﻿rrcxoDONTiDJs. 
  2 
  ,o 
  

  

  fossil 
  is 
  extremely 
  distorted 
  by 
  crushing 
  ; 
  while 
  the 
  two 
  specimens 
  

   compared 
  as 
  regards 
  the 
  dentition, 
  exhibiting 
  only 
  the 
  series 
  in 
  

   side-view, 
  do 
  not 
  display 
  homologous 
  teeth. 
  

  

  P. 
  65. 
  Obscurely 
  preserved 
  and 
  distorted 
  fish 
  in 
  hard 
  limestone, 
  

   described 
  and 
  figured, 
  Joe. 
  cit. 
  : 
  Hakel. 
  The 
  amount 
  

   and 
  direction 
  of 
  distortion 
  are 
  indicated 
  by 
  the 
  dis- 
  

   placement 
  of 
  the 
  lobes 
  of 
  the 
  tail. 
  Letuis 
  Coll. 
  

  

  Palaeobalistum 
  flabellatum 
  (Cope). 
  

  

  1886. 
  PycnodusJlabeUatus, 
  E. 
  D. 
  Cope, 
  Proc. 
  Amer. 
  Phil. 
  Soc. 
  vol. 
  xxiii. 
  

  

  p. 
  6. 
  

   1890. 
  Paheobalistiim 
  Jiabellatum, 
  A. 
  S. 
  Woodward, 
  Geol. 
  Mag. 
  [3] 
  

  

  vol. 
  vii. 
  p. 
  894. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  Cope 
  Collection, 
  Philadelphia. 
  

  

  A 
  species 
  attaining 
  a 
  length 
  of 
  about 
  l>2, 
  differing 
  from 
  other 
  

   forms 
  (according 
  to 
  Cope's 
  description) 
  in 
  its 
  relatively 
  short 
  anal 
  

   fin. 
  Dorsal 
  tin 
  comprising 
  53, 
  anal 
  fin 
  only 
  24 
  rays. 
  

  

  The 
  neural 
  spines 
  are 
  shown 
  to 
  be 
  united 
  by 
  interdigitations 
  of 
  

   their 
  laminar 
  expansions, 
  as 
  described 
  above 
  in 
  P. 
  goedeli. 
  The 
  

   circumstance 
  that 
  only 
  four 
  basal 
  bones 
  are 
  recognizable 
  in 
  the 
  

   pectoral 
  fin, 
  is 
  probably 
  due 
  to 
  imperfection 
  in 
  preservation 
  ; 
  there 
  

   being 
  distinctly 
  not 
  less 
  than 
  seven 
  in 
  P. 
  goedeli 
  (no. 
  39232). 
  

  

  Form. 
  $ 
  Lot.. 
  Cretaceous 
  : 
  Province 
  of 
  Sergipe 
  del 
  Bey, 
  Brazil. 
  

  

  Not 
  represented 
  in 
  the 
  Collection. 
  

  

  Fragments 
  apparently 
  of 
  a 
  species 
  of 
  Palceooalistum 
  from 
  the 
  

   Cretaceous 
  of 
  Comen, 
  Istria, 
  are 
  also 
  described 
  by 
  B. 
  Kner, 
  

   Sitzungsb. 
  k. 
  Akad. 
  AYiss., 
  math.-naturw. 
  CI. 
  vol. 
  lvi. 
  pt. 
  i. 
  (1867), 
  

   p. 
  1S3. 
  

  

  Genus 
  PYCNODUS, 
  Agassiz. 
  

   [Poiss. 
  Foss. 
  vol. 
  i. 
  1S33, 
  pi. 
  G. 
  fig. 
  1 
  (name 
  and 
  fig. 
  only), 
  vol. 
  ii. 
  

   pt. 
  i. 
  1S33, 
  p. 
  16, 
  and 
  pt. 
  ii. 
  1844, 
  p. 
  183.] 
  

   Syn. 
  Periodus, 
  L. 
  Agassiz, 
  ibid. 
  vol. 
  ii. 
  pt. 
  ii. 
  1844, 
  p. 
  201. 
  

  

  Trunk 
  deeply 
  fusiform, 
  gradually 
  passing 
  into 
  a 
  slender 
  caudal 
  

   pedicle. 
  Head- 
  and 
  opercular 
  bones 
  externally 
  rugose 
  and 
  punc- 
  

   tate 
  : 
  teeth 
  smooth, 
  or 
  with 
  a 
  slight 
  apical 
  pit 
  and 
  feeble 
  rugosity 
  ; 
  

   oral 
  surface 
  of 
  vomer 
  slightly 
  convex 
  from 
  side 
  to 
  side, 
  with 
  teeth 
  

   in 
  live 
  longitudinal 
  series 
  ; 
  splenial 
  dentition 
  comprising 
  three 
  

   series 
  of 
  teeth, 
  the 
  innermost 
  the 
  largest. 
  Neural 
  and 
  luenial 
  

   arches 
  of 
  the 
  axial 
  skeleton 
  of 
  trunk 
  expanding 
  to 
  encircle 
  the 
  

   notochord. 
  Fin-rays 
  delicate, 
  spaced, 
  articulated 
  and 
  somewhat 
  

  

  i 
  2 
  

  

  