﻿1102 
  FORIY-SEVENTR 
  REPORT 
  ON 
  THE 
  STATE 
  MUSEUM. 
  

  

  this 
  point, 
  it 
  is 
  important 
  to 
  first 
  consider 
  the 
  basis 
  of 
  a 
  classifi- 
  

   cation 
  and 
  the 
  significance 
  of 
  certain 
  structural 
  features. 
  We 
  

   have 
  come, 
  in 
  our 
  study 
  of 
  these 
  creatures, 
  very 
  close 
  to 
  the 
  point 
  

   where 
  any 
  grouping 
  of 
  genera 
  into 
  families, 
  or 
  of 
  these 
  

   into 
  broader 
  divisions, 
  is 
  so 
  palpably 
  a 
  violation 
  of 
  nature's 
  

   method 
  as 
  to 
  make 
  itself 
  felt 
  as 
  an 
  incumbrance. 
  Hence 
  

   the 
  purpose 
  of 
  our 
  treatment 
  of 
  these 
  genera 
  without 
  such 
  

   restrictions. 
  Even 
  among 
  the 
  generic 
  groups 
  there 
  is 
  so 
  often 
  an 
  

   almost 
  intangible 
  transition 
  from 
  one 
  to 
  another 
  that 
  the 
  employ- 
  

   ment 
  of 
  distinctive 
  terms 
  seems 
  at 
  times 
  quite 
  perfunctory 
  ; 
  but 
  

   with 
  the 
  increase 
  of 
  such 
  difficulties 
  the 
  nearer 
  our 
  classification 
  

   may 
  be 
  regarded 
  as 
  approaching 
  the 
  true 
  method 
  of 
  develop- 
  

   ment. 
  To 
  us 
  the 
  genus 
  represents 
  a 
  structural 
  unit, 
  a 
  point 
  of 
  

   departure; 
  species, 
  diverse 
  expressions 
  of 
  the 
  generic 
  type; 
  

   families, 
  associations 
  of 
  genera 
  representing 
  the 
  offspring 
  of 
  

   common 
  parentage. 
  

  

  A 
  classification 
  is 
  a 
  broken 
  and 
  punctuated 
  expression 
  of 
  

   organic 
  affinities 
  and 
  interrelations, 
  necessary 
  to 
  an 
  easy 
  treat- 
  

   ment 
  of 
  any 
  group 
  of 
  organisms, 
  capable 
  of 
  expressing 
  many 
  

   truths 
  in 
  regard 
  to 
  the 
  development 
  of 
  a 
  race, 
  but 
  even 
  in 
  its 
  

   most 
  perfect 
  state 
  an 
  index 
  and 
  confession 
  of 
  faulty 
  knowledge. 
  

  

  In 
  the 
  earlier 
  classifications 
  of 
  the 
  Brachiopoda 
  a 
  high 
  value 
  

   has 
  been 
  ascribed 
  to 
  the 
  disposition 
  of 
  the 
  muscular 
  scars 
  upon 
  

   the 
  inner 
  surfaces 
  of 
  the 
  valves, 
  the 
  form 
  of 
  the 
  genito- 
  vascular 
  

   sinuses 
  and 
  the 
  configuration 
  and 
  degree 
  of 
  calcification 
  of 
  the 
  

   brachia. 
  To 
  the 
  last 
  of 
  these 
  must 
  still 
  be 
  ascribed 
  a 
  high 
  degree 
  

   of 
  significance 
  notwithstanding 
  the 
  fact 
  that 
  in 
  the 
  individual 
  

   this 
  calcification 
  is 
  a 
  progressive 
  process, 
  increasing 
  in 
  extent 
  

   from 
  infancy 
  to 
  maturity. 
  The 
  plan 
  of 
  the 
  muscular 
  and 
  

   vascular 
  anatomy 
  is, 
  however, 
  among 
  the 
  Articulate 
  Brachiopods, 
  

   but 
  slightly 
  modified 
  through 
  their 
  histor}^ 
  and 
  in 
  all 
  their 
  

   variations, 
  but 
  in 
  the 
  Inarticulate 
  division 
  we 
  find 
  it 
  to 
  be 
  

   susceptible 
  of 
  a 
  more 
  varied 
  expression. 
  

  

  But 
  it 
  is 
  the 
  variation 
  of 
  form, 
  position 
  and 
  mode 
  of 
  enclosure 
  

   of 
  the 
  pedicle-passage 
  that 
  affords 
  the 
  most 
  satisfactory 
  index 
  of 
  

   lines 
  of 
  progress 
  and 
  development. 
  We 
  have 
  already 
  briefly 
  

   referred 
  to, 
  and 
  described 
  the 
  principal 
  modifications 
  of 
  these 
  

   parts, 
  but 
  a 
  restatement 
  of 
  these 
  structural 
  details 
  is 
  essential 
  to 
  

   our 
  purposes. 
  

  

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