﻿328 
  ACTINOPTERYGII. 
  

  

  teristic 
  teeth 
  are 
  also 
  scattered 
  below 
  the 
  jaw. 
  The 
  right 
  

   hypohyal 
  occurs, 
  both 
  large 
  and 
  robust. 
  The 
  large 
  gular 
  

   plate 
  is 
  completely 
  preserved, 
  two-thirds 
  as 
  broad 
  as 
  long, 
  

   obtusely 
  rounded 
  in 
  front, 
  truncated 
  behind. 
  There 
  are 
  

   no 
  other 
  recognizable 
  elements 
  worthy 
  of 
  note, 
  and 
  the 
  

   amount 
  of 
  disturbance 
  to 
  which 
  the 
  fossil 
  has 
  been 
  sub- 
  

   jected 
  is 
  indicated 
  by 
  the 
  fact, 
  that 
  the 
  left 
  suboperculum 
  

   is 
  displaced 
  to 
  the 
  hinder 
  part 
  of 
  the 
  caudal 
  region. 
  The 
  

   exposed 
  portion 
  of 
  this 
  plate 
  is 
  slightly 
  more 
  than 
  twice 
  

   as 
  broad 
  as 
  deep, 
  ornamented 
  with 
  a 
  very 
  fine 
  and 
  close 
  

   tuberculation 
  ; 
  and 
  there 
  is 
  a 
  small 
  ascending 
  process 
  at 
  

   its 
  antero-superior 
  angle. 
  Remains 
  of 
  the 
  pelvic 
  fins 
  

   opposed 
  to 
  the 
  dorsal 
  appear 
  to 
  comprise 
  some 
  slender 
  

   fulcra. 
  The 
  caudal 
  fin 
  is 
  best 
  preserved, 
  exhibiting 
  its 
  

   bifurcation 
  and 
  the 
  very 
  close 
  articulation 
  of 
  its 
  stout 
  

   rays 
  ; 
  fulcra 
  are 
  displayed 
  on 
  both 
  lobes, 
  those 
  on 
  the 
  

   upper 
  lobe 
  being 
  especially 
  large 
  and 
  distinctly 
  uniserial 
  

   at 
  the 
  base. 
  Scales 
  occur 
  sparsely 
  in 
  the 
  region 
  of 
  the 
  

   pelvic, 
  dorsal, 
  anal, 
  and 
  caudal 
  fins, 
  all 
  exhibiting 
  the 
  

   characteristic 
  tubercular 
  ornamentation. 
  On 
  the 
  few 
  

   principal 
  flank-scales 
  which 
  are 
  preserved, 
  the 
  tubercles 
  

   have 
  a 
  tendency 
  to 
  elongation 
  and 
  pass 
  in 
  the 
  hinder 
  half 
  

   into 
  conspicuous 
  striae. 
  The 
  peg 
  and 
  socket 
  for 
  articula- 
  

   tion 
  are 
  very 
  large, 
  as 
  usual. 
  The 
  ventral 
  scales 
  are 
  

   shown 
  to 
  have 
  been 
  narrowed, 
  as 
  also 
  are 
  those 
  immedi- 
  

   ately 
  covering 
  the 
  base 
  of 
  the 
  caudal 
  fin-rays. 
  

  

  Enniskillen 
  Coll. 
  

  

  P. 
  3649. 
  Fragments 
  of 
  mandible, 
  apparently 
  of 
  this 
  species, 
  labelled 
  

   Eugnathus 
  polyodon 
  by 
  Agassiz 
  and 
  noticed 
  by 
  Egerton, 
  

   loc. 
  cit. 
  1868, 
  p. 
  500 
  ; 
  Lyme 
  Regis. 
  Enniskillen 
  Coll. 
  

  

  P. 
  3648 
  a. 
  Imperfect 
  and 
  abraded 
  large 
  cranium, 
  doubtfully 
  of 
  this 
  

   species 
  ; 
  Lyme 
  Regis. 
  Enniskillen 
  Coll. 
  

  

  P. 
  875. 
  Hoof 
  of 
  a 
  similar 
  but 
  much 
  smaller 
  skull, 
  with 
  a 
  pair 
  of 
  otic 
  

   bones 
  displaced 
  behind 
  ; 
  Lyme 
  Regis. 
  Egerton 
  Coll. 
  

  

  Osteorachis 
  granulatus 
  (Egerton). 
  

   1868. 
  Isocolum 
  granulatum, 
  Sir 
  P. 
  Egerton, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  

  

  vol. 
  xxiv. 
  p. 
  501. 
  

   1872. 
  Isocolum 
  granulatum, 
  Sir 
  P. 
  Egerton, 
  Figs. 
  & 
  Descript. 
  Brit. 
  

  

  Organic 
  Remains, 
  dec. 
  xiii. 
  (Mem. 
  Geol. 
  Surv.), 
  no. 
  4, 
  pi. 
  iv. 
  

  

  Type. 
  Trunk 
  wanting 
  head 
  and 
  tail 
  ; 
  British 
  Museum. 
  

  

  A 
  fish 
  known 
  only 
  by 
  a 
  single 
  specimen 
  about 
  half 
  as 
  large 
  as 
  

  

  