﻿MACKOSEMIID 
  m 
  . 
  177 
  

  

  of 
  the 
  middle 
  of 
  the 
  flank 
  relatively 
  large, 
  becoming 
  smaller 
  both 
  

   dorsally 
  and 
  ventrally, 
  in 
  the 
  former 
  case 
  by 
  dichotomy 
  of 
  the 
  

   vertical 
  series; 
  abont 
  four 
  very 
  large 
  ridged-scales 
  on 
  the 
  ventral 
  

   border 
  between 
  the 
  anal 
  and 
  caudal 
  fins. 
  

  

  Macrosemius 
  rostratus, 
  Agassiz. 
  

   [Plate 
  III. 
  fig. 
  4.] 
  

  

  1834. 
  Macrosemius 
  rostratus, 
  L. 
  Agassiz, 
  Neues 
  Jahrb. 
  p. 
  388 
  (name 
  

  

  only). 
  

   1844. 
  Macrosemius 
  rostratus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  

  

  p. 
  150, 
  pi. 
  xlvii. 
  a. 
  fig. 
  1. 
  

   1851. 
  Macrosemius 
  rostratus, 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  

  

  math.-phys. 
  01. 
  vol. 
  vi. 
  p. 
  73. 
  

   1863. 
  Macrosemius 
  rostratus, 
  A. 
  Wagner, 
  ibid. 
  vol. 
  ix. 
  p. 
  647. 
  

   1863. 
  Macrosemius 
  insignis, 
  A. 
  Wagner, 
  ibid. 
  vol. 
  ix. 
  p. 
  648, 
  pi. 
  ii. 
  

  

  [Fish, 
  wanting 
  tail 
  ; 
  Palseontological 
  Museum, 
  Munich.] 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  Royal 
  Bohemian 
  Museum, 
  Prague. 
  

  

  The 
  type 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  03. 
  Head 
  with 
  

   opercular 
  apparatus 
  somewhat 
  longer 
  than 
  its 
  maximum 
  depth 
  and 
  

   occupying 
  about 
  one-quarter 
  of 
  the 
  total 
  length 
  of 
  the 
  fish 
  ; 
  the 
  

   maximum 
  depth 
  of 
  the 
  trunk 
  exceeding 
  twice 
  the 
  width 
  of 
  the 
  

   caudal 
  pedicle. 
  Rays 
  of 
  dorsal 
  fin 
  very 
  long 
  and 
  comparatively 
  

   slender, 
  without 
  denticles, 
  and 
  about 
  38-40 
  in 
  number 
  ; 
  the 
  length 
  

   of 
  those 
  of 
  the 
  hinder 
  portion 
  of 
  the 
  caudal 
  region 
  greater 
  than 
  the 
  

   depth 
  of 
  that 
  part 
  of 
  the 
  trunk. 
  Pelvic 
  fins 
  arising 
  well 
  in 
  advance 
  

   of 
  the 
  middle 
  point 
  between 
  the 
  pectoral 
  and 
  caudal 
  fins, 
  and 
  the 
  

   anal 
  arising 
  shortly 
  behind. 
  Scales 
  conspicuously 
  pectinated. 
  

  

  Closely 
  related 
  to 
  this 
  fish, 
  if 
  not 
  specifically 
  identical, 
  is 
  a 
  trunk 
  

   from 
  the 
  Lithographic 
  Stone 
  of 
  Kelheim, 
  said 
  to 
  be 
  slightly 
  deeper 
  

   in 
  proportion 
  to 
  its 
  length 
  but 
  not 
  otherwise 
  distinguished 
  from 
  

   the 
  typical 
  M. 
  rostratus. 
  It 
  is 
  described 
  as 
  the 
  type 
  of 
  M. 
  latiusculus 
  

   by 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  math.-phys. 
  CI. 
  vol. 
  vi. 
  

   (1851), 
  p. 
  74; 
  and 
  a 
  head 
  is 
  figured 
  under 
  the 
  same 
  name 
  by 
  

   K. 
  A. 
  von 
  Zittel, 
  Handb. 
  Palaeont. 
  vol. 
  iii. 
  (1887), 
  p. 
  218, 
  fig. 
  232 
  

   (copied 
  above, 
  fig. 
  29, 
  p. 
  163). 
  The 
  original 
  specimens 
  are 
  pre- 
  

   served 
  in 
  the 
  Palaeontological 
  Museum, 
  Munich. 
  

  

  Form, 
  fy 
  Loc. 
  Lower 
  Kimmeridgian 
  (Lithographic 
  Stone): 
  Bavaria. 
  

  

  37051. 
  Fine 
  specimen 
  0-275 
  in 
  length, 
  in 
  counterpart, 
  displaying 
  

   some 
  of 
  the 
  teeth, 
  a 
  few 
  ribs, 
  the 
  dorsal 
  and 
  caudal 
  fins, 
  

   and 
  the 
  greater 
  part 
  of 
  the 
  squamalion 
  ; 
  Solenhofen. 
  

  

  Haberlein 
  Coll. 
  

  

  PART 
  III. 
  n 
  

  

  