﻿Fig. 
  6. 
  — 
  An 
  enlargement 
  of 
  a 
  portion 
  of 
  the 
  specimens 
  represented 
  

   in 
  figures 
  3 
  and 
  4. 
  X 
  5. 
  

  

  Fig. 
  7. 
  — 
  A 
  portion 
  of 
  a 
  specimen 
  retaining 
  the 
  striated 
  external 
  

   chitinous 
  coat. 
  X 
  5. 
  

  

  Hamilton 
  shales, 
  at 
  450 
  and 
  4G0feet 
  in 
  the 
  Livonia 
  shaft. 
  

  

  380 
  

  

  