﻿U. 
  S. 
  NATIONAL 
  MUSEUM 
  

  

  PROCEEDINGS. 
  VOL., 
  103, 
  PLATE 
  7 
  

  

  Top: 
  Beaver 
  pond 
  at 
  milepost 
  62.6 
  of 
  Richardson 
  Highway, 
  x\laska. 
  Below 
  the 
  beaver 
  

   dam, 
  Polycelis 
  borealis 
  under 
  stones. 
  Bottom: 
  Stream 
  flowing 
  along 
  Richardson 
  High- 
  

   way, 
  Alaska, 
  at 
  milepost 
  26.3. 
  On 
  the 
  undersides 
  of 
  stones, 
  Polycelis 
  borealis. 
  

  

  