CHAPTER XV. 



LEGS AISD FEET OF ICHTHYORNIS AND APATORNIS. 



(Plates XXV, XXXIII and XXXIV.) 



The legs and feet in the two genera of Odontotomies are comparatively 

 small, and present no peculiar features. The remains preserved agree 

 most nearly with the corresponding parts in modern Carinate birds. 



The Femur. (Plates XXV and XXXIII.) 



The femur in Icldhyomis is a short and comparatively small bone. 

 The shaft is slender, and nearly smooth, being destitute of the rugosites 

 seen on the femur of Uesperomis. Both the articular faces present the 

 ordinary avian type of articulation, and the shaft of the bone is hollow, 

 with thin walls. The ratio of the fibular face to that for the tibia is 

 about the same as in the Tern, and the general proportions of the bone, as 

 to length, diameter of shaft, and size of articular faces, are nearly the same 

 as in that bird. The femur of Icldhyomis, however, is more than half the 

 length of the humerus, while in Sterna the femur is less than half as long 

 as the humerus. 



The femur of Apatornis is proportionally larger than in IcMhyornis. 

 The shaft is hollow, with thin walls, and the whole bone is nearly smooth, 

 as in most modem birds. There is, however, just behind the outer 

 condyle, on the inferior surface of the bone, a well marked pit for the 

 attachment of a ligament, and just behind the inner condyle, on the same 

 surface, is a low tubercle. The lateral surfaces of both condyles are also 



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