548 GEOLOGICAL SURVEY OF THE TERRITORIES. 



EXPLANATION OF PLATE XVII. 



Fig. 1. Lejndwrus glacialis, first foot; d, guatbobase or coxal lobe; c?', tlie same of the 



succeeding limb. 

 Fig. 2. Lepidurus couesii, first foot. 



Fig. 3. Lepidurus couesii, first foot of another (malformed?) individual. 

 Fig. 4. Lepidurus bilohatus, 5 , first foot. 

 Fig. 5. Lejyidurus glacialis $ , second foot. 

 Fig. 6. Lepidurus hilohatus, $ , second foot. 

 Fig. 7, Lepidurus couesii, second foot. 

 All enlarged ; drawn by the author, with the aid of the camera lucida. 



