iS8 



THE OSTEOLOGY OF THE REPTH^ES 



Propodials 



The humerus (Figs. 1 29-131), or first bone of the anterior ex- 

 tremity, articulates in the glenoid fossa of the scapular girdle, usu- 

 ally by a more or less complete, free, ball-and-socket joint, permit- 

 ting rotation. In most of the Cotylosauria (Figs. 128, 130, 132) and 



mecioa/t'pvt- 



"rO/cLi/auc 



ulnar corjd. 



Cesser 



troca,. 



flbuU 



Fig. 129. Theromorph limbs: Naosanrus, humerus, dorsal side, femur, ventral side. 

 One half natural 'size. 



stouter-limbed Theromorpha (Figs. 129, 131, 134) the articular sur- 

 face is more or less spiral-like, extending around the head from the 

 ventral postaxial to the dorsal preaxial side, permitting movement in 

 an antero-posterior direction with a concomitant partial rotation as 

 the hand, directed forward obliquely, is brought backward in walk- 

 ing. The bone was not depressible below a horizontal plane with- 

 out dislocation. The articular surface of the pterodactyl humerus 



