﻿454 
  EET. 
  0. 
  E. 
  WHIDBOENE 
  DESCRIPTION" 
  OF 
  THE 
  [Aug. 
  1 
  897,. 
  

  

  the 
  Lower 
  Devonian. 
  It 
  agrees 
  in 
  size 
  and 
  ribbing, 
  and, 
  so 
  far 
  as 
  

   can 
  be 
  seen, 
  in 
  internal 
  arrangement. 
  Again, 
  St. 
  subarachnoidal 
  (de 
  

   Vern.), 
  1 
  is 
  very 
  similar 
  and 
  may 
  be 
  identical, 
  but 
  is 
  mnch 
  smaller 
  

   and 
  appears 
  to 
  be 
  a 
  more 
  recurved 
  shell. 
  Kayser 
  distinguishes 
  

   St. 
  eocplanata 
  from 
  it 
  only 
  by 
  its 
  greater 
  size, 
  flatness, 
  and 
  width. 
  

  

  Orthis 
  spathulata, 
  F. 
  A. 
  Romer, 
  2 
  is 
  described 
  as 
  having 
  broad 
  ribs 
  

   and 
  narrow 
  furrows, 
  but 
  Orthis 
  aff. 
  spathulata, 
  Quenstedt, 
  3 
  which 
  

   is 
  identified 
  by 
  Kayser 
  4 
  with 
  St. 
  gigas 
  (M'Coy), 
  more 
  nearly 
  

   approaches 
  the 
  present 
  form. 
  

  

  ' 
  Steeptorhtnchtjs 
  ? 
  persarmentosus 
  (M'Coy).' 
  (PI. 
  XXXII. 
  figs. 
  4 
  

   &5.) 
  

  

  Locality. 
  Treborough. 
  Two 
  specimens. 
  

  

  Size. 
  About 
  10 
  mm. 
  long 
  by 
  25 
  mm. 
  wide. 
  

  

  Two 
  very 
  imperfect 
  specimens 
  accurately 
  agree 
  with 
  M'Coy's 
  

   figure, 
  5 
  except 
  that 
  they 
  are 
  rather 
  smaller 
  and 
  not 
  quite 
  so 
  wide. 
  

   They 
  show 
  the 
  same 
  coarse, 
  ramose, 
  median 
  and 
  fine, 
  straight, 
  lateral 
  

   ribs. 
  M'Coy 
  describes 
  this 
  shell 
  as 
  common 
  in 
  the 
  Lower 
  Devonian 
  

   of 
  Fowey, 
  Looe, 
  etc., 
  and 
  he 
  gives 
  a 
  very 
  similar 
  species, 
  Orthis 
  

   sarmentosa, 
  6 
  from 
  the 
  Bala 
  Beds. 
  

  

  Davidson, 
  however, 
  is 
  evidently 
  disinclined 
  to 
  regard 
  these 
  as 
  a 
  

   true 
  species 
  ; 
  and 
  our 
  examples 
  almost 
  certainly 
  seem 
  to 
  owe 
  their 
  

   peculiar 
  character 
  chiefly 
  to 
  distortion. 
  In 
  recording 
  it, 
  therefore, 
  

   I 
  do 
  not 
  suggest 
  that 
  St.'? 
  persarmentosus 
  is 
  a 
  true 
  species, 
  but 
  

   simply 
  that 
  our 
  shells 
  are 
  identical 
  with 
  M'Coy's 
  and 
  must 
  stand 
  or 
  

   fall 
  with 
  it. 
  It 
  may 
  be 
  noted 
  that 
  one 
  of 
  our 
  examples 
  of 
  Stropheo- 
  

   donta 
  eocplanata 
  shows 
  the 
  same 
  peculiarities 
  in 
  an 
  incipient 
  

   degree, 
  

  

  Chonetes 
  plebeia, 
  Schnur. 
  (PI. 
  XXXIII. 
  figs. 
  1 
  & 
  2.) 
  

  

  [Of 
  this 
  species 
  (Ehlert 
  says 
  (Bull. 
  Soc. 
  geol. 
  France, 
  ser. 
  3, 
  

   vol. 
  xi. 
  p. 
  519 
  : 
  ' 
  The 
  vertical 
  range 
  of 
  Ch. 
  sarcinulata 
  is 
  much 
  

   greater 
  than 
  that 
  of 
  Ch. 
  plebeia, 
  which 
  is 
  observable 
  particularly 
  in 
  

   the 
  inferior 
  beds 
  of 
  the 
  Devonian 
  Limestone, 
  where 
  sometimes 
  this 
  

   species 
  occurs 
  almost 
  exclusively.'] 
  

  

  Locality. 
  Treborough. 
  Common. 
  

  

  Size. 
  About 
  5 
  mm. 
  long 
  by 
  8 
  mm. 
  wide. 
  

  

  Description. 
  Shell 
  very 
  small, 
  slightly 
  transverse, 
  semi-oval. 
  

  

  1 
  1842. 
  D'Archiac 
  & 
  de 
  Verneuil, 
  Trans. 
  Geol. 
  Soc, 
  ser. 
  2, 
  vol. 
  vi. 
  pt. 
  ii. 
  

   p. 
  372 
  & 
  pi. 
  xxxvi. 
  fig. 
  3 
  ; 
  and 
  1889. 
  Kayser, 
  Abb. 
  k. 
  Preuss. 
  geol. 
  Landesanst., 
  

   n. 
  s., 
  pt. 
  i. 
  p. 
  101 
  & 
  pi. 
  xix. 
  figs. 
  1-2 
  a. 
  ' 
  

  

  2 
  1852. 
  F. 
  A. 
  Bomer, 
  ' 
  Beitr. 
  Harzgeb.' 
  pt. 
  ii. 
  p. 
  98 
  & 
  pi. 
  xv. 
  fig. 
  2. 
  

  

  3 
  1871. 
  Quenstedt, 
  ' 
  Petref. 
  Deutschl. 
  (Brachiop.) 
  ' 
  p. 
  583 
  & 
  pi. 
  hi. 
  figs. 
  53, 
  

   54. 
  

  

  4 
  1890. 
  Kayser, 
  Jahrb. 
  k. 
  Preuss. 
  geol. 
  Landesanst. 
  p. 
  101 
  & 
  pi. 
  xiii. 
  

   figs. 
  1, 
  2. 
  

  

  5 
  1852. 
  M'Coy, 
  ' 
  Brit. 
  Pal. 
  Foss.' 
  p. 
  385 
  & 
  pi. 
  ii 
  a. 
  fig. 
  9 
  ; 
  and 
  1865. 
  Davidson, 
  

   ' 
  Brit. 
  Foss. 
  Brack' 
  vol. 
  iii. 
  p. 
  84 
  & 
  pi. 
  xvi. 
  fig. 
  5. 
  

  

  6 
  1871. 
  Davidson, 
  'Brit. 
  Foss. 
  Brach.' 
  vol. 
  iii. 
  p. 
  262 
  & 
  pi. 
  xxxvi. 
  figs. 
  35-38. 
  

  

  