﻿196 
  MISS 
  G. 
  L. 
  ELLES 
  ON 
  THE 
  SUBGENERA. 
  [May 
  1 
  897, 
  

  

  and 
  oblique 
  to 
  the 
  long 
  axis 
  of 
  the 
  rhabdosoma. 
  There 
  are 
  about 
  

   36 
  thecal 
  apertures 
  in 
  the 
  space 
  of 
  an 
  inch. 
  The 
  thecae 
  are 
  

   inclined 
  at 
  their 
  origin 
  at 
  the 
  proximal 
  end 
  at 
  an 
  angle 
  of 
  about 
  

   45°, 
  but 
  curve 
  very 
  distinctly 
  after 
  this 
  in 
  an 
  outward 
  direction. 
  

   The 
  angle 
  of 
  inclination 
  changes 
  uniformly 
  from 
  the 
  proximal 
  up 
  to 
  

   the 
  distal 
  end, 
  where 
  it 
  is 
  about 
  20°. 
  There 
  appears 
  to 
  be 
  a 
  con- 
  

   tinuous 
  septum 
  in 
  this 
  variety, 
  but 
  its 
  course 
  is 
  rather 
  irregular 
  (see 
  

   PL 
  XIV. 
  fig. 
  8). 
  The 
  virgula 
  is 
  conspicuous, 
  is 
  distally 
  prolonged, 
  

   and 
  may 
  be 
  split 
  as 
  in 
  P. 
  palmeus 
  (restricted). 
  

  

  General 
  Characters. 
  — 
  This 
  variety 
  differs 
  from 
  P. 
  palmeus 
  (restr.) 
  

   in 
  

  

  (1) 
  Greater 
  width. 
  

  

  (2) 
  Greater 
  number 
  of 
  thecal 
  apertures 
  in 
  the 
  space 
  of 
  an 
  inch. 
  

  

  (3) 
  The 
  greater 
  angle 
  at 
  which 
  the 
  thecae 
  are 
  inclined 
  at 
  the 
  

  

  proximal 
  end. 
  

  

  (4) 
  The 
  greater 
  curvature 
  of 
  the 
  same 
  thecae. 
  

  

  Horizon. 
  — 
  This 
  variety 
  has 
  a 
  rather 
  shorter 
  range 
  than 
  P. 
  palmeus 
  

   (restr.). 
  It 
  first 
  appears 
  about 
  the 
  middle 
  of 
  the 
  zone 
  of 
  M. 
  gregarius 
  

   (Lapw.), 
  and 
  is 
  most 
  abundant 
  throughout 
  the 
  middle 
  and 
  upper 
  

   parts 
  of 
  that 
  zone. 
  I 
  have 
  never 
  found 
  a 
  specimen 
  in 
  the 
  Lower 
  

   Gala-Tarannon 
  beds. 
  It 
  seems 
  to 
  be 
  specially 
  characteristic 
  of 
  the 
  

   Middle 
  Birkhill 
  Shales. 
  

  

  It 
  occurs 
  in 
  Scandinavia 
  in 
  the 
  Rastrites-Shales 
  of 
  Tommarp 
  

   And 
  Bollerup 
  in 
  Skane, 
  at 
  Kongslena 
  in 
  Vestergotland, 
  and 
  at 
  

   Enan 
  in 
  Dalarne. 
  

  

  In 
  Bohemia 
  it 
  occurs 
  with 
  M. 
  proteus 
  (Lapw.) 
  at 
  Litohlav, 
  and 
  

   with 
  M. 
  fimbriatus 
  at 
  Berown 
  and 
  Zelkovice. 
  

  

  In 
  Thuringia 
  it 
  has 
  been 
  found 
  in 
  the 
  Rastrites-Sh&les 
  of 
  Riickers- 
  

   dorf 
  and 
  Heinrichsruhe. 
  

  

  British 
  Localities. 
  — 
  Moffat 
  District 
  : 
  Dobb's 
  Linn, 
  Garple 
  Linn, 
  

   •etc., 
  wherever 
  the 
  M. 
  gregarius-zone 
  is 
  typically 
  developed. 
  Lake 
  

   District 
  : 
  Skelgill. 
  Ireland 
  : 
  Coalpit 
  Bay, 
  Co. 
  Down. 
  

  

  Petalooraptus 
  palmeus, 
  var. 
  tenuis 
  (Barr.). 
  (PI. 
  XIV. 
  figs. 
  9-10.) 
  

  

  Structure 
  of 
  the 
  Proximal 
  End. 
  — 
  The 
  details 
  of 
  the 
  structure 
  

   -of 
  the 
  proximal 
  end 
  are 
  similar 
  to 
  those 
  in 
  P. 
  palmeus 
  (restr.). 
  

   The 
  sicula 
  is 
  perhaps 
  a 
  very 
  little 
  shorter 
  than 
  in 
  the 
  two 
  

   forms 
  previously 
  described. 
  It 
  is 
  furnished 
  with 
  a 
  long 
  apertural 
  

   spine. 
  

  

  The 
  earliest 
  thecae 
  are 
  shorter 
  than 
  in 
  P. 
  palmeus 
  (restr.), 
  and 
  are 
  

   almost 
  straight; 
  they 
  are 
  also 
  much 
  broader 
  in 
  proportion 
  to 
  their 
  

   length. 
  

  

  The 
  sicula 
  is 
  rather 
  more 
  than 
  -fa 
  inch 
  long. 
  The 
  first 
  theca 
  is 
  

   the 
  most 
  curved 
  ; 
  it 
  is 
  about 
  -^ 
  inch 
  in 
  length. 
  

  

  Character 
  of 
  Mature 
  Rhabdosoma. 
  — 
  This 
  form 
  is 
  often 
  small, 
  

   Tbut 
  it 
  may 
  be 
  as 
  much 
  as 
  J 
  inch 
  in 
  length. 
  The 
  width 
  of 
  fa 
  inch 
  

   is 
  maintained 
  throughout 
  its 
  length. 
  The 
  thecae 
  are 
  alternate 
  ; 
  they 
  

  

  