﻿S'20 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  The 
  compound 
  " 
  shoe-lifter," 
  divided 
  by 
  the 
  median 
  septum 
  in 
  

   the 
  brachial 
  valve 
  of 
  Dicamara, 
  is 
  like 
  the 
  corresponding 
  plate 
  in 
  

   the 
  pedicle-valve 
  in 
  having 
  no 
  connection 
  with, 
  or 
  origin 
  from 
  

   the 
  articulating 
  apparatus. 
  This 
  plate 
  is 
  not 
  a 
  cruralium, 
  and 
  in 
  

   precisely 
  the 
  same 
  sense 
  that 
  the 
  simple 
  "shoe-lifter" 
  is 
  not 
  a 
  

   spondylium. 
  Such 
  cases 
  as 
  Merista 
  and 
  Dicamara. 
  are, 
  there- 
  

   fore, 
  not 
  to 
  be 
  cited 
  as 
  examples 
  of 
  the 
  concurrence 
  of 
  spondylium 
  

   and 
  cruralium, 
  with 
  the 
  secondary 
  condition 
  of 
  the 
  pedicle- 
  cover- 
  

   ing 
  or 
  deltarium, 
  but 
  are, 
  rather, 
  illustrations 
  of 
  the 
  production 
  

   of 
  parts 
  which 
  may 
  be 
  similar 
  in 
  function 
  in 
  the 
  mature 
  condition, 
  

   but 
  are 
  totally 
  distinct 
  in 
  origin 
  ; 
  in 
  other 
  words, 
  interesting 
  

   instances 
  of 
  morphic 
  equivalents. 
  

  

  The 
  cardinal 
  area 
  is 
  a 
  feature 
  more 
  generally 
  developed 
  

   among 
  the 
  forms 
  included 
  by 
  Waagen 
  under 
  his 
  term 
  

   Aphaneropegmata, 
  (Protremata, 
  Beecher) 
  that 
  is, 
  among 
  forms 
  

   possessing 
  the 
  deltidium, 
  but 
  it 
  is 
  very 
  irregular 
  in 
  its 
  occurrence 
  

   among 
  all 
  the 
  articulate 
  Brachiopoda. 
  The 
  genus 
  Spirifer 
  fur- 
  

   nishes 
  a 
  most 
  striking 
  instance 
  of 
  its 
  persistence 
  in 
  the 
  deltarium- 
  

   bearing 
  shells 
  ; 
  its 
  usual 
  absence 
  in 
  Pentamercts 
  and 
  Conchidiqm 
  

   serves 
  to 
  demonstrate 
  that 
  it 
  is 
  not 
  an 
  indispensable 
  character 
  of 
  its 
  

   group. 
  It 
  is 
  probable 
  that 
  the 
  existence 
  of 
  this 
  area 
  has 
  little 
  funda- 
  

   mental 
  connection 
  with 
  the 
  condition 
  of 
  the 
  pedicle-passage. 
  It 
  is 
  

   a 
  very 
  palpable 
  fact 
  that 
  there 
  is 
  a 
  much 
  more 
  intimate 
  relation 
  

   between 
  this 
  area 
  and 
  the 
  general 
  form 
  of 
  the 
  shell 
  ; 
  thus 
  in 
  the 
  

   elongate 
  shells, 
  like 
  the 
  terebratuloids, 
  meristoids, 
  retzioids 
  and 
  

   the 
  pentameroids 
  for 
  the 
  most 
  part, 
  there 
  is 
  no 
  such 
  area 
  present. 
  

   Where 
  the 
  form 
  of 
  the 
  shell 
  is 
  more 
  generally 
  transverse, 
  as 
  

   among 
  the 
  Ojcthid,e, 
  in 
  Strophomena, 
  Clitamboniets, 
  Derbya, 
  

   Spirifer, 
  etc 
  , 
  the 
  area 
  is 
  highly 
  developed. 
  This 
  area 
  is 
  a 
  char- 
  

   acteristic 
  feature 
  of 
  all 
  early 
  deltidium-bearing 
  species, 
  and, 
  

   where 
  it 
  manifests 
  itself 
  occasionally 
  in 
  one 
  of 
  these 
  groups 
  

   which 
  has 
  for 
  the 
  most 
  part 
  lost 
  or 
  never 
  developed 
  this 
  area, 
  as 
  

   in 
  Porambonites, 
  Gtypidula 
  and 
  Pentamerella 
  among 
  the 
  pen- 
  

   tameroids, 
  its 
  appearance 
  may 
  be 
  regarded 
  as 
  the 
  resumption 
  of 
  a 
  

   primitive 
  or 
  original 
  character 
  which 
  was 
  normal 
  for 
  that 
  division 
  

   of 
  the 
  Articulates 
  in 
  some 
  period 
  of 
  its 
  history. 
  

  

  We 
  similarly 
  meet 
  with 
  a 
  cardinal 
  area 
  in 
  an 
  early 
  rhynchonel- 
  

   lid 
  type, 
  Orthorhynohula, 
  and 
  this 
  is 
  an 
  evidence 
  of 
  the 
  first 
  sig- 
  

   nificance 
  as 
  indicating 
  the 
  source 
  from 
  which 
  the 
  extensive 
  group 
  

  

  