﻿294 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  valve. 
  It 
  is 
  very 
  possible 
  this 
  triangular 
  species 
  may 
  belong 
  to 
  

   Obolella, 
  but 
  we 
  have 
  not 
  sufficient 
  evidence 
  of 
  this. 
  

  

  4. 
  Lixgula 
  Brlmoxti, 
  Rouault. 
  PI. 
  XVII. 
  fig. 
  6. 
  Rouault, 
  loc. 
  at. 
  

   p. 
  728. 
  

  

  I 
  think 
  this 
  broad 
  and 
  inflated 
  shell, 
  with 
  its 
  abruptly 
  truncate 
  

   and 
  even 
  emarginate 
  front, 
  greatly 
  arched 
  sides, 
  obtuse 
  beak, 
  and 
  

   close 
  conspicuous 
  lines 
  of 
  growth, 
  can 
  hardly 
  be 
  other 
  than 
  the 
  L. 
  

   Brimonti. 
  Rouault 
  describes 
  his 
  species 
  as 
  having 
  the 
  convexity 
  in 
  

   the 
  form 
  of 
  obtuse 
  ridges 
  running 
  from 
  the 
  beak 
  to 
  each 
  of 
  the 
  basal 
  

   angles. 
  Our 
  shell 
  has 
  this 
  character, 
  and 
  so 
  differs 
  from 
  the 
  L.HaivTcei 
  

   described 
  above. 
  

  

  The 
  remaining 
  species 
  must 
  be 
  compared 
  rather 
  with 
  those 
  foimd 
  

   by 
  Rouault 
  in 
  the 
  Upper 
  or 
  May 
  Sandstone, 
  of 
  Gahard 
  and 
  other 
  

   places 
  near 
  Rennes 
  ; 
  but 
  there 
  is 
  no 
  difference 
  appreciable 
  in 
  the 
  

   character 
  of 
  the 
  matrix, 
  and 
  I 
  suppose 
  they 
  have 
  been 
  derived 
  in 
  

   the 
  British 
  locality 
  from 
  the 
  same 
  beds 
  as 
  the 
  Lingulce 
  and 
  Fucoids 
  

   above 
  described. 
  

  

  5. 
  Orthis 
  redux, 
  Barrande. 
  PL 
  XVII. 
  fig. 
  7. 
  

  

  [0. 
  testwlinaria, 
  Barr. 
  and 
  De 
  Vern. 
  Bull. 
  Soc. 
  Geol. 
  Fr. 
  2nd 
  ser. 
  

   vol. 
  xii. 
  pi. 
  27. 
  fig. 
  9. 
  ?] 
  

  

  Circular, 
  not 
  half 
  an 
  inch 
  in 
  diameter, 
  with 
  only 
  a 
  slightly 
  pro- 
  

   minent 
  beak 
  to 
  the 
  larger 
  valve, 
  which 
  is 
  convex, 
  but 
  not 
  ridged, 
  

   and 
  closely 
  covered 
  by 
  straight 
  radiating 
  fine 
  striae 
  repeatedly 
  inter- 
  

   lined 
  till 
  they 
  become 
  very 
  close 
  and 
  fine 
  near 
  the 
  border. 
  The 
  

   dorsal 
  valve 
  is 
  flat 
  (fig. 
  7a) 
  or 
  slightly 
  convex 
  (fig. 
  76). 
  The 
  ventral 
  

   valve 
  has 
  widely 
  divergent 
  lamellae 
  and 
  rather 
  large 
  inconspicuous 
  

   muscular 
  scars 
  (fig. 
  7c). 
  The 
  dorsal 
  valve 
  with 
  short 
  divergent 
  

   teeth, 
  and 
  the 
  cardinal 
  process 
  prominent 
  and 
  rounded, 
  but 
  very 
  

   short. 
  The 
  central 
  ridge 
  is 
  broad 
  and 
  low, 
  and 
  the 
  muscles 
  ill 
  de- 
  

   fined. 
  

  

  I 
  should 
  have 
  thought 
  this 
  abundant 
  fossil 
  (equally 
  common 
  in 
  the 
  

   May 
  Sandstone) 
  to 
  be 
  the 
  0. 
  Filieieri 
  of 
  Rouault 
  ; 
  but 
  he 
  describes 
  

   that 
  species 
  as 
  having 
  a 
  large 
  area, 
  and 
  a 
  very 
  convex 
  (dorsal) 
  

   ventral 
  valve 
  covered 
  by 
  large 
  striae. 
  Ours 
  are 
  closely 
  striate, 
  but 
  

   with 
  prominent 
  striae 
  interlined 
  with 
  smaller 
  ones. 
  It 
  is 
  the 
  well- 
  

   known 
  0. 
  redux 
  of 
  Bohemia. 
  

  

  Ortliis 
  redux, 
  var. 
  PI. 
  XVII. 
  fig. 
  7d. 
  

  

  This 
  has 
  the 
  dorsal 
  valve 
  with 
  a 
  much 
  wider 
  hinge 
  than 
  the 
  last, 
  

   and 
  a 
  channel 
  all 
  down 
  it, 
  like 
  0. 
  parva 
  of 
  the 
  English 
  Silurian 
  

   rocks. 
  It 
  may 
  be 
  only 
  a 
  variety 
  of 
  the 
  preceding, 
  and 
  I 
  think 
  it 
  is 
  

   so, 
  but 
  note 
  the 
  differences. 
  It 
  is 
  very 
  like 
  the 
  figure 
  of 
  0. 
  testa- 
  

   dinar 
  i 
  a 
  above 
  quoted. 
  

  

  6. 
  Orthis 
  pulvinata, 
  spec. 
  nov. 
  PI. 
  XVII. 
  fig. 
  8. 
  

  

  Dorsal 
  valve 
  truly 
  transverse 
  oval, 
  | 
  inch 
  wide, 
  regularly 
  and 
  

   rather 
  strongly 
  convex, 
  the 
  area 
  not 
  so 
  wide 
  as 
  the 
  shell, 
  the 
  upper 
  

  

  