﻿.18 
  

  

  ACTINOPTERYGII. 
  

  

  ; 
  

  

  Genus 
  AETHALION, 
  Miinster. 
  

  

  [Neues 
  Jahrb. 
  1842, 
  p. 
  41.] 
  

  

  Maxilla 
  arched, 
  with 
  a 
  slightly 
  convex 
  dentigerous 
  border 
  ; 
  man- 
  

   dible 
  scarcely 
  prominent, 
  and 
  dentary 
  gradually 
  deepening 
  from 
  

   the 
  symphysis 
  backwards 
  without 
  any 
  marked 
  thickening 
  ; 
  teeth 
  

   minute 
  and 
  closely 
  arranged. 
  Opercular 
  apparatus 
  as 
  in 
  Leptolepis. 
  

   Vertebral 
  centra 
  strengthened 
  by 
  delicate 
  longitudinal 
  ridges 
  of 
  

   secondary 
  ossification. 
  Dorsal 
  fin 
  opposed 
  to 
  the 
  space 
  between 
  

   the 
  pelvic 
  pair 
  and 
  the 
  anal, 
  the 
  latter 
  comparatively 
  small 
  and 
  not 
  

   extended 
  ; 
  caudal 
  fin 
  deeply 
  forked. 
  No 
  enlarged 
  or 
  thickened 
  

   ridge-scales. 
  

  

  Aethalion 
  knorri 
  (Blainville). 
  

  

  1755. 
  Figure 
  by 
  G. 
  W. 
  Knorr, 
  Samml. 
  Merkwiirdigk. 
  Natur, 
  pi. 
  xxx. 
  

  

  fig. 
  2. 
  

   1818. 
  Clupea 
  knorri, 
  H. 
  D. 
  de 
  Blainville, 
  Nouv. 
  Diet. 
  d'Hist. 
  Nat. 
  

  

  vol. 
  xxvii. 
  p. 
  331. 
  

   1839. 
  Caturus 
  angustissimus, 
  G. 
  von 
  Miinster, 
  Neues 
  Jahrb. 
  p. 
  679. 
  

  

  [Imperfect 
  fish 
  ; 
  Palseontological 
  Museum, 
  Munich.] 
  

   1842. 
  Aethalion 
  injlatus, 
  G. 
  von 
  Miinster, 
  ibid. 
  p. 
  42. 
  [Ditto, 
  counter- 
  

   part 
  in 
  British 
  Museum.] 
  

   1842. 
  Aethalion 
  angustissimus, 
  G. 
  von 
  Miinster, 
  Beitr. 
  Petrefakt. 
  

  

  pt. 
  v. 
  p. 
  60, 
  pi. 
  v. 
  fig. 
  3. 
  [Imperfect 
  fish; 
  Palaeontological 
  

  

  Museum, 
  Munich.] 
  

   1844. 
  Leptolepis 
  crassus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  131, 
  

  

  pi. 
  lxi. 
  a. 
  fig. 
  5, 
  [Imperfect 
  fish 
  ; 
  Erlangen 
  Museum.] 
  

   1861. 
  Aethalion 
  angustissimus, 
  T. 
  0. 
  Winkler, 
  Descript. 
  Poiss. 
  Fofs. 
  

  

  Solenhofen 
  (Natuurk. 
  Verhandl. 
  Holland. 
  Maatsch. 
  [2] 
  vol. 
  xiv.), 
  

  

  p. 
  40, 
  fig. 
  6. 
  

   1861. 
  Aethalion 
  inflatus, 
  T. 
  0. 
  Winkler, 
  ibid. 
  p. 
  42, 
  fig. 
  7. 
  

   1861. 
  Aethalion 
  tenuis, 
  T. 
  C. 
  Winkler 
  (errore), 
  ibid. 
  p. 
  44, 
  fig. 
  8. 
  

   1863. 
  Aethalion 
  blainvillei, 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  

  

  math.-phys. 
  01. 
  vol. 
  ix. 
  p. 
  728. 
  [New 
  name.] 
  

   1863. 
  Aethalion 
  crassus, 
  A. 
  Wagner, 
  ibid. 
  p. 
  730. 
  

  

  Type. 
  Nearly 
  complete 
  fish. 
  

  

  The 
  type 
  species, 
  attaining 
  a 
  length 
  of 
  about 
  0*2. 
  Length 
  of 
  

   head 
  with 
  opercular 
  apparatus 
  much 
  exceeding 
  the 
  maximum 
  depth 
  

   of 
  the 
  trunk, 
  and 
  contained 
  somewhat 
  more 
  than 
  four 
  times 
  in 
  the 
  

   total 
  length 
  of 
  the 
  fish. 
  Vertebrae 
  50 
  in 
  number. 
  Dorsal 
  fin 
  with 
  

   about 
  15 
  rays, 
  arising 
  at 
  the 
  middle 
  point 
  of 
  the 
  back; 
  pelvic 
  

   fins 
  arising 
  immediately 
  in 
  advance 
  of 
  the 
  dorsal, 
  but 
  slightly 
  

   nearer 
  to 
  the 
  anal 
  than 
  to 
  the 
  pectorals 
  ; 
  origin 
  of 
  anal 
  fin. 
  which 
  

   has 
  about 
  10 
  rays, 
  midway 
  between 
  the 
  pelvic 
  and 
  caudal 
  fins. 
  

  

  