62 ODOXTORXITHES. 



Measurements of Clavicle. (No. 1206.) 



Distance in direct line between the ends, 78.0 mm 



Transverse diameter of upper extremity, 2.0 



Greatest diameter of lower extremity, 15.0 



Least diameter of lower extremity, 5.0 



Measurements. (No. 1207.) 



Greatest diameter of lower extremity, 15.0 mm 



Least diameter of lower extremity, 5.5 



Measurements. {Sesperornis crassipes, No. 1474.) 



Distance in direct line between the ends (approximate), 80.0 mm 



Transverse diameter of upper extremity, 3.0 



Greatest diameter of lower extremity, 12.0 



Least diameter of lower extremity, 5.0 



The Humerus. (Plate VIII, figures 1-4.) 



The wings of Sesperornis were represented by the humerus alone, and 

 this was rudimentary. The remaining- bones of the anterior extremity had 

 entirely disappeared, or, if minute remnants of them remained as ossicles, 

 they were loosely attached to the extremity of the humerus by cartilage, 

 and thus have left no trace of their union. In one specimen (number 

 1206,) the humerus is preserved entire, with most of the scapular arch, and 

 is shown in its natural position, in figure 14, at the beginning of the 

 present chapter, as well as in Plate XX. 



The humerus of Sesperornis is long and very slender, and somewhat 

 curved downward, especially in the distal half. The head is compressed, 

 and has a convex ovate articulation for insertion into the shallow glenoidal 

 cavity. The shaft is somewhat twisted, and of nearly equal width 

 throughout its entire length. When the humerus is in position, the 

 longer transverse axis of the middle of the shaft is horizontal, or at right 

 angles to the same axis of the head. The shaft is nearly solid, having 

 only a very small medullary cavity. There is no distinct radial or ulnar 

 crest, and no trace of articular facets on the distal extremity. 



The principal measurements of the above humerus of Sesperornis 

 regalis are as follows : 



