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  ACTINOPTERYGII. 
  

  

  Caturus 
  (Conodus) 
  chirotes 
  (Agassiz). 
  

   [Plate 
  VII. 
  figs. 
  2, 
  3.] 
  

  

  1839. 
  Eugnathus 
  cheirotes, 
  L. 
  Agassiz, 
  Neues 
  Jahrb. 
  p. 
  118. 
  

  

  1842-44. 
  Eugnathus 
  chirotes, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  ii. 
  

  

  p. 
  102, 
  pi. 
  lvii. 
  b. 
  

   1844. 
  Conodus 
  ferox, 
  L. 
  Agassiz, 
  ibid. 
  p. 
  105 
  (name 
  only). 
  [Portion 
  

  

  of 
  jaws 
  ; 
  British 
  Museum.] 
  

   1890. 
  Eugnathus 
  (?) 
  chirotes, 
  Woodward 
  & 
  Sherborn, 
  Catal. 
  Brit. 
  Foss. 
  

  

  Vertebrata, 
  p. 
  77. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  British 
  Museum. 
  

  

  The 
  type 
  species 
  of 
  the 
  undefined 
  genus 
  Conodus, 
  attaining 
  a 
  

   length 
  of 
  about 
  0*75. 
  Length 
  of 
  head 
  with 
  opercular 
  apparatus 
  

   apparently 
  exceeding 
  the 
  maximum 
  depth 
  of 
  the 
  trunk 
  and 
  con- 
  

   tained 
  about 
  four 
  times 
  in 
  the 
  total 
  length 
  of 
  the 
  fish. 
  External 
  

   bones 
  ornamented 
  in 
  part 
  with 
  sparse 
  tuberculations 
  ; 
  maxilla 
  

   thick 
  but 
  not 
  much 
  deepened, 
  the 
  hinder 
  two-thirds 
  of 
  its 
  dentigerous 
  

   margin 
  concavely 
  arched, 
  and 
  the 
  height 
  of 
  the 
  middle 
  teeth 
  not 
  

   equalling 
  the 
  depth 
  of 
  the 
  bone 
  at 
  their 
  point 
  of 
  insertion 
  ; 
  supra- 
  

   maxilla 
  sparsely 
  tuberculated, 
  half 
  as 
  long 
  as 
  the 
  maxilla 
  ; 
  pre- 
  

   maxillary 
  teeth 
  very 
  large, 
  apparently 
  equalling 
  in 
  size 
  those 
  of 
  

   the 
  middle 
  of 
  the 
  dentary, 
  which 
  are 
  somewhat 
  tumid 
  at 
  the 
  base 
  ; 
  

   splenial 
  teeth 
  relatively 
  very 
  small 
  and 
  numerous, 
  stout 
  and 
  not 
  

   much 
  curved; 
  enamel 
  restricted 
  to 
  the 
  apex 
  in 
  all 
  the 
  teeth. 
  

   Scales 
  for 
  the 
  most 
  part 
  smooth, 
  but 
  some 
  of 
  those 
  of 
  the 
  flank 
  

   exhibiting 
  longitudinal 
  crenulations. 
  

  

  Form. 
  Sf 
  hoc. 
  Lower 
  Lias 
  : 
  Dorsetshire. 
  

  

  P. 
  3643. 
  The 
  type 
  specimen 
  described 
  and 
  figured 
  by 
  Agassiz, 
  loc. 
  

   cit. 
  ; 
  Lyme 
  Regis. 
  The 
  head 
  seems 
  to 
  have 
  been 
  somewhat 
  

   deepened 
  in 
  the 
  fossil 
  by 
  the 
  upturning 
  and 
  fracture 
  of 
  

   the 
  cranium, 
  while 
  the 
  jaws 
  are 
  displaced 
  downwards. 
  

   The 
  otic 
  elements 
  are 
  well-ossified 
  and 
  the 
  thin 
  dermal 
  

   cheek-plates 
  are 
  conspicuous. 
  The 
  maxilla 
  is 
  much 
  

   fractured 
  and 
  imperfect, 
  but 
  some 
  of 
  the 
  slender 
  teeth 
  in 
  

   its 
  hindermost 
  portion 
  are 
  well 
  shown 
  ; 
  one 
  very 
  large 
  

   tooth 
  on 
  the 
  premaxilla 
  is 
  also 
  preserved. 
  The 
  mandible 
  

   is 
  obscured, 
  and 
  only 
  one 
  of 
  its 
  moderately 
  large 
  anterior 
  

   teeth 
  can 
  be 
  seen. 
  The 
  middle 
  portion 
  of 
  the 
  preoper- 
  

   culum 
  is 
  coarsely 
  rugose, 
  and 
  the 
  same 
  ornament 
  appears 
  

   slightly 
  on 
  other 
  fragments 
  of 
  the 
  external 
  plates. 
  The 
  

   ossifications 
  in 
  the 
  sheath 
  of 
  the 
  notochord 
  are 
  much 
  

   crushed, 
  but 
  evidently 
  consist 
  of 
  separate 
  pleurocentra 
  

  

  