﻿SEMI0N0TIDJ3. 
  

  

  91 
  

  

  as 
  long 
  as 
  the 
  frontals, 
  which 
  are 
  about 
  three 
  times 
  as 
  long 
  as 
  

   their 
  maximum 
  width, 
  very 
  narrow 
  in 
  front, 
  and 
  united 
  throughout 
  

   their 
  length 
  by 
  a 
  nearly 
  straight, 
  only 
  feebly 
  jagged, 
  median 
  suture 
  ; 
  

   tooth-bearing 
  portion 
  of 
  dentary 
  slender, 
  somewhat 
  deepened 
  by 
  the 
  

   sharp 
  downward 
  curve 
  of 
  its 
  inferior 
  border 
  at 
  the 
  symphysis. 
  

   Marginal 
  teeth 
  styliform, 
  but 
  slightly 
  tumid 
  ; 
  inner 
  teeth 
  mostly 
  

   larger 
  and 
  obtuse, 
  but 
  on 
  moderately 
  high 
  pedicles 
  ; 
  splenial 
  teeth 
  in 
  

   about 
  three 
  irregular, 
  concentric 
  series, 
  largest 
  within 
  ; 
  hinder 
  por- 
  

   tion 
  of 
  vomerine 
  dentition 
  comprising 
  three 
  widely-spaced 
  pairs 
  

   of 
  large 
  teeth 
  ; 
  hinder 
  pterygoid 
  teeth 
  very 
  small. 
  Sing-vertebrae 
  

   absent. 
  Fin-fulcra 
  large, 
  but 
  those 
  of 
  the 
  median 
  fins 
  slender; 
  

   distance 
  between 
  origin 
  of 
  pelvic 
  and 
  anal 
  fins 
  about 
  two-thirds 
  as 
  

   great 
  as 
  that 
  between 
  the 
  former 
  and 
  the 
  pectoral 
  fins. 
  Scales 
  large 
  

   and 
  smooth 
  ; 
  principal 
  flank-scales 
  not 
  much 
  deeper 
  than 
  broad, 
  with 
  

   a 
  close 
  series 
  of 
  long 
  and 
  acuminate 
  denticulations 
  on 
  the 
  hinder 
  

   border, 
  these 
  being 
  represented 
  by 
  a 
  gradually 
  decreasing 
  number 
  

   of 
  equally 
  large 
  and 
  acuminate 
  denticulations 
  on 
  the 
  posterior 
  

   abdominal 
  flank-scales 
  ; 
  caudal 
  flank- 
  scales 
  with 
  a 
  much-produced 
  

   postero-inferior 
  angle 
  ; 
  dorsal 
  ridge-scales 
  acutely 
  pointed, 
  in 
  part 
  

   conspicuous. 
  

  

  Form. 
  Sf 
  Loc. 
  Oxfordian 
  : 
  "Wiltshire 
  and 
  Huntingdonshire. 
  

  

  P. 
  7412. 
  The 
  type 
  specimen 
  described 
  by 
  Egerton, 
  loc. 
  cit. 
  ; 
  Christian 
  

   Malford, 
  near 
  Chippenham, 
  Wiltshire. 
  The 
  characters 
  of 
  

   the 
  abdominal 
  flank-scales 
  are 
  not 
  shown. 
  

  

  (?) 
  Presented 
  by 
  S. 
  P. 
  Pratt, 
  Esq. 
  

  

  P. 
  7413. 
  Portions 
  of 
  head 
  and 
  trunk 
  of 
  a 
  similar 
  specimen, 
  lateral 
  

   and 
  partly 
  ventral 
  aspect; 
  Christian 
  Malford. 
  The 
  left 
  

   dentary, 
  maxilla, 
  and 
  quadrate 
  are 
  displayed 
  from 
  the 
  

   outer 
  aspect, 
  with 
  other 
  more 
  fragmentary 
  bones; 
  and 
  

   the 
  characters 
  of 
  the 
  squamation 
  are 
  well 
  shown. 
  

  

  (?) 
  Presented 
  by 
  S. 
  P. 
  Pratt, 
  Esq. 
  

  

  P. 
  6839. 
  Fragmentary 
  head 
  and 
  trunk 
  ; 
  Peterborough. 
  The 
  skull 
  

   is 
  vertically 
  crushed, 
  displaying 
  the 
  frontal 
  bones 
  and 
  

   the 
  arrangement 
  of 
  the 
  teeth 
  on 
  the 
  vomerine 
  and 
  palato- 
  

   pterygoid 
  bones. 
  The 
  dentigerous 
  portion 
  of 
  the 
  right 
  

   mandibular 
  ramus 
  is 
  detached, 
  and 
  shown 
  of 
  two-thirds 
  

   the 
  natural 
  size 
  from 
  the 
  outer 
  and 
  oral 
  aspects 
  in 
  the 
  

   diagram, 
  fig. 
  19 
  (p. 
  100), 
  where 
  d 
  indicates 
  the 
  dentary, 
  

   and 
  spl. 
  the 
  splenial 
  element. 
  Several 
  other 
  more 
  or 
  less 
  

   fragmentary 
  bones 
  are 
  isolated. 
  The 
  upper 
  part 
  of 
  the 
  

   operculum, 
  so 
  far 
  as 
  preserved, 
  is 
  smooth 
  ; 
  and 
  there 
  

  

  