32 



NEW YORK STATE MUSEUM 



and is in contact with the rib for its entire length, sloping away 

 below ; in the last dorsal it appears only as an increased widening 

 of the rib for a certain distance along the usual site of its occupancy. 

 Sternal ribs agree with the dorsal ribs in being strong and robust ; 

 they possess quite extensive quadrate facets for sternal articulation 

 at their lower ends, and these bones when articulated in situ are so 

 placed that their anterior faces are visible from a direct lateral view. 



Fig. 15 Ribs of Cathartidae and Falconidae; m, rib from anterior dorsal vertebra, left 

 side, Gymnogyps; n. the same from the second dorsal vertebra of Catharista 

 urubu; o, the same from Neophron percnoyerus; p, the same trom 

 Circus hudsonius. All natural size. 



Their posterior ends are progressively, from before, backward, 

 curved in such a manner as to preserve the oval form of the chest 

 walls, and are very much dilated as we proceed in that direction ; at 

 their distal extremities they support the usual facets for the verte- 

 bral ribs. In the Secretary vulture they become very much com- 

 pressed from side to side as we examine them successively in the 

 order referred to, and in this course, too, in some of the Falconidae, 

 they become curved in an anteroposterior direction, the concave 

 margin being in front. In these birds, and in Neophron, the sternal 

 ribs are seen to be much slenderer than corresponding bones in the 

 Cathartidae [see fig. 15]. 



