﻿ACIPENSEEID^l. 
  43 
  

  

  Genus 
  ACIPENSER, 
  Linnaeus. 
  

   [Syst. 
  Nat. 
  ed. 
  10, 
  1758, 
  p. 
  237.] 
  

  

  External 
  bones 
  ornamented 
  with 
  tuberculations 
  of 
  ganoine. 
  Jaws 
  

   delicate, 
  and 
  minute 
  pointed 
  teeth 
  present 
  only 
  in 
  very 
  young 
  

   individuals 
  ; 
  spiracles 
  present. 
  A 
  few 
  slender 
  ribs. 
  Pectoral 
  fins 
  

   with 
  a 
  robust 
  anterior 
  ray 
  or 
  spine 
  ; 
  pelvic, 
  dorsal, 
  and 
  anal 
  fins 
  

   remote, 
  the 
  two 
  latter 
  opposed 
  ; 
  caudal 
  fin 
  inequilobate, 
  extending 
  to 
  

   the 
  extremity 
  of 
  the 
  upper 
  caudal 
  lobe. 
  Dermal 
  scutes 
  in 
  five 
  

   distinct 
  series, 
  one 
  dorsal, 
  two 
  pairs 
  lateral, 
  not 
  completely 
  envelop- 
  

   ing 
  the 
  caudal 
  pedicle. 
  

  

  Numerous 
  scutes, 
  pectoral 
  spines, 
  and 
  fragments 
  of 
  bone 
  indis- 
  

   tinguishable 
  from 
  the 
  corresponding 
  parts 
  of 
  the 
  existing 
  Acipenser, 
  

   are 
  known 
  from 
  Tertiary 
  formations 
  ; 
  but 
  no 
  examples 
  sufficing 
  for 
  

   specific 
  diagnosis 
  have 
  hitherto 
  been 
  discovered. 
  A 
  brief 
  enumera- 
  

   tion 
  of 
  the 
  known 
  fossils 
  is 
  given 
  below. 
  

  

  Acipenser 
  toliapicus, 
  Agassiz, 
  MS. 
  

  

  1844. 
  Acipenser 
  toliapicus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  p. 
  280 
  

  

  (name 
  only). 
  

   1889. 
  Acipenser 
  toliapicus, 
  A. 
  S. 
  Woodward, 
  Proc. 
  Geol. 
  Assoc, 
  vol. 
  xi. 
  

  

  p. 
  28, 
  pi. 
  i. 
  fig. 
  1. 
  

  

  Type. 
  Imperfect 
  scutes 
  ; 
  British 
  Museum, 
  

  

  A 
  provisional 
  name 
  given 
  to 
  the 
  earliest 
  known 
  scutes 
  of 
  Acipenser 
  

   from 
  the 
  London 
  Clay. 
  The 
  external 
  surface 
  is 
  very 
  deeply 
  pitted, 
  

   and 
  the 
  reticulations 
  are 
  nodose. 
  

  

  Form, 
  fy 
  Log. 
  Lower 
  Eocene 
  (London 
  Clay) 
  : 
  Isle 
  of 
  Sheppey. 
  

  

  P. 
  3372. 
  Two 
  dorsal 
  scutes 
  intended 
  by 
  Agassiz 
  to 
  be 
  the 
  type 
  

   specimens 
  of 
  the 
  species, 
  one 
  labelled 
  by 
  that 
  author, 
  the 
  

   other 
  described 
  and 
  figured 
  by 
  the 
  present 
  writer, 
  loc. 
  cit. 
  

  

  Ennishillen 
  Coll. 
  

  

  P. 
  529. 
  Somewhat 
  larger 
  scute, 
  labelled 
  by 
  Egerton 
  as 
  a 
  type 
  speci- 
  

   men. 
  Egerton 
  Coll. 
  

  

  37762. 
  Well-preserved 
  portion 
  of 
  another 
  scute. 
  Purchased, 
  1863. 
  

  

  24619. 
  Imperfect 
  left 
  infraclavicle 
  exhibiting 
  very 
  deep 
  pits 
  between 
  

   the 
  reticulations 
  on 
  the 
  exposed 
  outer 
  face. 
  

  

  Purchased, 
  1850. 
  

  

  44093. 
  A 
  less 
  imperfect, 
  larger 
  example 
  of 
  the 
  right 
  infraclavicle 
  

   0*115 
  in 
  length, 
  showing 
  the 
  smooth 
  inferior 
  margin. 
  

   Both 
  in 
  this 
  and 
  the 
  previous 
  specimen 
  the 
  external 
  

  

  