﻿U. 
  S. 
  NATIONAL 
  MUSEUM 
  

  

  PROCEEDINGS, 
  VOL. 
  XX 
  PL. 
  LXIX 
  

  

  Crayfishes. 
  

  

  Parastacii.'i 
  i-arirosus. 
  

   For 
  explamation 
  of 
  plate 
  see 
  page 
  694. 
  

  

  