﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  23I 
  

  

  Eusarcus 
  scorpionis 
  Grote 
  & 
  Pitt 
  (Buffalo 
  soc. 
  nat. 
  sci. 
  Bui. 
  3:1) 
  

   Distinguishing 
  characters. 
  Smaller 
  than 
  the 
  foregoing; 
  average 
  

  

  length 
  about 
  i 
  foot. 
  Appearance 
  strikingly 
  scorpioid. 
  Telson 
  

  

  strongly 
  curved. 
  

  

  In 
  the 
  Waterlime 
  at 
  North 
  Buffalo. 
  

  

  Genus 
  pterygotus 
  Agassiz 
  

  

  [Ety. 
  : 
  -Tspu^'ojTo?, 
  winged] 
  

  

  (1839. 
  Murchison. 
  Silurian 
  system, 
  p. 
  605) 
  

  

  Large, 
  often 
  gigantic 
  eurypterids, 
  with 
  a 
  semiovate 
  cephalothorax, 
  

   anterior 
  marginal 
  eyes 
  and 
  central 
  ocelli. 
  The 
  first 
  pair 
  of 
  cephalo- 
  

   thoracic 
  legs 
  (pre-oral) 
  very 
  long, 
  slender, 
  terminating 
  in 
  large 
  pin- 
  

   cers 
  or 
  chelae, 
  and 
  probably 
  prehensile 
  in 
  function. 
  Behind 
  the 
  

   mouth 
  are 
  four 
  pairs 
  of 
  slender 
  walking 
  legs, 
  and 
  behina 
  these 
  are 
  

   the 
  large 
  swimming 
  feet, 
  which 
  differ 
  from 
  those 
  of 
  Eurypterus 
  

   in 
  being 
  less 
  broadly 
  expanded 
  at 
  the 
  ends. 
  Telson 
  an 
  oval 
  plate, 
  

   either 
  terminating 
  in 
  a 
  short 
  projecting 
  point 
  or 
  bilobed. 
  

  

  Pterygotus 
  macrophthalmus 
  Hall 
  (1859. 
  Pal. 
  N. 
  Y. 
  3:418*), 
  

   Pterygotus 
  buffaloensis 
  Pohlman 
  (Buffalo 
  soc. 
  nat. 
  sci. 
  

   Bui. 
  4:17) 
  and 
  Pterygotus 
  acuticaudatus 
  Pohlman 
  

   (Buffalo 
  soc. 
  nat. 
  sci. 
  Bui. 
  4:42) 
  

  

  Distinguishing 
  characters. 
  Cephalothorax 
  subquadrate 
  or 
  taper- 
  

   ing 
  anteriorly; 
  eyes 
  very 
  large 
  and 
  high, 
  with 
  circular 
  base. 
  Chelae 
  

   (pincers) 
  with 
  angular 
  front 
  end 
  ; 
  posterior 
  denticles 
  on 
  larger 
  ramus 
  

   inclined 
  and 
  serrate. 
  

  

  In 
  the 
  Waterhme 
  at 
  North 
  Buiifalo. 
  

  

  Pterygotus 
  cobbi 
  Hall 
  (1859. 
  Pal. 
  N. 
  Y. 
  3:417*, 
  pi. 
  83B, 
  fig. 
  4), 
  

   Pterygotus 
  cummingsi 
  Grote 
  & 
  Pitt 
  (Buffalo 
  soc. 
  nat. 
  sci. 
  

   Bul.4:iS) 
  

  

  Distinguishing 
  characters. 
  Animal 
  large; 
  chelae 
  (pincers) 
  with 
  

   curved 
  front 
  ends 
  and 
  erect 
  non-serrate 
  denticles. 
  

  

  Rare 
  in 
  the 
  Waterlime 
  at 
  North 
  Buffalo. 
  

  

  Pterygotus 
  globicaudatus 
  Pohlman 
  (Buffalo 
  soc. 
  nat. 
  sci. 
  Bui. 
  4:42) 
  

   Distinguishing 
  characters. 
  Animal 
  rather 
  small; 
  surface 
  coarsely 
  

   tubercled; 
  telson 
  circular 
  without 
  median 
  keel. 
  

  

  A 
  single 
  specimen 
  from 
  the 
  Waterlime 
  of 
  North 
  Buffalo. 
  

  

  