150 ODOXTORNITHES. 



The nearest approach in size among modem birds to the radial 

 crest of IcMhyornis is perhaps to he found among raptorial species, where 

 its elongation along the shaft of the bone is considerable, but its height 

 is still proportionally much less than in the present genus. In Sterna, 

 this crest is even less than half the comparative size in IcMhyornis. The 

 ulnar tuberosity is also well developed, and, like the radial crest, is 

 nearly in the same plane with the head of the humerus. No pneumatic 

 foramina are to be seen in the specimens preserved. 



The distal end of the humerus of IcMhyornis resembles that of the 

 genus Arclea, rather than Sterna, the ectocondyloid process being repre- 

 sented only by a low tubercle. The shaft of the bone is hollow, with 

 moderately thin walls, and its length is about one-fifteenth less than that 

 of the ulna. In the genus Sterna, the humerus is about one-fifth less in 

 length than the ulna 



Dimensions of the humerus in the type specimen and in four other 

 species of the Odontotomies are given below : 



Measurements of Humerus. (IcMhyornis dlspar, No. 1450.) 



Length of humerus, 58.0 ram 



Greatest diameter of proximal end, 13.0 



Diameters of proximal articulation, 3.0-10.0 



Diameters of distal end, 9.6- 5.0 



Least diameters of shaft, -.. 3.0- 4.8 



Length from proximal end to rise of radial crest, 23.5 



Transverse diameter, across radial crest, 12.0 



Measurements of Humerus. {IcMhyornis dispar, No. 1730.) 



Length of humerus, 62.5 mm 



Greatest diameter of proximal end, 15. 



Transverse diameter of proximal end, - - 3.1 



Diameter of shaft, - 5.2 



Greatest diameter of distal end, ..- 9. 



Antero-posterior diameter of ulnar condyle, 5. 



Measurements of Humerus. (IcMhyornis victor, No. 1742.) 



Length of left humerus, 72. mm 



Greatest diameter of proximal end, - 17. 



Diameters of proximal articulation, .- 13-4. 



Diameters of distal end, 12.5-5.5 



Diameter of shaft (approximate), ,--, 6-5 



