EXPLANATION OF PLATE 49. 



A Fossil Egg from Arizona. 



Fig. 1. — Fractured surface of the broken egg, showing the contents; t, t' and 

 other darkened areas represent the bituminous material ; the 

 remainder of the cavity is filled with colemanite. (Natural 



size.) 



Fig. 2a. — A portion of the egg shell ground down on one side. s, corru- 

 gated outer surface; c, cellular lower layer. (X 275) 



Fig. 2&. — Cross-section of the shell fragment shown in figure 2a. s, corru- 

 gated outer surface; c, cellular lower layer. ( < 275) 



Fig. 3. — Outer surface of the shell, showing corrugations of the surface and 

 a large pit filled with bituminous material. (X 275) 



Fig. 4. — Cross-section of the pit shown in figure 3. ( ■ 275) 



