﻿PYCNODONTID^. 
  241 
  

  

  Type. 
  Mandibular 
  dentition. 
  

  

  A 
  large 
  species 
  known 
  only 
  by 
  the 
  dentition, 
  of 
  which 
  the 
  splenial 
  

   is 
  indistinguishable 
  from 
  that 
  of 
  G. 
  circularis. 
  Vomer 
  with 
  pro- 
  

   minent 
  mammillated 
  median 
  teeth, 
  usually 
  not 
  quite 
  equalling 
  the 
  

   two 
  flanking 
  series 
  in 
  width, 
  and 
  scarcely 
  more 
  elevated 
  than 
  the 
  

   outermost 
  of 
  the 
  latter, 
  which 
  comprises 
  triangular 
  teeth 
  rising 
  to 
  a 
  

   conical 
  apex 
  ; 
  inner 
  flanking 
  teeth 
  relatively 
  small, 
  low, 
  rounded, 
  

   and 
  highly 
  ornamented. 
  

  

  The 
  form 
  and 
  degree 
  of 
  ornamentation 
  of 
  the 
  principal 
  teeth 
  on 
  

   the 
  splenial 
  in 
  this 
  species 
  vary 
  considerably. 
  The 
  immature 
  and 
  

   smaller 
  specimens 
  are 
  named 
  G. 
  ornatissimus 
  by 
  Blake. 
  

   ■ 
  Form. 
  Sf 
  Loc. 
  Lower 
  Kimmeridgian 
  : 
  Dorsetshire, 
  Wiltshire, 
  and 
  

   Cambridgeshire 
  ; 
  N. 
  France. 
  

  

  P. 
  7456. 
  Pine 
  example 
  of 
  the 
  vomerine 
  dentition, 
  0*035 
  in 
  

   maximum 
  width 
  ; 
  Kimmeridge 
  Clay, 
  Poulshot, 
  Wiltshire. 
  

  

  41868, 
  43026, 
  43561, 
  43563, 
  44085. 
  Five 
  small 
  vomers, 
  the 
  two 
  

   first 
  comparatively 
  narrow 
  and 
  with 
  very 
  prominent 
  

   median 
  teeth 
  ; 
  Kimmeridge 
  Clay, 
  Weymouth. 
  

  

  Purchased, 
  1869,-71,-72,-73. 
  

  

  P. 
  1615, 
  P. 
  3785. 
  Three 
  similar 
  specimens 
  ; 
  Weymouth. 
  

  

  Egerton 
  and 
  EnnisJcillen 
  Colls. 
  

  

  P. 
  6151, 
  P. 
  6166. 
  Four 
  similar 
  specimens, 
  one 
  being 
  figured 
  by 
  

   Damon, 
  op. 
  cit. 
  pi. 
  xi. 
  fig. 
  4 
  ; 
  Weymouth. 
  These 
  and 
  the 
  

   splenials 
  numbered 
  P. 
  6168 
  may 
  be 
  regarded 
  as 
  the 
  type 
  

   specimens 
  of 
  the 
  so-called 
  Gyrodus 
  ornatissimus. 
  

  

  Damon 
  Coll. 
  

  

  P. 
  1618. 
  Plaster 
  cast 
  of 
  large 
  right 
  splenial; 
  Kimmeridge 
  Clay, 
  

   Boulogne. 
  Egerton 
  Coll. 
  

  

  32746. 
  Somewhat 
  smaller 
  left 
  splenial 
  ; 
  Kimmeridge 
  Clay, 
  Ely. 
  

  

  Purchased, 
  1857. 
  

  

  38553. 
  Imperfect 
  smaller 
  specimen, 
  probably 
  from 
  Ely. 
  

  

  Purchased, 
  1864 
  

  

  43025. 
  Fine 
  left 
  splenial 
  of 
  moderate 
  size; 
  Kimmeridge 
  Clay, 
  

   Weymouth. 
  Purchased, 
  1871. 
  

  

  41227, 
  41963. 
  Portions 
  of 
  right 
  and 
  left 
  splenials, 
  with 
  remarkably 
  

   smooth 
  principal 
  teeth, 
  and 
  the 
  first 
  specimen 
  exhibiting 
  

   a 
  supplementary 
  row 
  of 
  small 
  teeth 
  within 
  the 
  outermost 
  

   series; 
  Weymouth. 
  Purchased, 
  1868,-70. 
  

  

  PART 
  III. 
  E 
  

  

  