﻿EUGNATHID^. 
  323 
  

  

  exhibited, 
  and 
  distinctly 
  marked 
  with 
  the 
  finely 
  ridged, 
  

   partly 
  tuberculated 
  ornament. 
  A 
  few 
  slender 
  rays 
  

   gradually 
  increasing 
  in 
  length 
  occur 
  in 
  front 
  of 
  the 
  

   dorsal 
  fin, 
  but 
  there 
  are 
  no 
  fulcra 
  ; 
  the 
  stouter 
  rays 
  are 
  

   much 
  ornamented, 
  as 
  shown 
  in 
  the 
  enlarged 
  figure, 
  PI. 
  X. 
  

   fig. 
  4. 
  The 
  caudal 
  fin 
  is 
  large 
  and 
  much 
  forked, 
  with 
  

   stout 
  rays 
  anteriorly 
  but 
  very 
  delicate 
  rays 
  behind 
  ; 
  the 
  

   superior 
  fulcra 
  are 
  well 
  developed, 
  much 
  elongated, 
  and 
  

   ornamented 
  with 
  short 
  transverse 
  rugae 
  of 
  ganoine 
  ; 
  and 
  

   the 
  upper 
  caudal 
  lobe 
  was 
  evidently 
  somewhat 
  produced 
  

   as 
  usual 
  in 
  the 
  genus, 
  though 
  the 
  specimen 
  is 
  crushed 
  

   and 
  difficult 
  of 
  precise 
  interpretation. 
  Three 
  scales 
  from 
  

   the 
  region 
  of 
  the 
  dorsal 
  fin 
  are 
  shown 
  enlarged 
  in 
  PI. 
  X. 
  

   fig. 
  3, 
  and 
  the 
  lowermost 
  exhibits 
  the 
  feeble 
  rudiment 
  of 
  

   a 
  peg-and- 
  socket 
  articulation. 
  Ptirchased, 
  1866. 
  

  

  Ptycholepis 
  minor, 
  Egerton. 
  

   1852. 
  Ptycholepis 
  minor, 
  Sir 
  P. 
  Egerton, 
  Figs. 
  & 
  Descript. 
  Brit. 
  Or- 
  

   ganic 
  Remains, 
  dec. 
  vi. 
  (Mem. 
  Geol. 
  Surv.), 
  no. 
  7, 
  pi. 
  vii. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  British 
  Museum. 
  

  

  A 
  small 
  elongated 
  species, 
  the 
  length 
  of 
  the 
  head 
  with 
  opercular 
  

   apparatus 
  somewhat 
  exceeding 
  the 
  maximum 
  depth 
  of 
  the 
  trunk 
  

   and 
  occupying 
  about 
  one-quarter 
  of 
  the 
  total 
  length 
  of 
  the 
  fish. 
  

   The 
  ornament 
  of 
  the 
  external 
  bones 
  consisting 
  of 
  comparatively 
  

   delicate, 
  well-spaced 
  ridges 
  ; 
  the 
  scales 
  with 
  few 
  longitudinal 
  

   furrows, 
  sometimes 
  partly 
  convergent 
  behind, 
  and 
  with 
  some 
  con- 
  

   spicuous 
  vertical 
  folds 
  at 
  the 
  anterior 
  border. 
  

  

  The 
  feeble 
  nature 
  of 
  the 
  external 
  ornament 
  seems 
  to 
  be 
  charac- 
  

   teristic 
  of 
  this 
  species, 
  but 
  it 
  may 
  be 
  partly 
  a 
  deceptive 
  appearance 
  

   due 
  to 
  the 
  state 
  of 
  fossilization. 
  

  

  Form. 
  Sf 
  Loc. 
  Lower 
  Lias 
  : 
  Leicestershire. 
  

  

  P. 
  574, 
  P. 
  3694. 
  Type 
  specimen, 
  about 
  0-095 
  in 
  length, 
  in 
  counter- 
  

   part 
  ; 
  Barrow-on-Soar. 
  Egerton 
  <$f 
  Enniskillen 
  Colls. 
  

  

  P. 
  862. 
  Part 
  of 
  the 
  head, 
  abdominal 
  region, 
  and 
  pectoral 
  fin 
  of 
  a 
  

   much 
  larger 
  fish 
  ; 
  Barrow-on-ISoar. 
  Egerton 
  Coll. 
  

  

  Ptycholepis 
  avus, 
  Kner. 
  

  

  1866. 
  Ptycholepis 
  avus, 
  R. 
  Kner, 
  Sitzungsb. 
  k. 
  Akad. 
  Wiss., 
  math.- 
  

   naturw. 
  CI. 
  vol. 
  liii. 
  pt. 
  i. 
  p. 
  167, 
  pi. 
  ii. 
  fig. 
  2. 
  

  

  Type. 
  Distorted 
  fish 
  ; 
  Geological 
  Survey 
  Museum, 
  Vienna. 
  

   A 
  very 
  small 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  0*09. 
  Length 
  of 
  

   the 
  head 
  with 
  opercular 
  apparatus 
  somewhat 
  exceeding 
  the 
  maximum 
  

  

  y2 
  

  

  