﻿PYCNODONTID.^. 
  259 
  

  

  to 
  a 
  space 
  considerably 
  separated 
  throughout 
  its 
  extent 
  from 
  the 
  

   thin 
  oral 
  border 
  of 
  the 
  bone, 
  comprising 
  one 
  principal 
  series 
  of 
  

   teeth, 
  flanked 
  within 
  by 
  at 
  least 
  one 
  small 
  series 
  and 
  outside 
  by 
  

   two 
  or 
  more 
  small 
  series. 
  Scales 
  ornamented 
  with 
  reticulating 
  

   rugse. 
  

  

  This 
  amended 
  definition 
  is 
  given 
  on 
  the 
  assumption 
  that 
  the 
  so- 
  

   called 
  Gyrodus 
  angustus, 
  Agassiz, 
  belongs 
  to 
  the 
  same 
  genus 
  as 
  

   Pycnodus 
  subclavatus, 
  Agassiz. 
  The 
  splenial 
  bone 
  in 
  the 
  first- 
  

   named 
  species 
  differs 
  from 
  that 
  of 
  all 
  other 
  known 
  Pycnodonts 
  in 
  

   its 
  wide, 
  toothless 
  margin 
  ; 
  but 
  neither 
  in 
  the 
  so-called 
  Pycnodus 
  

   subclavatus 
  nor 
  in 
  any 
  of 
  the 
  associated 
  species 
  has 
  the 
  imperfect 
  

   nature 
  of 
  the 
  specimens 
  yet 
  permitted 
  the 
  observation 
  of 
  this 
  

   feature. 
  Future 
  discoveries 
  must 
  determine 
  whether 
  or 
  not 
  the 
  

   arrangement 
  here 
  adopted 
  is 
  justifiable. 
  

  

  The 
  splenial 
  dentition 
  of 
  Anomoeodus 
  is 
  arranged 
  as 
  in 
  Mesodon, 
  

   but 
  the 
  form 
  of 
  the 
  splenial 
  bone 
  itself 
  is 
  quite 
  different 
  from 
  that 
  

   of 
  the 
  last-named 
  genus, 
  being 
  similar 
  to 
  that 
  of 
  Pycnodus. 
  

  

  Anomoeodus 
  subclavatus 
  (Agassiz). 
  

  

  1799. 
  Figures 
  by 
  Faujas 
  St. 
  Fond, 
  Hist. 
  Nat. 
  Mont. 
  St. 
  Pierre, 
  Maes- 
  

  

  tricht, 
  pi. 
  xviii. 
  fig. 
  8, 
  pi. 
  xix. 
  fig. 
  4. 
  

   1833-44. 
  Pycnodus 
  subclavatus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  

  

  p. 
  17, 
  pt. 
  ii. 
  p. 
  198, 
  pi. 
  lxxii. 
  a. 
  fig. 
  59. 
  

   1848-52. 
  Pycnodus, 
  P. 
  Gervais, 
  Zool. 
  et 
  Pal. 
  Franc, 
  pi. 
  lxix. 
  

  

  fig. 
  23. 
  

   1872. 
  Pycnodus 
  cretaceus, 
  H. 
  E. 
  Sauvage 
  (err 
  ore), 
  Bibl. 
  jfecole 
  Hautes 
  

  

  Etudes, 
  vol. 
  v. 
  art. 
  9, 
  p. 
  13, 
  pi. 
  i. 
  figs. 
  3-6. 
  

   1887. 
  Coelodus 
  subclavatus, 
  K. 
  A. 
  von 
  Zittel, 
  Handb. 
  Palaeont. 
  vol. 
  iii. 
  

  

  p. 
  249. 
  

   1887. 
  Anomoeodus 
  subclavatus, 
  H. 
  Forir, 
  Ann. 
  Soc. 
  Ge"ol. 
  Belgique, 
  

  

  vol. 
  xiv. 
  Mem. 
  p. 
  25, 
  pi. 
  i. 
  fig. 
  1. 
  

  

  Type. 
  Principal 
  splenial 
  teeth 
  ; 
  Paris 
  Museum 
  of 
  Natural 
  History. 
  

  

  The 
  type 
  species, 
  known 
  only 
  by 
  the 
  splenial 
  dentition. 
  Teeth 
  

   of 
  the 
  principal 
  series 
  on 
  the 
  splenial 
  bone 
  slightly 
  arcuated, 
  tapering 
  

   and 
  turned 
  forwards 
  at 
  the 
  inner 
  extremity, 
  attaining 
  a 
  breadth 
  

   more 
  than 
  three 
  times 
  as 
  great 
  as 
  their 
  length 
  ; 
  those 
  of 
  the 
  single 
  

   inner 
  series 
  very 
  small 
  and 
  rounded, 
  irregularly 
  arranged 
  ; 
  flanking 
  

   teeth 
  in 
  four 
  irregular 
  series, 
  these 
  mostly 
  smooth 
  and 
  together 
  not 
  

   equalling 
  in 
  width 
  the 
  principal 
  series, 
  the 
  innermost 
  teeth 
  slightly 
  

   broader 
  than 
  long, 
  the 
  next 
  nearly 
  similar, 
  and 
  the 
  two 
  outermost 
  

   series 
  insignificant. 
  

  

  A 
  good 
  figure 
  of 
  this 
  form 
  of 
  dentition 
  is 
  published 
  by 
  Forir, 
  loc. 
  

   cit., 
  but 
  there 
  seems 
  to 
  be 
  much 
  variation 
  even 
  in 
  the 
  specimens 
  

  

  