  forward 
  closely 
  applied 
  to 
  the 
  outside 
  of 
  

   the 
  skull, 
  where 
  it 
  is 
  joined 
  by 
  the 
  oculomotor 
  nerve, 
  as 
  

   already 
  mentioned 
  ; 
  it 
  then 
  passes 
  round 
  a 
  process 
  of 
  the 
  bone 
  

   named 
  by 
  Prof. 
  Huxley 
  the 
  pterygo-palatine 
  to 
  the 
  outer 
  side 
  

   of 
  the 
  olfactory 
  lobe 
  ; 
  it 
  then 
  crosses 
  the 
  olfactory 
  sac, 
  imme- 
  

   diately 
  in 
  front 
  of 
  its 
  connexion 
  with 
  the 
  olfactory 
  lobe, 
  to 
  the 
  

   outer 
  edge 
  of 
  the 
  cartilage 
  dividing 
  the 
  two 
  olfactory 
  sacs 
  and 
  

   lobes 
  from 
  each 
  other, 
  which 
  is 
  termed 
  by 
  the 
  same 
  authority 
  

   the 
  mesethmoid 
  cartilage 
  ; 
  it 
  then 
  passes 
  forward 
  between 
  the 
  

   olfactory 
  sac 
  and 
  this 
  cartilage, 
  and 
  finally 
  dividing 
  into 
  two 
  

   branches, 
  is 
  distributed 
  to 
  the 
  external 
  skin 
  of 
  the 
  central 
  

   portion 
  of 
  the 
  upper 
  lip. 
  

  

  The 
  posterior 
  root 
  (PI. 
  VIII. 
  fig. 
  1, 
  co.) 
  gives 
  off 
  close 
  to 
  

   the 
  junction 
  of 
  its 
  two 
  branches 
  with 
  the 
  anterior 
  root 
  a 
  com- 
  

   municating 
  branch 
  to 
  the 
  vagus 
  ; 
  this 
  curves 
  round 
  through 
  

   the 
  outer 
  wall 
  of 
  the 
  ear-capsule, 
  external 
  to 
  the 
  semicircular 
  

   canals, 
  and 
  joins 
  the 
  vagus 
  just 
  beyond 
  where 
  the 
  branchial 
  

   nerves 
  and 
  the 
  visceral 
  branch 
  are 
  given 
  off, 
  so 
  that 
  it 
  only 
  

   joins 
  the 
  ramus 
  lateralis 
  ; 
  it 
  thus 
  differs 
  from 
  the 
  Lepidosiren 
  

   paradoxa, 
  in 
  which, 
  according 
  to 
  Hyrtl 
  *, 
  the 
  communicating 
  

   branch 
  joins 
  the 
  ganglion 
  of 
  the 
  vagus, 
  whereas 
  here 
  it 
  effects 
  

   a 
  junction 
  beyond 
  it. 
  

  

  The 
  junction 
  between 
  the 
  anterior 
  and 
  posterior 
  roots 
  of 
  

   the 
  trifacial 
  takes 
  place 
  in 
  a 
  slightly 
  different 
  manner 
  on 
  the 
  

   two 
  sides 
  ; 
  on 
  the 
  right 
  side 
  the 
  whole 
  of 
  both 
  roots 
  join 
  at 
  

   once, 
  on 
  the 
  left 
  side 
  there 
  is 
  a 
  supplementary 
  junction 
  in 
  the 
  

   shape 
  of 
  a 
  short 
  branch 
  from 
  the 
  posterior 
  root 
  which 
  joins 
  

   the 
  anterior 
  root 
  at 
  some 
  distance 
  along 
  its 
  course. 
  

  

  The 
  nerve 
  (PI. 
  VIII. 
  fig. 
  1, 
  m.) 
  resulting 
  from 
  this 
  junction 
  

  

  may 
  be 
  looked 
  upon 
  as 
  the 
  combined 
  superior 
  and 
  inferior 
  

  

  maxillary 
  ; 
  it 
  divides 
  into 
  two 
  brunches, 
  an 
  external 
  and 
  an 
  

  

  * 
  Abhandl. 
  d. 
  Loiiigl. 
  bohmisch. 
  Ge&ellsch. 
  d. 
  Wiss. 
  Bd. 
  iii. 
  (184^-4). 
  

  

  