﻿382 
  Prof. 
  T. 
  R. 
  Jones 
  on 
  the 
  

  

  water 
  form, 
  but 
  rather 
  an 
  old 
  marine 
  form 
  that 
  has 
  acquired 
  

   estuarine 
  habits 
  by 
  force 
  of 
  circumstances. 
  Its 
  existence 
  in 
  

   these 
  Pre- 
  Carboniferous 
  marine 
  strata 
  at 
  Cap 
  Bon- 
  Ami 
  

   supports 
  this 
  view 
  of 
  its 
  history. 
  

  

  Note. 
  — 
  For 
  an 
  account 
  of 
  fig. 
  11, 
  also 
  from 
  Cap 
  Bon-Ami, 
  

   see 
  further 
  on, 
  p. 
  383. 
  

  

  Remarks 
  as 
  to 
  Relationship. 
  

  

  Herr 
  M. 
  Verworn, 
  of 
  Berlin, 
  has 
  already 
  shown 
  us, 
  in 
  his 
  

   memoir 
  on 
  the 
  " 
  Developmental 
  History 
  of 
  the 
  Beyrichue 
  " 
  

   (Zeitschr. 
  deutsch. 
  geol. 
  Gesellsch. 
  1887, 
  pp. 
  27-31, 
  with 
  

   pi. 
  iii.), 
  that 
  his 
  Beyrichia 
  primitiva, 
  obtained 
  as 
  a 
  series 
  of 
  

   young 
  and 
  adult 
  forms 
  in 
  a 
  Silurian 
  limestone 
  from 
  the 
  Drift 
  

   at 
  Rixdorf, 
  near 
  Berlin, 
  is 
  a 
  Primitia 
  when 
  small 
  and 
  young, 
  

   and 
  becomes 
  more 
  and 
  more 
  Beyrichian 
  with 
  age, 
  until 
  it 
  

   becomes 
  identical 
  with, 
  or 
  at 
  least 
  very 
  closely 
  approaches, 
  

   Beyrichia 
  Saheriana, 
  the 
  presence 
  of 
  the 
  crenulated 
  marginal 
  

   flange 
  in 
  the 
  latter 
  being 
  the 
  chief 
  distinction. 
  If 
  identical, 
  

   the 
  species 
  would 
  stand 
  by 
  the 
  latter 
  name. 
  

  

  Mr. 
  C. 
  D. 
  Walcott 
  also, 
  in 
  his 
  memoir 
  on 
  the 
  " 
  Palaaon- 
  

   tology 
  of 
  the 
  Eureka 
  District," 
  U. 
  S. 
  Geol. 
  Survey, 
  4to, 
  

   Washington, 
  1884, 
  has 
  indicated 
  that 
  his 
  Devonian 
  Bey- 
  

   richia 
  {Primitia) 
  occidentalis 
  (p. 
  204, 
  pi. 
  xvii. 
  figs. 
  4 
  and 
  4 
  a) 
  

   begins 
  as 
  a 
  Primitia 
  and 
  becomes 
  a 
  Beyrichia 
  when 
  adult. 
  

  

  At 
  first 
  glance 
  the 
  group 
  of 
  Ostracoda 
  from 
  Dalhousie 
  

   (PI. 
  XVII. 
  figs. 
  1-9) 
  seemed 
  to 
  present 
  another 
  example 
  of 
  

   passage 
  from 
  Primitia 
  to 
  Beyrichia 
  ; 
  but 
  after 
  very 
  careful 
  

   consideration 
  I 
  feel 
  bound 
  to 
  confine 
  my 
  conclusions 
  to 
  the 
  

   following 
  : 
  — 
  (1) 
  The 
  probably 
  close 
  alliance 
  by 
  family 
  ties, 
  

   though 
  not 
  in 
  this 
  case 
  by 
  direct 
  descent, 
  of 
  the 
  two 
  small 
  

   Primitive 
  (figs. 
  1 
  and 
  2), 
  inasmuch 
  as 
  a 
  progressive 
  develop- 
  

   ment 
  of 
  the 
  edge 
  of 
  the 
  sulcus 
  in 
  fig. 
  1 
  might 
  lead 
  to 
  P. 
  

   stranyulata, 
  P. 
  bicornis, 
  and 
  others, 
  whilst 
  the 
  tubercles 
  in 
  

   fig. 
  2 
  lead 
  rather 
  to 
  Bollia 
  and 
  possibly 
  to 
  Strepula. 
  

  

  (2) 
  Though 
  the 
  sulcus 
  of 
  Primitia 
  may 
  represent 
  the 
  main 
  

   furrow 
  of 
  Beyrichia, 
  yet 
  the 
  tubercles, 
  sometimes 
  single 
  

   (on 
  one 
  or 
  the 
  other 
  side 
  of 
  the 
  sulcus), 
  sometimes 
  double 
  

   (one 
  on 
  each 
  side 
  of 
  the 
  sulcus), 
  are 
  too 
  uncertain 
  to 
  be 
  

   regarded 
  as 
  homologues 
  of 
  the 
  middle 
  lobe 
  of 
  Beyrichia. 
  In 
  

   this 
  respect 
  therefore 
  there 
  is 
  a 
  gap 
  in 
  the 
  relationship. 
  

  

  In 
  1860 
  M. 
  d'Eichwald 
  remarked 
  (' 
  Lethtea 
  Rossica,' 
  vol. 
  i. 
  

   livr. 
  7, 
  p. 
  1347), 
  after 
  noticing 
  the 
  apparent 
  relationship 
  of 
  

   the 
  two 
  variable 
  species 
  Beyrichia 
  tuberculata 
  (Kloden) 
  and 
  

  

  