﻿PYCN0D0NTIDJ5. 
  

  

  219 
  

  

  49147. 
  Plaster 
  cast 
  of 
  type 
  specimen 
  ; 
  Eichstadt. 
  Purchased, 
  1878. 
  

  

  37023. 
  A 
  fine 
  specimen, 
  in 
  counterpart, 
  with 
  crushed 
  head 
  and 
  

   wanting 
  part 
  of 
  the 
  ventral 
  margin 
  ; 
  Solenhofen. 
  The 
  

   best 
  side 
  of 
  the 
  fossil 
  is 
  shown 
  of 
  one-half 
  the 
  natural 
  

   size 
  in 
  PL 
  XY. 
  fig. 
  1, 
  with 
  some 
  parts 
  restored 
  from 
  the 
  

   opposite 
  side. 
  The 
  bones 
  of 
  the 
  cranial 
  roof 
  are 
  shown 
  

   to 
  be 
  especially 
  thick 
  and 
  marked 
  with 
  a 
  relatively 
  

   coarse 
  tubercular 
  ornament. 
  The 
  facial 
  bones 
  are 
  remark- 
  

   ably 
  delicate 
  and 
  finely 
  tuberculated, 
  exhibited 
  as 
  very 
  

   irregular 
  large 
  tesserae 
  below 
  the 
  orbit, 
  and 
  represented 
  

   by 
  the 
  remains 
  of 
  one 
  long 
  narrow 
  plate 
  (x) 
  above 
  

   the 
  upper 
  jaw. 
  The 
  sclerotic 
  of 
  the 
  eye 
  is 
  ossified 
  (scl.). 
  

   The 
  margin 
  of 
  the 
  vomer 
  (vo.) 
  is 
  exposed 
  in 
  the 
  upper, 
  

   aud 
  that 
  of 
  the 
  splenial 
  (spl.) 
  in 
  the 
  lower 
  jaw, 
  both 
  

   of 
  these 
  bearing 
  stout 
  teeth 
  on 
  moderately 
  elongated 
  

   pedicles 
  ; 
  and 
  the 
  external 
  face 
  of 
  the 
  mandible 
  is 
  com- 
  

   pleted 
  by 
  the 
  tuberculated 
  dentary 
  (d.) 
  and 
  angular 
  (ag.) 
  

   plates. 
  The 
  postero-superior 
  portion 
  of 
  the 
  mandible, 
  

   however, 
  is 
  obscured 
  by 
  the 
  thin 
  facial 
  bones. 
  Still 
  

   further 
  below 
  the 
  skull 
  are 
  two 
  elements 
  which 
  seem 
  to 
  

   be 
  identifiable 
  as 
  ceratohyal 
  (ch.) 
  and 
  hypohyal 
  (%.)> 
  

   both 
  very 
  small, 
  and 
  the 
  former 
  remarkably 
  deepened 
  

   behind. 
  Among 
  the 
  remains 
  of 
  branchial 
  and 
  branchio- 
  

   stegal 
  apparatus, 
  the 
  calcified 
  gill-filaments 
  (fig. 
  1 
  a) 
  are 
  

   especially 
  conspicuous, 
  each 
  exhibiting 
  a 
  widely 
  spaced 
  

   series 
  of 
  very 
  fine 
  denticles 
  on 
  its 
  upper 
  margin. 
  Frag- 
  

   ments 
  of 
  the 
  operculum 
  (op.) 
  indicate 
  that 
  this 
  plate 
  was 
  

   as 
  coarsely 
  tuberculated 
  as 
  the 
  cranial 
  roof; 
  so 
  also, 
  in 
  

   part 
  at 
  least, 
  was 
  the 
  preoperculum 
  (p.op.), 
  which 
  is 
  dis- 
  

   played 
  almost 
  entirely 
  from 
  its 
  inner 
  aspect, 
  and 
  seems 
  

   to 
  be 
  bounded 
  below 
  in 
  the 
  counterpart 
  of 
  this 
  fossil 
  by 
  

   one 
  or 
  perhaps 
  two 
  branchiostegal 
  rays. 
  Below 
  the 
  oper- 
  

   cular 
  apparatus 
  are 
  observed 
  very 
  small, 
  tuberculated, 
  

   imbricating 
  scales, 
  which 
  are 
  more 
  or 
  less 
  lozenge-shaped 
  

   and 
  broader 
  than 
  deep, 
  and 
  extend 
  as 
  a 
  covering 
  between 
  

   the 
  rami 
  of 
  the 
  mandible. 
  The 
  neural 
  spines 
  (n.) 
  of 
  the 
  

   vertebral 
  axis 
  are 
  exhibited 
  enveloped 
  in 
  the 
  squamation, 
  

   those 
  in 
  the 
  abdominal 
  region 
  thickened 
  and 
  extending 
  

   almost 
  or 
  quite 
  to 
  the 
  dorsal 
  ridge. 
  As 
  shown 
  by 
  im- 
  

   pressions 
  in 
  the 
  counterpart, 
  they 
  are 
  about 
  30 
  in 
  number 
  

   to 
  the 
  base 
  of 
  the 
  caudal 
  pedicle. 
  Immediately 
  behind 
  

   the 
  opercular 
  apparatus 
  are 
  remains 
  of 
  the 
  clavicle, 
  orna- 
  

   mented 
  with 
  large 
  tubercles 
  on 
  its 
  lower 
  expansion 
  (cl.) 
  ; 
  

  

  