﻿238 
  A.CTINOPTERYGII. 
  

  

  of 
  its 
  basal 
  cartilages 
  ; 
  Kelheim. 
  The 
  supposed 
  sclerotic 
  

   seems 
  to 
  exhibit 
  a 
  few 
  sparse 
  and 
  fine 
  granulations 
  as 
  in 
  

   the 
  last 
  specimen. 
  Egerton 
  and 
  Enniskillen 
  Colls. 
  

  

  P. 
  3768 
  a. 
  Very 
  small, 
  immature 
  fish, 
  wanting 
  the 
  caudal 
  region 
  ; 
  

   Kelheim. 
  Though 
  much 
  crushed, 
  this 
  specimen 
  is 
  in- 
  

   teresting 
  as 
  exhibiting 
  a 
  thickened 
  bar 
  behind 
  the 
  

   operculum, 
  extending 
  from 
  the 
  normal 
  upper 
  limit 
  of 
  the 
  

   clavicle 
  to 
  the 
  back 
  of 
  the 
  cranium, 
  thus 
  probably 
  a 
  

   supraclavicle. 
  Seven 
  basals 
  are 
  preserved 
  in 
  the 
  pectoral 
  

   fin. 
  Enniskillen 
  Coll. 
  

  

  Gyrodus 
  circularis, 
  Agassiz. 
  

  

  1833. 
  Sphcerodus 
  rhomboidalis, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  

  

  p. 
  15 
  (undefined). 
  

   1834-44. 
  Gyrodus 
  circularis, 
  L. 
  Agassiz, 
  Poiss. 
  Foss., 
  Feuill. 
  p. 
  18 
  

  

  (name 
  only), 
  and 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  300. 
  

   1834-44. 
  Gyrodus 
  punctatissimus, 
  L. 
  Agassiz, 
  ibid. 
  Feuill. 
  p. 
  18 
  (name 
  

  

  only), 
  and 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  301. 
  [Fragment 
  of 
  fish; 
  Palseontological 
  

  

  Museum, 
  Munich.] 
  (=.Microdon 
  gigas, 
  Agass. 
  MS.) 
  

   1834-44. 
  Gyrodus 
  rhomboidalis, 
  L. 
  Agassiz, 
  ibid. 
  Feuill. 
  p. 
  18 
  (name 
  

  

  only), 
  and 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  300. 
  [Imperfect 
  fish 
  ; 
  Palaeontological 
  

  

  Museum, 
  Munich.] 
  

   1836. 
  Gyrodus 
  multidens, 
  G. 
  von 
  Minister, 
  Neues 
  Jahrb. 
  p. 
  581. 
  

  

  [Imperfect 
  head 
  ; 
  Palaeontological 
  Museum, 
  Munich.] 
  

   1845. 
  Gyrodus 
  umbilicus, 
  Mandelslohe, 
  Wiirtt. 
  Jahresh. 
  vol. 
  i. 
  p. 
  153, 
  

  

  fig. 
  2. 
  

   1851. 
  Gyrodus 
  circularis, 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  math.- 
  

  

  phys. 
  01. 
  vol. 
  vi. 
  p. 
  10, 
  pi. 
  i. 
  fig. 
  1. 
  

   1851. 
  Gyrodus 
  rhomboidalis, 
  A. 
  Wagner, 
  ibid. 
  vol. 
  vi. 
  p. 
  19, 
  pi. 
  i. 
  fig. 
  2. 
  

   1851. 
  Gyrodus 
  multidens, 
  A. 
  Wagner, 
  ibid. 
  vol. 
  vi. 
  p. 
  23, 
  pi. 
  i. 
  figs. 
  3, 
  4. 
  

   1851. 
  Gyrodus 
  punctatissimus, 
  A. 
  Wagner, 
  ibid. 
  vol. 
  vi. 
  p. 
  27. 
  

   1855. 
  Gyrodus 
  umbilicus, 
  O. 
  Fraas, 
  Wiirtt. 
  Jahresh. 
  vol. 
  xi. 
  p. 
  100. 
  

   1862. 
  Gyrodus 
  titanius, 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  math.- 
  

  

  phys. 
  CI. 
  vol. 
  ix. 
  p. 
  331. 
  [Founded 
  on 
  the 
  type 
  specimen 
  of 
  

  

  G. 
  circularis, 
  Ag.] 
  

   1862. 
  Gyrodus 
  giganteus, 
  T. 
  C. 
  Winkler, 
  Descript. 
  Poiss. 
  Foss. 
  Solen- 
  

  

  hofen 
  (Natuurk. 
  Verhandl. 
  Holland. 
  Maatsch. 
  [2] 
  vol. 
  xiv.), 
  p. 
  80, 
  

  

  figs. 
  13-15. 
  [Nearly 
  complete 
  fish 
  ; 
  Teyler 
  Museum, 
  Haarlem.] 
  

   1867. 
  Gyrodus 
  titanius, 
  F. 
  A. 
  Quenstedt, 
  Handb. 
  Petrefakt. 
  ed. 
  2, 
  

  

  p. 
  254. 
  

   1881. 
  Gyrodus 
  titanius, 
  B. 
  Vetter, 
  Mittheil. 
  k. 
  mineral. 
  -geol. 
  Mus. 
  

  

  Dresden, 
  pt. 
  iv. 
  p. 
  21. 
  

   1887. 
  Gyrodus 
  titanius, 
  K. 
  A. 
  von 
  Zittel, 
  Handb. 
  Palaeont. 
  vol. 
  iii. 
  

  

  pp. 
  242, 
  243, 
  figs. 
  253, 
  255-257. 
  

  

  Type. 
  Nearly 
  complete 
  fish 
  ; 
  Palseontological 
  Museum, 
  Munich. 
  

   A 
  large 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  1*0. 
  Maximum 
  

  

  