﻿804 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  and 
  ready 
  destructibility 
  of 
  the 
  shells. 
  It 
  is 
  quite 
  natural 
  to 
  

   find 
  in 
  such 
  a 
  highly 
  organized 
  group 
  the 
  possibility 
  of 
  variation 
  

   more 
  frequently 
  manifested. 
  

  

  The 
  opinion 
  expressed 
  in 
  the 
  " 
  Conclusion 
  " 
  to 
  the 
  Brachiopoda 
  

   Inarticulata, 
  that 
  the 
  "feature 
  of 
  paramount 
  importance" 
  in 
  

   dealing 
  with 
  the 
  evolution 
  of 
  the 
  palaeozoic 
  brachiopodous 
  genera 
  

   " 
  will 
  be 
  found 
  in 
  the 
  character 
  of 
  the 
  pedicle-passage 
  " 
  (p. 
  161),* 
  

   its 
  conformation 
  and 
  accessories, 
  has 
  been 
  substantiated 
  by 
  all 
  

   the 
  later 
  investigations 
  of 
  this 
  work 
  and 
  is 
  still 
  maintained 
  as 
  

   the 
  true 
  basis 
  of 
  classification. 
  f 
  

  

  It 
  is 
  not 
  the 
  present 
  purpose 
  to 
  recapitulate 
  at 
  any 
  length 
  the 
  

   substance 
  of 
  the 
  deductions 
  already 
  set 
  forth 
  in 
  regard 
  to 
  the 
  

   Inarticulate 
  genera. 
  The 
  views 
  expressed 
  have 
  not 
  been 
  mate- 
  

   rially 
  modified 
  ; 
  but 
  during 
  the 
  interval 
  since 
  their 
  publication 
  

   an 
  extraordinary 
  interest 
  has 
  been 
  manifested 
  in 
  the 
  study 
  of 
  the 
  

   Brachiopoda 
  both 
  recent 
  and 
  fossil, 
  especially 
  in 
  France, 
  Austria 
  

   and 
  America, 
  and 
  the 
  additions 
  thereby 
  made 
  to 
  our 
  knowledge 
  

   invite 
  special 
  attention. 
  

  

  Lingula 
  has 
  been 
  shown 
  to 
  be 
  a 
  comprehensive 
  type, 
  not 
  exist- 
  

   ent 
  in 
  primordial 
  faunas. 
  As 
  yet 
  we 
  are 
  unable 
  to 
  indicate 
  any 
  

   difference 
  of 
  generic 
  importance 
  between 
  the 
  Lingula. 
  of 
  the 
  

   Lower 
  Silurian 
  and 
  that 
  of 
  existing 
  seas. 
  Its 
  elongate 
  form 
  is 
  

   not 
  primitive, 
  and 
  its 
  complicated 
  muscular 
  system 
  is 
  indicative 
  

   of 
  an 
  advanced 
  stage 
  of 
  progress. 
  We 
  may 
  therefore 
  look 
  for 
  

   the 
  precursors 
  of 
  this 
  type 
  of 
  structure 
  among 
  the 
  less 
  elongate 
  

   (Lingttlella) 
  and 
  more 
  orbicular 
  genera 
  (Ob- 
  lus 
  Obolella). 
  

   In 
  the 
  diagrammatic 
  scheme 
  of 
  the 
  derivation 
  of 
  Lingula, 
  given 
  

   upon 
  page 
  164 
  of 
  Part 
  I, 
  Lingttlella 
  and 
  Obolella 
  are 
  repre- 
  

   sented 
  as 
  divergent 
  from 
  some 
  unknown 
  earlier 
  inceptive 
  stock, 
  

   whose 
  existence, 
  represented 
  by 
  a 
  mark 
  of 
  interrogation, 
  was 
  

   deemed 
  probable 
  from 
  the 
  comparative 
  study 
  of 
  these 
  genera. 
  

  

  * 
  It 
  is 
  proper 
  to 
  explain 
  in 
  this 
  place, 
  that 
  though 
  the 
  title-page 
  to 
  Vol. 
  Ill, 
  Part 
  I, 
  bears 
  the 
  

   date 
  of 
  1892, 
  the 
  pages 
  relating 
  to 
  the 
  Inarticulata, 
  including 
  the 
  concluding 
  chapter 
  referred 
  

   to, 
  had 
  been 
  completed 
  and 
  printed 
  in 
  July, 
  1890. 
  Certain 
  of 
  these 
  (pp. 
  120-160), 
  relating 
  to 
  

   the 
  structure 
  and 
  development 
  of 
  the 
  pedicle-passage 
  in 
  Orbiculoidea, 
  Schizocranfa, 
  Tre- 
  

   matis, 
  etc., 
  were 
  reset 
  and 
  issued 
  separately 
  at 
  that 
  date, 
  with 
  lithographic 
  plates 
  (IV 
  e 
  and 
  

   IV 
  f), 
  and 
  this 
  printed 
  excerpt 
  was 
  distributed 
  among 
  students 
  of 
  the 
  Brachiopoda 
  as 
  well 
  as 
  

   to 
  the 
  general 
  scientific 
  public. 
  

  

  tThe 
  subordinal 
  classification 
  of 
  the 
  Brachiopoda 
  introduced 
  by 
  Waagen 
  (1883-1885) 
  was 
  

   based 
  to 
  some 
  extent 
  upon 
  the 
  conformation 
  of 
  the 
  peiicle-passage. 
  The 
  phyletic 
  value 
  of 
  

   variations 
  in 
  this 
  structure 
  was 
  first 
  clearly 
  indicated 
  by 
  Eugene 
  Deslongchamps, 
  and 
  has 
  

   been 
  subsequently 
  elaborated 
  by 
  several 
  writers. 
  

  

  