﻿1114 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  condition, 
  it 
  is 
  not 
  possible 
  to 
  give 
  it 
  great 
  weight 
  in 
  a 
  broader 
  

   grouping 
  of 
  the 
  genera, 
  for 
  we 
  find 
  that 
  Strophonella 
  is 
  

   but 
  a 
  reversed 
  Stropheodonta, 
  passing 
  through 
  similar 
  phases; 
  

   Amphistrophia 
  is 
  a 
  reversed 
  Brachyprion, 
  both 
  existing 
  in 
  faunas 
  

   of 
  the 
  same 
  age, 
  and 
  Strophomena 
  is 
  a 
  reversed 
  Kaeinesquina, 
  

   both 
  similarly 
  coexistent. 
  

  

  With 
  this 
  presentation 
  of 
  the 
  subject 
  it 
  seems 
  neither 
  necessary 
  

   nor 
  desirable 
  to 
  propose 
  any 
  broad 
  division 
  of 
  this 
  group 
  of 
  

   genera. 
  In 
  1846 
  Kino 
  proposed 
  to 
  embrace 
  Strophomena 
  and 
  its 
  

   allies 
  in 
  the 
  family 
  Strophomenidje. 
  The 
  large 
  number 
  of 
  generic 
  

   values 
  allied 
  to 
  Strophomena, 
  which 
  have 
  been 
  determined 
  since 
  

   that 
  date, 
  make 
  this 
  comprehensive 
  family 
  divisible 
  ad 
  libitum, 
  

   sed 
  non 
  in 
  majorem 
  Dei 
  gloriam. 
  

  

  The 
  calcareous 
  fixation 
  of 
  the 
  pedicle- 
  valve 
  to 
  extraneous 
  

   bodies 
  after 
  the 
  closure 
  of 
  the 
  pedicle-passage 
  and 
  atrophy 
  of 
  the 
  

   pedicle 
  itself, 
  is 
  repeatedly 
  manifested 
  by 
  these 
  shells. 
  This, 
  as 
  

   already 
  shown, 
  is 
  a 
  pre-adult 
  condition 
  in 
  Orthothetes, 
  Derbya 
  

   and 
  Streptorhynchus, 
  the 
  shell 
  becoming 
  wholly 
  free 
  before 
  full 
  

   growth 
  was 
  attained 
  ; 
  but 
  in 
  Lept^enisca 
  and 
  D 
  avidsonia 
  the 
  

   attachment 
  was 
  maintained 
  throughout 
  the 
  later 
  existence 
  of 
  the 
  

   shell. 
  

  

  The 
  impressions 
  left 
  by 
  the 
  spiral 
  arms 
  upon 
  the 
  interior 
  of 
  the 
  

   valves 
  in. 
  David3onia. 
  and 
  Lept^enisca, 
  and 
  also 
  observed 
  by 
  

   Davidson 
  in 
  a 
  specimen 
  of 
  Raftnesqiiina 
  Jukesi, 
  show 
  a 
  complete 
  

   correspondence 
  in 
  the 
  direction 
  and 
  curvature 
  of 
  the 
  coils, 
  and 
  

   we 
  are 
  left 
  to 
  infer 
  that 
  other 
  members 
  of 
  the 
  Strophomenidje 
  

   were 
  in 
  agreement 
  with 
  this 
  structure, 
  and 
  hence 
  that 
  the 
  arms 
  

   in 
  their 
  uncalcified 
  condition 
  approached 
  nearer 
  the 
  calcified 
  

   spirals 
  of 
  Koninckinidm 
  (Ccelospira, 
  Koninckinia, 
  etc.) 
  than 
  to 
  

   those 
  of 
  any 
  other 
  group. 
  

  

  The 
  condition 
  of 
  the 
  pedicle-passage 
  possessed 
  by 
  these 
  shells 
  

   is 
  maintained 
  by 
  Chonetes 
  and 
  Prodtjctus, 
  without 
  great 
  modifi- 
  

   cation 
  in 
  other 
  respects. 
  Chonetes 
  possesses 
  a 
  marginal 
  row 
  of 
  

   strong 
  cardinal 
  spines 
  or 
  tubes 
  communicating 
  with 
  the 
  internal 
  

   cavity 
  of 
  the 
  valves. 
  Yet 
  we 
  are 
  acquainted 
  with 
  forms 
  (e. 
  g., 
  

   Anoplia 
  nucleata) 
  in 
  which 
  these 
  spine-tubes 
  do 
  not 
  manifest 
  

   themselves 
  externally. 
  Produotus 
  is 
  normally 
  covered 
  with 
  

   spines 
  on 
  one 
  or 
  both 
  valves, 
  but 
  there 
  are 
  some 
  species 
  which 
  

   possess 
  none. 
  The 
  cardinal 
  area, 
  deltidium 
  and 
  teeth, 
  which 
  are 
  

  

  172 
  

  

  