﻿ETJGNATHID^. 
  329 
  

  

  the 
  preceding 
  species, 
  bat 
  very 
  doubtfully 
  distinct 
  from 
  the 
  latter 
  

   although 
  made 
  the 
  type 
  of 
  another 
  genus 
  (Isocolum) 
  by 
  Egerton. 
  

   The 
  specimen 
  is 
  not 
  much 
  smaller 
  than 
  no. 
  P. 
  3655 
  recorded 
  above, 
  

   but 
  its 
  vertebral 
  elements 
  and 
  scales 
  are 
  both 
  less 
  robust. 
  The 
  

   suboperculum 
  is 
  deeper 
  in 
  proportion 
  to 
  its 
  width 
  ; 
  and 
  the 
  striated 
  

   character 
  of 
  the 
  hinder 
  half 
  of 
  the 
  scales 
  appears 
  to 
  be 
  more 
  

   general. 
  

  

  Form. 
  $ 
  Loc. 
  Lower 
  Lias 
  : 
  Dorsetshire. 
  

  

  P. 
  3653. 
  The 
  type 
  specimen 
  described 
  and 
  figured 
  by 
  Egerton, 
  loc. 
  

   clt. 
  ; 
  Lyme 
  Regis. 
  The 
  operculum 
  is 
  somewhat 
  deeper 
  

   than 
  broad 
  and 
  completely 
  covered 
  with 
  granulations, 
  

   which 
  are 
  coarsest 
  near 
  the 
  superior 
  margin. 
  The 
  ossifi- 
  

   cations 
  in 
  the 
  notochordal 
  sheath 
  are 
  confined 
  to 
  separate 
  

   pleurocentra 
  and 
  hypocentra 
  ; 
  and 
  the 
  thick, 
  sigmoidally- 
  

   bent 
  neural 
  spines 
  in 
  the 
  abdominal 
  region 
  are 
  not 
  fused 
  

   with 
  their 
  comparatively 
  delicate 
  supporting 
  arches. 
  The 
  

   ribs 
  are 
  short 
  and 
  delicate, 
  while 
  the 
  neural 
  and 
  haemal 
  

   arches 
  in 
  the 
  caudal 
  region 
  are 
  especially 
  robust. 
  The 
  

   slender 
  fulcra 
  on 
  the 
  dorsal 
  and 
  pelvic 
  fins 
  appear 
  to 
  be 
  

   biserial. 
  The 
  squamation 
  is 
  very 
  little 
  disturbed, 
  and 
  the 
  

   narrowing 
  of 
  the 
  scales 
  on 
  the 
  ventral 
  aspect 
  is 
  well 
  

   shown 
  ; 
  many 
  of 
  the 
  principal 
  flank-scales 
  are 
  finely 
  

   denticulated. 
  EnnisTcilhn 
  Coll. 
  

  

  Genus 
  CATURUS, 
  Agassiz. 
  

   [Neues 
  Jahrb. 
  1834, 
  p. 
  387.] 
  

  

  Syn. 
  Urceus, 
  L. 
  Agassiz, 
  Poiss. 
  Foss. 
  vol. 
  ii. 
  pt. 
  i. 
  1833, 
  p. 
  12 
  (non 
  

  

  Urcsus, 
  Wagler, 
  1830). 
  

   Conodus, 
  L. 
  Agassiz, 
  ibid. 
  vol. 
  ii. 
  pt. 
  ii. 
  1844, 
  p. 
  105 
  (name 
  

  

  only). 
  

   Strobilodus, 
  A. 
  Wagner, 
  Abh. 
  k. 
  bay. 
  Akad. 
  Wiss., 
  math.-phys. 
  

  

  CI. 
  vol. 
  vi. 
  1851, 
  p. 
  75. 
  

   Endactis, 
  Sir 
  P. 
  Egerton, 
  Figs. 
  & 
  Descript. 
  Brit. 
  Organic 
  

  

  Remains, 
  dec. 
  ix. 
  (Mem. 
  Geol. 
  Surv. 
  1858), 
  no. 
  4. 
  

   Thlattodus, 
  R. 
  Owen, 
  Geol. 
  Mag. 
  vol. 
  iii. 
  1866, 
  p. 
  55. 
  

   Ditaxiodus, 
  R. 
  Owen, 
  ibid. 
  p. 
  107. 
  

  

  Trunk 
  elongate-fusiform. 
  External 
  head-bones 
  and 
  opercular 
  

   bones 
  feebly 
  ornamented 
  with 
  rugae 
  and 
  tuberculations, 
  all 
  except 
  

   the 
  cheek-plates 
  robust; 
  snout 
  obtusely 
  pointed, 
  and 
  maxilla 
  

   straight 
  or 
  with 
  a 
  slightly 
  concavely- 
  arched 
  dentigerous 
  border 
  ; 
  

   teeth 
  relatively 
  large 
  and 
  arranged 
  in 
  a 
  sparse 
  series 
  on 
  the 
  margin 
  

  

  