﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  20/ 
  

  

  rcsiliiun 
  occurs, 
  which 
  is 
  lodged 
  in 
  special 
  grooves 
  or 
  pits. 
  The 
  

   scars 
  marking 
  the 
  attachment 
  of 
  the 
  adductor 
  or 
  closing 
  muscle 
  

   or 
  muscles, 
  vary 
  greatly, 
  and 
  are 
  frequently 
  preserved 
  in 
  the 
  fossil 
  

   forms. 
  When 
  two 
  are 
  present, 
  they 
  are 
  designated, 
  respectively, 
  

   the 
  anterior 
  and 
  posterior 
  adductor 
  scars. 
  The 
  line 
  of 
  attachment 
  

   of 
  the 
  fleshy 
  mantle 
  which 
  builds 
  the 
  shells, 
  i. 
  e. 
  the 
  pallid 
  line, 
  

   is 
  often 
  visible. 
  Near 
  the 
  posterior 
  end 
  it 
  frequently 
  makes 
  a 
  re- 
  

   entrant 
  curve 
  — 
  the 
  pallid 
  ^/;n/^— 
  indicating 
  that 
  the 
  animal 
  had 
  a 
  

   retractile 
  siphon. 
  The 
  various 
  parts 
  described 
  are 
  indicated 
  in 
  fig. 
  

  

  134. 
  

  

  The 
  principal 
  soft 
  parts 
  of 
  the 
  animal 
  comprise: 
  the 
  mantle, 
  con- 
  

   sisting 
  of 
  two 
  fleshy 
  folds, 
  one 
  lining 
  each 
  valve, 
  and 
  building 
  it; 
  

   the 
  abdomen, 
  wath 
  the 
  anteriorly 
  placed 
  month, 
  and 
  the 
  antero-ventral 
  

   foot; 
  the 
  gills, 
  or 
  branehioe, 
  which 
  consist 
  of 
  complicated 
  lamellae 
  

   hanging 
  on 
  either 
  side 
  of 
  the 
  abdomen 
  in 
  the 
  mantle 
  cavity; 
  and 
  

   the 
  siphons 
  — 
  present 
  only 
  in 
  certain 
  forms 
  — 
  posteriorly 
  placed, 
  often 
  

   capable 
  of 
  great 
  extension, 
  and 
  serving, 
  the 
  one 
  for 
  the 
  entrance 
  

   of 
  the 
  water 
  and 
  food 
  particles, 
  and 
  the 
  other 
  for 
  the 
  exit 
  of 
  the 
  

   water 
  and 
  waste 
  products. 
  

  

  Genus 
  pterinea 
  Goldfuss 
  

  

  [Ety. 
  : 
  -7ep6>, 
  wing] 
  

  

  (1826. 
  Petre 
  facta 
  Germaniae, 
  p. 
  133) 
  

  

  Shell 
  inequivalve, 
  inequilateral; 
  posterior 
  side 
  winged, 
  anterior 
  

   end 
  nasute 
  or 
  with 
  a 
  well 
  defined 
  ear. 
  Ligament 
  internal; 
  liga- 
  

   mental 
  area 
  longitudinally 
  striated. 
  Cardinal 
  teeth 
  two 
  or 
  more; 
  

   lateral 
  teeth 
  linear 
  oblique. 
  Posterior 
  muscular 
  impression 
  large, 
  

   situated 
  on 
  the 
  post-umbonal 
  slope; 
  anterior 
  muscular 
  impression 
  

   small, 
  situated 
  within 
  the 
  rostral 
  cavity. 
  Test 
  ornamented 
  with 
  rays. 
  

  

  Pterinea 
  emacerata 
  (Conrad) 
  (Fig. 
  135). 
  Avicula 
  ema- 
  

   c 
  e 
  r 
  a 
  t 
  a 
  Conrad 
  (Hall. 
  1852. 
  Pal. 
  N. 
  Y. 
  2:228, 
  pi. 
  59) 
  

  

  Distinguishing 
  characters. 
  Moderately 
  — 
  ^p» 
  

  

  oblique; 
  large 
  and 
  posteriorly 
  concave 
  

   wing 
  often 
  extending 
  beyond 
  the 
  shell 
  

   below; 
  small 
  anterior 
  ear; 
  flat, 
  smooth 
  

   right 
  valve 
  with 
  striated 
  wing; 
  convex 
  

   left 
  valve, 
  with 
  strong 
  radii, 
  interrupted 
  " 
  

  

  by 
  fainter 
  concentric 
  striae. 
  ^'^- 
  ^^ 
  Pterinea 
  emacerata 
  

  

  Found 
  perhaps 
  in 
  the 
  Clinton 
  shale, 
  rarely 
  in 
  the 
  lower 
  and 
  mid- 
  

   dle 
  Rochester 
  shale 
  and 
  abundantly 
  in 
  the 
  upper 
  shale. 
  Niagara 
  

   sections. 
  Also 
  at 
  Lockport 
  and 
  elsewhere 
  (Hall). 
  

  

  