﻿Report 
  of 
  the 
  State 
  Geologist. 
  

  

  1035 
  

  

  septum. 
  Their 
  anterior 
  portion 
  is 
  always 
  free 
  while 
  their 
  pos- 
  

   terior 
  portions 
  are 
  sometimes 
  coalesced 
  into 
  a 
  single 
  piece. 
  In 
  

   the 
  brachial 
  valve 
  there 
  are 
  two 
  short 
  crural 
  plates 
  not 
  rising 
  to 
  

   more 
  than 
  one-third 
  the 
  height 
  of 
  the 
  shell 
  ; 
  these 
  may 
  remain 
  

   independent 
  or 
  sometimes 
  unite 
  to 
  form 
  a 
  single 
  piece. 
  

  

  The 
  muscles 
  are 
  attached 
  between 
  and 
  on 
  the 
  convergent 
  

   plates, 
  and, 
  in 
  the 
  brachial 
  valve, 
  also 
  in 
  front 
  of 
  them. 
  

  

  Surface-sculpture 
  variously 
  punctate. 
  Shell-structure 
  appa- 
  

   rently 
  fibrous. 
  

  

  Type, 
  Porambonites 
  intermedia. 
  Pander. 
  

  

  Distribution. 
  Silurian. 
  

  

  Noetlingia, 
  Hall. 
  1893. 
  

  

  Shells 
  exteriorly 
  like 
  Porambonites, 
  with 
  long, 
  straight 
  hinge- 
  

   line, 
  well-developed 
  cardinal 
  areas 
  and 
  biforate 
  

   beaks. 
  

  

  There 
  is 
  a 
  spondylium 
  in 
  each 
  valve, 
  that 
  of 
  

   the 
  pedicle-valve 
  being, 
  at 
  the 
  outset, 
  the 
  larger, 
  

   and 
  continuing 
  further 
  forward 
  than 
  the 
  other. 
  

   Both 
  are 
  supported 
  by 
  a 
  stout 
  median 
  septal 
  inal 
  ^ 
  ew 
  ~f 
  a 
  g 
  ^ 
  e 
  r 
  ci 
  ! 
  

   callosity, 
  which, 
  in 
  the 
  brachial 
  valve, 
  widens 
  men 
  nf 
  . 
  Noetlingia 
  

   and 
  becomes 
  lost 
  in 
  the 
  thickened 
  shell-substance 
  NEUIL 
  Csp 
  .)'. 
  

   of 
  the 
  muscular 
  region; 
  that 
  of 
  the 
  pedicle-valve 
  becomes 
  

   narrowed 
  anteriorly, 
  and 
  eventually 
  leaves 
  the 
  spondylium 
  free, 
  

  

  53 
  pi? 
  ^ 
  

  

  Fig. 
  444. 
  Fig. 
  445. 
  

  

  Fig. 
  446. 
  

  

  Fig. 
  447. 
  

  

  Fig. 
  448. 
  

  

  Fig. 
  449. 
  

  

  Fig. 
  450. 
  

  

  Figs. 
  446-452.— 
  Transverse 
  serial 
  sections 
  of 
  a 
  single 
  specimen 
  of 
  Noetlingia 
  Tscheffkini, 
  

   showing 
  the 
  structure 
  of 
  the 
  internal 
  apophyses 
  and 
  septa. 
  In 
  all 
  the 
  sections 
  the 
  pedicle- 
  

   valve 
  (p) 
  is 
  above, 
  the 
  brachial 
  valve 
  (b) 
  below. 
  

  

  or 
  nearly 
  so. 
  There 
  is 
  a 
  simple 
  linear 
  cardinal 
  process 
  in 
  the 
  

   spondylium 
  of 
  the 
  brachial 
  valve. 
  

  

  Type, 
  Noetlingia 
  Tscheffkini, 
  De 
  Yerneuil 
  (sp.). 
  

  

  Distribution. 
  Lower 
  Silurian. 
  

  

  