﻿378 
  Prof. 
  T. 
  R, 
  Jones 
  on 
  the 
  

  

  coarsely 
  pitted, 
  the 
  furrow 
  more 
  forward, 
  and 
  the 
  tubercle 
  

   smaller. 
  

  

  There 
  are 
  other 
  little 
  black 
  Primitive 
  (some 
  of 
  them 
  like 
  

   fig. 
  1) 
  on 
  the 
  specimen 
  with 
  fig. 
  3, 
  in 
  the 
  piece 
  of 
  hard 
  dark 
  

   argillaceous 
  limestone 
  no. 
  17. 
  

  

  Fig. 
  3 
  differs 
  from 
  the 
  other 
  forms 
  on 
  the 
  Plate 
  by 
  its 
  

   relatively 
  large 
  median 
  sulcus, 
  with 
  backward 
  curve, 
  and 
  by 
  

   its 
  relatively 
  long 
  subelliptical 
  outline. 
  

  

  Taking 
  the 
  relative 
  position 
  and 
  proportion 
  of 
  the 
  sulcus 
  

   into 
  consideration 
  we 
  may 
  see 
  that 
  it 
  is 
  variable 
  in 
  the 
  above- 
  

   described 
  Primitive 
  in 
  these 
  respects 
  : 
  — 
  

  

  Sulcus 
  relatively 
  large 
  in 
  figs. 
  3, 
  5, 
  8. 
  

  

  ,, 
  „ 
  small 
  in 
  figs. 
  1, 
  2, 
  4, 
  6, 
  7, 
  9. 
  

  

  ,, 
  straight 
  in 
  figs. 
  1, 
  2, 
  4, 
  5, 
  6. 
  

  

  ,, 
  curved 
  in 
  figs. 
  3, 
  7, 
  8, 
  9. 
  

  

  ,, 
  placed 
  forwards 
  in 
  figs. 
  1, 
  2, 
  4, 
  6, 
  7, 
  8, 
  9. 
  

  

  „ 
  ,, 
  nearly 
  in 
  the 
  middle 
  in 
  fig. 
  5. 
  

  

  „ 
  ,, 
  quite 
  in 
  the 
  middle 
  in 
  fig. 
  3. 
  

  

  With 
  regard 
  to 
  outline, 
  all 
  the 
  figures, 
  except 
  figs. 
  1 
  and 
  3, 
  

   show 
  high 
  (broad) 
  valves. 
  

  

  In 
  figs. 
  7 
  a 
  and 
  8, 
  and 
  perhaps 
  in 
  fig. 
  (>, 
  there 
  is 
  certainly 
  

   a 
  step 
  towards 
  the 
  formation 
  of 
  a 
  central 
  lobe 
  between 
  the 
  

   normal 
  sulcus 
  and 
  a 
  feeble 
  parallel 
  depression. 
  But 
  this 
  

   looks 
  more 
  like 
  an 
  abortive 
  attempt 
  to 
  produce 
  a 
  family 
  

   feature 
  than 
  such 
  a 
  regular 
  progression 
  of 
  growth 
  as 
  shown 
  

   by 
  M. 
  Verworn's 
  figures 
  1, 
  2, 
  3, 
  6, 
  5, 
  7, 
  9, 
  11, 
  4, 
  10, 
  and 
  

   perhaps 
  8. 
  

  

  II. 
  Upper- 
  Silurian 
  specimens 
  from 
  Cap 
  Bon-Ami. 
  

  

  Most 
  of 
  these 
  Ostracods 
  (PI. 
  XVII. 
  figs. 
  1-9) 
  retain 
  their 
  

   tests, 
  though 
  some 
  (figs. 
  7 
  and 
  8) 
  have 
  only 
  part 
  of 
  the 
  

   valve. 
  For 
  the 
  material 
  see 
  p. 
  374. 
  Having 
  been 
  magni- 
  

   fied 
  only 
  10 
  (instead 
  of 
  15) 
  diameters, 
  they 
  look 
  relatively 
  

   smaller 
  than 
  those 
  from 
  Campbellton 
  (see 
  p. 
  375). 
  

  

  3. 
  Primitia 
  mundula, 
  Jones, 
  var. 
  (PI. 
  XVII. 
  fig. 
  1.) 
  

  

  In 
  PI. 
  XVII., 
  fig. 
  1 
  (from 
  specimen 
  no. 
  25) 
  indicates 
  the 
  

   smallest 
  of 
  the 
  Primitice 
  found 
  among 
  the 
  Ostracoda 
  collected 
  

   at 
  Cap 
  Bon-Ami 
  ; 
  taken 
  by 
  itself 
  it 
  may 
  be 
  regarded 
  as 
  a 
  

   narrow 
  variety 
  of 
  P. 
  mundula, 
  Jones 
  (Ann. 
  & 
  Mag. 
  Nat. 
  Hist. 
  

   ser. 
  2, 
  vol. 
  xvi. 
  pp. 
  90, 
  174, 
  pi. 
  vi. 
  figs. 
  28 
  and 
  29, 
  and 
  

   noticed 
  in 
  subsequent 
  papers). 
  

  

  