﻿298 
  Mr. 
  A. 
  S. 
  Woodward's 
  Palceichthyohgical 
  Notes. 
  

  

  crest, 
  where 
  short 
  finer 
  wrinkles 
  are 
  often 
  intercalated. 
  The 
  

   form 
  of 
  the 
  coronal 
  crest, 
  however, 
  and 
  the 
  precise 
  characters 
  

   of 
  the 
  ornament 
  evidently 
  vary 
  in 
  different 
  parts 
  of 
  the 
  

   mouth, 
  as 
  indicated 
  by 
  the 
  four 
  enlarged 
  figures 
  (PL 
  XIV. 
  

   figs. 
  2 
  a, 
  b, 
  3, 
  3 
  a) 
  ; 
  and 
  in 
  some 
  teeth 
  the 
  superficial 
  trans- 
  

   verse 
  wrinkles 
  are 
  so 
  large 
  at 
  the 
  extremities 
  of 
  the 
  crown 
  as 
  

   to 
  impart 
  to 
  the 
  crest 
  a 
  serrated 
  aspect. 
  

  

  In 
  general 
  form 
  the 
  tooth 
  shown 
  in 
  PL 
  XIV. 
  fig. 
  3 
  has 
  

   perhaps 
  most 
  resemblance 
  to 
  the 
  Carboniferous 
  fossils 
  named 
  

   Venustodus 
  by 
  St. 
  John 
  and 
  Worthen 
  *, 
  the 
  latter 
  only 
  

   differing 
  in 
  the 
  smoothness 
  of 
  the 
  sides 
  of 
  the 
  coronal 
  emi- 
  

   nence 
  ; 
  but 
  the 
  nature 
  of 
  associated 
  remains 
  suggests 
  com- 
  

   parisons 
  with 
  other 
  types 
  possessing 
  ornamented 
  teeth. 
  As 
  

   already 
  pointed 
  out 
  by 
  Murchison 
  and 
  Strickland 
  (loc. 
  cit.), 
  

   there 
  occur 
  upon 
  the 
  same 
  horizon 
  as 
  the 
  teeth 
  ribbed 
  dorsal 
  

   fin-spines 
  of 
  the 
  form 
  first 
  discovered 
  in 
  Hybodus', 
  and 
  such 
  

   spines 
  not 
  having 
  been 
  met 
  with 
  in 
  association 
  with 
  any 
  teeth 
  

   except 
  those 
  of 
  Hybodus 
  at 
  the 
  time 
  of 
  Murchison 
  and 
  Strick- 
  

   land's 
  researches, 
  the 
  Keuper 
  specimens 
  received 
  the 
  name 
  of 
  

   Hybodus 
  heuperinus. 
  Agassiz, 
  however, 
  had 
  already 
  f 
  

   founded 
  the 
  genus 
  Leiacanthus 
  upon 
  similar 
  spines 
  from 
  the 
  

   French 
  Muschelkalk 
  on 
  the 
  erroneous 
  supposition 
  that 
  they 
  

   possessed 
  no 
  hinder 
  denticles 
  ; 
  and 
  it 
  is 
  now 
  known 
  that 
  

   ribbed 
  spines 
  of 
  the 
  same 
  type 
  also 
  charactarize 
  Acrodus. 
  

   Moreover, 
  an 
  example 
  of 
  the 
  hooked 
  cephalic 
  spines, 
  so 
  well 
  

   known 
  in 
  Hybodus 
  and 
  Acrodus, 
  has 
  been 
  found 
  with 
  one 
  of 
  

   these 
  dorsal 
  fin-spines 
  in 
  the 
  Keuper 
  of 
  Hippie, 
  Worcester- 
  

   shire 
  (Brit. 
  Mus. 
  no. 
  46957) 
  ; 
  and 
  there 
  is 
  thus 
  no 
  improb- 
  

   ability 
  in 
  the 
  supposition 
  that 
  the 
  teeth 
  just 
  described 
  pertain 
  

   to 
  a 
  Keuper 
  representative 
  of 
  either 
  Hybodus 
  or 
  Acrodus. 
  

  

  Taken 
  alone 
  the 
  teeth 
  are 
  more 
  suggestive 
  of 
  Acrodus 
  than 
  

   of 
  Hybodus 
  , 
  and 
  it 
  is 
  in 
  the 
  former 
  genus 
  that 
  the 
  present 
  writer 
  

   ventures 
  to 
  assign 
  them 
  a 
  provisional 
  position. 
  At 
  the 
  same 
  

   time 
  it 
  must 
  be 
  remembered 
  that 
  these 
  teeth 
  are 
  not 
  only 
  more 
  

   carinate 
  than 
  those 
  of 
  any 
  typical 
  species 
  of 
  Acrodus, 
  but 
  

   are 
  also 
  distinguished 
  by 
  the 
  presence 
  of 
  a 
  hollow 
  cavity 
  ; 
  and 
  

   Dr. 
  Otto 
  Jakel, 
  of 
  Strassburg, 
  informs 
  the 
  writer 
  that 
  he 
  will 
  

   shortly 
  propose 
  to 
  place 
  all 
  the 
  hollow 
  Acrodus-sh-cuped 
  teeth 
  of 
  

   the 
  Trias 
  in 
  a 
  distinct 
  genus. 
  The 
  English 
  Keuper 
  fossils, 
  

   indeed, 
  are 
  already 
  named 
  Lophodus 
  in 
  collections, 
  though 
  

   they 
  do 
  not 
  appear 
  to 
  have 
  been 
  described 
  under 
  this 
  name 
  J 
  ; 
  

  

  * 
  Pal. 
  Illinois, 
  vol. 
  yi. 
  (1875), 
  p. 
  .344. 
  

   f 
  Poiss. 
  Foss. 
  vol. 
  iii. 
  (18-37), 
  p. 
  55. 
  

  

  % 
  The 
  teeth 
  are 
  incidentally 
  mentioned 
  under 
  this 
  name 
  by 
  the 
  Rev. 
  

   W. 
  S. 
  Symonda, 
  'Old 
  Bones' 
  (1861), 
  p. 
  103. 
  

  

  