﻿SEMI0N0TID2E. 
  53 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  Newcastle-upon-Tyne 
  Museum. 
  

  

  A 
  species 
  about 
  as 
  large 
  as 
  the 
  type, 
  but 
  more 
  slender. 
  Head 
  

   with 
  opercular 
  apparatus 
  occupying 
  slightly 
  less 
  than 
  one-quarter 
  

   of 
  the 
  total 
  length 
  ; 
  maximum 
  depth 
  of 
  trunk 
  equalling 
  about 
  twice 
  

   that 
  of 
  the 
  caudal 
  pedicle 
  and 
  comprised 
  at 
  least 
  five 
  times 
  in 
  the 
  

   total 
  length. 
  Head 
  and 
  opercular 
  bones 
  faintly 
  rugose. 
  Scales 
  

   unornamented, 
  not 
  serrated, 
  relatively 
  larger 
  than 
  in 
  the 
  type 
  

   species. 
  

  

  Form. 
  Sf 
  Log. 
  Upper 
  Permian 
  (Magnesian 
  Limestone): 
  Durham. 
  

  

  44211. 
  Fish 
  about 
  0*06 
  in 
  length, 
  showing 
  some 
  of 
  the 
  supports 
  of 
  

   the 
  anal 
  and 
  caudal 
  fins, 
  and 
  an 
  enlarged 
  anal 
  scale 
  ; 
  

   Fulwell 
  Hill, 
  near 
  Sunderland. 
  Purchased, 
  1873. 
  

  

  P. 
  3482. 
  Imperfect 
  remains 
  of 
  a 
  fish 
  about 
  0*085 
  in 
  length 
  ; 
  

   Fulwell 
  Hill. 
  Enniskillen 
  Coll. 
  

  

  P. 
  4342 
  a. 
  Specimen 
  as 
  large 
  as 
  the 
  first 
  showing 
  only 
  fragments 
  of 
  

   the 
  fins 
  ; 
  Fulwell 
  Hill. 
  Enniskillen 
  Coll. 
  

  

  P. 
  4343. 
  More 
  imperfect 
  smaller 
  specimen 
  ; 
  Fulwell 
  Hill. 
  

  

  Enniskillen 
  Coll. 
  

  

  Acentrophorus 
  altus 
  (Kirkby). 
  

  

  1862. 
  PalcBoniscus 
  lotus, 
  J. 
  W. 
  Kirkby 
  (non 
  Redfield), 
  Ann. 
  Mag. 
  Nat. 
  

  

  Hist. 
  [3] 
  vol. 
  ix. 
  p. 
  268. 
  

   1864. 
  Palceoniscus 
  altus, 
  J. 
  W. 
  Kirkby, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xx. 
  

  

  p. 
  356, 
  pi. 
  xviii. 
  fig. 
  1. 
  

   1877. 
  Acentrophorus 
  altus, 
  R. 
  H. 
  Traquair, 
  ibid. 
  vol. 
  xxxiii. 
  p. 
  565. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  Newcastle-upon-Tyne 
  Museum. 
  

  

  A 
  species 
  about 
  as 
  large 
  as 
  the 
  type, 
  but 
  more 
  robust. 
  Head 
  

   with 
  opercular 
  apparatus 
  occupying 
  at 
  least 
  one- 
  quarter 
  of 
  the 
  

   total 
  length 
  ; 
  maximum 
  depth 
  of 
  trunk 
  equalling 
  about 
  twice 
  that 
  

   .of 
  the 
  caudal 
  pedicle, 
  and 
  comprised 
  only 
  three 
  times 
  in 
  the 
  total 
  

   length. 
  Head 
  and 
  opercular 
  bones 
  faintly 
  rugose 
  ; 
  operculum 
  as 
  

   deep 
  as 
  broad. 
  Scales 
  unornamented, 
  not 
  serrated. 
  

  

  Form. 
  Sf 
  Log. 
  Upper 
  Permian 
  (Magnesian 
  Limestone) 
  : 
  Durham. 
  

  

  The 
  only 
  known 
  examples 
  of 
  this 
  species 
  were 
  obtained 
  from 
  

   the 
  Old 
  Quarry, 
  Fulwell, 
  and 
  there 
  are 
  none 
  in 
  the 
  Collection. 
  

  

  Acentrophorus 
  glaphyrus 
  (Agassiz). 
  

   1835. 
  Palceoniscus 
  glaphyrus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  p. 
  98, 
  

  

  pi. 
  x 
  c. 
  figs. 
  1, 
  2. 
  

   1850. 
  Palceoniscus 
  glaphyrus, 
  W. 
  King, 
  Permian 
  Foss. 
  (Pal. 
  Soc), 
  

  

  p. 
  224, 
  pi. 
  xxii. 
  fig. 
  3 
  (? 
  fig. 
  4). 
  

  

  