OSTEOLOGY OF THE AEMOKED DINOSAUKIA. 



67 



The upper portion of the blade is flattened; about equally expanded fore and 

 aft ; upper end cut off at nearly right angles to the shaft, with a slightly thickened 

 rugose border. 



Passing toward the articular end the blade gradually contracts antero-posteri- 

 orly for two-thirds the length of the bone, while the transverse measurement grad- 

 ually increases. The progressive thickening of the bone continues to the articular 

 end,which presents a heavy massive surf ace for the humerus (pi. 21, fig. 3 g). In speci- 

 men No. 7362 this end has .a transverse thickness of 100 mm. and is quite deeply 

 cupped. Approaching the coracoid end the superior border turns upward at slightly 

 more than a right angle to the blade, as in the scapula of Diplodocus (see figure 

 by Hatcher 1 ), forming a broad, thin expansion of this end. No acromian process 

 is present. 



Two of the seven scapulae in the National Museum (Nos. 4934 and 7361) are 

 firmly coossified with the coracoid, forming with it a deep glenoid cavity of good 

 size. This fossa in No. 7361 measures 165 mm. across from lip to lip, its greatest 

 expanse. 



Measurements of scapulae. 





S. stenops 

 type 



No. 4934, 

 left. 



Stegosau- 

 rus sp. 



No. 7362, 

 right. 



Stegosau- 

 rus sp. 



No. 7361, 

 right. 



5. stenops. 



No. 7371, 



left. 



S. stenops. 



No. 4929, 



left. 





mm. 

 620 



226 

 384 



mm. 

 670 



1215 



mm. 

 685 



mm. 

 679 



192 



mm. 

 687 



215 



Greatest breadth, proximal 



Greatest breadth, distal end. . . 



380 

 140 



13S 



110 



135 







1 Estimated. 



Coracoid. — The coracoid is a subquadrate bone (pi. 20, fig. 1) which in very old 

 individuals becomes firmly coossified with the scapula. The superior portion of 

 the coracoid is thin, with convex external and concave internal surfaces. The lower 

 portion is much thickened, particularly that part contributing to the glenoid fossa, 

 which in No. 7376 measures 163 mm. in transverse width. The anterior portion of 

 the inf erior border is considerably thickened and roughened for ligamentary attach- 

 ment. 



The coracoid foramen is large and its elliptical internal opening is situated just 

 anterior to the coraco-scapula suture, continuing diagonally forward through the 

 coracoid a little below the center of the bone. There are five coracoids in the col- 

 lection, and all of them show this foramen to be entirely inclosed, and not a notch, 

 as figured by Marsh in his illustrations of this element of Stegosaurus ungulatus. 



1 Mem. Carnegie Mus., vol. 1, p. 44, fig. 14, 1901. 



