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  ACTIN0PTEKYG1I. 
  

  

  large, 
  extended 
  forwards 
  as 
  short, 
  acute 
  ridges 
  ; 
  anterior 
  half 
  of 
  the 
  

   scale 
  smooth 
  or 
  marked 
  with 
  finer 
  transverse 
  ridges. 
  

  

  Form. 
  6f 
  Log. 
  Upper 
  Triassic 
  (Lettenkohl) 
  : 
  Wiirtemberg. 
  

  

  P. 
  7402. 
  Two 
  fragments 
  of 
  dolomite 
  with 
  scales 
  and 
  a 
  thin 
  tuber- 
  

   culated 
  bone 
  ; 
  Comburg, 
  near 
  Hall. 
  One 
  scale 
  is 
  smooth 
  

   n 
  its 
  anterior 
  half. 
  Purchased. 
  

  

  Genus 
  PRISTISOMUS, 
  A. 
  S. 
  Woodward. 
  

  

  [Foss. 
  Fishes 
  Hawkesbury 
  Series, 
  Gosford 
  (Mem. 
  Geol. 
  Surv. 
  

  

  N. 
  S. 
  Wales, 
  Palseont. 
  no. 
  4, 
  1890), 
  p. 
  32.] 
  

  

  Trunk 
  deeply 
  fusiform. 
  Marginal 
  teeth 
  large, 
  styliform, 
  and 
  in 
  

   olose 
  series. 
  Fin-fulcra 
  small. 
  Paired 
  fins 
  moderately 
  developed 
  ; 
  

   dorsal 
  and 
  anal 
  fins 
  remote, 
  not 
  much 
  extended, 
  the 
  former 
  partly 
  

   opposed 
  to 
  the 
  latter 
  ; 
  caudal 
  fin 
  robust, 
  scarcely 
  forked. 
  Three 
  or 
  

   more 
  series 
  of 
  the 
  flank-scales 
  vertically 
  elongated; 
  dorsal 
  and 
  

   ventral 
  scales 
  as 
  broad 
  as 
  deep 
  ; 
  a 
  dorsal 
  and 
  ventral 
  series 
  of 
  

   prominent, 
  acuminate 
  ridge-scales. 
  

  

  Pristisomus 
  gracilis, 
  A. 
  S. 
  Woodward. 
  

  

  1890. 
  Pristisomus 
  gracilis, 
  A. 
  S. 
  Woodward, 
  op. 
  cit. 
  p. 
  33, 
  pi. 
  v. 
  fig. 
  1, 
  

   pi. 
  vi. 
  fig. 
  1, 
  pi. 
  viii. 
  fig. 
  1. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  Geol. 
  Survey 
  Museum, 
  Sydney. 
  

  

  The 
  type 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  0'12. 
  Head 
  with 
  

   opercular 
  apparatus 
  occupying 
  about 
  one-quarter 
  of 
  the 
  total 
  length 
  ; 
  

   trunk 
  gracefully 
  fusiform, 
  the 
  maximum 
  depth 
  contained 
  more 
  than 
  

   two-and-a-half 
  times 
  in 
  the 
  total 
  length 
  of 
  the 
  fish. 
  Dorsal 
  and 
  

   anal 
  fins 
  almost 
  of 
  equal 
  size, 
  much 
  elevated, 
  and 
  with 
  a 
  relatively 
  

   short 
  base-line. 
  

  

  Form. 
  Sf 
  Log. 
  Lower 
  Hawkesbury- 
  Wianamatta 
  Series 
  (Upper 
  

   Trias) 
  : 
  Gosford, 
  New 
  South 
  Wales. 
  

  

  P. 
  6275. 
  Fish 
  wanting 
  paired 
  fins. 
  By 
  exchange, 
  1890. 
  

  

  P. 
  6277. 
  Slab 
  showing 
  another 
  specimen 
  associated 
  with 
  P. 
  crassus. 
  

  

  By 
  exchange, 
  1890. 
  

  

  Pristisomus 
  latus, 
  A. 
  S. 
  Woodward. 
  

   1890. 
  Pristisomus 
  latus, 
  A. 
  S. 
  Woodward, 
  op. 
  cit. 
  p. 
  35, 
  pi. 
  v. 
  figs. 
  2-4. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  Geol. 
  Survey 
  Museum, 
  Sydney. 
  

  

  A 
  slightly 
  larger 
  species 
  than 
  the 
  type, 
  with 
  somewhat 
  deeper 
  

  

  