﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  25I 
  

  

  having 
  groove-like 
  sculpture. 
  There 
  are 
  three 
  cardinal 
  teeth, 
  one 
  

   in 
  the 
  right 
  and 
  two 
  in 
  the 
  left 
  valve; 
  the 
  lateral 
  teeth 
  are 
  strong. 
  

   Locality. 
  Goat 
  island. 
  

  

  Genus 
  unio 
  Retzius. 
  1788 
  

  

  The 
  shell 
  is 
  inequilateral, 
  elongated, 
  rounded 
  in 
  front 
  and 
  pointed 
  

   behind, 
  with 
  a 
  slight 
  posterior 
  ridge 
  ; 
  beaks 
  full, 
  slightly 
  sculptured 
  ; 
  

   surface 
  smooth. 
  

  

  TJnio 
  gibbosus 
  Barnes 
  1823 
  (Fig. 
  188). 
  Unio 
  nasuta 
  

   Lamarck 
  (1819. 
  Animanx 
  sans 
  vcrtehrcs, 
  6:75). 
  Unio 
  gib- 
  

   bosus 
  Barnes 
  (1823. 
  Am, 
  jour. 
  sci. 
  6:262) 
  

  

  Shell 
  solid, 
  ovate 
  and 
  elongated; 
  rounded 
  at 
  the 
  anterior 
  end, 
  

   angulated 
  slightly 
  at 
  the 
  posterior; 
  dorsal 
  margin 
  straight 
  or 
  nearly 
  

   so; 
  ventral 
  margin 
  oval; 
  muscle 
  impressions 
  deep 
  and 
  well 
  defined; 
  

  

  Fig. 
  188 
  Unio 
  gibbosus 
  

  

  teeth 
  large 
  and 
  strong, 
  the 
  left 
  valve 
  having 
  two 
  cardinals, 
  and 
  two 
  

   laterals; 
  growth 
  lines 
  coarse; 
  pallial 
  line 
  deep 
  and 
  clear; 
  beaks 
  turn- 
  

   cated 
  and 
  slightly 
  sculptured, 
  the 
  sculpture 
  consisting 
  of 
  two 
  or 
  

   three 
  strong 
  ridges 
  running 
  parallel 
  to 
  the 
  growth 
  lines. 
  

  

  Found 
  in 
  nearly 
  all 
  the 
  localities. 
  This 
  species 
  seems 
  to 
  have 
  

   been 
  the 
  most 
  common 
  of 
  the 
  Unios. 
  

  

  Genus 
  quadrula 
  Rafinesque. 
  1820 
  

   Shell 
  thick, 
  heavy 
  and 
  solid; 
  teeth 
  large 
  and 
  strong. 
  

   Quadrula 
  solida 
  (Lea) 
  Simpson 
  1900 
  (Fig. 
  189). 
  Unio 
  

   solidus 
  Lea 
  (1838. 
  Phil. 
  soc. 
  Trans. 
  6:13). 
  Quadrula 
  

   solida 
  Simpson 
  (1900. 
  U. 
  S. 
  nat. 
  nius. 
  Proc. 
  22:ySg) 
  

  

  Shell 
  oval, 
  solid 
  and 
  thick, 
  surface 
  marked 
  by 
  concentric 
  growth 
  

   lines; 
  anterior 
  end 
  rounded; 
  posterior 
  end 
  sHghtly 
  angulated; 
  dorsal 
  

  

  