﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  I93 
  

  

  median 
  septum 
  in 
  the 
  brachial 
  valve, 
  which 
  divides 
  posteriorly, 
  so 
  

   far 
  as 
  to 
  form 
  an 
  elongate 
  cavity, 
  which 
  does 
  not 
  extend 
  to 
  the 
  bot- 
  

   tom 
  of 
  the 
  valve. 
  No 
  cardinal 
  process. 
  In 
  the 
  pedicle 
  valve 
  slen- 
  

   der 
  vertical 
  lamellae 
  support 
  the 
  teeth. 
  

  

  Camarotoechia 
  obtusiplicata 
  Hall 
  (Fig. 
  io6). 
  Atrypa 
  ob- 
  

   tus 
  ipl 
  ic 
  at 
  a 
  Hall 
  (1852. 
  Pa/. 
  A^. 
  F. 
  2:279, 
  pi. 
  58, 
  fig. 
  2a-h) 
  

  

  Distinguishing 
  characters. 
  Gibbous, 
  subspheroidal 
  form 
  ; 
  strongly 
  

   convex 
  brachial, 
  and 
  flatter 
  pedicle 
  valve; 
  deep 
  sinus 
  of 
  pedicle 
  

  

  Fig. 
  106 
  Camarotoechia 
  obtusip'icata 
  

  

  valve 
  with 
  three 
  plications 
  (rarely 
  four); 
  depressed 
  incurved 
  beak 
  of 
  

   pedicle 
  valve; 
  simple, 
  obtvisely 
  rounded 
  or 
  flattened 
  plications; 
  faint 
  

   concentric 
  striae; 
  strongly 
  emarginate 
  front. 
  

  

  Found 
  in 
  the 
  lower 
  part 
  of 
  the 
  lower 
  Rochester 
  shales 
  at 
  Niagara* 
  

   Also 
  in 
  the 
  shales 
  and 
  limestones 
  at 
  Lockport 
  (Hall). 
  

  

  Camarotoechia 
  ( 
  ?) 
  neglecta 
  Hall 
  (Fig. 
  107). 
  Atrypa 
  

   neglect 
  a 
  Hall 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:70, 
  274, 
  pi. 
  23 
  and 
  57) 
  

  

  Distinguishing 
  characters. 
  Convex 
  

   valves, 
  brachial 
  valve 
  deepest, 
  sides 
  

   sloping 
  abruptly 
  to 
  the 
  beak; 
  strongly 
  

   defined 
  sinus 
  and 
  fold, 
  in 
  adult 
  individ- 
  

   ual, 
  the 
  former 
  with 
  three, 
  the 
  latter 
  

   with 
  four 
  plications; 
  profound 
  frontal 
  

   emargination; 
  plications 
  rounded. 
  ^^^ 
  ^^^^ 
  

  

  Found 
  in 
  the 
  lower 
  Clinton 
  limestone 
  

  

  . 
  _^ 
  , 
  , 
  . 
  , 
  Fig. 
  107 
  Camarotoechia 
  (?; 
  neglrcta 
  

  

  m 
  the 
  Clinton 
  lenses 
  and 
  m 
  the 
  upper 
  

  

  part 
  of 
  the 
  lower 
  and 
  the 
  middle 
  Rochester 
  shales 
  at 
  Niagara. 
  

   Also 
  more 
  rarely 
  in 
  the 
  upper 
  shales. 
  Found 
  also 
  at 
  Lockport 
  and 
  

   elsewhere 
  (Hall). 
  

  

  Camarotoechia 
  acinus 
  Hall 
  (Fig. 
  108). 
  Rhynchonella 
  

   acinus 
  Hall 
  (A^. 
  Y. 
  state 
  mus. 
  nat. 
  hist. 
  2Sth 
  an. 
  rep't, 
  p. 
  163, 
  

   pi. 
  26) 
  

  

  Distinguishing 
  characters. 
  Small 
  size; 
  longitudinally 
  ovate 
  form, 
  

   narrowing 
  toward 
  beak, 
  truncate 
  in 
  front; 
  subequally 
  convex 
  valves; 
  

  

  • 
  

  

  