﻿326 
  ACTINOPTERYGII. 
  

  

  back 
  ; 
  anal 
  fin 
  much 
  smaller 
  than 
  the 
  dorsal. 
  Scales 
  finely 
  and 
  

   closely 
  tuberculated 
  ; 
  the 
  tubercles 
  only 
  rarely 
  fusing 
  into 
  trans- 
  

   verse 
  striae 
  on 
  the 
  hinder 
  half 
  of 
  the 
  scale. 
  

   Form. 
  Sf 
  Loc. 
  Lower 
  Lias 
  : 
  Dorsetshire. 
  

  

  P. 
  3654. 
  The 
  type 
  specimen, 
  being 
  the 
  head 
  and 
  greater 
  portion 
  of 
  

   trunk, 
  vertically 
  crushed, 
  described 
  and 
  figured 
  by 
  

   Egerton, 
  loc. 
  cit. 
  1872 
  ; 
  Lyme 
  Regis. 
  Both 
  description 
  

   and 
  figure 
  are 
  unsatisfactory. 
  The 
  head 
  is 
  crushed 
  

   obliquely 
  and 
  exposed 
  from 
  below. 
  Remains 
  of 
  a 
  large 
  

   gular 
  plate 
  appear 
  between 
  the 
  fragments 
  of 
  the 
  smooth 
  

   mandibular 
  rami, 
  and 
  there 
  are 
  clusters 
  of 
  the 
  small 
  

   slender 
  teeth. 
  The 
  premaxilla 
  cannot 
  be 
  identified 
  with 
  

   certainty, 
  and 
  there 
  is 
  no 
  evidence 
  as 
  to 
  how 
  the 
  teeth 
  were 
  

   disposed 
  ; 
  one 
  narrow 
  fragment 
  of 
  bone 
  shows 
  the 
  bases 
  

   of 
  three 
  series 
  of 
  teeth. 
  On 
  one 
  large 
  expanded 
  bone, 
  

   which 
  may 
  be 
  entopterygoid, 
  the 
  teeth 
  cover 
  an 
  extensive 
  

   area 
  and 
  are 
  in 
  part 
  merely 
  fine 
  granulations. 
  The 
  

   hyomandibular 
  is 
  well 
  shown 
  on 
  one 
  side, 
  but 
  in 
  the 
  

   published 
  drawing 
  it 
  is 
  not 
  distinguished 
  from 
  an 
  adjoin- 
  

   ing 
  element 
  which 
  appears 
  to 
  be 
  the 
  displaced 
  meta- 
  

   pterygoid. 
  The 
  process 
  of 
  the 
  hyomandibular 
  for 
  the 
  

   support 
  of 
  the 
  operculum 
  is 
  long, 
  but 
  its 
  hinder 
  end 
  is 
  

   connected 
  with 
  the 
  upper 
  and 
  lower 
  extremities 
  of 
  the 
  

   element 
  by 
  a 
  thin 
  lamina 
  of 
  bone. 
  Behind 
  the 
  hyoman- 
  

   dibular, 
  parts 
  of 
  the 
  operculum 
  and 
  suboperculum 
  are 
  

   seen 
  from 
  within. 
  The 
  vertebral 
  centra 
  are 
  not 
  " 
  com- 
  

   pletely 
  ossified," 
  but 
  are 
  represented 
  merely 
  by 
  distinct 
  

   hypocentra 
  and 
  pleurocentra 
  ; 
  their 
  arches 
  are 
  obscurely 
  

   indicated 
  through 
  the 
  displaced 
  squamation. 
  The 
  

   tubercles 
  on 
  the 
  scales 
  are 
  occasionally 
  elongated, 
  and 
  on 
  

   the 
  hinder 
  portion 
  of 
  some 
  of 
  the 
  flank-scales 
  they 
  are 
  

   observed 
  to 
  pass 
  into 
  transverse 
  striaa 
  which 
  terminate 
  in 
  

   feeble 
  denticulations. 
  The 
  fins 
  are 
  too 
  fragmentary 
  for 
  

   detailed 
  description. 
  Enniskillen 
  Coll. 
  

  

  P. 
  876 
  x. 
  Fragmentary 
  remains 
  of 
  head, 
  pectoral 
  fins, 
  and 
  anterior 
  

   scales 
  : 
  Lyme 
  Regis. 
  Part 
  of 
  the 
  smooth 
  outer 
  face 
  of 
  

   the 
  left 
  dentary, 
  with 
  its 
  coronoid 
  elevation, 
  is 
  shown 
  ; 
  

   and 
  there 
  are 
  scattered 
  examples 
  of 
  the 
  characteristic 
  

   slender 
  teeth. 
  The 
  cranial 
  roof 
  is 
  imperfectly 
  exposed 
  

   from 
  within, 
  and 
  there 
  are 
  remains 
  of 
  the 
  hyomandibular, 
  

   supposed 
  entopterygoid, 
  and 
  numerous 
  other 
  elements. 
  

   The 
  operculum, 
  though 
  fragmentary, 
  is 
  clearly 
  deeper 
  

  

  