﻿194 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  a 
  single 
  plication 
  in 
  sinus 
  of 
  pedicle 
  valve 
  and 
  two 
  on 
  fold 
  of 
  

   brachial 
  valve 
  ; 
  few 
  plications 
  on 
  either 
  side 
  of 
  fold 
  or 
  sinus. 
  

  

  Fig 
  108 
  Camarotoechia 
  acinus. 
  A 
  specimen 
  in 
  which 
  the 
  fold 
  and 
  sinus 
  are 
  not 
  developed. 
  Enf 
  

   lar^'ed 
  x 
  4 
  

  

  Found 
  in 
  the 
  crystalline 
  upper 
  Clinton 
  limestone 
  at 
  Niagara. 
  

   The 
  species 
  was 
  originally 
  described 
  from 
  the 
  western 
  Niagara. 
  

  

  Genus 
  rhynchonella 
  Fischer 
  de 
  Waldheim 
  

   [Ety. 
  : 
  puyxo?, 
  beak] 
  

   (1809. 
  Notice 
  dcs 
  fos. 
  gouv. 
  Moscow, 
  p. 
  35; 
  Hall 
  & 
  Clarke. 
  1893. 
  

   Pal. 
  N. 
  Y. 
  V. 
  8, 
  pt 
  2, 
  p. 
  177, 
  178) 
  

  

  Subpyramidal 
  plicated 
  shells 
  with 
  a 
  prominent 
  anterior 
  linguiform 
  

   extension. 
  Dental 
  lamellae 
  and 
  a 
  dorsal 
  median 
  septum 
  occur, 
  but 
  

   no 
  cardinal 
  process; 
  crura 
  are 
  present, 
  but 
  other 
  arm 
  supports 
  are 
  

   wanting. 
  

  

  Ehynchonella 
  robusta 
  Hall 
  (Fig. 
  109). 
  

  

  Atrypa 
  robusta 
  Hall 
  (1852. 
  Pal. 
  

   N. 
  Y. 
  2:yi, 
  pi. 
  23) 
  

  

  Distinguishing 
  characters. 
  Large 
  size; 
  ro- 
  

   bust 
  character; 
  brachial 
  valve 
  most 
  convex; 
  

   broad, 
  ill 
  defined 
  fold 
  and 
  sinus; 
  coarse 
  

  

  Fig. 
  109 
  Rhynchonella 
  robusta 
  j-QUnded 
  plicationS. 
  

  

  Found 
  in 
  the 
  uppermost 
  beds 
  of 
  the 
  Clinton 
  series 
  at 
  Niagara. 
  

   Also 
  east 
  of 
  Lockport 
  (Hall). 
  ^^^ 
  

  

  Rhynchonella 
  (?) 
  bidens 
  Hall 
  (Fig. 
  no), 
  /p-^ 
  ^^^ 
  

   Atrypa 
  bidens 
  Hall 
  (1852. 
  Pal. 
  N. 
  Y. 
  

   2:69, 
  pi. 
  23) 
  

  

  Distinguishing 
  characters. 
  Much 
  smaller 
  than 
  

   preceding; 
  strong 
  convexity 
  of 
  valves; 
  deep 
  sinus 
  pj^ 
  ^^.^hynchoneiia 
  

   with 
  one 
  plication; 
  fold 
  consisting 
  of 
  two 
  rounded 
  ^^^^^^^^^^ 
  

   plications; 
  rather 
  broad, 
  rounded 
  lateral 
  plicae; 
  strongly 
  emarginate 
  

   front. 
  

  

  Found 
  in 
  the 
  lower 
  Clinton 
  beds 
  at 
  Lockport 
  (Hall). 
  Probably 
  

   also 
  at 
  Niagara. 
  

  

  