﻿228 
  ACTIN0PTERYG1I. 
  

  

  1852. 
  Pycnodus 
  hugii, 
  F. 
  A. 
  Quenstedt, 
  Handb. 
  Petrefakt. 
  p. 
  213, 
  pi. 
  xvi. 
  

  

  fig. 
  10. 
  

   1856. 
  Mic?'odon 
  hugii, 
  J. 
  J. 
  Heckel, 
  Denkschr. 
  k. 
  Akad. 
  Wiss., 
  math.- 
  

  

  naturw. 
  CI. 
  vol. 
  xi. 
  p. 
  201. 
  

   (?) 
  1858. 
  Pyknodus 
  hugii, 
  F. 
  A. 
  Quenstedt, 
  Der 
  Jura, 
  p. 
  781, 
  pi. 
  xcvi. 
  

  

  figs. 
  30, 
  31. 
  

   1860. 
  Pycnodus 
  hugii, 
  F. 
  J. 
  Pictet, 
  Rept. 
  & 
  Poiss. 
  Foss. 
  Jura 
  Neu- 
  

  

  chatelois, 
  p. 
  56, 
  pi. 
  xiii. 
  figs. 
  4-8, 
  pi. 
  xix. 
  fig. 
  2. 
  

   (?) 
  1860. 
  Pycnodus 
  notabilis, 
  F. 
  J. 
  Pictet 
  (? 
  errore), 
  ibid. 
  p. 
  58, 
  pi. 
  xiv. 
  

  

  fig. 
  1. 
  

   1864. 
  Pycnodus 
  irregularis, 
  H. 
  Credner 
  (errore), 
  Zeitschr! 
  deutsch. 
  

  

  geol. 
  Ges. 
  vol. 
  xvi. 
  p. 
  244, 
  pi. 
  xi. 
  fig. 
  5. 
  

   1875. 
  Microdon 
  hugii, 
  K. 
  Fricke, 
  Palaeontogr. 
  vol. 
  xxii. 
  p. 
  371 
  , 
  pi. 
  xx. 
  

  

  figs. 
  10-16. 
  

   1880. 
  Microdon 
  hugii, 
  C. 
  Struckmann, 
  Wealdenbild. 
  Hannover, 
  p. 
  90, 
  

  

  pi. 
  iii. 
  fig. 
  8. 
  

  

  Type. 
  Portions 
  of 
  mandibular 
  dentition 
  ; 
  Soleure 
  Museum. 
  

  

  A 
  large 
  species, 
  known 
  only 
  by 
  the 
  dentition. 
  Yomerine 
  denti- 
  

   tion 
  [according 
  to 
  Fricke] 
  very 
  narrow, 
  and 
  the 
  teeth 
  of 
  the 
  median 
  

   and 
  inner 
  paired 
  series 
  widely 
  spaced 
  ; 
  median 
  teeth 
  of 
  irregularly 
  

   rounded 
  form, 
  scarcely 
  broader 
  than 
  long 
  ; 
  those 
  of 
  the 
  inner 
  paired 
  

   series 
  irregularly 
  triangular 
  or 
  quadrangular, 
  antero-posteriorly 
  

   elongated 
  ; 
  those 
  of 
  the 
  outer 
  paired 
  series 
  narrowest 
  and 
  much 
  

   elongated 
  antero-posteriorly. 
  Splenial 
  teeth 
  closely 
  arranged 
  ; 
  

   those 
  of 
  the 
  principal 
  series 
  about 
  twice 
  as 
  broad 
  as 
  long 
  and 
  more 
  

   or 
  less 
  truncated 
  at 
  their 
  outer 
  end 
  ; 
  those 
  of 
  the 
  innermost 
  series 
  

   and 
  of 
  the 
  inner 
  flanking 
  series 
  relatively 
  small 
  and 
  about 
  equal 
  in 
  

   size 
  ; 
  those 
  of 
  the 
  outermost 
  series 
  larger 
  than 
  the 
  latter, 
  though 
  

   less 
  than 
  half 
  as 
  large 
  as 
  the 
  principal 
  teeth, 
  slightly 
  elongated 
  

   transversely 
  and 
  truncated 
  at 
  the 
  inner 
  end. 
  

  

  The 
  largest 
  known 
  splenial 
  dentition 
  measures 
  about 
  0*05 
  in 
  

   length, 
  and 
  the 
  irregular 
  subdivision 
  of 
  some 
  of 
  the 
  teeth 
  is 
  

   frequently 
  observed. 
  

  

  Form. 
  Sf 
  Log. 
  Corallian 
  and 
  Kimmeridgian 
  : 
  Hanover, 
  Wiirtem- 
  

   berg, 
  an 
  Switzerland. 
  Portlandian 
  : 
  Hanover 
  ; 
  (?) 
  also 
  S. 
  England. 
  

   Purbeckian: 
  Hanover. 
  

  

  P. 
  1654 
  a, 
  b. 
  Left 
  splenial 
  dentition, 
  somewhat 
  broken, 
  and 
  another 
  

   abnormal 
  fragmentary 
  specimen 
  ; 
  Kimmeridgian, 
  Soleure, 
  

   Switzerland. 
  Egerton 
  Coll. 
  

  

  P. 
  7443. 
  Left 
  splenial 
  ; 
  Kimmeridgian, 
  Sohlewerke, 
  Hanover. 
  

  

  Purchased, 
  1895. 
  

  

  P. 
  2297. 
  Imperfect 
  small 
  left 
  splenial 
  dentition 
  ; 
  Portlandian, 
  

   Hanover. 
  Presented 
  by 
  Mrs. 
  Burton, 
  1882. 
  

  

  