﻿PYCNODONTID^;. 
  231 
  

  

  A 
  species 
  of 
  small 
  or 
  moderate 
  size, 
  known 
  only 
  by 
  the 
  splenial 
  

   dentition. 
  Teeth 
  closely 
  arranged 
  ; 
  those 
  of 
  the 
  innermost 
  series 
  

   minute 
  and 
  round 
  ; 
  those 
  of 
  the 
  principal 
  series 
  about 
  twice 
  

   as 
  broad 
  as 
  long 
  ; 
  teeth 
  of 
  the 
  inner 
  flanking 
  series 
  broader 
  than 
  

   long 
  and 
  larger 
  than 
  those 
  of 
  the 
  outermost 
  row, 
  which 
  are 
  

   rounded. 
  

  

  Form. 
  Sf 
  Log. 
  Bathonian 
  : 
  Oxfordshire. 
  

  

  P. 
  523. 
  Type 
  specimen 
  ; 
  Stonesfield 
  Slate, 
  Stonesfield. 
  Egerton 
  Coll. 
  

  

  Microdon 
  (?) 
  discoides 
  (A. 
  8. 
  Woodward). 
  

  

  1844. 
  Pycnodus 
  discoides, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  199 
  

  

  (name 
  only). 
  

   1890. 
  Mesodon 
  discoides, 
  A. 
  S. 
  Woodward, 
  Proc. 
  Geol. 
  Assoc, 
  vol. 
  xi. 
  

  

  p. 
  300, 
  pi. 
  iii. 
  fig. 
  82. 
  

  

  Type. 
  Imperfect 
  vomer 
  ; 
  British 
  Museum. 
  

  

  A 
  species 
  doubtfully 
  ascribed 
  to 
  Microdon, 
  known 
  only 
  by 
  the 
  

   unique 
  vomer 
  recorded 
  below. 
  Yomerine 
  teeth 
  round 
  and 
  well 
  

   spaced 
  ; 
  those 
  of 
  the 
  median 
  series 
  not 
  much 
  exceeding 
  the 
  outer 
  

   lateral 
  teeth 
  in 
  size 
  ; 
  inner 
  paired 
  teeth 
  only 
  about 
  half 
  as 
  large 
  as 
  

   the 
  others. 
  

  

  Form. 
  Sf 
  Loc. 
  Bathonian 
  : 
  Oxfordshire. 
  

  

  P. 
  524. 
  Type 
  specimen, 
  described 
  and 
  figured 
  loc. 
  cit. 
  1890; 
  Great 
  

   Oolite, 
  Little 
  Gibraltar, 
  near 
  Oxford. 
  Egerton 
  Coll. 
  

  

  The 
  following 
  specimens 
  of 
  Mesodon 
  are 
  not 
  specifically 
  deter- 
  

   mined 
  : 
  — 
  

  

  P. 
  7444. 
  Vomer 
  ; 
  Kimmeridgian, 
  Langenberg, 
  Hanover. 
  

  

  Purchased, 
  1895. 
  

  

  P. 
  3756. 
  Vomer 
  resembling 
  Microdon 
  in 
  its 
  anterior 
  half, 
  but 
  the 
  

   inner 
  lateral 
  teeth 
  not 
  interposed 
  between 
  the 
  median 
  

   teeth 
  in 
  its 
  hinder 
  half 
  ; 
  Purbeckian, 
  Swanage. 
  

  

  Ennishillen 
  Coll. 
  

  

  The 
  following 
  species 
  of 
  Microdon 
  have 
  also 
  been 
  founded 
  upon 
  

   portions 
  of 
  dentition, 
  but 
  there 
  are 
  no 
  examples 
  in 
  the 
  Collection 
  : 
  — 
  

  

  Microdon 
  corcdli: 
  Pycnodus 
  coralli, 
  H. 
  E. 
  Sauvage, 
  Bull. 
  Soc. 
  

  

  Sci. 
  Nat. 
  Yonne, 
  vol. 
  xxxiii. 
  pt. 
  ii. 
  (1879), 
  p. 
  32, 
  pi. 
  ii. 
  

  

  fig. 
  2. 
  — 
  Upper 
  Corallian 
  ; 
  Tonnerre, 
  Tonne, 
  France. 
  

  

  [Right 
  splenial 
  ; 
  Cotteau 
  Collection.] 
  

   Microdon 
  distantidens 
  : 
  Pycnodus 
  distantidens 
  , 
  F. 
  J. 
  Pictet, 
  Kept. 
  

  

  et 
  Poiss. 
  Foss. 
  Jura 
  Neuchatelois 
  (1860), 
  p. 
  67, 
  pi. 
  xv. 
  

  

  