﻿198 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Hinge 
  line 
  generally 
  long 
  and 
  straight; 
  pedicle 
  valve 
  usually 
  with 
  

   moderately 
  high 
  area, 
  with 
  an 
  open 
  delthyrium, 
  the 
  margins 
  of 
  

   which 
  are 
  prolonged 
  into 
  stout 
  simple 
  teeth, 
  supported 
  by 
  dental 
  

   lamellae. 
  Area 
  of 
  the 
  brachial 
  valve 
  the 
  lower. 
  A 
  calcareous 
  

   brachidium 
  in 
  the 
  form 
  of 
  a 
  double 
  spire, 
  whose 
  apexes 
  are 
  directed 
  

   toward 
  the 
  cardinal 
  angles, 
  nearly 
  fills 
  the 
  cavity 
  of 
  the 
  shell. 
  

  

  Spirifer 
  radiatus 
  Sowerby 
  (Fig. 
  116) 
  (Hall. 
  1852. 
  Pal.N.Y. 
  

   2:66, 
  pi. 
  22, 
  p. 
  265, 
  pi. 
  54) 
  

  

  Distinguishing 
  characters. 
  Moderately 
  large 
  size; 
  pedicle 
  valve 
  

  

  with 
  strongly 
  incurved 
  beak, 
  moderate 
  area, 
  and 
  broad 
  shallow 
  

  

  '^^'^v 
  

  

  Fig. 
  116 
  Spirifer 
  radiatus 
  showing 
  variation 
  

  

  mesial 
  sinus; 
  flattened 
  median 
  fold; 
  fine 
  uniform 
  radiating 
  striae 
  

   covering 
  all 
  parts 
  of 
  the 
  shell. 
  

  

  Found 
  in 
  the 
  Clinton 
  limestones 
  and 
  lenses 
  and 
  in 
  the 
  lower 
  and 
  

   middle 
  Rochester 
  shales 
  at 
  Niagara; 
  sometimes 
  abundant. 
  Also 
  at 
  

   Lockport 
  and 
  elsewhere 
  (Hall). 
  

  

  The 
  shell 
  varies 
  greatly 
  in 
  form 
  and 
  proportions 
  ;~*sometimes 
  the 
  

   hinge 
  area 
  is 
  much 
  extended 
  or 
  the 
  hinge 
  extremities 
  are 
  rounded 
  

   and 
  the 
  hinge 
  line 
  shorter 
  than 
  the 
  shell 
  below. 
  Faint 
  plications 
  

   near 
  the 
  fold 
  and 
  sinus 
  also 
  occur 
  in 
  some 
  specimens, 
  connecting 
  

   this 
  species 
  with 
  the 
  next. 
  

  

  Spirifer 
  niagarensis 
  Conrad 
  (Fig. 
  117) 
  (Hall. 
  1852. 
  Pal. 
  

   N. 
  Y. 
  2:264, 
  pi. 
  54) 
  

  

  '-^-M^ 
  Distinguishing 
  characters. 
  Moderately 
  

  

  ' 
  ^ 
  large 
  size; 
  convex, 
  with 
  nearly 
  equal 
  valves; 
  

  

  M 
  m 
  strongly 
  incurved 
  beak 
  of 
  pedicle 
  valve; 
  

   J 
  ^^m^m 
  moderate 
  area; 
  numerous 
  fine, 
  rounded, 
  de- 
  

   ■ 
  ^HIHPIP 
  pressed 
  plications, 
  which 
  become 
  obsolete 
  

  

  Fig. 
  117 
  spirifer 
  niagarensis 
  toward 
  the 
  extremities, 
  and 
  sometimes 
  ap- 
  

   pear 
  quite 
  flattened 
  out 
  on 
  the 
  surface; 
  fine 
  thread-like 
  radiating 
  

   striae 
  covering 
  plications 
  and 
  interspaces 
  alike. 
  

  

  