WINGS OF ICHTHYORNIS AND APATORNIS. 153 



proximal end than in that genus, agreeing better in both these respects 

 with the ulna of Ardea. The shaft of the bone is hollow, with thin 

 walls, and presents faint but unmistakable evidence of the attachment 

 of about a dozen secondary quill-feathers. The distal end of the ulna 

 resembles that of Ardea, rather than that of Sterna. 



The dimensions of the ulna in three species of Ichthyornis are as 

 follows : 



Measurements of Ulna. (Ichthyornis dispar, No. 1450.) 



Length of ulna, 62. mm 



Diameter of shaft, 2,6 



Greatest diameter of proximal articulation, 5.0 



Greatest diameter of distal articulation, 5.7 



Least diameter of distal articulation, 5.0 



Measurements of Ulna, (Ichthyornis agilis, No. 1453.) 



Length of left ulna, _ 75. mm 



Diameter of proximal end, 9. 



Diameter of distal end, 8. 



Measurements of Ulna. (Ichthyornis validus, No. 1740.) 



Length of ulna, 68.5 mm 



Greatest diameter of proximal end, 6.5 



Transverse diameter of proximal end, 6. 



Diameter of shaft, 3.1 



Diameter of proximal end, across curve, 6. 



Greatest diameter of proximal end, 6.2 



The Caepal Bones. (Plate XXX.) 



The two bones of the carpus are preserved in the genus Apatomis, 

 and resemble the same bones in existing Carinatce. They may be com- 

 pared with the corresponding bones in a Cormorant (Graculns dilqphus.) 

 The radial carpal has a proximal articular surface, somewhat broader than 

 that of the Cormorant. The distal articulation, for the metacarpal, resem- 

 bles considerably the same face in Gracidus, but the inner face, articu- 

 lating with the ulna, is proportionally more transverse, and shorter in the 

 line of the length of the wing. 



