﻿MACR0SEMIIB2E. 
  179 
  

  

  1854. 
  Disticholepis 
  fourneti, 
  V. 
  Thiolliere, 
  Poiss. 
  Foss. 
  Bugey, 
  pt. 
  i. 
  

  

  pi. 
  viii. 
  

   1873. 
  Disticholepis 
  fourneti, 
  V. 
  Thiolliere, 
  ibid. 
  pt. 
  ii. 
  p. 
  15. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  Lyons 
  Museum. 
  

  

  A 
  large 
  species 
  attaining 
  a 
  length 
  of 
  about 
  0*3. 
  Head 
  with 
  

   opercular 
  apparatus 
  longer 
  than 
  its 
  maximum 
  depth, 
  and 
  occupying 
  

   about 
  one-quarter 
  of 
  the 
  total 
  length 
  of 
  the 
  fish 
  ; 
  maximum 
  depth 
  

   of 
  the 
  trunk 
  scarcely 
  more 
  than 
  twice 
  as 
  great 
  as 
  the 
  width 
  of 
  the 
  

   caudal 
  pedicle. 
  Rays 
  of 
  dorsal 
  fin 
  about 
  34 
  in 
  number, 
  very 
  stout, 
  

   and 
  denticulated 
  on 
  their 
  posterior 
  border 
  ; 
  those 
  of 
  the 
  hinder 
  half 
  

   of 
  the 
  fin 
  somewhat 
  expanded 
  distally, 
  and 
  their 
  length 
  not 
  ex- 
  

   ceeding 
  the 
  depth 
  of 
  the 
  caudal 
  region 
  of 
  the 
  trunk. 
  Pelvic 
  fins 
  

   arising 
  almost 
  midway 
  between 
  the 
  pectoral 
  and 
  caudal 
  fins, 
  and 
  

   the 
  anal 
  arising 
  shortly 
  behind. 
  Scales 
  usually 
  covered 
  with 
  fine 
  

   striae 
  extending 
  from 
  the 
  delicate 
  pectinations 
  of 
  the 
  hinder 
  border. 
  

  

  This 
  is 
  the 
  type 
  species 
  of 
  the 
  so-called 
  Disticholepis, 
  which 
  is 
  

   regarded 
  by 
  Wagner 
  (Gelehrte 
  Anzeig. 
  k. 
  bay. 
  Akad. 
  Wiss. 
  1860, 
  

   p. 
  402) 
  as 
  doubtfully 
  distinct 
  from 
  Macrosemius. 
  

  

  It 
  is 
  not 
  improbable 
  that 
  the 
  fish 
  from 
  Cirin, 
  erroneously 
  ascribed 
  

   by 
  Thiolliere 
  (op. 
  cit. 
  pt. 
  ii. 
  p. 
  14, 
  pi. 
  v, 
  fig. 
  2) 
  to 
  Macrosemius 
  

   rostratus, 
  is 
  a 
  small 
  example 
  of 
  this 
  species. 
  

  

  Form. 
  <$f 
  Loo. 
  Lower 
  Kimmeridgian 
  (Lithographic 
  Stone) 
  : 
  Ain, 
  

   France. 
  

  

  P. 
  4685. 
  The 
  greater 
  portion 
  of 
  the 
  trunk, 
  with 
  the 
  dorsal 
  and 
  

   caudal 
  fins, 
  of 
  a 
  large 
  individual 
  chiefly 
  shown 
  in 
  im- 
  

   pression 
  ; 
  Cirin. 
  Purchased, 
  1884. 
  

  

  P. 
  4685 
  a. 
  Imperfect 
  impression 
  of 
  a 
  fish 
  0*2 
  in 
  length, 
  showing 
  

   all 
  the 
  fins 
  ; 
  Cirin. 
  Purchased, 
  1884. 
  

  

  P. 
  1091. 
  Hinder 
  abdominal 
  and 
  caudal 
  regions 
  of 
  a 
  small 
  indi- 
  

   vidual, 
  much 
  fractured; 
  Cirin. 
  Distinct 
  denticles 
  of 
  

   ganoine 
  are 
  seen 
  upon 
  the 
  posterior 
  border 
  of 
  some 
  of 
  the 
  

   hinder 
  dorsal 
  fin-rays. 
  Ecjerton 
  Coll. 
  

  

  Macrosemius 
  pectoralis, 
  Sauvage. 
  

  

  1883. 
  Macrosemius 
  pectoralis, 
  H. 
  E. 
  Sauvage, 
  Bull. 
  Soc. 
  G6ol. 
  France, 
  

   [3] 
  vol. 
  xi. 
  p. 
  477, 
  pi. 
  xii. 
  fig. 
  17. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  counterpart 
  in 
  British 
  Museum. 
  

  

  A 
  very 
  small 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  0'055. 
  Head 
  

   with 
  opercular 
  apparatus 
  considerably 
  longer 
  than 
  its 
  maximum 
  

   depth, 
  and 
  occupying 
  about 
  one-third 
  of 
  the 
  length 
  of 
  the 
  fish 
  to 
  

   the 
  base 
  of 
  the 
  caudal 
  fin 
  ; 
  caudal 
  pedicle 
  very 
  slender, 
  its 
  width 
  

  

  n 
  2 
  

  

  