﻿Vol. 
  S3-] 
  

  

  PETALOGRAPTTTS 
  AND 
  CEPHALOGRAPTT7S. 
  

  

  203 
  

  

  No. 
  

  

  No. 
  of 
  thecae. 
  

  

  Length. 
  

  

  Locality. 
  

  

  26. 
  

  

  5 
  

  

  A 
  

  

  Dobb's 
  Linn, 
  Moffat. 
  

  

  12. 
  

  

  7 
  

  

  — 
  -3" 
  

  

  j> 
  >> 
  >> 
  

  

  2. 
  

  

  8 
  

  

  If 
  

  

  55 
  

  

  55 
  55 
  

  

  13. 
  

  

  10 
  

  

  * 
  

  

  55 
  

  

  )» 
  55 
  

  

  8. 
  

  

  11 
  

  

  i 
  

  

  55 
  

  

  5 
  5> 
  

  

  21. 
  

  

  12 
  

  

  * 
  

  

  55 
  

  

  5 
  55 
  

  

  18. 
  

  

  13 
  

  

  * 
  

  

  „ 
  

  

  5 
  >5 
  

  

  4 
  1 
  . 
  

  

  14 
  

  

  T 
  3 
  , 
  

  

  55 
  

  

  55 
  55 
  

  

  7. 
  

  

  14 
  

  

  3 
  

  

  55 
  

  

  5 
  

  

  1. 
  

  

  15 
  

  

  T 
  3 
  S 
  

  

  55 
  

  

  5 
  55 
  

  

  11. 
  

  

  15 
  

  

  A 
  

  

  „ 
  

  

  J 
  55 
  

  

  3. 
  

  

  16 
  

  

  TB 
  

  

  ,, 
  

  

  5 
  55 
  

  

  9. 
  

  

  16 
  

  

  + 
  T 
  3 
  . 
  

  

  „ 
  

  

  » 
  55 
  

  

  10. 
  

  

  16 
  

  

  + 
  T 
  3 
  

  

  „ 
  

  

  5, 
  

  

  29. 
  

  

  18 
  

  

  1 
  

   5 
  

  

  Skelgill. 
  

  

  23. 
  

  

  18 
  

  

  i 
  

  

  Dobb's 
  Linn, 
  Moffat. 
  

  

  14. 
  

  

  19 
  

  

  4-i 
  

  

  Skelgill. 
  

  

  A. 
  

  

  19 
  

  

  5 
  

   T8 
  

  

  Tominarp, 
  Skane. 
  

  

  17. 
  

  

  20 
  

  

  rV 
  

  

  Dobb's 
  Linn, 
  Moffat. 
  

  

  4 
  2 
  . 
  

  

  20' 
  

  

  f 
  

  

  Skelgill. 
  

  

  16. 
  

  

  21 
  

  

  * 
  

  

  55 
  

  

  General 
  Characters. 
  — 
  This 
  species 
  has 
  sometimes 
  a 
  superficial 
  

   resemblance 
  to 
  young 
  forms 
  of 
  P. 
  palmeus 
  (Barr. 
  restr.), 
  and 
  P. 
  

   palmeus, 
  var. 
  latus 
  (Barr.), 
  but 
  can 
  be 
  readily 
  distinguished 
  from 
  

   them. 
  

  

  (1) 
  The 
  sicula 
  is 
  longer, 
  and 
  attains' 
  a 
  greater 
  height 
  in 
  the 
  

  

  thecal 
  series 
  than 
  in 
  any 
  varieties 
  of 
  P. 
  palmeus 
  (Barr.). 
  

  

  (2) 
  The 
  proximal 
  end 
  is 
  more 
  protracted 
  than 
  in 
  those 
  varieties. 
  

  

  (3) 
  The 
  maximum 
  width 
  is 
  attained 
  later 
  than 
  in 
  either 
  P. 
  

   palmeus 
  (restr.), 
  or 
  P. 
  palmeus, 
  var. 
  latus 
  (Barr.). 
  In 
  this 
  

   species 
  it 
  is 
  never 
  attained 
  till 
  half 
  way 
  up 
  the 
  rhabdosoma, 
  

   while 
  in 
  all 
  forms 
  of 
  P. 
  palmeus 
  (Barr.) 
  it 
  is 
  attained 
  at 
  

   once. 
  

  

  (4) 
  There 
  is 
  no 
  trace 
  of 
  a 
  septum 
  on 
  the 
  reverse 
  side. 
  In 
  P. 
  

   jpalmeus 
  (restr.) 
  and 
  in 
  var. 
  latus 
  (Barr.) 
  a 
  continuous 
  

   septum 
  is 
  present. 
  

  

  (5) 
  In 
  this 
  species 
  the 
  distal 
  end 
  is 
  gently 
  rounded 
  off, 
  and 
  the 
  

  

  rhabdosoma 
  decreases 
  in 
  width 
  distally. 
  In 
  the 
  forms 
  of 
  

   P. 
  palmeus 
  (Barr.) 
  the 
  rhabdosoma 
  retains 
  its 
  maximum 
  

   width 
  quite 
  up 
  to 
  the 
  distal 
  end, 
  which 
  is 
  usually 
  abruptly 
  

   truncate. 
  

  

  p2 
  

  

  