﻿446 
  HEY. 
  G. 
  F. 
  WHIDBORNE 
  DESCRIPTION" 
  OF 
  THE 
  [Aug. 
  1 
  897, 
  

  

  one, 
  and 
  therefore 
  they 
  cannot 
  (on 
  this 
  basis) 
  be 
  identical 
  with 
  

   G. 
  punctatus. 
  

  

  On 
  the 
  other 
  hand, 
  in 
  G. 
  laciniatus, 
  P. 
  Eomer 
  1 
  (as 
  also 
  in 
  

   G. 
  rotundifrons, 
  Emmerich, 
  2 
  G. 
  acutifrons, 
  Schliiter, 
  3 
  and 
  G. 
  Grotii, 
  

  

  F. 
  A. 
  Eomer, 
  4 
  which 
  Kayser 
  identifies 
  with 
  it), 
  and 
  still 
  more 
  so 
  in 
  

  

  G. 
  Lethcea?, 
  Kayser, 
  5 
  the 
  spines 
  seem 
  usually 
  much 
  shorter, 
  closer, 
  

   and 
  stouter 
  than 
  in 
  our 
  specimens, 
  the 
  terminal 
  spine 
  particularly 
  

   so. 
  In 
  G. 
  limbatus, 
  Schliiter, 
  6 
  they 
  are 
  said 
  to 
  be 
  shaped 
  like 
  those 
  

   of 
  G. 
  laciniatus, 
  but 
  separated 
  by 
  equally 
  wide 
  intervals. 
  In 
  

   <J. 
  Galliteles, 
  Green, 
  as 
  figured 
  by 
  Hall, 
  7 
  they 
  vary 
  much, 
  being 
  

   sometimes 
  as 
  stout 
  and 
  short 
  as 
  in 
  G. 
  laciniatus, 
  and 
  sometimes 
  

   more 
  like 
  ours 
  ; 
  but 
  its 
  pygidium 
  is 
  much 
  broader, 
  and 
  its 
  cheek- 
  

   spines 
  much 
  stouter. 
  If 
  Hall, 
  indeed, 
  were 
  right 
  in 
  referring 
  all 
  

   his 
  specimens 
  to 
  one 
  species 
  (a 
  reference 
  which 
  Kayser 
  questions), 
  

   the 
  development 
  of 
  the 
  terminal 
  spine 
  would 
  have 
  little 
  specific 
  

   weight. 
  G. 
  laciniatus, 
  Barrois, 
  8 
  seems, 
  as 
  suggested 
  by 
  himself, 
  to 
  

   agree 
  with 
  some 
  forms 
  of 
  G. 
  Galliteles. 
  Gryjohceus 
  sp., 
  Kayser 
  9 
  

   (identified 
  by 
  him 
  with 
  the 
  Phacops 
  stellifer, 
  Burmeister, 
  of 
  

   F. 
  A. 
  Eomer 
  10 
  ), 
  is 
  imperfect, 
  but, 
  so 
  far 
  as 
  can 
  be 
  seen, 
  is 
  very 
  like 
  

   our 
  pygidia, 
  except 
  that 
  it 
  is 
  broader. 
  In 
  Ph. 
  stellifer, 
  Burmeister, 
  11 
  

   itself 
  the 
  tail 
  seems 
  broader, 
  the 
  terminal 
  spine 
  longer, 
  and 
  the 
  

   glabella-lobes 
  differently 
  arranged. 
  G. 
  Pleione, 
  Hall, 
  12 
  appears 
  to 
  

   be 
  known 
  only 
  by 
  a 
  single 
  imperfect 
  pygidium, 
  which 
  looks 
  as 
  

   though 
  it 
  possibly 
  might 
  agree 
  with 
  ours 
  ; 
  Kayser 
  has 
  doubtfully 
  

   quoted 
  it 
  from 
  Daun 
  (Lower 
  Devonian). 
  

  

  It 
  may 
  be 
  noted 
  that, 
  while 
  in 
  most 
  of 
  our 
  pygidia 
  the 
  spines 
  

   seem 
  very 
  acute 
  and 
  narrow, 
  in 
  one 
  specimen 
  they 
  are 
  broader 
  and 
  

   more 
  blade-like. 
  Possibly 
  this 
  may 
  be 
  due 
  to 
  a 
  difference 
  in 
  sex. 
  

