﻿400 
  ACTINOPTERYGII. 
  

  

  those 
  of 
  the 
  pterygoid 
  bones 
  more 
  or 
  less 
  granular. 
  Gular 
  plate 
  

   present. 
  Pectoral 
  fins 
  large 
  and 
  sickle-shaped, 
  consisting 
  of 
  closely- 
  

   apposed, 
  unjointed 
  and 
  unbranched 
  rays, 
  of 
  which 
  the 
  majority 
  

   terminate 
  successively 
  at 
  the 
  oblique, 
  trenchant 
  anterior 
  margin. 
  

  

  The 
  teeth 
  of 
  this 
  genus 
  from 
  European 
  Cretaceous 
  formations 
  

   were 
  originally 
  referred 
  by 
  Agassiz 
  (Poiss. 
  Foss., 
  Peuill. 
  1835, 
  

   p. 
  55) 
  in 
  error 
  to 
  Saurocephalus 
  of 
  Harlan 
  (Journ. 
  Acad. 
  Nat. 
  Sci. 
  

   Philad. 
  vol. 
  iii. 
  1824, 
  p. 
  337) 
  ; 
  while 
  the 
  pectoral 
  fins 
  were 
  wrongly 
  

   described 
  as 
  fin-rays 
  of 
  Ptychodus 
  (Agassiz, 
  ibid. 
  vol. 
  iii. 
  1837, 
  

   p. 
  56). 
  The 
  mistake 
  in 
  the 
  identification 
  of 
  the 
  teeth 
  was 
  first 
  

   pointed 
  out 
  by 
  Leidy 
  (he. 
  cit. 
  1857), 
  who, 
  however, 
  failed 
  to 
  recog- 
  

   nize 
  that 
  the 
  elongated 
  rostrum 
  belonged 
  to 
  the 
  same 
  fish 
  as 
  these 
  

   fossils. 
  The 
  pectoral 
  fin-rays 
  were 
  first 
  proved 
  to 
  be 
  not 
  Elasmo- 
  

   branch 
  by 
  Cope 
  (he. 
  cit. 
  1875), 
  and 
  their 
  identity 
  with 
  Protosphy- 
  

   rarna 
  was 
  subsequently 
  determined 
  both 
  by 
  Cope 
  (in 
  A. 
  S. 
  Wood- 
  

   ward, 
  Proc. 
  Geol. 
  Assoc, 
  vol. 
  x. 
  1888, 
  p. 
  321) 
  and 
  by 
  A. 
  R. 
  Crook 
  

   (Paheontogr. 
  vol. 
  xxxix. 
  1892, 
  p. 
  110). 
  The 
  best 
  description 
  of 
  

   the 
  head 
  hitherto 
  published 
  is 
  that 
  by 
  J. 
  Felix 
  (Zeitschr. 
  deutsch. 
  

   geol. 
  Ges. 
  vol. 
  xlii. 
  1890, 
  pp. 
  278-302, 
  pis. 
  xii.-xiv.) 
  ; 
  but 
  neither 
  

   Crook 
  nor 
  the 
  present 
  writer 
  has 
  observed 
  any 
  evidence 
  of 
  the 
  

   so-called 
  " 
  praedentale 
  " 
  described 
  by 
  this 
  author. 
  The 
  thickening 
  

   of 
  the 
  alveolar 
  border 
  of 
  the 
  dentary 
  bone 
  is 
  interpreted 
  by 
  Cope 
  as 
  

   an 
  anomalous 
  median 
  element. 
  

  

  Protosphyrsena 
  ferox, 
  Leidy. 
  

  

  1822. 
  " 
  Undetermined," 
  G. 
  A. 
  Mantell, 
  Foss. 
  South 
  Downs, 
  p. 
  228, 
  

  

  pi. 
  xxxiii. 
  figs. 
  7-9. 
  

   1835-44. 
  Saurocephalus 
  lanciformis, 
  L. 
  Agassiz 
  {errore), 
  Poiss. 
  Foss., 
  

  

  Feuill. 
  p. 
  55, 
  vol. 
  v. 
  pt. 
  i. 
  p. 
  102, 
  pi. 
  xxv. 
  c. 
  figs. 
  21-29. 
  

   1844. 
  Saurocephalus 
  lanceolatus, 
  L. 
  Agassiz, 
  ibid. 
  vol. 
  v. 
  pt. 
  i. 
  p. 
  8 
  

  

  (misprint). 
  

   1850. 
  Saurocephalus 
  lanciformis 
  ,¥ 
  . 
  Dixon, 
  Geol. 
  Sussex, 
  p. 
  374, 
  pi. 
  xxx. 
  

  

  fig. 
  21, 
  pi. 
  xxxi. 
  fig. 
  12, 
  pi. 
  xxxii 
  * 
  fig. 
  1, 
  pi. 
  xxxiv. 
  fig. 
  11. 
  

   1857. 
  Protosphyrcena 
  ferox, 
  J. 
  Leidy, 
  Trans. 
  Amer. 
  Phil. 
  Soc. 
  vol. 
  xi. 
  

  

  p. 
  95. 
  

   1857. 
  Xiphias 
  dixoni, 
  J. 
  Leidy, 
  ibid. 
  p. 
  95. 
  [Rostrum; 
  British 
  Mu- 
  

   seum.] 
  

   (?) 
  1860. 
  Saurocephalus 
  lanciformis, 
  V. 
  Kiprijanoff, 
  Bull. 
  Soc. 
  Imp. 
  

  

  Nat. 
  Moscou, 
  vol. 
  xxxiii. 
  pt. 
  i. 
  p. 
  666, 
  pi. 
  x. 
  fig. 
  4. 
  

  

  1877. 
  Brisichthe 
  dixoni, 
  E. 
  D. 
  Cope, 
  Bull. 
  U.S. 
  Geol. 
  Surv. 
  Territ. 
  

   vol. 
  iii. 
  p. 
  823. 
  

  

  1878. 
  Erisichthe 
  dixoni, 
  W. 
  Davies, 
  Geol. 
  Mag. 
  [2] 
  vol. 
  v. 
  p. 
  260, 
  

   pi. 
  viii. 
  fig. 
  3. 
  

  

  1878. 
  Protosphyrcena 
  ferox, 
  E. 
  T. 
  Newton, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  

   vol. 
  xxxiv. 
  p. 
  789. 
  

  

  

  