THE PECTORAL AND PELVIC GIRDLES 



149 



sauria, or rather of that division called the Predentata, or order Orni- 

 thischia. In the other divisions, the Theropoda (Fig. 122 a) and 

 Sauropoda (Fig. 122 b), the pubes have the normal reptilian struc- 

 ture, though unusually stout and strong, meeting in the middle below 



Fig. 122, Pelves (Dinosauria): A, Ceratosaurus (Saurischia). After Marsh. One sixteenth 

 natural size. B, Apatosaurus (Saurischia). After Marsh. One thirty-second natural size. 

 C, Triceratops (Ornithischia). After Marsh. One twenty-fourth natural size. D, Stegosaurus 

 (Ornithischia). After Marsh. One twentieth natural size. E, Trachodon (Ornithischia). 

 One tenth natural size. 



in a firm symphysis, much elongated in the Theropoda. The sym- 

 physis of the ischia is less strong. 



The pubes of the Ornithischia (Fig. 122 c-e) have been the sub- 

 ject of much dispute and speculation. Each is composed of two pro- 

 jections or processes : the anterior one, the so-called prepuhis, or pre- 



