﻿400 
  

  

  A.CTINOPTEEYGII. 
  

  

  pt. 
  i. 
  (1866), 
  p. 
  183, 
  pi. 
  ii. 
  fig. 
  3; 
  W. 
  Deecke, 
  Palaa- 
  

   ontogr. 
  vol. 
  xxxv. 
  (1889), 
  p. 
  126.— 
  Upper 
  Trias 
  ; 
  Raibl, 
  

   Carinthia. 
  [Museum 
  of 
  Imperial 
  Geological 
  Survey, 
  

   Vienna.] 
  

   Prohalecites 
  porro, 
  W. 
  Deecke, 
  loc. 
  cit. 
  p. 
  125, 
  pi. 
  vii. 
  figs. 
  5-7. 
  

   Pholidophorus 
  porro, 
  C. 
  Bellotti, 
  in 
  A. 
  Stoppani, 
  Studii 
  

   Geol. 
  e 
  Paleont. 
  Lombardia 
  (1857), 
  p. 
  430 
  ; 
  0. 
  G. 
  Costa, 
  

   Ittiol. 
  Toss. 
  Ital. 
  (1873), 
  p. 
  65, 
  pi. 
  v. 
  fig. 
  9.— 
  Upper 
  

   Trias 
  ; 
  Perledo, 
  Como. 
  [The 
  type 
  species 
  of 
  Prohalecites. 
  

   Milan 
  Museum.] 
  

  

  Either 
  to 
  the 
  Pholidophoridae 
  or 
  to 
  the 
  Leptolepidae 
  may 
  also 
  

   probably 
  be 
  referred 
  the 
  unique 
  fragmentary 
  fossil 
  described 
  as 
  

   follows 
  : 
  — 
  

  

  Megalopterus 
  raiblianus, 
  R. 
  Kner, 
  Sitzungsb. 
  k. 
  Akad. 
  Wiss., 
  

   math.-naturw. 
  CI. 
  vol. 
  liii. 
  pt. 
  i. 
  (1866), 
  p. 
  174, 
  pi. 
  iv. 
  

   fig. 
  1. 
  — 
  Upper 
  Trias 
  ; 
  Eaibl, 
  Carinthia. 
  [Imperfect 
  

   caudal 
  region 
  ; 
  Imperial 
  Geological 
  Survey 
  Museum, 
  

   Vienna. 
  The 
  type 
  species 
  of 
  Megalopterus.! 
  

  

  Family 
  OLIGOPLEUMD^E. 
  

  

  Trunk 
  fusiform. 
  Head 
  with 
  delicate 
  membrane- 
  bones, 
  scarcely, 
  

   if 
  at 
  all, 
  enamelled 
  ; 
  mandibular 
  suspensorium 
  nearly 
  vertical 
  or 
  

   inclined 
  forwards, 
  and 
  gape 
  of 
  mouth 
  wide 
  ; 
  teeth 
  small 
  or 
  of 
  

   moderate 
  size. 
  Vertebral 
  centra 
  well-ossified, 
  with 
  no 
  distinct 
  

   pleurocentra 
  and 
  hypocentra 
  in 
  any 
  part 
  of 
  the 
  column 
  ; 
  large 
  free 
  

   neural 
  spines 
  in 
  the 
  abdominal 
  region 
  ; 
  ribs 
  short 
  ; 
  no 
  fused 
  or 
  

   expanded 
  haemal 
  arches 
  at 
  the 
  base 
  of 
  the 
  tail. 
  Intermuscular 
  

   bones 
  rare 
  or 
  absent. 
  Fin-fulcra 
  present 
  ; 
  dorsal 
  and 
  anal 
  fins 
  

   acuminate 
  in 
  front, 
  of 
  variable 
  length. 
  Scales 
  thin, 
  more 
  or 
  less 
  

   rounded, 
  and 
  deeply 
  imbricating. 
  

  

  Synopsis 
  of 
  Genera. 
  

  

  I. 
  Dorsal 
  fin 
  short-based. 
  

  

  Vertebral 
  centra 
  not 
  pitted 
  ; 
  mandible 
  pro- 
  

   minent 
  ; 
  dorsal 
  opposed 
  to 
  anal 
  fin 
  Oligopleurus 
  (p. 
  491) 
  . 
  

  

  Vertebral 
  centra 
  with 
  two 
  lateral 
  pits 
  ; 
  man- 
  

   dible 
  not 
  prominent; 
  greater 
  portion 
  of 
  

   dorsal 
  in 
  advance 
  of 
  anal 
  fin 
  Oeonoscopus 
  (p. 
  494). 
  

  

  II. 
  Dorsal 
  fin 
  extended. 
  

  

  Vertebral 
  centra 
  with 
  two 
  lateral 
  pits 
  ; 
  fulcra 
  

   on 
  all 
  fins 
  ; 
  anal 
  fin 
  short, 
  opposed 
  to 
  

   hinder 
  end 
  of 
  dorsal 
  ; 
  caudal 
  fin 
  forked 
  . 
  . 
  Spathiurus 
  (p. 
  498). 
  

  

  