DINOSAURIA. 215 



and axis are fused with one or more of the succeeding cervical vertebne 

 to support the massive head, and the articular ends of the free centra 

 are flattened. The dorsal vertebra} have remarkably short centra. The 

 true lumbars, two in number, are fused with the sacrum, which com- 

 prises four vertebrae, firmly united both by the centra and neural spines, 

 and bearing double transverse processes. The neural canal in the sacrum 

 is not specially enlarged. The first four caudal vertebrae are also fused 

 with the sacrum, and the transverse processes of three of these abut 

 against the ilium. The tail is of moderate . length, with small chevron 



FIG. 134. 



Sterrholophus flabellatus ; skull from the left lateral aspect, one-twentieth 

 nat. size. Cretaceous ; Wyoming, a, external narial opening ; b, orbit ; 

 c, supratemporal vacuity; e, epi- occipital plates; h, horn -core ; h', nasal 

 horn-core ; p, predentary (restored in outline) ; q, quadrate ; r, rostral bone 

 (restored in outline). (After Marsh.) 



bones placed intervertebrally. In the pectoral arch the coracoid, per- 

 forated as usual, is rather small, and is sometimes fused with the scapula 

 in old individuals. The humerus resembles that of Stegosaunis, but is 

 nearly as long as the femur. The radius and ulna are comparatively 

 short and stout, and the latter exhibits a very large olecranon process. 

 There are five hoofed digits in the manus. In the pelvic arch the 

 ilium is much elongated, and its anterior extension forms a horizontally 

 expanded plate; the pubis is massive, but exhibits only a very slight 

 trace of a post-pubis; the ischium is smaller than the pubis, more 

 elongated, and not in close contact with its fellow of the opposite side. 



