552 
Fig. 1. 
FIG. 2. 
Fig. 3. 
Fig. 4. 
F14. 5. 
GEOLOGICAL SURVEY OF THE TERRITORIES. 
EXPLANATION OF PLATE XIX. 
Apus lucasanus, first foot; cl, gnathobase ; cl, that of the following appendage. 
Apus equalis, second pair of feet. 
Apus newberryi, 2, second pair of feet. 
Apus longicaudatus, second pair of feet. 
Apus lucasanus, ; second pair of feet; differs from the female in having the 
filaments on the gill. 
