﻿PACHYCORMIDJE. 
  397 
  

  

  A 
  few 
  teeth 
  of 
  variable 
  size 
  are 
  arranged 
  in 
  a 
  single 
  

   irregular 
  series 
  on 
  the 
  margin 
  of 
  the 
  vomerine 
  area, 
  the 
  

   largest 
  being 
  three 
  teeth 
  on 
  the 
  right 
  side. 
  The 
  pre- 
  

   maxilla 
  (figs. 
  3, 
  3 
  «, 
  pmx.) 
  is 
  triangular 
  in 
  form 
  and 
  

   laterally 
  compressed, 
  with 
  thickened 
  alveolar 
  border 
  ; 
  

   and 
  the 
  upper 
  margin 
  of 
  its 
  inner 
  face 
  exhibits 
  a 
  long 
  

   narrow 
  facette 
  (/.) 
  for 
  direct 
  articulation 
  with 
  the 
  cranium. 
  

   The 
  maxilla 
  (figs. 
  3, 
  3 
  a, 
  mcc.) 
  is 
  long 
  and 
  slender 
  and 
  gently 
  

   arched, 
  and 
  sends 
  forwards 
  a 
  process 
  (incomplete 
  in 
  this 
  

   specimen) 
  on 
  the 
  inner 
  side 
  of 
  the 
  premaxilla 
  resting 
  

   immediately 
  above 
  its 
  thickened 
  oral 
  border 
  (fig. 
  3 
  a, 
  p.). 
  

   Posteriorly 
  the 
  bone 
  is 
  imperfect, 
  but 
  there 
  remains 
  part 
  

   of 
  the 
  rugose 
  facette 
  overlapped 
  by 
  the 
  supramaxilla 
  

   (fig. 
  3, 
  s.mcc.). 
  The 
  outer 
  face 
  of 
  the 
  maxilla, 
  as 
  also 
  the 
  

   lower 
  portion 
  of 
  the 
  outer 
  face 
  of 
  the 
  premaxilla, 
  is 
  orna- 
  

   mented 
  with 
  fine 
  tuberculations 
  like 
  those 
  of 
  the 
  rostrum 
  ; 
  

   and 
  the 
  extreme 
  outer 
  margin 
  of 
  the 
  alveolar 
  border 
  bears 
  

   very 
  minute 
  teeth 
  or 
  pointed 
  tubercles. 
  The 
  teeth 
  of 
  the 
  

   maxilla 
  are 
  comparatively 
  small 
  and 
  uniform, 
  all 
  well- 
  

   spaced 
  ; 
  while 
  those 
  of 
  the 
  premaxilla 
  are 
  much 
  larger, 
  

   closely 
  arranged, 
  and 
  apparently 
  largest 
  in 
  the 
  middle 
  of 
  

   the 
  bone. 
  The 
  dentary 
  (fig. 
  4) 
  is 
  imperfect, 
  only 
  the 
  

   thickened 
  alveolar 
  border 
  being 
  preserved, 
  though 
  this 
  

   for 
  the 
  greater 
  part 
  of 
  its 
  length. 
  The 
  teeth 
  are 
  fused 
  

   with 
  the 
  bone 
  in 
  sockets 
  which 
  are 
  incomplete 
  on 
  the 
  

   inner 
  side 
  ; 
  they 
  are 
  all 
  well 
  spaced, 
  largest 
  in 
  the 
  middle 
  

   of 
  the 
  element, 
  and 
  considerably 
  exceed 
  the 
  maxillary 
  

   teeth 
  in 
  size. 
  Leeds 
  Coll. 
  

  

  P. 
  6917. 
  Imperfect 
  head 
  and 
  portions 
  of 
  fins 
  of 
  a 
  typical 
  fish; 
  near 
  

   Peterborough. 
  The 
  extremity 
  of 
  the 
  rostrum 
  is 
  wanting, 
  

   and 
  the 
  head 
  is 
  so 
  much 
  fractured 
  that 
  several 
  interesting 
  

   features 
  in 
  its 
  osteology 
  are 
  exhibited. 
  All 
  the 
  external 
  

   bones 
  are 
  ornamented 
  with 
  very 
  fine, 
  closely-arranged 
  

   tuberculations. 
  The 
  cranium 
  is 
  too 
  much 
  crushed 
  for 
  

   description; 
  but 
  a 
  robust 
  ossification 
  is 
  shown 
  in 
  the 
  

   prefrontal 
  region 
  on 
  the 
  right 
  side, 
  and 
  the 
  greater 
  part 
  

   of 
  the 
  parasphenoid 
  is 
  also 
  exposed. 
  The 
  latter 
  element 
  

   is 
  considerably 
  expanded 
  in 
  front 
  and 
  bears 
  an 
  elongate 
  

   patch 
  of 
  minute 
  granular 
  teeth 
  immediately 
  in 
  advance 
  of 
  

   the 
  pair 
  of 
  foramina 
  for 
  the 
  internal 
  carotids. 
  Among 
  

   the 
  remains 
  of 
  cheek-plates, 
  some 
  of 
  the 
  characteristic 
  small 
  

   circumorbitals 
  are 
  shown 
  on 
  the 
  left 
  side. 
  The 
  maxillre 
  

   (muff.) 
  and 
  preniaxillae 
  (pma?.), 
  similar 
  to 
  those 
  of 
  the 
  last 
  

  

  