﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  189 
  

  

  Distinguishing 
  characters. 
  Nearly 
  circular 
  and 
  equivalve; 
  finely 
  

   striated 
  surface; 
  dichotomous 
  striae 
  running 
  upward 
  and 
  outward 
  

   on 
  the 
  hinge 
  line; 
  narrow 
  short 
  hinge 
  area; 
  slightly 
  sinuous 
  front. 
  

  

  Found 
  in 
  the 
  lower 
  Clinton 
  limestone 
  (?). 
  Also 
  east 
  of 
  Lockport 
  

   (Hall). 
  

  

  Genus 
  scenidium 
  Hall 
  

  

  [Ety.: 
  cxrjvtdov, 
  little 
  tent] 
  

  

  (i860. 
  A^. 
  Y. 
  state 
  cab. 
  nat. 
  hist, 
  i^th 
  reft, 
  p. 
  70; 
  1892. 
  Pal. 
  N. 
  Y. 
  

  

  V. 
  8, 
  pt 
  I, 
  p. 
  241) 
  

  

  Shells 
  subpyramidal, 
  somewhat 
  semicircular; 
  with 
  or 
  without 
  

   median 
  sinus 
  or 
  elevation; 
  pedicle 
  valve 
  elevated, 
  subpyramidal; 
  

   beak 
  straight 
  or 
  sHghtly 
  arched; 
  cardinal 
  area 
  large, 
  triangular, 
  di- 
  

   vided 
  by 
  a 
  narrow 
  fissure, 
  sometimes 
  closed 
  at 
  the 
  summit 
  by 
  a 
  con- 
  

   cave 
  plate. 
  Brachial 
  valve 
  depressed 
  convex 
  to 
  concave; 
  cardinal 
  

   line 
  usually 
  equal 
  to 
  width' 
  of 
  shell; 
  cardinal 
  

   process 
  simple 
  or 
  divided, 
  and 
  extending 
  as 
  a 
  

   median 
  septum 
  through 
  the 
  length 
  of 
  the 
  shell. 
  

   Spondylium 
  in 
  the 
  pedicle 
  valve. 
  

  

  Scenidium 
  pyramidale 
  Hall 
  (Fig. 
  100). 
  Or- 
  

   this 
  pyramidale 
  Hall 
  (1852. 
  Pal. 
  

  

  N. 
  Y. 
  2:251, 
  pi. 
  52, 
  fig. 
  2a-z) 
  ' 
  Fig. 
  lOOScenidium 
  pyramid- 
  

  

  7-, 
  . 
  . 
  • 
  I 
  • 
  7 
  TV 
  /r 
  • 
  1 
  ^1® 
  enlarged 
  

  

  JJistinguishing 
  characters. 
  Mmute, 
  subpyra- 
  

   midal; 
  flat 
  semicircular 
  brachial 
  valve, 
  centrally 
  depressed; 
  ex- 
  

   tremely 
  elevated 
  pedicle 
  valve 
  with 
  large 
  triangular 
  area; 
  strong 
  

   radiating 
  striae, 
  sometimes 
  dichotomous; 
  lamellose 
  concentric 
  

   striae. 
  » 
  

  

  Found 
  in 
  the 
  Rochester 
  shale 
  at 
  Lockport 
  (Hall) 
  and 
  may 
  also 
  

   occur 
  at 
  Niagara. 
  

  

  Genus 
  anastrophia 
  Hall 
  

   [Ety.: 
  dvd, 
  back; 
  (TTpo<pyj, 
  a 
  turning] 
  

  

  (1867. 
  A^. 
  Y. 
  state 
  cab. 
  nat. 
  hist. 
  20th 
  an. 
  reft, 
  p. 
  163; 
  1893. 
  Pal. 
  

   N. 
  Y. 
  V. 
  8, 
  pt 
  2, 
  p. 
  224) 
  

  

  Pentameroid 
  shells 
  with 
  a 
  spoon-shaped 
  cavity 
  (spondylimn) 
  

   under 
  the 
  beak 
  of 
  the 
  pedicle 
  valve 
  and 
  with 
  a 
  moderate 
  cardinal 
  

   line 
  but 
  no 
  hinge 
  area; 
  surface 
  with 
  numerous 
  sharp 
  plications 
  ex- 
  

   tending 
  to 
  the 
  beak. 
  

  

  

  