﻿MACKOSEMIIDiB. 
  171 
  

  

  Ophiopsis 
  dorsalis, 
  Agassiz. 
  

   1844. 
  Ophiopsis 
  dorsalis, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  p. 
  291, 
  

   pi. 
  xxxvi. 
  fig. 
  5. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  British 
  Museum. 
  

  

  A 
  much 
  elongated 
  species, 
  attaining 
  a 
  length 
  of 
  0*16. 
  Head 
  

   with 
  opercular 
  apparatus 
  occupying 
  one-fifth 
  of 
  the 
  total 
  length 
  ; 
  

   maximum 
  depth 
  of 
  trunk 
  twice 
  as 
  great 
  as 
  the 
  width 
  of 
  the 
  caudal 
  

   pedicle, 
  and 
  contained 
  somewhat 
  more 
  than 
  six 
  times 
  in 
  the 
  total 
  

   length. 
  Head 
  and 
  opercular 
  bones 
  externally 
  rugose. 
  Dorsal 
  fin 
  

   comprising 
  not 
  less 
  than 
  35 
  rays 
  and 
  occupying 
  the 
  greater 
  part 
  of 
  

   the 
  back, 
  not 
  so 
  deep 
  as 
  the 
  trunk 
  at 
  its 
  point 
  of 
  origin 
  ; 
  pelvic 
  

   fins 
  arising 
  slightly 
  in 
  advance 
  of 
  the 
  middle 
  point 
  between 
  the 
  

   pectorals 
  and 
  caudal. 
  Scales 
  smooth 
  and 
  somewhat 
  concave 
  exter- 
  

   nally, 
  those 
  of 
  the 
  flank 
  finely 
  serrated 
  on 
  the 
  hinder 
  border, 
  those 
  

   of 
  the 
  caudal 
  region 
  often 
  irregularly 
  punctated. 
  

  

  Form. 
  Sf 
  Log. 
  Purbeck 
  Beds 
  : 
  Dorsetshire. 
  

  

  P. 
  466. 
  Type 
  specimen 
  ; 
  probably 
  from 
  Swanage, 
  erroneously 
  

   described 
  by 
  Agassiz 
  as 
  from 
  the 
  Lower 
  Oolite 
  of 
  North- 
  

   ampton. 
  Egerton 
  Coll. 
  

  

  P. 
  7496. 
  A 
  more 
  imperfectly 
  preserved 
  specimen, 
  in 
  counterpart 
  ; 
  

   Swanage. 
  Purchased. 
  

  

  Ophiopsis 
  flesheri 
  (Agassiz). 
  

  

  1844. 
  Pholidophorus 
  Jlesherii, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  

  

  p. 
  281, 
  pi. 
  xxxvii. 
  fig. 
  8. 
  

   1887. 
  Ophiopsis 
  flesheri, 
  K. 
  A. 
  von 
  Zittel, 
  Handb. 
  Palseont. 
  vol. 
  iii. 
  

  

  p. 
  217. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  imperfect 
  counterpart 
  in 
  British 
  

   Museum. 
  

  

  A 
  much 
  elongated 
  species, 
  attaining 
  a 
  length 
  of 
  0*2. 
  Head 
  with 
  

   opercular 
  apparatus 
  occupying 
  one-fifth 
  of 
  the 
  total 
  length 
  ; 
  maxi- 
  

   mum 
  depth 
  of 
  trunk 
  twice 
  as 
  great 
  as 
  the 
  width 
  of 
  the 
  caudal 
  

   pedicle, 
  and 
  contained 
  seven 
  times 
  in 
  the 
  total 
  length. 
  Dorsal 
  fin 
  

   occupying 
  about 
  half 
  the 
  length 
  of 
  the 
  back, 
  and 
  apparently 
  much 
  

   elevated 
  in 
  front; 
  pelvic 
  fins 
  arising 
  slightly 
  in 
  advance 
  of 
  the 
  

   middle 
  point 
  between 
  the 
  pectorals 
  and 
  caudal. 
  [Scales 
  apparently 
  

   serrated.] 
  

  

  Form. 
  Sf 
  Log. 
  Inferior 
  Oolite 
  : 
  Northamptonshire. 
  

  

  47138. 
  Portion 
  of 
  counterpart 
  of 
  the 
  type 
  specimen, 
  extending 
  

   from 
  the 
  back 
  of 
  the 
  head 
  to 
  the 
  middle 
  of 
  the 
  caudal 
  

   region; 
  from 
  the 
  railway- 
  tunnel 
  near 
  Blisworth. 
  The 
  

  

  