SHOULDER GIRDLE OF HESPERORNIS. 61 



The measurements which, follow are taken from the sternum of 

 Hesperornis regalis (number 1206), and that of Hesperornis crassvpes 

 (number 1474). 



Measurements of Sternum [Hesperornis regalis. No. 1206.) 



Total length (approximate), 200.0 mm 



Extent of articulations for ribs, 47.0 



Diameter of first articulation for a rib, 13.0 



Diameter of second articulation for a rib, 13.0 



Diameter of third articulation for a rib, 13.0 



Diameter of fourth articulation for a rib, 9.0 



Measurements (Hesperornis crassipes. No. 1474.) 



Length of sternum, 196. mm 



Greatest transverse diameter of sternum, 160.0 



Transverse diameter of sternum behind articulation for ribs, 86.0 



Least transverse diameter of sternum behind articulation for ribs, 77.0 



Extent of articulations for ribs, . 52.0 



Diameter of first articulation for a rib, 13.0 



Diameter of second articulation for a rib, 12.0 



Diameter of third articulation for a rib, 12.0 



Diameter of fourth articulation for a rib, 12.0 



Diameter of fifth articulation for a rib, 9.0 



Extent of lateral margin beyond last articulation, 92.0 



The Clavicles. (Plates VII-VIII.) 



The clavicles of Hesperornis are separate, and are unlike those in any 

 recent adult birds, although they strongly resemble the corresponding 

 bones in some embryonic forms. The upper extremity is slender, and 

 was united by ligament with the clavicular process of the coracoid. The 

 shaft of the bone is much curved, and gradually expands below to the end, 

 which is depressed, and transversely truncated. The extremity has an 

 articular face for union with its fellow on the median line, and the two were 

 evidently united by cartilage, and attached to the manubrial part of the 

 sternum. The position of the clavicles in the skeleton is shown in the cut 

 on page 58 (figure 14), and also in Plate VIII, figure 8, cl. 



The measurements of two clavicles in Hesperornis regalis, (numbers 

 1206 and 1207), and one also of Hesperornis crassipes, (number 1474), are 

 as follows : 



