548 GEOLOGICAL SURVEY OF THE TERRITORIES. 
EXPLANATION OF PLATE XVII. 
Fig. 1. Lepidurus glacialis, first foot; cl, gnathobase or coxal lobe; cl', the same of the 
succeeding limb. : 
Fig. 2. Lepidurus couesti, first foot. 
Fic. 3. Lepidurus couesii, first foot of another (malformed?) individual. 
Fig. 4. Lepidurus bilobatus, 2, first foot. 
Fig. 5. Lepidurus glacialis 9 , second foot. 
Fig. 6. Lepidurus bilobatus, 2 , second foot. 
Fig. 7. Lepidurus couesii, second foot. 
All enlarged ; drawn by the author, with the aid of the camera lucia. 
