﻿390 
  ACTINOPTERYG1I. 
  

  

  The 
  following 
  specimens 
  are 
  not 
  specifically 
  determined 
  : 
  — 
  

  

  P. 
  3704. 
  Imperfect 
  head 
  and 
  abdominal 
  region, 
  the 
  latter 
  much 
  

   deepened 
  and 
  with 
  remarkably 
  small 
  scales 
  ; 
  Upper 
  Lias, 
  

   Ilminster, 
  Somersetshire. 
  The 
  operculum 
  is 
  triangular 
  

   and 
  slightly 
  deeper 
  than 
  broad. 
  Enniskillen 
  Coll. 
  

  

  P. 
  900. 
  Imperfect 
  head, 
  pectoral 
  fin, 
  and 
  anterior 
  scales 
  of 
  a 
  small 
  

  

  fish 
  ; 
  Ilminster. 
  Egerton 
  Coll. 
  

  

  32245. 
  Remains 
  of 
  small 
  fish 
  with 
  relatively 
  small 
  scales 
  ; 
  Upper 
  

  

  Lias, 
  Curcy, 
  Normandy. 
  Tesson 
  Coll. 
  

  

  An 
  imperfect 
  head 
  of 
  Pachycormus 
  from 
  the 
  Upper 
  Lias 
  of 
  Lozere, 
  

   Prance, 
  has 
  also 
  been 
  described 
  under 
  the 
  name 
  of 
  Cephenoplosus 
  

   typus 
  by 
  H. 
  E. 
  Sauvage, 
  Revue 
  Sci. 
  Nat. 
  vol. 
  ii. 
  (1874), 
  p. 
  430, 
  

   pi. 
  viii. 
  Nothing 
  is 
  known 
  of 
  the 
  species 
  from 
  the 
  Lower 
  Lias 
  of 
  

   Lyme 
  Regis 
  named 
  Pachycormus 
  leptosteus 
  by 
  Agassiz, 
  Poiss. 
  Foss. 
  

   vol. 
  ii. 
  pt. 
  ii. 
  (1844), 
  p. 
  114. 
  

  

  The 
  fragmentary 
  head 
  and 
  pectoral 
  fin 
  described 
  as 
  follows 
  is 
  

   commonly 
  compared 
  with 
  Pachycormus 
  : 
  — 
  

  

  Saurichthys 
  gujas 
  — 
  Lyco&us 
  gigas, 
  F. 
  A. 
  Quenstedt, 
  Der 
  Jura 
  

   (1858), 
  p. 
  240, 
  pi. 
  xxxiii. 
  fig. 
  1. 
  — 
  Upper 
  Lias 
  ; 
  Holzmaden, 
  

   Wiirtemberg. 
  [Tubingen 
  University 
  Museum.] 
  

  

  Quenstedt 
  places 
  next 
  to 
  this 
  some 
  problematical 
  cranial 
  bones 
  

   from 
  the 
  Upper 
  Lias 
  of 
  Ohmden, 
  described 
  under 
  the 
  provisional 
  

   name 
  of 
  Pachylepis, 
  op. 
  cit. 
  p. 
  241, 
  pi. 
  xxxiii. 
  figs. 
  12-15. 
  

  

  Genus 
  HYPSOCORMUS, 
  Wagner. 
  

  

  [Gelehrte 
  Anzeig. 
  k. 
  bay. 
  Akad. 
  Wiss. 
  vol. 
  1. 
  I860, 
  p. 
  214.] 
  

  

  Trunk 
  laterally 
  compressed 
  and 
  irregularly 
  fusiform, 
  relatively 
  

   deep 
  in 
  the 
  abdominal 
  region, 
  very 
  narrow 
  at 
  the 
  extremity 
  of 
  the 
  

   caudal 
  pedicle. 
  Head 
  small 
  and 
  less 
  deep 
  than 
  the 
  trunk; 
  rostrum 
  

   moderately 
  produced 
  ; 
  prem 
  axilla 
  large 
  and 
  triangular 
  in 
  shape 
  ; 
  

   maxilla 
  long 
  and 
  slender. 
  Dentition 
  powerful, 
  all 
  the 
  principal 
  

   teeth 
  round 
  or 
  oval 
  in 
  section, 
  without 
  sharp 
  edges, 
  and 
  fixed 
  in 
  

   incomplete 
  sockets 
  ; 
  those 
  of 
  the 
  vomerine 
  and 
  splenial 
  bones 
  

   especially 
  large 
  ; 
  those 
  of 
  the 
  maxilla, 
  premaxilla, 
  and 
  dentary 
  in 
  

   a 
  single 
  widely-spaced 
  series, 
  with 
  minute 
  clustered 
  teeth 
  exter- 
  

   nally 
  ; 
  those 
  of 
  the 
  pterygoid 
  bones 
  more 
  or 
  less 
  granular. 
  Gular 
  

   plate 
  present. 
  Ossifications 
  in 
  sheath 
  of 
  notochord 
  absent 
  ; 
  ribs 
  

   short 
  and 
  slender. 
  Fin-fulcra 
  minute 
  or 
  absent. 
  Pectoral 
  fins 
  large 
  

   and 
  sickle-shaped, 
  with 
  straight 
  anterior 
  border 
  stiffened 
  by 
  the 
  

   fusion 
  of 
  the 
  foremost 
  three 
  or 
  four 
  rays, 
  which 
  gradually 
  increase 
  

  

  