﻿PYCNODONTIDJE. 
  273 
  

  

  the 
  fish. 
  Vertebral 
  axis 
  at 
  origin 
  of 
  dorsal 
  fin 
  much 
  above 
  the 
  

   middle 
  of 
  the 
  trunk. 
  [Teeth 
  not 
  satisfactorily 
  known.] 
  Dorsal 
  

   and 
  anal 
  fins 
  acuminate 
  in 
  front, 
  rapidly 
  becoming 
  low 
  and 
  

   fringe-like, 
  with 
  distant 
  fin-rays 
  behind 
  ; 
  the 
  dorsal 
  fin 
  with 
  

   53 
  rays, 
  occupying 
  nearly 
  two-thirds 
  of 
  the 
  back, 
  the 
  anal 
  fin 
  

   with 
  slightly 
  less 
  than 
  50 
  rays. 
  Hinder 
  margin 
  of 
  caudal 
  fin 
  

   deeply 
  sinuous. 
  Scales 
  robust 
  on 
  the 
  anterior 
  half 
  of 
  the 
  trunk, 
  

   but 
  extended 
  in 
  more 
  delicate 
  form 
  over 
  the 
  middle 
  of 
  the 
  caudal 
  

   region. 
  

  

  This 
  species 
  is 
  distorted 
  in 
  such 
  various 
  ways 
  when 
  fossilized, 
  

   that 
  it 
  seems 
  probable 
  the 
  body 
  was 
  less 
  laterally 
  compressed 
  than 
  

   in 
  P. 
  orbiculatum 
  and 
  P. 
  ponsorti. 
  The 
  form 
  of 
  the 
  median 
  fins 
  

   and 
  the 
  extension 
  of 
  the 
  squamation 
  over 
  the 
  caudal 
  region 
  may 
  

   even 
  be 
  regarded 
  as 
  necessitating 
  the 
  removal 
  of 
  the 
  fish 
  from 
  the 
  

   genus 
  Palceohalistum. 
  

  

  Form. 
  Sf 
  Log. 
  Upper 
  Cretaceous 
  : 
  Mt. 
  Lebanon, 
  Syria. 
  

  

  P. 
  4001, 
  P. 
  4781. 
  A 
  fine 
  specimen, 
  in 
  counterpart, 
  somewhat 
  

   shortened 
  and 
  deepened 
  by 
  crushing 
  : 
  Hakel, 
  near 
  

   Djebail. 
  The 
  head 
  is 
  much 
  fractured, 
  but 
  exhibits 
  the 
  

   large 
  backwardly- 
  directed 
  process 
  from 
  the 
  hinder 
  margin 
  

   of 
  the 
  cranial 
  roof 
  -bone 
  in 
  the 
  parietal 
  region'. 
  The 
  

   expanded 
  neural 
  and 
  haemal 
  arches 
  of 
  the 
  axial 
  skeleton 
  

   of 
  the 
  trunk 
  are 
  distinct; 
  the 
  laminar 
  expansion 
  on 
  the 
  

   neural 
  and 
  haemal 
  spines 
  is 
  confined 
  to 
  their 
  front 
  margin, 
  

   and 
  there 
  is 
  no 
  interlocking. 
  The 
  supports 
  bearing 
  the 
  

   auterior 
  elevated 
  rays 
  of 
  the 
  dorsal 
  and 
  anal 
  fins 
  are 
  

   strengthened 
  by 
  considerable 
  wings. 
  Some 
  of 
  the 
  deli- 
  

   cate 
  ribs 
  of 
  the 
  squamation 
  on 
  the 
  middle 
  of 
  the 
  caudal 
  

   region 
  are 
  also 
  preserved. 
  Lewis 
  Coll. 
  

  

  P. 
  61, 
  P. 
  62. 
  Imperfect 
  head 
  and 
  trunk 
  in 
  counterpart, 
  the 
  vomerine 
  

   teeth, 
  as 
  exposed 
  in 
  side 
  view, 
  figured 
  by 
  Davis, 
  loc. 
  cit. 
  

   pi. 
  xxiii. 
  fig. 
  1 
  a 
  ; 
  Hakel. 
  Though 
  the 
  skull 
  is 
  displayed 
  

   in 
  side 
  view, 
  it 
  is 
  so 
  much 
  crushed 
  and 
  fractured 
  that 
  it 
  

   does 
  not 
  afford 
  any 
  osteological 
  information 
  of 
  importance. 
  

   The 
  remarkable 
  interlocking 
  of 
  the 
  laminar 
  expansions 
  of 
  

   the 
  neural 
  and 
  haemal 
  spines 
  described 
  below 
  in 
  no. 
  

   P. 
  4002, 
  is 
  shown 
  by 
  delicate 
  impressions 
  not 
  only 
  in 
  

   the 
  caudal 
  region 
  but 
  also 
  in 
  some 
  of 
  the 
  neural 
  arches 
  

   of 
  the 
  abdominal 
  region. 
  The 
  external 
  bones 
  and 
  scales 
  

   are 
  punctate. 
  Some 
  of 
  the 
  scales 
  are 
  preserved 
  on 
  the 
  

   caudal 
  region, 
  but 
  they 
  do 
  not 
  extend 
  quite 
  to 
  the 
  base 
  of 
  

   the 
  median 
  fins 
  ; 
  they 
  are 
  shown 
  to 
  be 
  quite 
  minute 
  as 
  

  

  PART 
  III. 
  t 
  

  

  