﻿502 
  

  

  ACTINOPTEKYGII. 
  

  

  

  and 
  there 
  is 
  no 
  trace 
  of 
  a 
  gular 
  plate 
  in 
  any 
  specimen 
  examined 
  by 
  

   the 
  present 
  writer. 
  

  

  One 
  pair 
  of 
  large 
  supratemporal 
  plates 
  occurs 
  behind 
  the 
  occiput, 
  

   and 
  the 
  whole 
  of 
  the 
  trunk 
  is 
  covered 
  with 
  imbricating 
  cycloidal 
  

   scales, 
  which 
  are 
  distinctly 
  invested 
  with 
  ganoine 
  in 
  their 
  exposed 
  

   portion. 
  The 
  vertebral 
  centra 
  are 
  in 
  the 
  form 
  of 
  constricted 
  cylin- 
  

   ders, 
  not 
  completely 
  severing 
  the 
  intervertebral 
  portions 
  of 
  the 
  

   notochord 
  ; 
  and 
  they 
  are 
  often 
  strengthened 
  in 
  the 
  later 
  species 
  by 
  

   longitudinal 
  streaks 
  of 
  bone 
  on 
  the 
  periphery. 
  The 
  ribs 
  are 
  robust, 
  

   extending 
  almost 
  or 
  quite 
  to 
  the 
  ventral 
  border 
  ; 
  and 
  some 
  speci- 
  

   mens 
  seem 
  to 
  show 
  that 
  they 
  are 
  attached 
  to 
  broad 
  laminar 
  

   parapophyses. 
  The 
  delicate 
  neural 
  arches 
  in 
  the 
  abdominal 
  region 
  

   do 
  not 
  appear 
  to 
  have 
  been 
  fused 
  with 
  the 
  centra, 
  while 
  the 
  right 
  

   and 
  left 
  halves 
  are 
  separate, 
  and 
  the 
  short 
  neural 
  spines 
  are 
  loosely 
  

   apposed 
  to 
  them. 
  Both 
  the 
  neural 
  and 
  haemal 
  arches 
  in 
  the 
  caudal 
  

   region 
  are 
  fused 
  with 
  the 
  vertebral 
  centra 
  and 
  with 
  their 
  respective 
  

   spines 
  ; 
  and 
  where 
  the 
  arch 
  joins 
  the 
  spine 
  there 
  is 
  sometimes 
  a 
  

   slight 
  triangular 
  expansion 
  of 
  the 
  bone. 
  Intermuscular 
  bones 
  are 
  

   observed 
  across 
  the 
  neural 
  arches 
  in 
  the 
  abdominal 
  region. 
  

  

  The 
  basal 
  bones 
  of 
  the 
  pectoral 
  fin 
  are 
  unknown, 
  but 
  the 
  pelvic 
  

   fin-supports 
  are 
  often 
  well 
  exhibited. 
  Each 
  of 
  the 
  latter 
  is 
  trian- 
  

   gular 
  in 
  form, 
  tapering 
  forwards 
  and 
  thickened 
  on 
  the 
  outer 
  border. 
  

   There 
  is 
  nothing 
  worthy 
  of 
  note 
  in 
  the 
  supports 
  of 
  the 
  median 
  fins, 
  

   except 
  that 
  the 
  foremost 
  two 
  or 
  three 
  elements 
  in 
  the 
  dorsal 
  are 
  

   sometimes 
  fused 
  together. 
  

  

  Leptolepis 
  bronni, 
  Agassiz. 
  

  

  1830. 
  Cyprinus 
  coryphcenoides, 
  H. 
  G. 
  Bronn, 
  Neues 
  Jahrb. 
  p. 
  14, 
  pi. 
  i. 
  

  

  fig. 
  1. 
  

   1832. 
  Leptolepis 
  bronnii, 
  L. 
  Agassiz, 
  ibid. 
  p. 
  146. 
  

   1833-44. 
  Leptolepis 
  bronnii, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  p. 
  13 
  ; 
  

  

  pt. 
  ii. 
  pp. 
  133, 
  294. 
  

   1852. 
  Leptolepis 
  constrictus, 
  Sir 
  P. 
  Egerton, 
  Figs. 
  & 
  Descript. 
  Brit. 
  

  

  Organic 
  Remains, 
  dec. 
  vi. 
  (Mem. 
  Geol. 
  Surv.), 
  no. 
  9, 
  pi. 
  ix. 
  

  

  [Nearly 
  complete 
  fishes 
  ; 
  Bath 
  Museum.] 
  

   1858. 
  Leptolepis 
  bronnii, 
  F. 
  A. 
  Quenstedt, 
  Der 
  Jura, 
  p. 
  238, 
  pi. 
  xxxiii. 
  

  

  figs. 
  8-11. 
  

   1874. 
  Leptolepis 
  constrictus, 
  H. 
  E. 
  Sauvage, 
  Rev. 
  Sci. 
  Nat. 
  vol. 
  ii. 
  

  

  p. 
  418, 
  pi. 
  vii. 
  fig. 
  4, 
  and 
  in 
  Durnortier, 
  Etudes 
  Paleont. 
  Depots 
  

  

  Jurass. 
  Bassin 
  Rhone, 
  pt. 
  iv. 
  p. 
  29. 
  

   1874. 
  Leptolepis 
  affinis, 
  H. 
  E. 
  Sauvage, 
  ibid. 
  p. 
  419, 
  pi. 
  vii. 
  figs. 
  5-9, 
  

  

  and 
  op. 
  cit. 
  p. 
  30. 
  [Nearly 
  complete 
  fish.] 
  

   (?) 
  1874. 
  Leptolepis 
  pronus, 
  H. 
  E. 
  Sauvage, 
  ibid. 
  p. 
  424, 
  pi. 
  vii. 
  fig. 
  1 
  

  

  [Nearly 
  complete 
  fish.] 
  

   (?) 
  1874. 
  Leptolepis 
  pachystetus, 
  H. 
  E. 
  Sauvage, 
  ibid. 
  p. 
  426, 
  pi. 
  vii. 
  

  

  figs. 
  2, 
  3. 
  [Nearly 
  complete 
  fish.] 
  

  

  