﻿Report 
  of 
  the 
  State 
  Oeoloqisi. 
  811 
  

  

  is 
  similar 
  evidence. 
  In 
  Kutorgina 
  Zatourensis, 
  Matthew 
  described 
  

   a 
  minute 
  tooth 
  on 
  either 
  side 
  of 
  the 
  pedicle-opening,* 
  and 
  it 
  has 
  

   been 
  stated 
  that 
  K. 
  cingulqta 
  shows 
  faint 
  traces 
  of 
  articulating 
  

   processes 
  at 
  or 
  near 
  the 
  extremities 
  of 
  the 
  cardinal 
  line.f 
  Such 
  

   cases 
  indicate, 
  in 
  the 
  texture 
  and 
  composition 
  of 
  the 
  shell, 
  a 
  

   direct 
  passage 
  from 
  the 
  most 
  primitive 
  inarticulate 
  to 
  the 
  articu- 
  

   late 
  type. 
  In 
  this 
  feature 
  only, 
  the 
  connection 
  between 
  the 
  two 
  

   divisions 
  of 
  the 
  class 
  is 
  no 
  closer 
  or 
  more 
  clearly 
  manifested 
  

   than 
  in 
  the 
  instances 
  mentioned, 
  but 
  it 
  has 
  been 
  shownj 
  that 
  

   Kutorgina 
  cingulata 
  may 
  retain 
  a 
  pedicle- 
  covering 
  or 
  external 
  

   sheath, 
  in 
  fact 
  a 
  true 
  deltidium 
  bearing 
  an 
  apical 
  perforation, 
  

   like 
  that 
  in 
  Clitambonites. 
  A 
  deltidium-like 
  structure 
  is 
  highly 
  

   developed 
  or 
  fully 
  retained 
  at 
  maturity 
  in 
  Iphidea. 
  

  

  This 
  is 
  evidence 
  of 
  the 
  highest 
  moment, 
  and 
  shows 
  conclu- 
  

   sively 
  the 
  line 
  along 
  which 
  the 
  clitambonitoids 
  and 
  strophomen- 
  

   oids 
  have 
  been 
  derived. 
  It 
  is 
  an 
  immediate 
  departure 
  from 
  the 
  

   primitive 
  type 
  of 
  the 
  brachiopod 
  into 
  the 
  articulate 
  subtype. 
  

  

  Passage 
  from 
  the 
  inarticulate 
  to 
  the 
  articulate 
  plan 
  of 
  struc- 
  

   ture 
  was 
  thus 
  effected 
  at 
  a 
  very 
  early 
  period; 
  indeed, 
  almost 
  at 
  

   the 
  outset 
  of 
  the 
  history 
  of 
  the 
  group. 
  The 
  continuance 
  of 
  the 
  

   two 
  types 
  has 
  since 
  been 
  that 
  of 
  diverging 
  series, 
  constantly 
  

   widening 
  the 
  structural 
  gap 
  between 
  them. 
  We 
  have 
  no 
  

   evidence 
  that 
  this 
  chasm 
  has 
  been 
  bridged 
  at 
  any 
  other 
  point 
  

   than 
  near 
  its 
  source 
  ; 
  the 
  inclinations 
  from 
  the 
  one 
  type 
  toward 
  

   the 
  other, 
  shown 
  in 
  the 
  articulating 
  processes 
  of 
  Barroisella, 
  

   Tomasina, 
  etc., 
  represent 
  uncompleted 
  accessory 
  lines 
  of 
  develop- 
  

   ment, 
  which 
  were 
  abruptly 
  terminated 
  without 
  accomplishing 
  the 
  

   full 
  transition. 
  Such 
  forms 
  have 
  left 
  no 
  descendants, 
  so 
  far 
  as 
  

   known. 
  

  

  Before 
  entering 
  upon 
  a 
  summary 
  of 
  the 
  phyletic 
  relations 
  of 
  

   the 
  genera 
  of 
  the 
  Articulata, 
  it 
  is 
  important 
  to 
  apprehend 
  the 
  

   full 
  significance 
  of 
  the 
  modifications 
  here 
  appearing 
  in 
  the 
  struc- 
  

   ture 
  of 
  the 
  pedicle-passage 
  and 
  the 
  surfaces 
  upon 
  which 
  the 
  

   muscular 
  bands 
  are 
  implanted; 
  in 
  other 
  words, 
  the 
  origin 
  and 
  

   development 
  of 
  the 
  deltidium, 
  the 
  deltidial 
  plates 
  and 
  the 
  spoon- 
  

   shaped 
  muscular 
  platform, 
  or 
  spondylium, 
  which 
  may 
  occur 
  in 
  

  

  * 
  Illustrations 
  of 
  the 
  Fauna 
  of 
  the 
  St. 
  John 
  Group, 
  No. 
  3, 
  p. 
  42. 
  1885. 
  

   t 
  Beecheb, 
  American 
  Journal 
  of 
  Science, 
  vol. 
  XLIV, 
  p. 
  138. 
  1892. 
  

   X 
  Beecher, 
  loc. 
  cit. 
  

  

  