﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  

  

  223 
  

  

  Fig. 
  In4 
  lUaenus 
  loxus 
  

  

  at 
  all 
  marked 
  in 
  either. 
  Glabella 
  smooth, 
  indistinct, 
  eyes 
  large, 
  

   round, 
  lateral 
  cheeks 
  small. 
  Thorax 
  usually 
  consisting 
  of 
  10 
  seg- 
  

   ments, 
  with 
  smooth 
  pleurae. 
  

  

  Illaenus 
  ioxus 
  Hall 
  (Fig. 
  154). 
  B 
  u 
  - 
  

  

  mastis 
  barriensis 
  Hall 
  (1852. 
  

  

  Pal. 
  N. 
  Y. 
  2:302, 
  pi. 
  66) 
  

  

  Distinguishing 
  characters. 
  Elongate 
  

  

  elliptic 
  form; 
  rounded, 
  nearly 
  equal 
  

  

  cephalon 
  and 
  pygidium, 
  with 
  the 
  triloba- 
  

  

  tion 
  scarcely 
  marked 
  ; 
  large 
  eyes 
  near 
  the 
  

  

  posterior 
  lateral 
  border 
  of 
  the 
  cephalon; 
  

  

  faint 
  trilobation 
  of 
  thorax 
  with 
  very 
  

  

  broad 
  central 
  lobe; 
  granulose 
  or 
  punc- 
  

   tate 
  surface. 
  

  

  Found 
  in 
  the 
  Clinton 
  limestone 
  lenses 
  

  

  in 
  great 
  abundance, 
  usually 
  represented 
  

  

  only 
  by 
  cephala 
  and 
  pygidia. 
  These 
  

  

  are 
  often 
  crowded 
  together 
  in 
  great 
  profusion 
  to 
  the 
  exclusion 
  of 
  

  

  nearly 
  every 
  other 
  fossil. 
  Also 
  found 
  

   rarely 
  in 
  the 
  lower 
  and 
  middle 
  Roches- 
  

   ter 
  shale 
  at 
  Niagara. 
  Also 
  found 
  at 
  

   Lockport 
  and 
  elsewhere 
  (Hall). 
  

  

  Genus 
  dalmanites 
  Barrande 
  

  

  [Ety. 
  : 
  proper 
  name] 
  

  

  (1852. 
  Systcme 
  siliiricn 
  Boh. 
  v. 
  i) 
  

  

  Cephalon 
  distinctly 
  trilobate, 
  with 
  a 
  

   large 
  glabella 
  and 
  prolonged 
  lateral 
  or 
  

   genal 
  spines; 
  glabella 
  tumid, 
  widest 
  in 
  

   front, 
  and 
  divided 
  by 
  three 
  well 
  marked 
  

   lateral 
  furrows 
  ; 
  facial 
  -suture 
  extending 
  

   from 
  in 
  front 
  of 
  the 
  genal 
  angles 
  in- 
  

   ward 
  to 
  the 
  eyes 
  and 
  thence 
  forward 
  

   around 
  the 
  glabella 
  ; 
  eyes 
  large, 
  with 
  

   numerous 
  distinct 
  lenses. 
  Thorax 
  of 
  

   II 
  segments 
  with 
  grooved 
  pleurae. 
  

   Pygidium 
  large, 
  of 
  many 
  segments, 
  

  

  triangular 
  and 
  often 
  pointed 
  or 
  extended 
  into 
  a 
  mucronate 
  

  

  termination. 
  

  

  Fig. 
  155 
  Dalmanites 
  limulurus 
  

  

  