﻿pycnodontid^:. 
  239 
  

  

  depth 
  of 
  trunk 
  somewhat 
  less 
  than 
  its 
  length 
  from 
  the 
  scapular 
  

   arch 
  to 
  the 
  base 
  of 
  the 
  caudal 
  fin, 
  and 
  head 
  with 
  opercular 
  

   apparatus 
  occupying 
  less 
  than 
  one-third 
  of 
  the 
  total 
  length 
  ex- 
  

   clusive 
  of 
  the 
  caudal 
  fin. 
  External 
  head-bones 
  ornamented 
  with 
  

   tuberculations. 
  Dentition 
  closely 
  arranged, 
  with 
  comparatively 
  

   feeble 
  ornament, 
  soon 
  worn 
  smooth. 
  Yomer 
  with 
  prominent 
  flat- 
  

   topped 
  median 
  teeth, 
  higher 
  than 
  either 
  of 
  the 
  flanking 
  series, 
  and 
  

   equalling 
  or 
  exceeding 
  these 
  two 
  series 
  together 
  in 
  width 
  ; 
  the 
  

   inner 
  flanking 
  series 
  somewhat 
  smaller 
  than 
  the 
  outer, 
  of 
  which 
  the 
  

   teeth 
  are 
  not 
  much 
  elevated. 
  Splenial 
  with 
  principal 
  teeth 
  broader 
  

   than 
  long, 
  about 
  equalling 
  in 
  width 
  the 
  two 
  flanking 
  series, 
  of 
  which 
  

   the 
  outermost 
  is 
  much 
  the 
  largest 
  ; 
  inner 
  flanking 
  teeth 
  equalling 
  in 
  

   size 
  those 
  of 
  the 
  innermost 
  series. 
  Dorsal 
  fin 
  occupying 
  the 
  hinder 
  

   half 
  of 
  the 
  back, 
  and 
  its 
  maximum 
  elevation 
  equalling 
  at 
  least 
  one 
  

   third 
  of 
  the 
  depth 
  of 
  the 
  trunk 
  at 
  its 
  insertion. 
  Scales 
  towards 
  the 
  

   dorsal 
  margin 
  ornamented 
  with 
  distant 
  tubercles, 
  the 
  others 
  marked 
  

   with 
  a 
  delicate 
  reticulation, 
  partly 
  also 
  tuberculated. 
  

  

  Form. 
  <$f 
  Loc. 
  Lower 
  Kimmeridgian 
  (Lithographic 
  Stone) 
  : 
  Bavaria 
  

   and 
  Wiirtemberg. 
  

  

  49146. 
  Plaster 
  cast 
  of 
  type 
  specimen, 
  the 
  head 
  figured 
  by 
  Wagner, 
  

   loc. 
  cit. 
  1851, 
  pi. 
  i. 
  fig. 
  1 
  ; 
  Solenhofen, 
  Bavaria. 
  

  

  Purchased, 
  1878. 
  

  

  37039. 
  A 
  fine 
  specimen 
  0-68 
  in 
  length, 
  with 
  imperfect 
  head 
  and 
  

   paired 
  fins 
  : 
  Solenhofen. 
  Haberlein 
  Coll. 
  

  

  37792. 
  Head 
  with 
  imperfect 
  trunk 
  and 
  dorsal 
  fin 
  of 
  a 
  still 
  larger 
  

   fish 
  ; 
  Solenhofen. 
  The 
  mouth 
  is 
  open, 
  and 
  the 
  worn 
  

   vomerine 
  and 
  splenial 
  dentition 
  has 
  been 
  well 
  extricated 
  

   from 
  the 
  matrix. 
  Two 
  of 
  the 
  anterior 
  prehensile 
  teeth 
  of 
  

   the 
  lower 
  jaw 
  and 
  one 
  in 
  the 
  upper 
  jaw 
  are 
  also 
  shown. 
  

   Some 
  of 
  the 
  small, 
  coarsely 
  tuberculated 
  scales 
  are 
  shown 
  

   below 
  the 
  hinder 
  part 
  of 
  the 
  mandible. 
  Haberlein 
  Coll. 
  

  

  P. 
  1622. 
  Fragment 
  of 
  squamation 
  ; 
  Solenhofen. 
  Egerton 
  Coll. 
  

  

  P. 
  3775. 
  Smaller 
  fragment 
  ; 
  Daiting, 
  Bavaria. 
  EnnisHllen 
  Coll. 
  

  

  35532. 
  Plaster 
  cast 
  of 
  vomerine 
  dentition 
  probably 
  of 
  this 
  species, 
  

   described 
  and 
  figured 
  by 
  Count 
  von 
  Mandelslohe, 
  loc. 
  cit. 
  

   1845 
  ; 
  Wippingen, 
  near 
  Blaubeuren, 
  Wiirtemberg. 
  

  

  Purchased, 
  1859. 
  

  

  It 
  is 
  not 
  improbable 
  that 
  to 
  Gyrodus 
  circularis 
  must 
  also 
  be 
  

   assigned 
  the 
  portions 
  of 
  dentition 
  named 
  Gyrodus 
  umbilicus 
  (L. 
  

  

  