NO. 2127. OSTEOLOGY OF THE8CEL08AURU8—GILM0RE. 599 



The coracoid is a small subquadrangular plate of bone. Its glenoid 

 border is the stoutest part, being heavier than the scapula contribu- 

 tion to this fossa. The internal surface is concave, the external con- 

 vex. The lower border is incurved, the anterior or sternal margin is 

 thin and regularly rounded. The coracoid foramen is placed well 

 forward toward the center of the bone, but its large size, as shown in 

 figure 10 is in part due to the imperfection of this part of the specimen. 



Measurements of scapula and coracoid, No. 7760. 



mm. 



Greatest length of scapula and coracoid 235 



Greatest length of scapula 186 



Greatest breadth of scapula ^ 107 



Least breadth of scapula 42 



Greatest expanse of glenoid cavity 35 



Humerus. — None of the humeri in the United States National 

 Museum collections are perfectly preserved, and the description to 

 foUow is based upon a right humerus (Cat. No. 5031, Amer. Mus. Nat. 

 Hist.) kindly loaned me by Mr. Barnum Brown, of the American 

 Museum of Natural History, New York City. It is of the same size 

 as the distal portions of the humeri belonging to the type, and in all 

 probabihty belongs to an animal of similar proportions. 



The humerus of Thescelosaurus is indistinguishable from that of 

 Camptosaurus, except that the head instead of being centrally located 

 on the proximal end is nearer the external border. Just above the 

 middle of the bone is a well-developed radial crest on the antero- 

 extemal border and renders the anterior aspect of this surface de- 

 cidedly concave transversely (fig. 11). The shaft is slightly twisted, 

 due to the change in direction of its surfaces. Below the deltoid 

 ridge the shaft is constricted and suboval in cross-section, the greatest 

 diameter being transverse. 



The internal border is broadly concave from end to end; the 

 external border is convex, the curve being somewhat less than that of 

 the opposite border. The distal end is condylarly divided, the con- 

 dyles being separated by wide, shallow grooves, both front and back. 

 The measurements of tliis humerus (No. 5031, Amer. Mus. Nat. Hist.) 

 are : Greatest length, 215 mm. ; greatest width, proximal end, 65 mm. ; 

 greatest width, distal end, 44 mm. ; least width of shaft, 22 mm. 



Ulna. — The uhia is about equally expanded at the two ends, the 

 shaft being contracted and subcircular in cross-section at the center. 

 As in Camptosaurus and Hypsilophodon, the olecranon does not appear 

 to have extended much about the articular surface for the humerus. 

 The distal end was opposed by the ulnare and intermedimn elements 

 of the carpus, as well shown in the articulated limb (fig. 11). 



The greatest length of the left ulna is 154 mm., the width of the 

 proximal end 42 mm., and width of the distal end 32 mm. 



1 Estimated. 



