﻿178. 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  free 
  end, 
  presents 
  a 
  surface 
  for 
  the 
  attachment 
  of 
  the 
  didnctor, 
  or 
  

   opening 
  muscles, 
  the 
  opposite 
  ends 
  of 
  which 
  are 
  attached 
  near 
  the 
  

   center 
  of 
  the 
  pedicle 
  valve, 
  where 
  they 
  often 
  leave 
  pronounced 
  scars. 
  

   A 
  contraction 
  of 
  these 
  muscles 
  pulls 
  on 
  the 
  cardinal 
  process, 
  and 
  

   draws 
  the 
  beak 
  of 
  the 
  brachial 
  valve 
  toward 
  the 
  interior 
  of 
  the 
  pedi- 
  

   cle 
  valve, 
  and 
  thus 
  opens 
  the 
  valves. 
  Adductor 
  muscles 
  passing 
  

   from 
  valve 
  to 
  valve 
  and 
  also 
  commonly 
  leaving 
  scars, 
  close 
  the 
  

   valves 
  again. 
  Below 
  the 
  cardinal 
  process 
  and 
  often 
  merged 
  with 
  

   it, 
  is 
  an 
  elevated 
  hinge 
  plate 
  whose 
  surface 
  often 
  serves 
  for 
  muscu- 
  

   lar 
  attachment. 
  

  

  Beneath 
  the 
  beak 
  of 
  each 
  valve 
  frequently 
  occurs 
  a 
  fiat 
  " 
  cardinal 
  

   area 
  ", 
  bounded 
  above 
  by 
  the 
  cardinal 
  slopes 
  and 
  below 
  by 
  the 
  ar- 
  

   ticulating 
  margin 
  or 
  hinge 
  line. 
  This 
  area 
  is 
  commonly 
  divided 
  in 
  

   the 
  center 
  by 
  a 
  triangular 
  fissure 
  (delthyrium). 
  It 
  may 
  be 
  covered 
  

   either 
  by 
  a 
  single 
  plate 
  (deltidiiiin) 
  or 
  by 
  two 
  plates 
  which 
  join 
  in 
  

   the 
  center 
  (deltidial 
  plates). 
  

  

  The 
  important 
  surface 
  features 
  of 
  the 
  shell 
  are 
  : 
  the 
  lines 
  of 
  growth, 
  

   the 
  radiating 
  plications 
  or 
  striaiions, 
  the 
  fold 
  or 
  medial 
  elevation, 
  

   and 
  the 
  sinus 
  or 
  medial 
  depression, 
  the 
  fold 
  commonly 
  occurring 
  on 
  

   the 
  brachial, 
  and 
  the 
  sinus 
  on 
  the 
  pedicle 
  valve. 
  

  

  Genus 
  lingula 
  Bruguiere 
  

  

  [Ety.: 
  //«^i//a, 
  little 
  tongue] 
  

   (1789. 
  Hist. 
  not. 
  des 
  vers 
  testaccs; 
  1892. 
  Pal. 
  N. 
  Y. 
  v. 
  8, 
  pt 
  i, 
  p. 
  2) 
  

  

  Shell 
  with 
  the 
  valves 
  nearly 
  equal 
  and 
  varying 
  in 
  outline 
  from 
  

   elongate 
  ovate 
  to 
  subtriangular, 
  always 
  longer 
  than 
  wide; 
  valves 
  

  

  arched. 
  Animal 
  attached 
  by 
  a 
  Icn^ 
  

   ^ 
  '\ 
  muscular 
  pedicle 
  which 
  protrudes 
  

  

  / 
  ' 
  % 
  /^\ 
  from 
  between 
  the 
  beaks 
  of 
  the 
  two 
  

  

  "% 
  / 
  % 
  valves. 
  

  

  / 
  % 
  Lingula 
  cnneata 
  Conrad 
  (Fig. 
  G:) 
  

  

  ■ 
  j 
  / 
  ' 
  '. 
  (Hall. 
  1852. 
  Fcl. 
  N. 
  F. 
  2:8, 
  pi. 
  <) 
  

  

  \ 
  / 
  \ 
  , 
  Distinguishing 
  characters. 
  Acute'y 
  

  

  \-,_^_^ 
  cuneate 
  form; 
  very 
  acute 
  beak 
  with 
  

  

  ng. 
  81 
  Lingula 
  cuneata 
  enlarged 
  X 
  2 
  nearly 
  rectilinear 
  margins; 
  slightly 
  

  

  curved 
  base; 
  valves 
  convex 
  near 
  the 
  beak, 
  flatter 
  toward 
  front; 
  fine 
  

  

  longitudinal 
  striae. 
  

  

  Found 
  in 
  the 
  upper 
  Medina 
  sandstones 
  at 
  Niagara. 
  Also 
  at 
  

   Lockport 
  etc. 
  (Hall). 
  

  

  