  

  From 
  the 
  above 
  comparisons 
  it 
  does 
  not 
  seem 
  that 
  we 
  can 
  identify 
  

   our 
  fossil 
  very 
  certainly 
  with 
  any 
  known 
  species 
  • 
  but 
  on 
  the 
  other 
  

   hand 
  the 
  distinctions 
  observable 
  are 
  not, 
  in 
  the 
  state 
  of 
  our 
  present 
  

   material, 
  sufficiently 
  pronounced 
  to 
  justify 
  us 
  in 
  treating 
  it 
  at 
  

   present 
  as 
  a 
  distinct 
  species. 
  I 
  therefore 
  place 
  it 
  provisionally 
  as 
  a 
  

   variety 
  of 
  G. 
  laciniatus, 
  only 
  observing 
  that 
  I 
  expect 
  that, 
  when 
  

   better 
  specimens 
  are 
  found, 
  it 
  will 
  prove 
  to 
  be 
  quite 
  as 
  distinct 
  

   from 
  it 
  as 
  are 
  several 
  of 
  the 
  various 
  forms 
  that 
  are 
  quoted 
  above. 
  

  

  1 
  1844. 
  F. 
  Eomer, 
  'Kheinisch. 
  Uebergangsgeb.' 
  p. 
  82 
  & 
  pi. 
  ii. 
  fig. 
  8.. 
  

  

  2 
  1839. 
  Emmerich, 
  'Dissert. 
  Trilob.' 
  p. 
  23, 
  fig. 
  1, 
  and 
  1846, 
  Burmeister, 
  

   'Organ. 
  Trilob.' 
  p. 
  92 
  & 
  pi. 
  iv. 
  fig. 
  2. 
  

  

  3 
  1881. 
  Schliiter, 
  Verhandl. 
  n. 
  Vereins 
  Eheiui. 
  vol. 
  xxxviii. 
  p. 
  144. 
  

  

  4 
  1843. 
  F. 
  A. 
  Eomer, 
  ' 
  Verst. 
  Harzgeb.' 
  p. 
  39 
  & 
  pi. 
  xi. 
  fig. 
  11. 
  

  

  5 
  1889. 
  Kayser, 
  Abh. 
  k. 
  Preuss. 
  geol. 
  Landesanst., 
  n. 
  s., 
  pt. 
  i. 
  pp. 
  81, 
  86, 
  & 
  

   pi. 
  xi. 
  figs. 
  3, 
  5, 
  6, 
  & 
  pi. 
  xxiii. 
  figs. 
  7-9. 
  

  

  6 
  1881. 
  Schliiter, 
  Verhandl. 
  n. 
  Vereins 
  Preuss. 
  ser. 
  4, 
  year 
  8, 
  p. 
  77. 
  

  

  7 
  1888. 
  Hall, 
  'Pal. 
  N.Y.' 
  vol. 
  vii. 
  p. 
  45, 
  pi. 
  xvi. 
  figs. 
  5-22 
  & 
  pl.xviA. 
  

  

  8 
  1889. 
  Barrois, 
  Mem. 
  Soc. 
  Geol. 
  Nord, 
  vol. 
  iii. 
  p. 
  267 
  & 
  pi. 
  xvii. 
  fig. 
  11. 
  

  

  9 
  1889. 
  Kayser, 
  Abh. 
  k. 
  Preuss. 
  geol. 
  Landesanst., 
  n. 
  s., 
  pt. 
  i. 
  p. 
  82 
  & 
  pi. 
  xi. 
  

   &g. 
  4. 
  

  

  10 
  1850. 
  F. 
  A. 
  Eomer, 
  * 
  Beitr. 
  z. 
  geolog. 
  Kenntn. 
  d. 
  nordwestl. 
  Oberharz,' 
  

   pt. 
  i. 
  p. 
  62 
  & 
  pi. 
  ix. 
  fig. 
  28. 
  

  

  11 
  1846. 
  Burmeister, 
  ' 
  Organ. 
  Trilob.' 
  p. 
  97 
  & 
  pi. 
  iv. 
  fig. 
  8. 
  

  

  12 
  1888. 
  Hall, 
  ' 
  Pal. 
  N.Y.* 
  vol. 
  vii. 
  p. 
  41 
  & 
  pi. 
  xvi 
  a. 
  fig. 
  2. 
  

  

  