Plate I. 



Figure 1. — Skull of the type of P. longiceps Marsh, No. 1177; seen from the left side. 

 xO.34 



Figure 2. — Fragmentary mandible of Pteranodon sp., No. 2478 ; seen from the right side, 

 x 0.64 



Figure 3. — The same specimen ; seen from the left side, x 0.64 



