﻿SEMIONOTID^]. 
  55 
  

  

  Genus 
  SEMIONOTUS, 
  

  

  [Neues 
  Jahrb. 
  1832, 
  p. 
  144.] 
  

  

  Syn. 
  Ischypterus, 
  Sir 
  P. 
  Egerton, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  iii- 
  

   1847, 
  p. 
  277. 
  

  

  Trunk 
  fusiform. 
  Marginal 
  teeth 
  slender, 
  conical, 
  and 
  somewhat 
  

   spaced, 
  inner 
  teeth 
  stouter 
  ; 
  opercular 
  apparatus 
  well-developed, 
  

   with 
  a 
  narrow 
  arched 
  preoperculum. 
  Ribs 
  ossified. 
  Fin-fulcra 
  

   large. 
  Paired 
  fins 
  small 
  ; 
  dorsal 
  fin 
  large, 
  arising 
  at 
  or 
  behind 
  the 
  

   middle 
  of 
  the 
  back 
  and 
  in 
  part 
  opposed 
  to 
  the 
  relatively 
  small 
  anal 
  ; 
  

   caudal 
  fin 
  slightly 
  forked. 
  Scales 
  smooth 
  or 
  feebly 
  ornamented, 
  

   and 
  the 
  narrow 
  overlapped 
  margin 
  not 
  produced 
  at 
  the 
  angles 
  ; 
  

   flank-scales 
  not 
  more 
  than 
  twice 
  as 
  deep 
  as 
  broad, 
  and 
  those 
  of 
  the 
  

   ventral 
  aspect 
  nearly 
  as 
  deep 
  as 
  broad 
  ; 
  the 
  dorsal 
  ridge-series 
  of 
  

   acuminate 
  scales 
  forming 
  a 
  prominent 
  crest. 
  

  

  . 
  Semionotus 
  bergeri, 
  Agassiz. 
  

   [Plate 
  II. 
  fig. 
  3.] 
  

  

  1832. 
  Palceoniscum 
  arenaceum, 
  H. 
  A. 
  C. 
  Berger, 
  Verstein. 
  Sandst. 
  

   Coburg. 
  Gegend. 
  p. 
  18, 
  pi. 
  i. 
  fig. 
  1. 
  

  

  1833. 
  Semionotus 
  spixi, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  p. 
  8 
  (name 
  

   only). 
  

  

  1833-36. 
  Semionotus 
  bergeri, 
  L. 
  Agassiz, 
  ibid. 
  pp. 
  8, 
  224, 
  pi. 
  xxvu 
  

   figs. 
  2, 
  3. 
  

  

  1834. 
  Semionotus 
  bergeri, 
  L. 
  Agassiz, 
  Neues 
  Jahrb. 
  p. 
  380. 
  

  

  1843. 
  Semionotus 
  esox, 
  H. 
  A. 
  C. 
  Berger, 
  Neues 
  Jahrb. 
  p. 
  86. 
  [Dis- 
  

   torted 
  fish; 
  Royal 
  Geological 
  Museum, 
  Gottingen.] 
  

  

  1851. 
  Semionotus 
  bergeri, 
  0. 
  von 
  Schauroth, 
  Zeitschr. 
  deutsch. 
  geol. 
  

   Ges. 
  vol. 
  iii. 
  p. 
  405, 
  pi. 
  xvii. 
  

  

  1854. 
  Semionotus, 
  J. 
  G. 
  Bornemann, 
  ibid. 
  vol. 
  vi. 
  p. 
  612, 
  pi. 
  xxv. 
  

  

  1854. 
  Semionotus 
  bergeri, 
  H. 
  A. 
  C. 
  Berger, 
  Neues 
  Jahrb. 
  p. 
  321. 
  

  

  (?) 
  1861. 
  Semionotus 
  bergeri, 
  0. 
  Fraas, 
  Wiirtt. 
  Jahresh. 
  vol. 
  xvii. 
  pp. 
  93, 
  

   94, 
  pi. 
  i. 
  fig. 
  6. 
  

  

  1864. 
  Semionotus 
  bergeri, 
  J. 
  Striiver, 
  Zeitschr. 
  deutsch. 
  geol. 
  Ges.. 
  

   vol. 
  xvi. 
  p. 
  305, 
  pi. 
  xiii. 
  figs. 
  1, 
  3, 
  4. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  University 
  Geological 
  Museum, 
  Gottingen. 
  

  

  The 
  type 
  species, 
  a 
  fish 
  more 
  than 
  three 
  times 
  as 
  long 
  as 
  its 
  

   greatest 
  depth, 
  attaining 
  a 
  length 
  of 
  about 
  0-18. 
  Trunk 
  regularly 
  

   fusiform, 
  the 
  depth 
  of 
  the 
  caudal 
  pedicle 
  somewhat 
  more 
  than 
  one- 
  

   third 
  as 
  great 
  as 
  the 
  maximum 
  depth 
  of 
  the 
  abdominal 
  region. 
  

   Head 
  with 
  opercular 
  apparatus 
  occupying 
  nearly 
  one-quarter 
  of 
  

   the 
  total 
  length 
  ; 
  the 
  external 
  bones 
  sparsely 
  tuberculated. 
  Pelvic 
  

   fins 
  arising 
  nearly 
  midway 
  between 
  the 
  pectorals 
  and 
  the 
  anal 
  ; 
  

   dorsal 
  fin 
  arising 
  immediately 
  behind 
  the 
  middle 
  of 
  the 
  back, 
  much 
  

  

  