﻿l82 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Genus 
  strophonella 
  Hall 
  

   [Ety. 
  : 
  azpoifo^^ 
  turned 
  around] 
  

   (1879. 
  A^. 
  Y. 
  state 
  miis. 
  nat. 
  hist., 
  26th 
  an. 
  reft, 
  p. 
  153; 
  Hall 
  & 
  

   Clarke. 
  1892. 
  Pal. 
  N. 
  Y. 
  v. 
  8, 
  pt 
  i, 
  p. 
  290) 
  

  

  Shells 
  with 
  the 
  form 
  and 
  structure 
  of 
  Stropheodonta, 
  but 
  

   with 
  the 
  relative 
  convexity 
  of 
  the 
  valves 
  reversed. 
  

  

  Strophonella 
  striata 
  Hall 
  (Fig. 
  87) 
  Leptaena 
  striata 
  

   Hall 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:259, 
  pL 
  53, 
  % 
  7) 
  

  

  Distinguishing 
  characters. 
  Semielliptic, 
  almost 
  

   flat, 
  hinge 
  line 
  equal 
  to 
  or 
  a 
  little 
  longer 
  than 
  width 
  

   of 
  shell; 
  fine, 
  rounded, 
  radiating 
  surface 
  striae, 
  

   which 
  increase 
  by 
  implantation; 
  fine 
  concentric 
  

  

  Fig. 
  87 
  strophonella 
  

   striata 
  StriaC. 
  

  

  Found 
  in 
  the 
  middle 
  and 
  upper 
  Rochester 
  shale 
  at 
  Niagara. 
  

   Strophonella 
  ( 
  ?) 
  patenta 
  Hall 
  (Fig. 
  88). 
  Leptaena 
  pat- 
  

   enta 
  Hall 
  (1852. 
  Pal. 
  N. 
  Y. 
  2:60, 
  pi. 
  21) 
  

   Distinguishing 
  characters. 
  Wider 
  than 
  high; 
  hinge 
  not 
  auriculate; 
  

  

  liiliU 
  

  

  Fig. 
  88 
  Strophonella 
  {1, 
  patenta 
  with 
  enlarged 
  surface 
  features 
  

  

  fine 
  unequal 
  radii 
  crossed 
  by 
  finer 
  concentric 
  striae; 
  Inner 
  surfaces 
  

   of 
  valves 
  thickly 
  covered 
  with 
  sharp 
  points. 
  

  

  Found 
  in 
  the 
  Clinton 
  limestones 
  and 
  lenses 
  and 
  doubtfully 
  in 
  the 
  

   middle 
  Rochester 
  shales 
  at 
  Niagara. 
  

  

  Genus 
  plectambonites 
  Pander 
  

   [Ety.: 
  -/3.£zro9, 
  plaited; 
  afiiSwv, 
  beak] 
  

   (1830. 
  Beitrdge 
  ziir 
  Gcognosie 
  des 
  Russ. 
  Reiche's. 
  p. 
  ^o. 
  Hall 
  

   & 
  Clarke, 
  1892; 
  Pal. 
  N. 
  Y. 
  v. 
  8, 
  pt 
  i, 
  p. 
  2t,6, 
  295) 
  

  

  • 
  Shells 
  small, 
  concavo-convex; 
  surface 
  striae 
  very 
  fine, 
  often 
  alter- 
  

   nating 
  in 
  size; 
  hinge 
  line 
  making 
  greatest 
  width, 
  extremities 
  often 
  

  

  