Plate XIII. 



Figure 1. — Four free dorsal vertebras of Pteranodon sp., No. 2616; seen from below, 

 x 1.0 



Figure 2. — Fragmentary sacrum of Pteranodon sp., No. 2616; seen from below. x 1.0 



Figure 3. — Sacrum of Pteranodon sp., No. 2489: seen from below, x 1.0 



Figure 4. — Five caudal vertebras of the same individual ; seen from above, obliquely, 

 x 1.0 



