﻿SEMIONOTrD^E. 
  109 
  

  

  1854. 
  Lepidotusjittoni, 
  J. 
  Morris, 
  ibid. 
  p. 
  331. 
  

  

  1854. 
  Lepidotus 
  mantelli, 
  J. 
  Morris, 
  ibid. 
  p. 
  332. 
  

  

  1860. 
  Lepidotus 
  Jittoni, 
  J. 
  E. 
  Lee, 
  Geologist, 
  vol. 
  iii. 
  p. 
  458, 
  pi. 
  xii. 
  

  

  1887. 
  Lepidotus 
  mantelli, 
  W. 
  Branco, 
  Abh. 
  geol. 
  Specialk. 
  Preussen 
  n. 
  

  

  Thiiring. 
  Staaten, 
  vol. 
  vii. 
  p. 
  345, 
  pi. 
  iii. 
  figs. 
  1, 
  2. 
  

   1890. 
  Lepidotus 
  mantelli, 
  Woodward 
  & 
  Sherborn, 
  Catal. 
  Brit. 
  Foss. 
  

  

  Vertebrata, 
  p. 
  112. 
  

  

  Type. 
  Portion 
  of 
  fish 
  ; 
  British 
  Museum. 
  

  

  A 
  species 
  attaining 
  a 
  length 
  of 
  about 
  1 
  metre. 
  Trunk 
  very 
  

   robust, 
  and 
  head 
  with 
  opercular 
  apparatus 
  occupying 
  about 
  one- 
  

   quarter 
  of 
  the 
  total 
  length 
  of 
  the 
  fish. 
  Maximum 
  width 
  of 
  operculum 
  

   nearly 
  two-thirds 
  as 
  great 
  as 
  its 
  depth, 
  and 
  equalling 
  about 
  one- 
  

   third 
  the 
  length 
  of 
  the 
  head 
  ; 
  frontal 
  profile 
  very 
  slightly 
  bent 
  and 
  

   snout 
  acute. 
  External 
  bones 
  more 
  or 
  less 
  rugose 
  or 
  tuberculated 
  ; 
  

   parietal 
  bones 
  much 
  less 
  than 
  half 
  as 
  long 
  as 
  the 
  frontals, 
  which 
  

   are 
  three 
  times 
  as 
  long 
  as 
  their 
  maximum 
  width, 
  very 
  narrow 
  in 
  

   front, 
  and 
  united 
  throughout 
  their 
  length 
  by 
  a 
  nearly 
  straight 
  

   median 
  suture; 
  mandibular 
  symphysis 
  very 
  robust, 
  the 
  dentary 
  

   bone 
  being 
  much 
  horizontally 
  extended 
  to 
  support 
  the 
  large 
  denti- 
  

   gerous 
  splenial. 
  Inner 
  teeth 
  very 
  short 
  and 
  stout, 
  the 
  majority, 
  

   when 
  unworn, 
  with 
  a 
  slightly 
  acuminate 
  crown, 
  but 
  always 
  smooth 
  ; 
  

   marginal 
  teeth 
  also 
  robust 
  ; 
  splenial 
  teeth 
  in 
  five 
  (sometimes 
  six) 
  

   irregular 
  concentric 
  series 
  increasing 
  in 
  size 
  within; 
  pterygo- 
  

   palatine 
  teeth 
  in 
  three 
  (sometimes 
  four) 
  longitudinal 
  series 
  increasing 
  

   in 
  size 
  within 
  ; 
  vomerine 
  dentition 
  increasing 
  in 
  size 
  backwards, 
  the 
  

   anterior 
  teeth 
  very 
  irregular, 
  in 
  about 
  four 
  longitudinal 
  series, 
  the 
  

   largest 
  posterior 
  teeth 
  comprising 
  two 
  pairs 
  with 
  one 
  median 
  tooth 
  

   in 
  advance. 
  Ping-vertebrae 
  present 
  in 
  the 
  adult. 
  Ein-fulcra 
  very 
  

   large 
  ; 
  pelvic 
  fins 
  arising 
  nearer 
  to 
  the 
  pectorals 
  than 
  to 
  the 
  anal 
  ; 
  

   anal 
  fin 
  arising 
  opposite 
  the 
  hinder 
  extremity 
  of 
  the 
  dorsal. 
  Scales 
  

   smooth, 
  those 
  on 
  the 
  flanks 
  often 
  crimped 
  towards 
  their 
  hinder 
  

   border 
  and 
  more 
  or 
  less 
  coarsely 
  serrated, 
  those 
  of 
  the 
  lateral 
  line 
  

   deeply 
  notched, 
  and 
  all 
  showing 
  oblique 
  ridges 
  when 
  worn; 
  prin- 
  

   cipal 
  flank-scales 
  somewhat 
  deeper 
  than 
  broad 
  ; 
  dorsal 
  ridge-scales 
  

   inconspicuous 
  but 
  acuminate. 
  

  

  Form, 
  fy 
  Loc. 
  Wealden 
  : 
  S.E. 
  England 
  and 
  N. 
  Germany. 
  

  

  2456. 
  Hinder 
  portion 
  of 
  head 
  with 
  part 
  of 
  the 
  abdominal 
  region, 
  

   described 
  and 
  figured 
  by 
  Agassiz, 
  torn, 
  cit. 
  p. 
  263, 
  pi. 
  xxx. 
  c 
  . 
  

   fig. 
  1, 
  and 
  to 
  be 
  regarded 
  as 
  the 
  type 
  specimen; 
  Heath- 
  

   field. 
  The 
  drawing 
  is 
  very 
  unsatisfactory, 
  and 
  there 
  is 
  no 
  

   indication 
  of 
  the 
  few 
  coarse 
  denticulations 
  exhibited 
  by 
  

   some 
  of 
  the 
  scales. 
  The 
  left 
  hyomandibular 
  and 
  meta- 
  

  

  